Zinc acrylate

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Aug 1983 - 22 Nov 1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Acrylic acid was administered by gavage to 50 Wistar rats (20 males, 20 females) for 3 months. For comparison a group of untreated animals (10 males, 10 females) was used as a control. Doses were 150 and 375 mg test substance per kg body weight/day.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: 42 days old
- Weight at study initiation:
- male animals: 183 .3 (166 - 202) g
- female animals: 146.9 (133 - 162) g
- Fasting period before study: no
- Housing: singly in Type DK III stainless steel wire cages
- Diet (ad libitum): ground Kliba 343 rat/mouse/hamster "A" food supplied by KLINGENTALMUHLE AG, CH-4303, Kaiseraugst, Switzerland
- Water (ad libitum): tap water
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70 % (80 % only for short periods)
- Photoperiod (hrs dark / hrs light): 12 hours

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
For preparation of the test substance preparations the substance was weighed in a measuring flask in a varying amount according to dose group, the flask made up to the mark with doubly distilled water, and then shaken. The solutions were prepared in such a way that 5 mL of solution contained 150 or 375 mg of acrylic acid. The animals of the control group received the solvent doubly distilled water as a control, also by gavage.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

In order to check the correctness of the amounts of acrylic acid weighed, control analyses of the concentrations of each dose were carried out before the beginning of the study, after 4 and 8 weeks of the study, and toward the end of the study. The corresponding determinations were effected by gas chromatography.
Results of analytical dose verification: 147.5 - 151.21 mg/5 mL water and 359.3 - 375.21 mg/5 mL water were determined.

Duration of treatment / exposure:

90 days

Frequency of treatment:

5 days/week

Remarks:

Doses / Concentrations:
150 and 375 mg/kg bw
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
In a parallel study (Project No. 74C0380/8239) in connection with the testing for chronic toxicity, Wistar rats received the substance with the drinking water in various doses (0, 120, 800, 2000 and 5000 ppm) over a period of 3 months (satellite groups) or 12 months (main groups).
The present study was intended to be able to compare between continuous administration with the drinking water and single (bolus) administration by gavage on working days, the study being designed in particular to investigate the extend of the irritating effect of acrylic acid on the digestive tract.
For this study, therefore, doses were chosen which roughly corresponded to the two highest doses in the drinking water study. At 150 mg/kg body weight (= approx. 2000 ppm - factor 13.3) effects on the body weight gain and on the feed and drinking water consumption were expected. 375 mg/kg body weight (= approx. 5000 ppm - factor 13.3) should additionally lead to organ alterations (among others kidney and digestive tract).

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily


BODY WEIGHT: Yes
- Time schedule for examinations: weekly


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes


WATER CONSUMPTION: Yes
- Time schedule for examinations: weekly


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: No


CLINICAL CHEMISTRY: No


URINALYSIS: No


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
After sacrifice, the animals were weighed, necropsied, assessed by gross pathology, and the organs weighed.
In addition to the weight of the exsanguinated animal bodies the absolute and relative weights (organ weight/100 g body weight) of the following organs were determined:
liver, kidneys, spleen, testes, ovaries, adrenals, brain.

HISTOPATHOLOGY: Yes
All the organs listed below were fixed in toto or in representative parts depending on their size in a 4 % buffered formaldehyde solution at room temperature:
all gross lesions, head, heart, thoracic aorta, trachea (with larynx), lung with stem bronchi (right and left), esophagus, stomach (forestomach and glandular stomach), small intestines (duodenum, jejunum, ileum), large intestines (cecum, colon, rectum), salivary glands, liver, pancreas, spleen, thymus, sternum with sternal marrow, kidney, urinary bladder, testes, prostate, seminal vesicle, ovaries, uterus in toto, pituitary, adrenals, thyroids (with parathyroids), brain, skeletal muscle (m. massetor), eye with optic nerve, skin, mesenteric lymph nodes, mammary gland, tongue, buccal mucosa, nasal mucosa.

In the case of the tongue a medial longitudinal section was examined.
The buccal mucosa was removed from the region of the molars and examined as longitudinal section.
In the case of the esophagus a cross-section from the segment in the vicinity of the stomach was examined.
In the case of the liver and kidneys a slide for fat demonstration was prepared in extension of the study protocol. After decalcification of the facial part of the skull a section was removed at the level of the 2nd crista palatinae and the 1st molar. The side facing the molar was intended to be the area of section. This level contains ectoturbinals, endoturbinals with nasal septum, maxillary sinus, nasopharyngeal duct, and to some extent also sections of the molars.

Statistics:

Clinical examinations and pathology: The statistical significance of body and organ weights was carried out using a t-test generalized by Williams for simultaneous comparison of several dose groups with a control group.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Whereas the control animals did not exhibit any clinically evident signs, severe findings attributable to the administration of the test substance were caused in many but not all of the animals that received 150 or 375 mg of test substance/kg body weight. In a number of animals a premature death was the result. From about the 3rd week of the study onward, an increasing number of animals manifested pronounced tympania (gaseous distention of the stomach or abdomen), frequently accompanied by dyspnoea and cyanosis. In addition, several animals began as early as in the first week of the study to make unphysiological utterances, which most closely resembled those made by ducklings. Finally, in some animals - usually shortly before death occurred - appearances typical of agony, such as hypothermia, apathy and piloerection, were seen; moreover, numerous rats that died prematurely showed a reduced general state of health. Overall, the clinical signs in the animals of test group 2 (375 mg/kg bw) were considerably more pronounced than in those in test group 1 (150 mg/kg bw), as was also shown by a comparison of the respective mortality rates. However, in test group 2 (375 mg/kg bw) one female animal was to be found which was free from clinical signs for the whole period of the study, and furthermore in 4 male rats of this group only temporary signs were observed, which had disappeared by the end of the study.

Mortality:

mortality observed, treatment-related

Description (incidence):

Numerous animals of test groups 1 and 2 (150 and 375 mg/kg bw) died before the end of the period planned for the study. The mortality rate was between 50 and 90 % depending on group and sex, and the intercurrent deaths occurred between the 14th and 81st day of the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Whereas the change in body weight in the animals of test group 1 (150 mg/kg bw) took a similar course to that of the corresponding control animals, the male animals of test group 2 (375 mg/kg bw) exhibited a slightly or moderately retarded weight gain. In the female animals of the latter group a corresponding trend was only barely perceptible during the first 3 weeks of the study. Therefore an evaluation of the parameter is no longer rational
because of the intercurrent deaths (see Mortality).

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Neither the male nor the female rats of test groups 1 and 2(150 and 375 mg/kg bw) exhibited any marked differences with respect to the mean daily feed consumption in comparison with the corresponding control groups.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

The altogether greatly varying mean daily drinking water consumption of the rats used did not reveal any clearly dose-dependent trend; moreover, opposing trends were at times detectable in the male and female animals. Thus, for example, after 21 days of the study the male rats of the control group exhibited a markedly higher drinking water consumption than those of test groups 1 and 2 (150 and 375 mg/kg bw), whereas at this point the female rats of the two test groups consumed more water than the corresponding control group. Hence, all in all no clear effect of the test substance on the drinking water consumption was observed.

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Description (incidence and severity):

Of the organ weights of the animals sacrificed at the end of the study only the relative liver weight of the female animals of group 1 (150 mg/kg bw) was significantly increased (level of significance 5%). The increase was very slight and without relevance, the more so as a similar change was not observed in the male animals in group 2 (375 mg/kg bw). Also due to the small number of weights available for evaluation (group 1: 5 males, 5 females; group 2: 4 males, 1 female) no clear statement on adverse effects can be made.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Of the animals of dose groups 1 and 2 sacrificed at the end of the study, only 1 male and 3 female animals of group 1 did not exhibit any pathological changes. In the remaining animals, including those from group 2, there were findings suggesting an irritation of the stomach; in several animals the plica marginata was slightly or markedly thickened, in 2 animals the gastric mucosa was hyperemic, and 1 animal had hemorrhagic erosions/ulcerations in the glandular stomach. The other findings in the animals sacrificed are to be assessed as isolated findings independent of the administration of the test substance.
The gastrointestinal tracts of the animals that died intercurrently were usually empty or, in a few instances, exhibited a minimal content of feed or fluid. In all of the animals, the stomach and the entire or parts of the intestinal tract were distended with tympania. Since tympania had been observed clinically and intra vitam before, a postmortal genesis is to be excluded so that in the animals that died prematurely tympania has to be assumed as the cause of death in connection with the clinical signs.
The findings in the lungs (emphysema, edema, etc.) are also to be regarded as a consequence of the tympania and a resulting elevation of the diaphragm (Roehmheld's syndrome). The findings in the stomachs of the animals that died intercurrently corresponded to those in the animals sacrificed at the end of the study, but the cases with hemorrhagic erosions/ulcerations in the glandular stomach were relatively more frequent. Involutions of the spleen were seen in 6 animals and sharp liver margins in one animal, indicating the poor nutritional state of these animals that died intercurrently.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The gross-pathological findings were largely confirmed on histopathological evaluation of the animals sacrificed and those that died intercurrently, and additional cases usually diagnosed; in the stomach a pronounced hyperemia of the mucosal apices and erosions in the glandular stomach with/without cellular reactions were frequently observed. Under the microscope, the thickening of the plica marginata represented a submucosal edema or a slight degree of epithelial hyperplasia in this region. The fact that, particularly in the case of the male animals, the slight thickenings of the plica marginata seen on grosspathological inspection could not always be confirmed histopathologically, may be due to a shrinking process as a result of the fixation. On the other hand, thickenings which are perhaps still to be regarded as physiological borderline cases were noticed before during gross pathology.

For the tympania in the gastrointestinal tract, there was no histopathological equivalent suggesting a bacterial participation with morphological changes. The histopathological findings in the lungs were also equivalent to those in gross pathology (alveolar hyperemia, alveolar edema, alveolar emphysema, dystelectases). Unexpected findings were observed at examination of the nasal mucosa. Catarrhal and/or catarrhal- purulent rhinites were found in the nasal cavities and/or in the naso-pharyngeal duct of more than half of the animals of the dose groups and in individual animals also in the sinus maxillaris; in four of the animals they were even of a necrotizing character. In many animals there was in addition atrophy/metaplasia of the
mucosa in the ventral region of the nasopharyngeal duct and, in isolated cases, also in the regions of the respiratory epithelium of the nasal cavities. In 2 animals the submucosa of the nasal mucosa was thickened or fibrosed, and an increased goblet cell activity was determined in 3 animals. It must therefore be assumed that the changes are associated with the administration of the test substance, since a corresponding state of inflammation was not seen in any of the control animals. However, it may be said that it is rather improbable that these findings were due to a systemic effect of the substance. It is more likely that they are directly related to the administration by gavage because portions of the test substance were regurgitated during introduction into or withdrawal of the tube from the stomach, or drops adhering to the tube got into the pharyngeal duct on withdrawal. The ventral localization of the changes and the purulent mucus in the pharynx of one animal, diagnosed during gross pathology, also support this assumption.

The most noteworthy histopathological finding, however, was seen in the kidneys of the majority of the animals that died intercurrently. Thus, in 10 out of 11 male animals in the two dose groups a necrotizing tubular nephrosis on the basis of a ballooning degeneration with subsequent fragmentation of the epithelia in the cortical region was diagnosed. With the female animals this was the case in 11 out of 14. Wíth the animals of the dose groups sacrificed at the end of the study this finding was remarkably enough absent and not even suggested. The extent to which this finding is related to a
primary nephrotoxic effect of the substance, or whether it is of a secondary ischemic nature, was not to be derived from the morphological picture. However, a tubulonecrosis on the basis of an ischemia could be explained by the tympania, beginning with a respiratory hypoxidosis intra vitam (see clinical dyspnoea) and, with progressing tympania, by a direct compression of the afferent and/or efferent renal vessels. This is indicated by the fact
that the kidney findings were only obtained in animals that died intercurrently having tympania in the gastrointestinal tract. Out of the 4 animals that died and exhibited no tubulonecrosis, 2 animals showed pronounced cloudy swelling of the epithelia and the other 2 animals moderately increased tubular dilatation. These findings may similarly be interpreted as a consequence of ischemia. The pronounced fatty degeneration of tubular epithelia in individual female animals is a further indicator for damage. Although the degenerative renal changes were to some extent considerably masked by postmortal autolytic tissue alterations, they could still be distinguished from the latter relatively clearly as having occurred intra vitam.

In the liver no pathological differences between the control and the dose groups were seen, with the exception of one animal with vacuolar degeneration. In this connection, special mention is to be made of the fatty deposits; they were not increased in the sense of an ischemic fatty degeneration of liver cells. This, too, would substantiate the assumption that the kidney findings occurred within a relatively short time and mechanically as a result of a local compression ischemia and not as a result of a general hypoxidosis. A third possibility to be discussed would be the question of a slight nephrotoxic effect of the test substance being enhanced by the effect of the compression ischemia.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Key result

Dose descriptor:

LOAEL

Effect level:

150 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: overall effects

Key result

Critical effects observed:

not specified

Summary:

375 mg/kg body weight group:

Body weight change:

- slightly to moderately retarded growth of the male rats, also suggested in the female rats during the first 3 weeks of the study

Clinical signs:

- in most of the animals employed, from the 3rd week of administration onwards tympania of the gastrointestinal tract, frequently accompanied by cyanosis and dyspnoea

- in the case of individual animals unphysiological utterances

Mortality:

- premature death of 6 out of 10 male and 9 out of 10 female rats

Gross-pathological and histopathological findings:

- irritations of the stomach such as thickening of the plica marginata, hyperemia and hemorrhagic erosions/ ulcerations of the gastric mucosa

- elevation of the diaphragm (Roemheld syndrome), pulmonary edema/emphysema and alveolar hyperemia and dystelectases as a consequence of the already clinically evident tympania

- catarrhal or catarrhal purulent rhinites in some of the animals

- necrotizing tubular nephroses mostly in the animals that died prematurely

150 mg/kg body weight group:

Clinical signs:

- in some animals from the 3rd week of administration onward tympania of the gastrointestinal tract, accompanied in some animals by cyanoais and dyspnoea

Mortality:

- premature death of 5 out of 10 animals used per sex

Gross-pathological and histopathological findings:

- as for test group 2 (375 mg/kg body weight) but frequently less pronounced and in a smaller number of animals

Conclusions:

Under the study conditions, the LOAEL based on overall effects was established at 150 mg/kg bw/day (equivalent to 432 mg zinc diacrylate/kg/day).

Executive summary:

A study was conducted to determine repeated dose toxicity of acrylic acid. The test substance was administered by gavage to 50 Wistar rats (20 males, 20 females) for 3 months. A group of untreated animals (10 males, 10 females) was used as a control. Selected doses were 150 and 375 mg test substance per kg bw/day.

The following effects were observed in 375 mg/kg body weight group:

 

-         Body weight change: slightly to moderately retarded growth of the male rats, also suggested in the female rats during the first 3 weeks of the study

-         Clinical signs:

o   in most of the animals employed, from the 3rd week of administration onwards tympania of the gastrointestinal tract, frequently accompanied by cyanosis and dyspnoea

o   in the case of individual animals unphysiological utterances

-         Mortality: premature death of 6 out of 10 male and 9 out of 10 female rats

-         Gross-pathological and histopathological findings:

o   irritations of the stomach such as thickening of the plica marginata, hyperemia and hemorrhagic erosions/ ulcerations of the gastric mucosa

o   elevation of the diaphragm (Roemheld syndrome), pulmonary edema/emphysema and alveolar hyperemia and dystelectases as a consequence of the already clinically evident tympania

o   catarrhal or catarrhal purulent rhinites in some of the animals

o   necrotizing tubular nephroses mostly in the animals that died prematurely

 

The following effects were observed in 150 mg/kg body weight group:

-              Clinical signs: in some animals from the 3rd week of administration onward tympania of the gastrointestinal tract, accompanied in some animals by cyanoais and dyspnoea

-              Mortality: premature death of 5 out of 10 animals used per sex

-              Gross-pathological and histopathological findings: as for test group 2 (375 mg/kg body weight) but frequently less pronounced and in a smaller number of animals

Under the study conditions the LOAEL based on overall effects was established at 150 mg/kg bw/day (equivalent to 432 mg zinc diacrylate/kg/day) (BASF, 1987).

Reference 2

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Aug 1983 - 24 Aug 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 452 (Chronic Toxicity Studies)

Principles of method if other than guideline:

Acrylic acid was administered in 4 different doses (120, 800, 2000 and 5000 ppm corresponding to about 9, 61, 140 and 331 mg/kg body weight/day, respectively) in the drinking water to male and female Wistar rats for 3 (satellite groups) or 12 (main groups) months.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain: Wistar (Chbb = THOM (SPF))
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: 42 days old
- Weight at study initiation:
- male animals (main groups): 181.3 (155-202) g
- male animals (sat. groups): 180 .9 (163-199) g
- female animals (main groups): 145.3 (127-177) g
- female animals (sat. groups): 146.9 ( 131-169) g
- Fasting period before study: no
- Housing: singly in Type DK III stainless steel wire cages
- Diet (ad libitum): ground Kliba 343 rat/mouse/hamster "A" food supplied by KLINGENTALMUHLE AG, CH-4303, Kaiseraugst, Switzerland
- Water (ad libitum): tap water
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70 %
- Photoperiod (hrs dark / hrs light): 12 hours/ 12 hours

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

The test substance preparations were freshly prepared 3 times a week. The test substance was weighed out for each test group and added to the appropriate amount of drinking water. The drinking water was agitated with a magnetic stirrer until the test substance had completely dissolved, which
took about 3 minutes.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses to check the concentrations were carried out on each dose at the start of the study and after 3, 6 and 12 months. The determinations were carried out by gas chromatography.
The actual concentrations in the test solutions were found to be in the ranges 95 to 107, 90 to 96, 95 to 100 and 94 to 100 % of the target concentrations of 120, 800, 2000 and 5000 ppm, respectively.

Duration of treatment / exposure:

3 (satellite groups) and 12 months (main groups)

Frequency of treatment:

continuously

Remarks:

Doses / Concentrations:
120, 800, 2000 und 5000 ppm (corresponding to approx. 6/10, 40/66, 100/150, 200/375 mg/kg body weight/day for males/females)
Basis:
nominal in water

No. of animals per sex per dose:

10 (satellite groups) or 20 (main groups) animals

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day (Monday to Friday) or once a day (Saturdays, Sundays and public holidays)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly during the first three months, then every 4 weeks

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: weekly during the first three months, at intervals of 3 months after the third month of the study

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: about 4, 12, 26 and 51 weeks after the start of administration
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: 10
- Parameters examined:
Hemoglobin, Erythrocytes, Hematocrit, Mean hemoglobin content per erythrocyte, Mean cell volume, Mean corpuscular hemoglobin concentration, Platelets, Leukocytes, Prothrombin time (Hepato Quick's Test)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: about 4, 12, 26 and 51 weeks after the start of administration
- Animals fasted: No
- How many animals: 10
- Parameters examined:
Blood chemistry: Total bilirubin, Creatinine, Urea, Sodium, Potassium, Total protein, Glucose, Inorganic phosphate, Calcium, Chloride, Triglycerides, Cholesterol, Albumin
Enzyme activities: Glutamic-pyruvic transaminase, Alkaline phosphatase, Glutamic-oxalacetic transaminase

URINALYSIS: Yes
- Time schedule for collection of urine: about 3, 11, 25 and 50 weeks after the start of treatment
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No
- Parameters were examined:
pH, protein, glucose, ketones, bilirubin, blood, nitrite, urobilinogen, sediment

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
The animals were exsanguinated, dissected and the gross pathology was assessed. The exsanguinated animals, and the liver, kidneys, testes/ovaries, spleen, brain and adrenals were weighed and the relative organ weights were determined.

HISTOPATHOLOGY: Yes
The following organs/tissues were fixed in 4% formaldehyde solution:
- liver, kidneys, adrenals, heart, lungs, thymus, esophagus, jejunum, colon, urinary, bladder, salivary glands, aorta, eyes, brain, thyroids/parathyroids, stomach, ileum, rectum, uterus, representative lymph nodes, accessory genital organs, skin, femur with articular surface, buccal mucosa, cervical/
thoracic/ lumbar cord, nasal mucosa, spleen, testes/epididymides, ovaries, pituitary, trachea, duodenum, cecum, pancreas, sternum with marrow, peripheral nerve, skeletal muscles, female mammary gland, tongue, all gross lesions

A medial longitudinal section of the tongue (satellite groups) was examined.
The buccal mucosa ( satellite groups) was removed from the region of the molars and examined as a longitudinal section.
After the facial bones had been decalcified (satellite groups) a fragment at the level of the 2nd palatine ridge and of the 1st molar was removed. The side facing the molars was intended to be the cut surface. The section contains the ectoturbinates, endoturbinates with nasal septum, maxillary sinus, nasopharyngeal duct as well as, in some cases, parts of the molars.

Other examinations:

The mean amount of test substance consumed each day (in mg per kg body weight) was calculated by way of example for weeks 1, 13, 25, 37 and
52 of the study (main groups) and for the entire duration of the study (satellite groups) at weekly intervals.

Statistics:

Clinical examination and pathology: Statistical significance was determined by analysis of variance (ANOVA) followed by a Dunnett Test or a t-test generalized by WILLIAMS (pathology) for the simultaneous comparison of several dose groups with a control group.
Clinical chemistry/haematology: To test for significance, the t-test was used to compare the individual dose groups with the control group.
Urinanalysis: A chi2 test was carried out in appropriate 2 x 2 contingency tables to assess whether particular features differed between the control
and test groups.

Clinical signs:

no effects observed

Description (incidence and severity):

The 4 doses administered by addition to the drinking water (120, 800, 2000 and 5000 ppm) resulted in no impairment of general wellbeing of any of the animals in this study.
Apart from one male animal in main group (120 ppm) which, having previously attracted attention due to a marked increase in the consumption of drinking water and an anemic appearance, died after 326 days of the study, no animal in the main or satellite groups died prematurely. The gross-pathological findings of this animal indicated chronic progressive nephropathy.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The mean body weights of the male rats in main and satellite groups (2000 and 5000 ppm) were up to about 9 % below those of the control animals from 1 week after the start of administration up to the end of the study. In contrast, the mean body weights of the other males and of all the females treated with acrylic acid corresponded to those of the relevant controls. The rather marginal effect on the body weights of the male rats in the 2000 and 5000 ppm groups has to be viewed in the context of the reduction in the consumption of food and/or drinking water by these animals and must be attributed to the administration of the test substance.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Only the male rats in the main and satellite group at the highest dose of 5000 ppm showed reduced food consumption throughout the study. In contrast, the food consumptions of the other animals treated with acrylic acid solutions were comparable with those of the relevant control groups. The reduction in food consumption by the male animals in highest dose group (5000 ppm; main and satellite groups), although slight, was seen throughout the study and must be regarded as connected with administration of the test substance.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

The consumption of drinking water by the male animals in the main and satellite groups receiving 120 and 800 ppm was the same or somewhat higher than that of the relevant control groups; in contrast, the corresponding figures for the animals in the 5000 ppm group were distinctly (up to about 20 %) lower, and for the rats in the 2000 ppm were less markedly lower (not more than about 13 %) than the figures for the controls.
The consumption of drinking water by the female rats in the main and satellite groups (120 and 800 ppm) showed nothing abnormal on comparison with the controls. The differences found, which were mainly slight and independent of the dose, are of an incidental nature. In contrast, the drinking water consumption by the animals in the highest dose main and satellite groups (5000 ppm) was reduced, although only slightly, throughout the study. At times, the female rats in the 2000 ppm group also showed a tendency to this.
The marked reduction in the drinking water consumed by the male animals in test group (5000 ppm) and the less pronounced reduction in the drinking water consumption of the male rats in test group (2000 ppm) and the female animals in test groups (2000 and 5000 ppm) are attributed to the test substance.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the haematology which were unambiguously attributable to the test substance administration.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the clinical chemistry which were unambiguously attributable to the test substance administration.

Urinalysis findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the urinanalysis which were unambiguously attributable to the test substance administration.

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

At 5000 ppm in the male animals a fall in the absolute adrenal weight, and increased relative kidney, brain and testes weight were observed. In the female animals of the highest dose group (5000 ppm) a fall in the relative spleen weight was found. The changes are very slight and there is no similar change in the other sex. Furthermore, the computed increases in the relative weights are regarded as the consequence of the reduction in the body weight while the absolute weights of the relevant organs remained unchanged. Thus, the weight changes are not regarded as having pathognomonic relevance.

Gross pathological findings:

no effects observed

Description (incidence and severity):

None of the individual findings from the grosspathological assessment showed any relevant connection with the administration of the test substance.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

None of the individual findings from the histopathological assessment showed any relevant connection with the administration of the test substance.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Effect level:

40 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

food consumption and compound intake

water consumption and compound intake

Key result

Dose descriptor:

NOAEL

Effect level:

375 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

food consumption and compound intake

water consumption and compound intake

Key result

Dose descriptor:

LOAEL

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: body weight; water consumption and compound intake

Key result

Critical effects observed:

not specified

Conclusions:

The following findings were obtained and assessed as being related to the test substance:

5000 ppm group:

- reduced food consumption by the male rats (main and satellite groups)

- distinctly reduced drinking water consumption (main and satellite groups) by the males, and to a slight extent also by the female rats

- retarded body weight gain of the male rats (main and satellite groups)

2000 ppm group:

- slight reduction in drinking water consumption by both sexes (main and satellite groups)

- marginal effect on body weight gain of the male rats (main and satellite groups)

120 and 800 ppm groups:

- no changes which could be connected with the test substance administered.

In conclusion, it can be said that administration of various doses of acrylic acid in the drinking water for up to 12 months to male and female Wistar rats produced nothing in the clinical chemistry, haematology, urinanalysis or gross-pathological or histopathological findings, or changes in organ weights, which was unambiguously connected with administration of the test substance. Only at the two higher doses (2000 and 5000 ppm) did the animals show clinical signs (reduced consumption of drinking water and/or food, retarded body weight gain) which has to be regarded as related to the test substance. The reaction of the male animals was more sensitive than that of the females.

Acrylic acid at 2000 ppm (corresponding to 140 mg/kg bw) was unpalatable to rats. Thus, for the carcinogenicity study, a lower maximum dose of 1200 ppm was selected.

Conclusions:

Under the study conditions, administration of various doses of acrylic acid in the drinking water for up to 12 months to male and female Wistar rats produced no effects in the clinical chemistry, haematology, urinalysis or gross-pathological or histopathological findings, or changes in organ weights, which was unambiguously connected with administration of the test substance. Only at the two higher doses (2000 and 5000 ppm) did the animals show clinical signs (reduced consumption of drinking water and/or food, retarded body weight gain) which were regarded as related to the test substance. The reaction of the male animals was more sensitive than that of the females. . The NOAEL for male rats was established at 40 mg/kg/bw (equivalent to 115 mg zinc diacrylate/kg/day) and that for female rats at 375 mg/kg/bw (equivalent to 1080 mg zinc diacrylate/kg/day). The established LOAEL based on body weight, water consumption and test substance intake was 100 mg/kg bw (equivalent to 288 mg zinc diacrylate/kg/day) (BASF, 1987).

Executive summary:

The following findings were obtained and assessed as being related to the test substance:

5000 ppm group:

-              reduced food consumption by the male rats (main and satellite groups)

-              distinctly reduced drinking water consumption (main and satellite groups) by the males, and to a slight extent also by the female rats

-              retarded body weight gain of the male rats (main and satellite groups)

2000 ppm group:

-              slight reduction in drinking water consumption by both sexes (main and satellite groups)

-              marginal effect on body weight gain of the male rats (main and satellite groups)

120 and 800 ppm groups:

-              no changes which could be connected with the test substance administered.

Under the study conditions, administration of various doses of acrylic acid in the drinking water for up to 12 months to male and female Wistar rats produced no effects in the clinical chemistry, haematology, urinalysis or gross-pathological or histopathological findings, or changes in organ weights, which was unambiguously connected with administration of the test substance. Only at the two higher doses (2000 and 5000 ppm) did the animals show clinical signs (reduced consumption of drinking water and/or food, retarded body weight gain) which were regarded as related to the test substance. The reaction of the male animals was more sensitive than that of the females. The NOAEL for male rats was established at 40 mg/kg/bw (equivalent to 115 mg zinc diacrylate/kg/day) and that for female rats at 375 mg/kg/bw (equivalent to 1080 mg zinc diacrylate/kg/day

). The established LOAEL based on body weight, water consumption and test substance intake was 100 mg/kg bw (equivalent to 288 mg zinc diacrylate/kg/day) (BASF, 1987).

Reference 3

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Groups of 15 Fischer 344 rats/sex/dose were administered acrylic acid in the drinking-water at doses of 83, 250, and 750 mg/kg bw/day over a study period of 3 months.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Microbiological Associates, Inc., Walkersville, MD
- Age at study initiation: 41 days
- Weight at study initiation: males: 105-142 g; females: 81-110 g
- Housing: 3 males or 5 females/cage
- Diet (ad libitum): Zeigler Brothers NIH-07 Rat and Mouse Ration
- Water (ad libitum): tap water originating from the Beaver Run Reservoir, Westmoreland County, PA

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Fresh test solutions were prepared each week, with the percentage of acrylic acid in the water adjusted to maintain a relatively constant dosage level in g/kg bw.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability of aqueous solutions of acrylic acid was determined using a gas chromatographic procedure. Samples were stored for up to 3 weeks at room temperature with aliquots tested for acrylic acid content at frequent intervals. Stability of acrylic acid was determined for solutions stored in standard glass bottles as well as dosing solutions stored in water bottles under actual study conditions. In addition, the concentration of acrylic acid in the dosing preparations was determined monthly during the study.
Aqueous solutions of acrylic acid were found to be stable for at least 3 weeks when stored at room temperature. Solutions stored in animal water bottles were stable for at least 1 week.

Duration of treatment / exposure:

90 days

Frequency of treatment:

continuously

Remarks:

Doses / Concentrations:
83, 250, and 750 mg/kg bw/d
Basis:
nominal in water

No. of animals per sex per dose:

15

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily


BODY WEIGHT: Yes
- Time schedule for examinations: weekly


FOOD CONSUMPTION:
- Food consumption for cage determined: Yes, weekly



WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: weekly


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: approx. 2 weeks before sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: 15
- Parameters examined: red and white blood cell counts (RBC and WBC), measurement of hemoglobin, calculation of hematocrit and differential and reticulocyte counts.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: approx. 2 weeks before sacrifice
- Animals fasted: Yes
- How many animals: 15
- Parameters examined: measurement of serum concentration of total cholesterol (CHOL), serum urea nitrogen, glucose, alkaline phosphatase (ALP), aspaitate transaminase (AST), alanine transaminase (ALT) and creatine phosphokinase (CPR).


URINALYSIS: Yes
- Time schedule for collection of urine: approx. 2 weeks before sacrifice
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters examined: specific gravity, pH, protein, glucose, ketone, bilirubin, occult blood, nitrite, color and turbidity.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
All rats were given a complete gross necropsy examination and organ weights were recorded for the liver, kidneys, heart, spleen, brain and testes.

HISTOPATHOLOGY: Yes
The following tissues were taken and fixed in 10 % neutral buffered formalin:
Pituitary*, Thyroids*, Parathyroids*, Adrenals*, Heart*, Great vessels - Aorta, Thymus*, Spleen*, Cervical lymph node, Uterus, Cervix, Vagina, Vulva, Testes*, Epididymides*, Prostate, Seminal vesicles, Rectum, Kidneys*, Bronchial lymph node, Mesenteric lymph node*, Mediastinal lymph node, Nasal cavity*, Larynx, Trachea*, Lungs*, Ovaries*, Oviduct*, Liver*, Pancreas*, Brain*, Spinal cord, Sciatic nerve, Eyes*, Extraorbital lacrimal gland, Harderian gland, Inner and middle ears, Skin*, Urinary bladder*, Mammary gland*, Tongue*, External ear, Submandibular salivary gland, Adipose tissue, Parotid salivary gland, Sternal bone marrow, Sublingual salivary gland, Gastrocnemius muscle, Esophagus*, Stomach*, Duodenum*, Jejunum, Ileum, Cecum, Colon*, Anterior thigh muscle, Knee joint, Femur, Costochondral junction, Sternum*, Vertebrae, Any lesions*.

The tissues marked with *, as well as any other tissues with gross lesions, were etamined microscopically on all high dose and control animals. Only those tissues with gross lesions were examined microscopically from the intermediate and low level animals.

Statistics:

For every experimental parameter measured, the results of each of the three test levels (high, medium, low) were compared with the control group. To evaluate the statistical significance of possible changes in continuous data, the analysis of variance (ANOVA) validated by Bartlett's test for homogeneity of variance, was used. Individual mean differences were identified by Duncan's multiple range test when indicated by a significant F value for ANOVA. In the case of heterogenous variances, as indicated by Bartlett's test, the Paired group F test, and either the Cochran or the Student t-test were used to identify significant differences. Enumerative data were evaluated statistically by NxR Chi Square test; differences between groups were delineated by Fisher's Exact test. Non-parametric data were compared by a distribution-free multiple comparison method. The fiducial limit of 0.05 was employed as the critical level of difference not attributable to chance.

Clinical signs:

no effects observed

Description (incidence and severity):

There were no deaths in the three-month study period. No clinical signs were observed in any of the animals.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight gain was depressed markedly for both sexes at the high dosage level. This effect was statistically highly significant in these groups throughout the study. Further examination shows statistical reduction of body weight gain for the intermediate level males at 4 of the 10 comparison intervals and for the females from 41 through 90 doses.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Significant reductions in diet consumption were observed for both sexes at the high dosage level.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

There was a dose-related reduction in water consumption for all male test animals and for females at the high and intermediate levels as well. Water consumption for the low level males, while statistically significant, was numerically close to that of the controls. Furthermore, in a previous study by the same laboratory (Report 42-558), water consumption in male rats receiving as much as 420 mg/kg bw/day of acrylic acid in the drinking water was numerically and statistically equivalent to the controls. Therefore, the change in water consumption observed for the low level male rats is not considered to be toxicologically important.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

The only significant finding was an elevation of the red blood cell count for the low level females. This change was not dose-related and is not considered biologically important; it is probably an artifact.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

An increase in serum urea nitrogen was noted for the high level male rats. In the females, a decrease of serum cholesterol and increases of serum urea nitrogen, glucose, alkaline phosphatase and aspartate transaminase were observed among the high dosage level animals. In addition, dosage-related increases of serum urea nitrogen and alkaline phosphatase and a decrease in serum cholesterol were observed at the intermediate dosage level for the females.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

In both sexes at the high and intermediate levels, increases of urine specific gravity and urine protein were observed. A decrease in urine pH was noted for the high level female rats as well. Alterations in fluid balance resulting from decreased fluid intake may underlie the changes in serum urea nitrogen, urine specific gravity and urine protein. An alternate explanation of direct or indirect renal toxicity supported by increased relative kidney weights in both sexes at the high and intermediate levels is possible.

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The effect of acrylic acid on the organ weights of the rats was obvious in the high dosage level in both sexes.
n the male rats this effect included:
(1) Significant reduction in absolute liver, spleen, heart and brain weights.
(2) Significant increase in relative (as % of body weight) liver, kidney, spleen, brain and testes weights.

In the female rats, the effects on the organ weights at the high dose level included:
(1) Significant reduction in absolute liver, spleen and heart weights.
(2) Significant increase in absolute kidney weight and relative kidney and brain weights.

Furthermore, the significant increases in relative kidney and testes weights for the intermediate level males and absolute and relative kidney weights for the intermediate level females are dose-related deleterious effects.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No significant treatment related gross lesions were noted in any animal on the study.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No significant difference in prevalence of microscopic lesions was noted between animals treated with acrylic acid and controls. Malacia within the optic nerves was observed in 2/15 high dose males versus 0/15 control males (P = 0.48) and 1/15 high dose females versus 0/15 control females (P = 1.00). The true prevalence of this lesion in the study could not be determined. However, the unilaterality of this lesion concomitant with absence of lesions within the spinal cord and sciatic nerve indicate that this lesion is not attributable to the treatment with acrylic acid.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Effect level:

83 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Diet and water consumption, body and organ weight changes and abnormal clinical chemical and urine analysis parameters

Key result

Dose descriptor:

LOAEL

Effect level:

250 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Diet and water consumption, body and organ weight changes and abnormal clinical chemical and urine analysis parameters

Key result

Critical effects observed:

not specified

Deleterious effects were observed at the high dosage level (750 mg/kg bw/day) and at the intermediate level (250 mg/kg bw/day) in both sexes. These effects included diet and water consumption, body and organ weight changes and abnormal clinical chemical and urinalysis parameters. At the low dosage level (83 mg/kg bw/day), a significant reduction in water consumption was noted for the male rats. Since this effect is only a moderate reduction of water intake and since the variance is relatively small, the toxicological significance is considered minimal. The slight increase in red blood cells noted for the low dosage level females is considered to be an artifact. Accordingly, the maximum no ill-effect level for three-month ingestion of acrylic acid in the rat is estimated to be at or slightly lower than 83 mg/kg bw/day. Based on this consideration and the findings concerning the effect of acrylic acid at the intermediate and high levels, the minimum effect level is estimated to be 250 mg/kg bw/day.

Summary of results of 90 days of inclusion of Acrylic acid in the drinking water of male rats:

 

Dosage goal [mg/kg bw/d]	750		250		83		control
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Dosage attained [mg/kg bw/d]	740	50	250	10	84	4	0	0
Diet consumption [g/kg bw/d]	14.0***	0.6	16.2	0.6	16.4	0.9	16.9	0.6
Water consumption [mL/rat/d]	13.0***	0.7	17.5***	0.8	19.4**	1.3	21.4	0.7
Body weight gain [g]	141.5***	21.5	188.2	23.5	196.7	17.3	200.6	20.2
Liver weight [g]	9.33***	1.25	11.30	1.64	11.17	0.85	11.08	0.89
Liver wt as % bw	3.52*	0.15	3.61	0.38	3.50	0.15	3.40	0.14
Kidney weight [g]	2.06	0.22	2.20	0.18	2.14	0.16	2.15	0.13
Kidney wt as % bw	0.78***	0.04	0.71***	0.03	0.67	0.03	0.66	0.02
Spleen weight [g]	0.53**	0.05	0.60	0.08	0.61	0.06	0.60	0.06
Spleen wt as % bw	0.20**	0.02	0.19	0.02	0.19	0.02	0.18	0.01
Heart weight [g]	0.71**	0.09	0.81	0.10	0.83	0.08	0.82	0.10
Heart wt as % bw	0.27	0.02	0.26	0.02	0.26	0.02	0.25	0.03
Brain weight [g]	1.74**	0.08	1.81	0.08	1.81	0.08	1.84	0.06
Brain wt as % bw	0.66***	0.05	0.58	0.04	0.57	0.03	0.57	0.03
Testes weight [g]	2.72	0.17	2.82	0.14	2.73	0.14	2.72	0.32
Testes wt as % bw	1.04***	0.06	0.91*	0.07	0.86	0.07	0.84	0.11

* p< 0.05, ** p< 0.01, *** p< 0.001

Summary of results of 90 days of inclusion of Acrylic acid in the drinking water of female rats:

 

Dosage goal [mg/kg bw/d]	750		250		83		control
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Dosage attained [mg/kg bw/d]	720	50	250	10	84	3	0	0
Diet consumption [g/kg bw/d]	8.7**	0.3	10.2	0.6	10.6	0.2	10.4	0.4
Water consumption [mL/rat/d]	8.6***	0.5	11.8***	0.7	14.9	0.8	15.0	0.7
Body weight gain [g]	48.0***	8.2	68.4*	9.8	82.1	11.1	78.0	10.8
Liver weight [g]	4.91***	0.50	5.61	0.47	5.84	0.57	5.70	0.45
Liver wt as % bw	3.27	0.22	3.29	0.18	3.16	0.14	3.19	0.13
Kidney weight [g]	1.34**	0.10	1.37***	0.07	1.29	0.08	1.24	0.08
Kidney wt as % bw	0.89***	0.04	0.80***	0.06	0.70	0.04	0.69	0.03
Spleen weight [g]	0.37***	0.04	0.43	0.04	0.46	0.05	0.43	0.05
Spleen wt as % bw	0.24	0.02	0.25	0.02	0.25	0.02	0.24	0.02
Heart weight [g]	0.45***	0.04	0.54	0.05	0.55	0.06	0.54	0.07
Heart wt as % bw	0.30	0.02	0.32	0.02	0.30	0.02	0.30	0.03
Brain weight [g]	1.61	0.12	1.68	0.08	1.66	0.10	1.65	0.14
Brain wt as % bw	1.07***	0.09	0.99	0.08	0.90	0.08	0.93	0.10

* p< 0.05, ** p< 0.01, *** p< 0.001

 

 

Conclusions:

Under the study conditions, the LOAEL was estimated to be 250 mg/kg bw/day (equivalent to 720 mg zinc diacrylate/kg/day) and NOAEL 83 mg/kg bw/day (nominal) (equivalent to 239 mg zinc diacrylate/kg/day).

Executive summary:

A study was conducted to determine the repeated dose toxicity of the test substance when administered to rats for 90 days. Groups of 15 Fischer 344 rats/sex/dose were administered acrylic acid in the drinking water. The mean overall doses of acrylic acid were 740, 250 and 84 mg/kg bw/day for males and 720, 250 and 84 mg/kg bw/day for females. Deleterious effects were observed at the high dose level (750 mg/kg bw/day) and at the intermediate level (250 mg/kg bw/day) in both sexes. These effects included diet and water consumption, body and organ weight changes and abnormal clinical chemical and urinalysis parameters. At the low dose level (83 mg/kg bw/day), a significant reduction in water consumption was noted for the male rats. Since this effect is only a moderate reduction of water intake and since the variance is relatively small, the toxicological significance is considered minimal. The slight increase in red blood cells noted for the low dose level females is considered to be an artefact. Accordingly, the maximum no ill-effect level for three-month ingestion of acrylic acid in the rat is estimated to be at or slightly lower than 83 mg/kg bw/day. Based on this consideration and the findings concerning the effect of acrylic acid at the intermediate and high levels, the LOAEL was estimated to be 250 mg/kg bw/day (equivalent to 720 mg zinc diacrylate/kg/day) and the NOAEL at 83 mg/kg bw/day (nominal) (equivalent to 239 mg zinc diacrylate/kg/day)

Reference 4

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Shizuoka Agriculture Cooperative Association for Laboratory Animals
- Age at study initiation: Four wk
- Weight at study initiation: 120-150 g (male); 90-110 g (female)
- Fasting period before study: No data
- Housing: Stainless cages with a wire-meshed bottom
- Diet: Pulverized chows M (Oriental Yeast Co.), ad libitum, mixed with test material
- Water: Ad libitum
- Acclimation period: One wk


ENVIRONMENTAL CONDITIONS
- Temperature: 24±1 °C
- Humidity: 55±5 %
- Air changes (per hr): No data
- Photoperiod: 10 h dark/14 h light cycle

Route of administration:

oral: feed

Vehicle:

other: Mixed with basic feed

Details on oral exposure:

PREPARATION OF DOSING DIET:

DIET PREPARATION
- Rate of preparation of diet (frequency): No data
- Mixing appropriate amounts with (Type of food): Pulverized chows M
- Storage temperature of food: No data

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

No data

Duration of treatment / exposure:

13 wk

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
0, 300, 3000, 30000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

12

Control animals:

yes, plain diet

Details on study design:

The animals were divided into four groups, each of which included 12 animals of each sex and fed on diets containing Zinc sulphate at
four different concentration levels 0, 300, 3,000 and 30,000 ppm, for 13 wk.

Positive control:

No

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: Twice a wk

OPHTHALMOSCOPIC EXAMINATION: No data
- Time schedule for examinations: Not applicable
- Dose groups that were examined: Not applicable

HAEMATOLOGY: Yes
- Time schedule for collection of blood: No data
- Anaesthetic used for blood collection: Yes (under light ether anaesthesia)
- Animals fasted: No data
- How many animals: 48
- Parameters checked: Erythrocyte count, hemoglobin, leukocyte count, differential count of leukocyte


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: No data
- Animals fasted: No data
- How many animals: 48
- Parameters checked: Total plasma protein, alkaline phosphatase, glucose, urea nitrogen, SGOT, SGPT, cholesterol and calcium.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
After necropsy at the termination of the study the following organs were weighed: Brain, pituitary, thyroid, heart, thymus, liver, kidney, spleen, adrenals, gonads (testes or ovaries), and muscles (triceps surae).

HISTOPATHOLOGY: Yes (see table)
- For histopathology following organs and tissues were collected: Brain, pituitary, thyroid, heart, thymus, liver, kidney, spleen, adrenals, gonads (testes or ovaries), and muscles (triceps surae), submaxillary glands, lungs, mesenteric lymph nodes, pancreas, stomach, small and large intestine, accessory genital organs, bone and bone marrow (sternum and femur), and lesions of gross abnormalities
- 3 or 4 µm paraffin sections from the specimens were stained with hematoxylineosin, periodic acid Schiff's reaction and azan for microscopic observations.

Other examinations:

None

Statistics:

Student's t-test was used to estimate the statistical differences between controls and treated groups

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Showed symptom of discarding the diet from the food jar by picking it out with their fore-limbs. This symptom began a week
after commencement of the experiment and persisted throughout the study. No moribund animals of either sex were found.
- At ≤ 3,000 ppm: No remarkable signs in either sex. Two females, one of the control and one of the 3,000 ppm group, were killed in extremis due to suppurative pyelitis during the study.

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Depressed weight gain and dwarfism. Weight gain of females in this group was slightly depressed during the study with significant
differences to control animals in the 1st to 5th wk of the study.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Food intake of males decreased after the third wk of the study. A similar reduction was seen in females of this group during the 1st to 6th wk but then disappeared. A slightly lower value of average food and water intake was reported only in males.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

There were some fluctuations in food efficiency in each group.
- At 30,000 ppm: Slight reduction in overall average value.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: A moderate reduction in leukocyte count was shown in both sexes. Males showed a slight decrease in hematocrit and hemoglobin concentration.
- At 3,000 ppm: No remarkable changes in animals but there was a slight increment of hemoglobin concentration in females

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Significant reductions or reductive tendencies were seen in rats in the following parameters: SGOT and SGPT in all male groups, total protein, cholesterol and calcium levels in males in the 30,000 ppm group and calcium level in females in both the 3,000 and 30,000 ppm groups.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: A slight or moderate decrease in absolute and relative weights was seen in the liver and kidney among males
- Significant fluctuations of absolute or relative organ weights were seen in various organs from chemically treated groups of both species, no clear relationship with the treatment could be shown.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

No remarkable lesions were attributable to the treatment.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Pancreatic lesions as well as degeneration and necrosis of the acinar cells, clarification of centroacinar cells and interstitial fibrosis. No other lesions attributable to the treatment.
- No histopathological abnormalities were observed in the bone or male genital organs which had elsewhere been reported to have sustained toxic changes due to an overdose of Zinc.

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Effect level:

3 000 ppm

Sex:

male/female

Basis for effect level:

other: No remarkable clinical signs in either sex at ≤ 3000 ppm diet admix, approximately equivalent to 234 (males) and 243 (females) mg/kg bw/day (i.e. ca. 53.5 mg Zn/kg bw/day or 170 mg zinc diacrylate/kg bw/day)

Key result

Dose descriptor:

LOEL

Effect level:

30 000 ppm

Sex:

male/female

Basis for effect level:

other: haematological effects and pancreatic damage; 30000 ppm approximately equivalent to 2514 mg/kg/day (male) and 2486 mg/kg/day (female)

Key result

Critical effects observed:

not specified

Conclusions:

Under the study conditions, the NOAEL of the test substance in rats was determined to be 3000 ppm (approximately equivalent to 234 (males) and 243 (females) mg/kg bw/day, i.e. ca. 53.5 mg Zn/kg bw/day or 170 mg zinc diacrylate/kg bw/day).

Executive summary:

A study was conducted to evaluate the subchronic toxicity (13 weeks) of the test substance in Wister rats. The study followed a method equivalent or similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents). Rats of both sexes were fed a diet containing the test material at 0, 300, 3000 and 30000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed. Animals in the 30000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters and regressive changes of the pancreatic exocrine gland. There were no remarkable clinical signs in either sex in groups at ≤3,000 ppm. Under the study conditions, the NOAEL of the test substance in rats was determined to be 3000 ppm (approximately equivalent to 234 (males) and 243 (females) mg/kg bw/day (Maita, 1981), i.e. ca. 53.5 mg Zn/kg bw/day or 170 mg zinc diacrylate/kg bw/day).

Reference 5

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

no

Limit test:

no

Species:

mouse

Strain:

ICR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Shizuoka Agriculture Cooperative Association for Laboratory Animals
- Age at study initiation: Four wk
- Weight at study initiation: 25-30 g (male); 20-25 g (female)
- Fasting period before study: No data
- Housing: Four animals housed in each stainless cage with a wire-meshed bottom
- Diet: Pulverized chows F (Oriental Yeast Co.), ad libitum, mixed with test material
- Water: Ad libitum
- Acclimation period: One wk

ENVIRONMENTAL CONDITIONS
- Temperature: 24±1 °C
- Humidity: 55±5 %
- Air changes (per hr): No data
- Photoperiod: 10 h dark/14 h light cycle

Route of administration:

oral: feed

Vehicle:

other: Mixed with basic feed

Details on oral exposure:

PREPARATION OF DOSING DIET:

DIET PREPARATION
- Rate of preparation of diet (frequency): No data
- Mixing appropriate amounts with (Type of food): Pulverized chows F
- Storage temperature of food: No data

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

No data

Duration of treatment / exposure:

13 wk

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
0, 300, 3000, 30000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

12

Control animals:

yes, plain diet

Details on study design:

The animals were divided into four groups, each of which included 12 animals of each sex and fed on diet containing Zinc sulphate at four different concentration levels 0, 300, 3,000 and 30,000 ppm, for 13 wk.

Positive control:

No

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily


BODY WEIGHT: Yes
- Time schedule for examinations: Weekly


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes


WATER CONSUMPTION: Yes
- Time schedule for examinations: Twice a week


HAEMATOLOGY: Yes
- Time schedule for collection of blood: No data
- Anaesthetic used for blood collection: Yes (under light ether anaesthesia)
- Animals fasted: No data
- How many animals: 48
- Parameters checked: Erythrocyte count, hemoglobin, leukocyte count, differential count of leukocyte


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: No data
- Animals fasted: No data
- How many animals: 48
- Parameters checked: Total plasma protein, alkaline phosphatase, glucose, urea nitrogen, SGOT, SGPT, cholesterol and calcium.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
After necropsy at the termination of the study the following organs were weighed: Brain, pituitary, thyroid, heart, thymus, liver, kidney, spleen, adrenals, gonads (testes or ovaries), and muscles (triceps surae).

HISTOPATHOLOGY: Yes
- For histopathology following organs and tissues were collected: Brain, pituitary, thyroid, heart, thymus, liver, kidney, spleen, adrenals, gonads (testes or ovaries), and muscles (triceps surae), submaxillary glands, lungs, mesentery lymph nodes, pancreas, stomach, small and large intestine, accessory genital organs, bone and bone marrow (sternum and femur), and lesions of gross abnormalities
- 3 or 4 µm paraffin sections from the specimens were stained with hematoxylin-eosin, periodic acid Schiff's reaction and azan for microscopic observations.

Other examinations:

None

Statistics:

Student's t-test was used to estimate the statistical differences between controls and treated groups

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

effects observed, treatment-related

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY:
- At 30,000 ppm: Depressed spontaneous motility before death or sacrifice. Four males and one female in this group were found dead or killed in extremis during the study. Histological findings of these animals revealed impairment of the urinary tract and regressive changes in the exocrine gland of the pancreas. Mortality was 33.3% in males and 8.3% in females.
- At ≤ 3,000 ppm: No treatment related toxic signs

BODY WEIGHT AND WEIGHT GAIN:
- At 30,000 ppm: A more prominently retarded growth resulting in smaller body size than those of other groups.
- At 300 ppm: A significant but very slight depression of weight gain was seen in females for a week after commencement, followed by a rapid recovery to the control level.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- At 30,000 ppm: The food intake of male and female mice was depressed during the first week of the study in comparison to that of the controls but showed a tendency to recover afterwards. Average food intake of these animals then remained at only a slightly lower level than that of the control group.

FOOD EFFICIENCY:
Markedly lower than those of the control group during the first week of the study, corresponding to the decrease in food intake.
-At 30,000 ppm: The overall average food efficiency was much lower than the control group.
- At 3,000 ppm: No data

WATER CONSUMPTION:
-At 30,000 ppm: Decreased in both sexes during the first week. Though males soon recovered, females showed persistent lower intake during the study.


HAEMATOLOGY:
Male and female mice in the 30,000 ppm group showed moderately lower values in hematocrit and hemoglobin concentration than those of the control group; the leukocyte count in males also decreased moderately. Morphological changes of erythrocyte anisocytosis, polychromatophilia and poikilocytosis, were seen in six males and four females which. were reported by necropsy or microscopic observation to have fore-stomach ulcers. Though some significant fluctuations were seen in hematocrit, no dose dependent abnormalities were found in hemoglobin concentration and erythrocyte count in males or females at less than 3,000 ppm group.

CLINICAL CHEMISTRY:
-At 30,000 ppm: A slight to moderate decrease in total protein, glucose and cholesterol and a moderate to marked increase in alkaline phosphatase and urea nitrogen. Additional significant changes occurring in these animals were depression of SGPT level and increase in calcium level in females, and an increase of SGOT level in males
- At 3,000 ppm: Some fluctuations with significant differences from controls were seen in several parameters but these were all within the acceptable historical limits of mice of this strain and age.


ORGAN WEIGHTS:
-At 30,000 ppm: Coincidental increase in absolute and relative weight was found in the thyroids of males and the kidneys of females
- At ≤ 3,000 ppm: Statistically not significant values when compared to control


GROSS PATHOLOGY
-At 30,000 ppm: Marked emaciation, ischemic discoloration of the kidney and thyroid, atrophy of the pancreas, edematous thickening of the upper small intestine and slight splenomegaly were recorded in addition to several cases of fore stomach ulcer.


HISTOPATHOLOGY: NON-NEOPLASTIC
-At 30,000 ppm: There were lesions attributable to the treatment in the pancreas, upper intestine, stomach, spleen and kidney The pancreatic acinar cells had swollen nuclei with an increased number of clarified nucleoli and whirl-like profiles in their cytoplasm which were more basophilically
stained than the controls. Single cell necrosis of the acinar cells was also a common feature in these animals. Moreover, a decrease in the number of acinus and ductule like metaplasia of acinar cells was demonstrated. There was mucosal catarrh in the upper intestine with proliferation of epithelial
cells and edema at lamina propria, slight to moderate ulcerative lesions in the boundary of the fore-stomach and proliferation of erythropoietic immature cells in the splenic red pulp of these animals. Regressive changes of the renal cortex were observed in the females.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Key result

Dose descriptor:

NOAEL

Effect level:

3 000 ppm

Sex:

male/female

Basis for effect level:

other: No remarkable clinical signs in either sex

Remarks on result:

other: Approximately equivalent to 458 mg/kg/day (males) and 479 mg/kg/day (females), i.e. ca. 104 (males) or 109 (females) mg Zn/kg bw/day and 331 (males) or 346 (females) mg zinc diacrylate/kg bw/day

Key result

Dose descriptor:

LOAEL

Effect level:

30 000 ppm

Sex:

male/female

Basis for effect level:

other: haematological and biochemical effects. Pathological and histopathological changes observed in kidneys, thyroid, GI tract and pancreas

Remarks on result:

other: Approximately equivalent to 4927 mg/kg/day (males) and 4878 mg/kg/day (females)

Key result

Critical effects observed:

not specified

See the attached pdf for the following figure and tables:

Fig. 1. Group mean body weights in mice

Table 1. Food, chemical, water intake and food efficiency in mice

Table 3. Hematology-mean values in mice

Table 5. Blood biochemistry-mean values in mice

Table 7. Absolute and relative organ weights in mice

Conclusions:

Under the study conditions, the NOAEL in mice was determined to be 3000 ppm (i.e. approximately 458 mg/kg/day in male mice or 479 mg/kg/day in female mice, i.e. ca. 104 (males) or 109 (females) mg Zn/kg bw/day and 331 (males) or 346 (females) mg zinc diacrylate/kg bw/day.

Executive summary:

A study was conducted to evaluate the subchronic (13 week) toxicity of the test substance in ICR mice. The study followed was equivalent or similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents). Mice of both sexes were fed a diet containing test substance at 0, 300, 3000 and 30000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed. Animals in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters, decreased water intake and significant deviations in biochemical parameters. Histopathological lesions included catarrh at the upper intestine, ulcers at the boundary of fore- and glandular stomach, proliferation of erythropoietic immature cells in the splenic red pulp as well as pancreatic lesions. Under the study conditions, the NOAEL in mice was determined to be 3000 ppm (i.e. approximately 458 mg/kg/day in male mice or 479 mg/kg/day in female mice (Maita, 1981), i.e. ca. 104 (males) or 109 (females) mg Zn/kg bw/day and 331 (males) or 346 (females) mg zinc diacrylate/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

170 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

NOAEL (rat) = 234 mg/kg bw/day (male) and 243 mg/kg bw/day (female) (i.e. ca. 53.5 mg Zn/kg bw/day or 170 mg zinc diacrylate/kg bw/day)

System:

other: No remarkable clinical signs in either sex at ≤ 3000 ppm diet admix, approximately equivalent to 234 mg/kg/day (male) and 243 mg/kg/day (female) (equivalent to approximately 53.5 mg Zn/kg bw)

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral

Zinc sulphate studies

Study 1:

A study was conducted to evaluate the subchronic (13 week) toxicity of the test substance in ICR mice. The study followed was equivalent or similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents). Mice of both sexes were fed a diet containing test substance at 0, 300, 3000 and 30000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed. Animals in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters, decreased water intake and significant deviations in biochemical parameters. Histopathological lesions included catarrh at the upper intestine, ulcers at the boundary of fore- and glandular stomach, proliferation of erythropoietic immature cells in the splenic red pulp as well as pancreatic lesions. Under the study conditions, the NOEL in mice was determined to be 3000 ppm (i.e. approximately 458 mg/kg/day in male mice or 479 mg/kg/day in female mice (Maita, 1981), i.e. ca. 104 (males) or 109 (females) mg Zn/kg bw/day and 331 (males) or 346 (females) mg zinc diacrylate/kg bw/day.

Study 2:

A study was conducted to evaluate the subchronic toxicity (13 weeks) of the test substance in Wister rats. The study followed a method equivalent or similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents). Rats of both sexes were fed a diet containing the test material at 0, 300, 3000 and 30000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed. Animals in the 30000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters and regressive changes of the pancreatic exocrine gland. There were no remarkable clinical signs in either sex in groups at ≤3,000 ppm. Under the study conditions, the NOAEL of the test substance in rats was determined to be 3000 ppm (approximately equivalent to 234 (males) and 243 (females) mg/kg bw/day (Maita, 1981), i.e. ca. 53.5 mg Zn/kg bw/day or 170 mg zinc diacrylate/kg bw/day).

 

Acrylic acid studies

Study 1:

A study was conducted to determine repeated dose toxicity of acrylic acid. The test substance was administered by gavage to 50 Wistar rats (20 males, 20 females) for 3 months. A group of untreated animals (10 males, 10 females) was used as a control. Selected doses were 150 and 375 mg test substance per kg bw/day.

The following effects were observed in 375 mg/kg body weight group:

 

-         Body weight change: slightly to moderately retarded growth of the male rats, also suggested in the female rats during the first 3 weeks of the study

-         Clinical signs:

o   in most of the animals employed, from the 3rd week of administration onwards tympania of the gastrointestinal tract, frequently accompanied by cyanosis and dyspnoea

o   in the case of individual animals unphysiological utterances

-         Mortality: premature death of 6 out of 10 male and 9 out of 10 female rats

-         Gross-pathological and histopathological findings:

o   irritations of the stomach such as thickening of the plica marginata, hyperemia and hemorrhagic erosions/ ulcerations of the gastric mucosa

o   elevation of the diaphragm (Roemheld syndrome), pulmonary edema/emphysema and alveolar hyperemia and dystelectases as a consequence of the already clinically evident tympania

o   catarrhal or catarrhal purulent rhinites in some of the animals

o   necrotizing tubular nephroses mostly in the animals that died prematurely

 

The following effects were observed in 150 mg/kg body weight group:

-              Clinical signs: in some animals from the 3rd week of administration onward tympania of the gastrointestinal tract, accompanied in some animals by cyanoais and dyspnoea

-              Mortality: premature death of 5 out of 10 animals used per sex

-              Gross-pathological and histopathological findings: as for test group 2 (375 mg/kg body weight) but frequently less pronounced and in a smaller number of animals

Under the study conditions the LOAEL based on overall effects was established at 150 mg/kg bw/day (equivalent to 432 mg zinc diacrylate/kg/day) (BASF, 1987).

Study 2:

A study was conducted to determine the repeated dose toxicity of the test substance when administered to rats for 90 days. Groups of 15 Fischer 344 rats/sex/dose were administered acrylic acid in the drinking water. The mean overall doses of acrylic acid were 740, 250 and 84 mg/kg bw/day for males and 720, 250 and 84 mg/kg bw/day for females. Deleterious effects were observed at the high dose level (750 mg/kg bw/day) and at the intermediate level (250 mg/kg bw/day) in both sexes. These effects included diet and water consumption, body and organ weight changes and abnormal clinical chemical and urinalysis parameters. At the low dose level (83 mg/kg bw/day), a significant reduction in water consumption was noted for the male rats. Since this effect is only a moderate reduction of water intake and since the variance is relatively small, the toxicological significance is considered minimal. The slight increase in red blood cells noted for the low dose level females is considered to be an artefact. Accordingly, the maximum no ill-effect level for three-month ingestion of acrylic acid in the rat is estimated to be at or slightly lower than 83 mg/kg bw/day. Based on this consideration and the findings concerning the effect of acrylic acid at the intermediate and high levels, the LOAEL was estimated to be 250 mg/kg bw/day (equivalent to 720 mg zinc diacrylate/kg/day) and NOAEL 83 mg/kg bw/day (nominal) (equivalent to 239 mg zinc diacrylate/kg/day) (IATG, 1980).

Study 3:

A study was conducted to determine the repeated dose toxicity of the test substance when administered to rats for up to 12 months according to OECD Guideline 452. Acrylic acid was administered at 4 different doses (120, 800, 2000 and 5000 ppm, corresponding to about 9, 61, 140 and 331 mg/kg body weight/day, respectively) in the drinking water of male and female Wistar rats for 3 (satellite groups) or 12 (main groups) months.

 

The following findings were obtained and assessed as being related to the test substance:

5000 ppm group:

-              reduced food consumption by the male rats (main and satellite groups)

-              distinctly reduced drinking water consumption (main and satellite groups) by the males, and to a slight extent also by the female rats

-              retarded body weight gain of the male rats (main and satellite groups)

2000 ppm group:

-              slight reduction in drinking water consumption by both sexes (main and satellite groups)

-              marginal effect on body weight gain of the male rats (main and satellite groups)

120 and 800 ppm groups:

-              no changes which could be connected with the test substance administered.

Under the study conditions, administration of various doses of acrylic acid in the drinking water for up to 12 months to male and female Wistar rats produced no effects in the clinical chemistry, haematology, urinalysis or gross-pathological or histopathological findings, or changes in organ weights, which was unambiguously connected with administration of the test substance. Only at the two higher doses (2000 and 5000 ppm) did the animals show clinical signs (reduced consumption of drinking water and/or food, retarded body weight gain) which were regarded as related to the test substance. The reaction of the male animals was more sensitive than that of the females. The NOAEL for male rats was established at 40 mg/kg/bw (equivalent to 115 mg zinc diacrylate/kg/day) and that for female rats at 375 mg/kg/bw (equivalent to 1080 mg zinc diacrylate/kg/day). The established LOAEL based on body weight, water consumption and test substance intake was 100 mg/kg bw (equivalent to 288 mg zinc diacrylate/kg/day) (BASF, 1987).

Justification for classification or non-classification

Based on studies conducted on substances representative of its individual constituents, the test substance does not warrant classification for repeated dose toxicity according to EU CLP (1272/2008) criteria.