2-ethylhexanoic acid, iron salt

Endpoint summary

Description of key information

No repeated dose toxicity study with 2-ethylhexanoic acid, iron salt is available, thus, the repeated dose toxicity will be addressed with existing data on the individual moieties iron and 2-ethylhexanoate.

Considering the role of iron in human metabolic processes, it is highlighted that iron has several vital functions in the body and is an essential nutrient for humans. Additionally,no adverse effects were observed for the moiety 2-ethylhexanoic acid. According to the criteria of REGULATION (EC) No 1272/2008 and its subsequent adaptions, 2-ethylhexanoic acid, iron salt does neither have to be classified and has no obligatory labelling requirement for repeated oral toxicity nor for specific target organ toxicity after repeated exposure (STOT RE).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

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

Iron

Considering the role of iron in human metabolic processes, it is highlighted that iron has several vital functions in the body. It serves as a carrier of oxygen to the tissues from the lungs by red blood cell haemoglobin, as a transport medium for electrons within cells, and as an integrated part of important enzyme systems in various tissues. It is an essential constituent of oxygen carriers, such as haemoglobin and myoglobin, and the iron contained within haem is essential for the redox reactions of numerous cytochromes. Insufficient intake results in the deficiency condition anaemia, adverse outcomes of pregnancy, impaired psychomotor development and cognitive performance and reduced immune function.

Any elemental iron in the diet is absorbed as non-haem iron following its dissolution in the acid stomach contents. The absorption of non-haem iron can be increased substantially by the presence of ligands, such as ascorbate, citrate and fumarate, as well as the presence of amino acids (e.g. cysteine) and oligopeptides resulting from meat digestion (Mulvihill et al., 1998). In contrast, very stable complexes, for example with phytates, phosphates and oxalates, impair non-haem iron absorption. Depending on the concentration of supportive or inhibitory ligands in the intestinal lumen the absorption of non-haem iron can vary by a factor of 10 in single-meal studies, but the effects are less pronounced in more long-term studies (Hallberg and Rossander, 1984; Rossander, 1987; Hunt and Roughead 2000). Iron is reversibly stored within the liver as ferritin and haemosiderin whereas it is transported between different compartments in the body by the protein transferrin. Iron excretion via the kidneys is very low, and body iron is highly conserved. Renal elimination is not controlled as part of iron homeostasis or the control of excess body stores. Normally, only about 0.1 mg is lost daily in urine. The sloughing of mucosal enterocytes results in elimination of absorbed iron before it reaches the systemic circulation and accounts for the loss of 0.6mg per day into the intestinal lumen. About 0.2-0.3 mg is lost daily from the skin. The total daily loss is equivalent to about 0.05 % of body iron content (Green et al., 1968).

 

Animal data

Ferrous iron:

In a repeated dose toxicity study with reproductive and developmental screening (according to OECD 422 and under GLP), iron(II)sulfate was administered to rats at doses of 30, 100, 300 and 1000 mg/kg bw/day via gavage (Pharmaceutical and Food Safety Bureau 2002).

 General observation revealed salivation in males and females in the ≥300 mg/kg bw/day groups. This was transient and only observed immediately after administration, and there were no neurological symptoms such as convulsion or morphological changes to the salivary glands, and so the salivation was attributed to irritation by the test substance, and was not deemed to be a symptom of toxicity. After the administration 1000 mg/kg bw/day of the test item, one male and one female died. These animals had exhibited salivation on observation of general condition. Necropsy of the dead animals revealed adrenal hypertrophy in the male and pituitary tumour, atrophy of the thymus, dark red discolouration of the lungs and adrenal hypertrophy in the female. Histological examination revealed mineral deposition in the heart, congestion of the lungs and yellow-brown pigment deposition in the periportal hepatocytes in the male and congestion and oedema in the lungs and mineral deposition in the liver in the female. Body weights in the 1000 mg/kg bw/day group were significantly lower throughout the administration period in the males. Haematology tests revealed low RBC and APTT values, and high MCV, MCH and reticulocyte levels in males, but no changes attributable to administration were observed in the females. Blood biochemistry test revealed low total protein, albumin and Ca levels, and high ALT, γ-GTP and A/G levels in males and high γ-GTP and organic phosphorus levels in females. The necropsies revealed dark red spots and ulceration of the glandular stomach mucosa in males in the 1000 mg/kg bw/day group, but no changes caused by administration were observed in the females. Further, organ weight measurements revealed high absolute and relative adrenal weights and high relative liver weights in males in the 1000 mg/kg bw/day group, and high absolute and relative liver weights in females in the 1000 mg/kg bw/day group. Microscopical investigation revealed that the stomach findings are characterised as ulceration of the glandular stomach in one male, erosion of the glandular stomach in one male, inflammatory cell infiltration of the glandular stomach submucosa in two males, haemorrhage of the glandular stomach submucosa in one male, and vacuolisation of the forestomach epithelium in one male. The liver findings were yellow-brown pigment deposition in periportal hepatocytes in all six males, and yellow-brown pigment deposition in periportal Kupffer cells in three males and yellow-brown pigment deposition in periportal hepatocytes in all six females. After the administration 300 mg/kg/day of the test item, merely blood biochemistry tests revealed slightly elevated organic phosphorus levels in females in the 300 mg/kg group, which is not considered being adverse. In conclusion, the no observed adverse effect level (NOAEL) for systemic toxicity of 300 mg/kg bw/day (equivalent to 60 mg Fe/kg bw/day) was concluded for both sexes based on the increased relative liver weight and increased gamma glutamylpeptidase in males and females at the 1000 mg/kg bw/day dose level.

In an unbound study by Appel et al. 2001, groups of 40 male Sprague-Dawley rats each were fed iron(II) sulfate supplemented diet, resulting in doses of 2.84, 5.69, or 11.54 mg Fe/kg bw/day. Twenty rats of each group were sacrificed after 31 days of feeding and 20 rats of each group were sacrificed after 61 days of feeding. The following parameters were measured: clinical signs, body weights, food consumption, food conversion efficiency, haematology, clinical chemistry as well as gross pathology, organ weights and histopathology of selected organs (liver, spleen and all gross lesions). A NOAEL for male rats of >11.54 mg Fe/kg bw/day was derived. The NOAEL is based on a lack of test substance-related effects on clinical signs, body weight, organ weights, food consumption, haematology, clinical chemistry, gross pathology, and histopathology.

The National Institute of Environmental Research conducted a combined repeated dose toxicity study with reproductive and developmental toxicity screening in rats. Rats were exposed to ferrous chloride for 42-54 days (males: 42 days, females: 42-54 days). Animals were divided into four treatment groups exposed to 0, 125, 250 and 500 mg/kg bw day. The NOAEL was concluded to be 125 mg/kg/day for males and females, equivalent to 55 mg Fe/kg/day. This NOAEL is based on changes in body weight gain, liver and adrenal weight, mean cell volume and cholinesterase in males, and changes in body weight gain, liver and thymus weight and metheamoglobin in females. The original reference could not be obtained and this study entry is based on an available study summary, but the study was approved by the OECD procedure on Mutual Acceptance of Data (MAD).

 

Ferric iron:

In a range finding study for carcinogenicity testing, groups of 10 male and 10 female Fischer 344 rats were administered ferric chloride hexahydrate (FeCl3 6H2O) via drinking water ad libitum for a exposure period of 13 weeks (Sato et al. 1985). The dose levels were 0%, 0.12 %, 0.25 %, 0.5 %, 1.0 % or 2.0 % (equivalent to 80, 154, 277, 550, and 1231 mg/kg bw/day for males and 88, 176, 314, 571, and 1034 mg/kg bw/day for females, respectively). The following parameters were examined: clinical signs, mortality, body weight, water consumption, haematology, clinical chemistry, gross pathology, organ weights and histopathology. No mortality was observed during the course of the study. A significant suppression of 17 % to 60 % in the intake of drinking water was observed in the groups given doses of 0.5 % and above. Males of the treatment groups demonstrated a dose-dependent increase of serum iron levels. The histopathological examination revealed brown pigment deposition in the keratin layers of the oesophageal mucosa in the groups given doses of 0.25 % and above and in the laminae propriae of the large intestine in the 2.0 % group. A NOAEL of 277 mg/kg bw/day for the male and 314 mg/kg bw/day for the female animals was derived, based on reduction in the rate of body weight gain.

Human data

The side effects of oral iron preparations increase with increase in dosage, but there are fewer side effects with slow delivery systems or if the iron is taken with food (Brock et al., 1985; Reddaiah et al., 1989). The adverse gastrointestinal effects are related to the concentration of iron in the intestinal lumen (Cook et al., 1990).

A daily dose of 50 mg of iron produced a higher incidence of gastrointestinal effects in subjects given conventional ferrous sulphate compared with subjects given the same amount in a wax-matrix (Brock et al., 1985), and also in subjects given ferrous sulphate compared with subjects given the same amount of iron as bis-glycino iron (Coplin et al., 1991). Neither of these studies included a placebo group, and therefore the association with iron is based on different responses to different preparations. A higher incidence of side effects was reported in subjects given 60 mg of iron as iron fumarate daily compared with placebo; daily doses of 120 mg of iron as fumarate for 8 weeks given to 19 young women in a double blind cross-over study resulted in gastrointestinal effects in 5 subjects while receiving iron, compared with 2 while taking placebo (Frykman et al., 1994).

Iron overload with clinical symptoms, which has only been found in adult subjects homozygous for hereditary haemochromatosis, those under long-term, high-dose medical treatment with iron, and those given repeated blood transfusions. Such information is of no relevant for the chemicals safety assessment.

 

2-ethylhexanoic acid

Several repeated oral dose studies for 2-ethylhexanoic acid were available for assessment. A diet containing 0.5% 2-ethylhexanoic acid caused no adverse effect in rats in a 13 week feeding study (dose levels were 0, 0.1, 0.5, or 1.5%, calculated NOAEL ca. 300 mg/kg bw/day). No adverse effect was observed in mice receiving a diet containing 0.5 % 2-ethylhexanoic acid in a 13 week feeding study (dose levels were 0, 0.1, 0.5, or 1.5%). The NOAEL was calculated to be 200 mg/kg bw/day. Both NOAELs were based on reduced food consumption and a decreased rate of body weight gain in the high dose groups. In both studies, all toxicity observed at higher concentrations (changes in clinical chemistry, absolute and relative organ weights, microscopic changes in kidney liver and fore stomach) was reversible within 28 days after exposure ceased.

Based on the absence of any (severe) adverse effects at low doses in subacute and semichronic toxicity study with a.o. rats, classification for repeated dose toxicity is not warranted according to EU Directive 67/548/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.

2-ethylhexanoic acid, iron salt

Since no repeated dose toxicity study is available specifically for 2-ethylhexanoic acid, iron salt, information on the individual assessment entities iron and 2 –ethylhexanoic acid is used for the hazard assessment and when applicable for the risk characterisation of 2-ethylhexanoic acid, iron salt. Considering the role of iron in human metabolic processes, it is highlighted that iron has several vital functions in the body and is an essential nutrient for humans and due to its high homeostatic control is void of adverse systemic effects in humans under normal and foreseeable conditions of use. No adverse effects were observed for the moiety 2-ethylhexanoic acid in a number of repeated dose toxicity studies in animals. For the purpose of hazard assessment of 2-ethylhexanoic acid, iron salt, the point of departure for the most sensitive endpoint of each moiety will be used for the DNEL derivation. In case of 2-ethylhexanoic acid in 2-ethylhexanoic acid, iron salt, the NOAEL of 100 mg/kg bw/day for the developmental toxicity will be used. In case of iron the Tolerable Upper Intake Level (UL) of 30 mg/kg bw/day based on human data will be used.

Justification for classification or non-classification

Considering the role of iron in human metabolic processes, it is highlighted that iron has several vital functions in the body and is an essential nutrient for humans and due to its high homeostatic control is void of adverse systemic effects in humans under normal and foreseeable conditions of use. No adverse effects were observed for the moiety 2-ethylhexanoic acid. According to the criteria of regulation (EC) no. 1272/2008, 2-ethylhexanoic acid, iron salt is not classified for specific target organ toxicity after repeated exposure (STOT-RE, oral).