Strontium carbonate

Toxicity to birds

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to birds: acute oral toxicity test

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline study, but scientifically sound work that provides relevant information on the health and effects of dietary Sr-addition to hens and their eggs

Qualifier:

no guideline followed

Principles of method if other than guideline:

Increasing doses of Sr were fed to 13-wk old pullets for 11 months.

GLP compliance:

not specified

Dose method:

feed

Analytical monitoring:

no

Details on preparation and analysis of diet:

Standard commercial diet to which Sr (as SrCO3) was added
Ca and total P levels of the diet, according to manufacturer's specifications, were 36 and 6.5 g/kg, respectively.

Test organisms (species):

other: White Leghorn hens

Details on test organisms:

13wk old , Withe Leghorn pullets; Hy LineW-36

Limit test:

no

Total exposure duration (if not single dose):

11 mo

No. of animals per sex per dose and/or stage:

49 animals per dose; 7 replicates per dose, each replicate containing 7 organisms

Control animals:

yes

Nominal and measured doses / concentrations:

0, 3000, 4500, 6000 ppm Sr (added as SrCO3) - corresponding to 2, 3, 4 mmol Sr/kg/day

Details on test conditions:

Pullets were singly weighed, housed in cages, put into egg production at 17 wk of age, and fed ad libitum throughout

Details on examinations and observations:

At 45 wk of age, 20 birds were randomly selected from all replicates in each group and weighed, blood samples were collected by cardiac puncture from 10 birds per treatment, the animals were decapitated, and the bones were removed.
The remaining 29 in each group were continued on the diets until 60 wk of age, when they were treated similarly.
Egg production was measured on a daily basis throughout the experiment. Birds that did not lay for 5 consecutive days were excluded from the study. Egg weight was measured every 2 wk. To assess eggshell quality, the contents of eggs were removed, and shells were washed, dried at 100°C for 18h and weighed.
Bone and eggshell ash composition were determined as follows: ash was dissolved in 70% nitric acid overnight. The acid ash mixture was diluted with distilled water to a total volume of 25 mL and was further diluted by 0.2 nitric acid for Sr determination
Sr was measured by atomic absorption spectrophotometry (AAnalyst600; Perkin Elmer Instruments)

Duration (if not single dose):

11 mo

Dose descriptor:

NOEC

Effect level:

> 6 000 mg/kg diet

Conc. / dose based on:

element

Basis for effect:

other: body weight, feed intake, egg production, egg weight and eggshell quality

Further details on results:

These diets resulted in an increase of eggshell Sr-levels and increase of Sr in bone and plasma, with no significant effects on Ca-content. Body weight, feed intake, egg production, egg weight and eggshell quality were not affected by Sr treatment. Based on their findings the authors concluded that the administered amounts of Sr improved the structural properties of bone and increased μCT parameters of bone formation in laying hens. The material properties of bone, however, were not significantly affected by Sr.

Conclusions:

The reported data are useful in a weight-of-evidence approach for the evaluation of Sr-toxicity to birds

Reference 2

Endpoint:

long-term toxicity to birds: reproduction test

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline study, but scientifically sound work that provides relevant information on the health and effects of dietary Sr-addition to fertility, egg quality and fertility (embryo survival)

Qualifier:

no guideline followed

Principles of method if other than guideline:

Adult White leghorn Hens were fed a standard laying diet with different Sr-doses for a 4 wk period

GLP compliance:

not specified

Dose method:

feed

Analytical monitoring:

not specified

Details on preparation and analysis of diet:

standard laying diet, containing 2.93% Ca, 0.79% total P, 17% protein, 2750 kcal. M.E./kg
dietary levels of Sr were 1.5 and 3% Sr, added as SrCO3.

Test organisms (species):

other: White Leghorn

Details on test organisms:

Birds were artificially inseminated twice during both the third and fourth wk of the experiment.

Limit test:

no

Total exposure duration (if not single dose):

4 wk

No. of animals per sex per dose and/or stage:

not specified

Nominal and measured doses / concentrations:

1.5% and 3% of Sr (added as SrCO3) in diet

Details on test conditions:

not specified

Details on examinations and observations:

The eggs saved during the exposure period were incubated for 21 d and the eggshells, day-old chicks, and/or embryos were collected for analysis (inc. Sr-content)

Duration (if not single dose):

4 wk

Dose descriptor:

NOEC

Effect level:

< 1.5 other: % Sr in diet

Conc. / dose based on:

element

Basis for effect:

other: hatchability of eggs

Duration (if not single dose):

4 wk

Dose descriptor:

NOEC

Effect level:

1.5 other: %Sr in diet

Conc. / dose based on:

element

Basis for effect:

other: egg production, fertility

Duration (if not single dose):

4 wk

Dose descriptor:

NOEC

Effect level:

>= 3 other: %Sr in diet

Conc. / dose based on:

element

Basis for effect:

other: egg weight

Mortality and sub-lethal effects:

Little or no effect was observed on the liveability of the chick embryos up to 18 old of incubation, but a dramatic reduction in survival occurred between 18-21d of incubation

Effects on reproduction:

. Hatchability in the control was 84%; hatchability in the 1.5% or 3% Sr treatments was zero.

Further details on results:

A shell thickness of 0.35 mm was noted in eggs resulting from a 0% and 1.5% level of Sr in food. A significantly lower value of 0.30 mm was observed for the 3% Sr treatment. Ca-content in the egg shells was reduced from 35% to 24% for the 3% Sr dietary treatment. Strontium in the eggshell increased from 0.08 to 6.75%.

Conclusions:

The reported data are useful in a weight-of-evidence approach for the evaluation of Sr-toxicity to birds

Reference 3

Endpoint:

toxicity to birds, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline study, and route of administration (injection in yolk or on chorioallantoic membrane) are not ecological relevant. Study, however, provides information on the relationship between internal concentrations (single doses) and survival

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sr-effects in 4d or 8d old embryo's were studies by injecting Sr into the yolk or onto the chorioallantioc membrane (CAM)

GLP compliance:

not specified

Dose method:

other: single dose into the yolk or onto the CAM

Analytical monitoring:

no

Test organisms (species):

other: eggs of White Leghorn

Limit test:

yes

Remarks:

whole developmental period of embryo (up to day 18)

Nominal and measured doses / concentrations:

no details are provided: 3/4 doses were evaluated

Details on test conditions:

volume of test agent injected per egg: 0.05 to 0.2 cc
Number of eggs per dose: 6 to 10
Embryos were candled daily and, each day, the dead embryos were recorded and examined
Experiment continued until day 18 of incubation, when all embryos were sacrificed
Embryos were weighed and their development was evaluated

Duration (if not single dose):

18 d

Dose descriptor:

other: LD50

Effect level:

0.8 other: mg/egg

Remarks on result:

other: injection into 4d old yolk

Duration (if not single dose):

18 d

Dose descriptor:

other: LD50

Effect level:

3.8 other: microatoms/egg

Remarks on result:

other: injection into 4d old yolk

Duration (if not single dose):

18 d

Dose descriptor:

other: LD50

Effect level:

> 94 other: microatoms/egg

Remarks on result:

other: injection into 8d old yolk

Duration (if not single dose):

18 d

Dose descriptor:

other: LD50

Effect level:

54 other: microatoms

Remarks on result:

other: injection onto CAM of 8d old egg

Description of key information

Data from three different studies with chicken (hens) are considered for the derivation of a safe concentration of Sr in food: Weber et al (1971), Doberenz et al (1969) and Shahnazari et al (2006).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for birds:

6 000 mg/kg food

Additional information

Data from three different studies with chicken (hens) are considered for the derivation of a safe concentration of Sr in food: Weber et al (1971), Doberenz et al (1969) and Shahnazari et al (2006):

- Weber et al (1971) found 0% hatchability in eggs that originated from hens given a diet that contained 1.5% or 3.0% Sr (i.e., 15,000 or 30,000 ppm Sr)

- Doberenz et al. (1969) found significant effects on plasma calcium, shell thickness and shell calcium; levels were lowered by dietary levels higher than 1.5% Sr (i.e., 15,000 ppm Sr). Based on this study alone, a NOEC of 15,000 ppm could be proposed; however, as mentioned before Weber et al. (1971) observed 0% hatchability in eggs originating from hens that were fed a diet containing such Sr-concentration. The endpoint “hatchability” was not considered in the study by Doberenz et al (1969).

- Shahnazari et al (2006) fed 13 wk old pullets (egg production at wk 17) for a 43 wk period with three different Sr-treatments (3000, 4500 and 6000 ppm) and found that none of the three treatments adversely affected body weight, feed intake, egg production, egg weight and eggshell quality. The value of 6000 ppm of Sr in food is considered as a relevant NOEC for birds.

Based on this information, the PNECoral for Sr could be derived based on a 47wk-NOEC-value of 6,000 ppm Sr. It is noteworthy that this value is below a value of 6,700 ppm that was reported in a study with young pigs (Bartley and Reber, 1961): a diet based on 0.67% Sr, combined with 0.16%Ca resulted in incoordination and weakness, followed by posterior paralysis. No further information on test duration and Ca-requirement for young pigs in a normal diet is available, and therefore a correct assessment of this data point is currently not feasible.

According to ECHA-Guidance (ECHA, 2008: Chapter R.10 – Dose (concentration)-response regarding environment, and assessment factor of 30 needs to be applied on the lowest chronic NOEC. Hence, an estimated PNECoral for strontium is 6,000 μg/g food / 30 = 200 μg/g dry wt in food. Mora reported internal Sr-concentration levels from insects that originated from areas with elevated Sr-levels in sediment, and these concentrations were situated between 8 and 117 μg/g dry wt, i.e., well below the PNECoral of 200 μg/g dry wt.

It should be noted that, according to the ECHA technical guidance on environmental hazard assessment, ‘if a substance has a bioaccumulation potential and a low degradability, it is necessary to consider whether the substance also has the potential to cause toxic effects if accumulated in higher organisms.’ It further states that the assessment of secondary poisoning takes place as a tiered process, where the first step is to evaluate the bioaccumulative potential of a substance, following the criterion that if BCF ≥ 100 (together with considerations regarding biodegradability). When this criterion is met, the subsequent step to calculate a PNECoral,predator is needed.

As strontium does not meet this requirement, no PNECoral,predator is required for this substance.