Zinc acrylate

Toxicity to reproduction

Administrative data

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

Well-documented study report, comparable to guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1980

Report date:

1980

Reference 2

Reference Type:

publication

Title:

Subchronic and Reproductive Toxicology Studies on Acrylic Acid in the Drinking Water of the Rat.

Author:

DePass L. R. et al.

Year:

1983

Bibliographic source:

Drug and Chemical Toxicology 6: 1-20

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Principles of method if other than guideline:

10 male and 20 female rats per group were administered acrylic acid at dosage goals of 0, 83, 250 and 750 mg/kg/bw/day in drinking water. At the end of 13 weeks, the male and female rats from each group were mated one male to two females for a 15-day period. Females were introduced into male cages. Rats ware assigned to treatment groups using a computer generated random number scheme. The F0 generation rats were sacrificed after weaning of the F1 generation and were approximately 194 days old at the time of sacrifice. The F1 generation rats were sacrificed at 21 days of age. Treatment effects were determined by statistical comparison of mortality, body weight change, food and water consumption, organ weight change and histological evaluation of tissues from sacrificed animals.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

79-10-7

Molecular formula:

C3H4O2

Details on test material:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 97.8%
- Lot No.: 42-19

Test animals

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: (P): 41 days
- Weight at study initiation: (P) Males: 111-139 g; Females: 85-118 g
- Housing: During mating, two females were placed in a cage with one male; at this time all rats received acrylic acid at the concentration in the water for the respective female groups. Fifteen days after the first mating, cohabitation was discontinued and the individual females were placed in plastic cages fitted with wire rod metal tops. Ab-sorb-dri hardwood chips were used for bedding in the plastic cages.
- Diet (ad libitum): Zeigler Brothers NIH-07
- Water (ad libitum): Tap water


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Photoperiod (hrs dark / hrs light): no data

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on mating procedure:

- M/F ratio per cage: 1/2
- Length of cohabitation: 15 days
- After successful mating each pregnant female was caged (how): Fifteen days after the first mating, cohabitation was discontinued and the individual females were placed in plastic cages fitted with wire rod metal tops.

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. The mean dosage levels attained were quite close to the dosage goals for each group. The mean overall dosages of acrylic acid were 0.73, 0.25 and 0.085 g/kg/bw/day for males and 0.72,
0.25 and 0.083 g/kg/bw/day for females.

Duration of treatment / exposure:

Exposure period: 13 weeks
before the mating and afterwards during the gestation and lactation periods.
Premating exposure period (males): 13 weeks
Premating exposure period (females): 13 weeks
Duration of test: approx. 6 months

Frequency of treatment:

continuously

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 83, 250, 750 mg/kg bw/d
Basis:
nominal in water

No. of animals per sex per dose:

10 males and 20 females

Control animals:

yes, concurrent vehicle

Positive control:

none

Examinations

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS:
Daily observation for clinical signs

BODY WEIGHT:
Individual body weights for each F0 animal were determined weekly.

FOOD CONSUMPTION:
The food consumption rate was recorded weekly. Fresh diet was added to the jars every week.

WATER CONSUMPTION:
The water consumption rate was recorded weekly. Fresh solutions were prepared each week, with the percentage of acrylic acid in the water (X) adjusted to maintain a relatively constant dosage level (K) in g/kg according to formula:

X = 100 KW / G

Where X and K are explained above:
W = predicted mean body weight, kg
G = mean water consumption, ml

Oestrous cyclicity (parental animals):

not examinated

Sperm parameters (parental animals):

not examinated

Litter observations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities.

Postmortem examinations (parental animals):

SACRIFICE
Five male and five female rats, randomly selected from each dosage level of the F0 parents, were anesthetized with methoxyflurane and sacrificed by severing the brachial vesseis to permit exsanguination.


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


HISTOPATHOLOGY / ORGAN WEIGHTS
The following tissues were taken and fixed in 10% neutral buffered formalin, processed for paraf in embedding, sectioned at 5 microns and stained with hematoxylin and eosin on all high dose and control animals. Only those tissues with gross lesions were examined microscopically from the intermediate and low level animals.
Pituitary, thyroids, parathyroids, adrenals, heart, thymus, spleen, testes, epididymides, kidneys, urinary bladder, tongue, submandibular salivary gland, esophagus, stomach, duodenum, colon, mesenteric lymph node, nasal cavity, trachea, lungs, ovaries, oviduct, liver, pancreas, brain, eyes, skin, mammary gland, sternum, any lesions.

Postmortem examinations (offspring):

SACRIFICE
Five male and five female rats, randomly selected from each dosage level of the F1 weanlings, were anesthetized with methoxyflurane and sacrificed by severing the brachial vesseis to permit exsanguination.


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


HISTOPATHOLOGY / ORGAN WEIGHTS
The following tissues were taken and fixed in 10% neutral buffered formalin, processed for paraf in embedding, sectioned at 5 microns and stained with hematoxylin and eosin on all high dose and control animals. Only those tissues with gross lesions were examined microscopically from the intermediate and low level animals.
Pituitary, thyroids, parathyroids, adrenals, heart, thymus, spleen, testes, epididymides, kidneys, urinary bladder, tongue, submandibular salivary gland, esophagus, stomach, duodenum, colon, mesenteric lymph node, nasal cavity, trachea, lungs, ovaries, oviduct, liver, pancreas, brain, eyes, skin, mammary gland, sternum, any lesions.

Statistics:

For every experimental parameter or index measured, the results of each of the three test levels were compared with the control group. To evaluate the statistical significance of possible changes in continuous data, the analysis of variance (ANOV) 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 ANOV. In the case of heterogeneous 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

Reproductive indices:

The following reproductive parameters were evaluated statistically:
1. Fertility index - the proportion of females that were pregnant of the number that were mated or the proportion of the males shown to be fertile of the number that were mated.
2. Gestation Index - the proportion of pregnancies that resulted in litters with live pups.
3. Gestation Survival Index - the proportion of newborn pups that were alive at birth.
4. Pups born alive per litter.
5. Days from mating to litter.

Offspring viability indices:

The following reproductive parameters were evaluated statistically:
1. 5-Day Survival Index - the proportion of liveborn that survived 5 days.
2. 21-Day Survival Index - the proportion of pups retained on day 5 that survived 21 days.
3. Pups weaned per pups alive at birth.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, treatment-related

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS):
There were no significant abnormal clinical signs observed. No deaths occurred during the study.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS):
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. At the highest dosage level there were effects on diet and water consumption, body weight gain and organ weights (liver, kidneys, spieen, testes, brain). At the intermediate dosage level, a decrease in water consumption was noted for both sexes. Body weight gain was reduced while liver and kidney weights (absolute and/or relative) were increased for the female rats. At the lowest dosage level, absolute liver and kidney weights and relative liver weights were increased for the females. These changes were possibly chemically induced.


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS):
At the highest dose, a numerical reduction of the fertility (male and female) and gestation indices, pups born alive and pups weaned was observed.


ORGAN WEIGHTS (PARENTAL ANIMALS):
The effect of acrylic acid on the organ weights was obvious at the high dosage level in both sexes. In the male rats this effect included: Significant reduction in absolute liver weight and significant increase in relative kidney, spleen and testes weights.
In the female rats, the effects on organ weights at the high dose level included: Significant reduction in absolute liver and spleen weights and significant increase in relative kidney and brain weights. Furthermore, the significant increases in relative liver weight and absolute and relative kidney weights for the intermediate level females are considered to be dose-related effects. The significant increase in absolute liver and kidney weights and relative liver weights in the lowest dosage level females are possibly chemically-induced changes. However, the significant increase in female fertility in this group precludes the probability that reproductive behavior was affected by these changes. They are, therefore, considered to be of no biological importance on reproduction.


GROSS PATHOLOGY (PARENTAL ANIMALS):
There were no gross lesions which could be attributed to treatment with acrylic acid.

HISTOPATHOLOGY (PARENTAL ANIMALS):
Histopathological examination revealed no treatment-related lesions associated with the ingestion of acrylic acid.

Effect levels (P0)

1

Key result

Dose descriptor:

NOAEL

Effect level:

83 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Body and organ weights.

2

Key result

Dose descriptor:

NOAEL

Effect level:

250 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: fertility index; gestation index

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Details on results (F1)

CLINICAL SIGNS (OFFSPRING):
There were no significant abnormal clinical signs observed. There were no consistent findings in the spontaneous death of neonatal rats.


BODY AND ORGAN WEIGHT (OFFSPRING)
The effects at the highest dosage level of the parent generation were similar to those observed for the highest dosage level of the progeny. Here
also, there were effects on body weight gain and organ weights (liver, heart, kidneys, brain, spleen).


GROSS PATHOLOGY (OFFSPRING):
There were no gross lesions which could be attributed to treatment with acrylic acid.


HISTOPATHOLOGY (OFFSPRING)
Histopathological examination revealed no treatment-related lesions associated with the ingestion of acrylic acid.

Effect levels (F1)

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

250 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Pup body and organ weights; number of pups born alive and pups weaned

Overall reproductive toxicity

Key result

Reproductive effects observed:

not specified

Any other information on results incl. tables

Mean body weight changes (g)

Week of treatment	0 mg/kg/bw/d		83 mg/kg/bw/d		250 mg/kg/bw/d		750 mg/kg/bw/d
	male	female	male	female	male	female	male	female
Mean bw at day 0	124.5	99.4	124.0	101.3	125.3	102.4	121.4	99.0
1	29.8	12.7^x	28.6	14.2	31.2	13.8^x	24.1^a	10.6^a
2	62.2	26.8	56.8	27.6	63.1	23.5^a	51.3^b	21.4^c
3	89.2	37.6	83.4	38.1	91.7	36.6	75.7^b	30.0^c
4	112.2	47.6	106.5	46.7	111.1	45.4	93.6^b	36.9^c
5	130.3	55.6	126.7	55.8	128.6	52.5	106.7^b	41.6^c
6	145.3	63.6	142.2	63.8	141.8	58.6^a	119.0^c	47.2^c
7	159.5	69.4	154.2	70.3	153.0	63.6^a	127.8^c	49.8^c
8	171.8	73.3	167.7	74.1	162.6	67.1^a	125.6^c	52.1^c
9	181.1	75.9	176.4	77.2	170.1	69.2^a	131.6^c	53.0^c
10	191.4	79.9	187.6	81.0	180.0	73.3^a	139.2^c	55.2^c
11	200.1	82.4	194.9	83.3	185.4	74.5^b	142.8^c	57.4^c
12	205.2	84.4	200.6	86.0	191.7	78.0^a	144.7^c	58.6^c

^a0.05>p>0.01

^b0.01>P>0.001

^cP<0.001

^xOne clinically ill rat excluded from statistical evaluation of body weight gain.

Reproductive Performance

Parameter	Dose (mg/kg/bw/d
	0	83	250	750
Fertility index (males)^a	80	100	80	60
Fertility index (female)^b	50	95	75	45
Gestation index^c	100	100	100	89
Gestation survival index^d	100	100	100	100
5-Day survival index^e	100	100	100	100
21-Day survival index^f	100	100	100	100
Pups born alive/Litter^g	6	8	9	4
Pups weaned/Pups alive at birth (100)^g	100	100	100	42

 ^aLitters sired per males mated x 100

^bDeliveries per females mated x 100

^cLitters with live pups/total pregnancies x 100

^dPups born viable/total pups delivered x 100, median per litter

^ePups viable at day 5/pups born viable x 100, median per litter

^fPups viable on day 21/pupe retained at day 5 x 100, median per litter

^gMedians

Applicant's summary and conclusion

Conclusions:

At the highest dosage level, the preponderance of statistical significance in many parameters in both parents and progeny concomitant with generally lowered reproductive indices is a clearly dose-related toxic effect. Therefore, based on the above findings the maximum dosage level that did not produce a deleterious reproductive effect for one generation of exposure of acrylic acid in the drinking water of rats was estimated to be 250 mg/kg bw/day (equivalent to 720 mg zinc diacrylate/kg/day).

Executive summary:

A study was conducted to evaluate the reproductive toxicity potential of the test substance in rats for one generation. The method was equivalent to OECD Guideline415. 10 male and 20 female rats per group were administered acrylic acid at dose goals of 0, 83, 250 and 750 mg/kg/bw/day in drinking water. At the end of 13 weeks, the male and female rats from each group were mated one male to two females for a 15 d period. The F0 generation rats were sacrificed after weaning of the F1 generation and were approximately 194 d old at the time of sacrifice. The F1 generation rats were sacrificed at 21 d of age. Treatment effects were determined by statistical comparison of mortality, body weight change, food and water consumption, organ weight change and histological evaluation of tissues from sacrificed animals. Deleterious effects were observed at the high dose level in both sexes for parents and progeny. These effects included diet and water consumption, body and organ weight changes. Furthermore, there was a numerical reduction in the fertility and gestation indices and the number of pups weaned. At the intermediate level, although the reproductive parameters were equivalent to those of the controls, dose-related effects were seen for water consumption and body and organ weights in the parent rats. At the low dose level, organ weight changes observed in the female rats of the parent generation are considered to be of minimal biological significance. The results of the reproduction study do not indicate a substantial deleterious effect of acrylic acid on reproductive performance, since there were no statistically significant differences among the treated and control groups. However, the data should be interpreted cautiously because of a relatively atypical control group. For example, high dose females had relatively low fertility (45%) but this value was equivalent to that of the controls (50%). Although the average fertility index for earlier Fischer rat studies was 82%, the occurrence of a concurrent control group with lower fertility makes it impossible to determine whether the low fertility of the high dose females was treatment-related. Similarly, the typical (median) historical control value of 9 pups per litter for Fischer rats differs substantially from the control median of 6 in this study. Therefore, reduced litter size at the high dose level may or may not have been a treatment-related effect. In spite of the difficulty in interpreting the possible reproductive effects of acrylic acid at the high dose level, the results of the reproduction study indicate that there was no adverse effect at the two lower levels. This conclusion is justified whether one uses the concurrent control data or historical control data as basis for comparison. In summary, although numerous treatment-related effects were observed at the two highest dose levels, many of these may be the result of reduced food and water consumption rather than specific toxic effects of acrylic acid. At the highest dose level, the preponderance of statistical significance in many parameters in both parents and progeny concomitant with generally lowered reproductive indices is a clearly dose-related toxic effect. Therefore, based on the above findings the maximum dose level that did not produce a deleterious reproductive effect for one generation of exposure of acrylic acid in the drinking water of rats was estimated to be 250 mg/kg bw/day (equivalent to 720 mg zinc diacrylate/kg/day) (IATG, 1980).