4-hydroxybutyl acrylate

Endpoint summary

Description of key information

Data for 4 -hydroxybutyl acrylate:

-oral:NOAEL = 40 mg/kg bw (BASF, 2022; OECD 408/422)

Data from the structural analogue 2-hydroxyethyl acrylate (CAS No. 818-61-1):

- oral: NOAEL = approx. 196 – 305 mg/kg bw/day (Sherman rats, no guideline, 100 days, diet)

- oral: NOAEL = approx. 125 - 131 mg/kg bw/day (Beagle dogs, no guideline, 97 days, diet)

- inhalation: LOAEC = 5 ppm corresponding to approx. 0.024 mg/L (Sherman rats, local effects, no guideline, 28 days, vapour)

- inhalation: NOAEC = 0.5 ppm corresponding to approx. 0.0024 mg/L (Sprague-Dawley rats, pneumonia, no guideline, 18 months, vapour)

- dermal: no data

Data from the structural analogue Methyl acrylate (CAS No. 96-33-3):

- oral: NOAEL = 5 mg/kg bw/day (DowChemCo, rats, OECD 408. 90 days, drinking water)

- oral: LOAEL = 20 mg/kg bw/day (DowChemCo, rats, OECD 408, 90 days, drinking water)

- inhalation: NOAEC = 0.082 mg/L (BASF, rats, OECD 413, 12 weeks, vapour)

- inhalation: LOAEC = 0.44 mg/L (BASF, rats, OECD 413, 12 weeks, vapour)

- dermal: no data

 

Data from the structural analogue hydroxypropyl acrylate (CAS No. 25584-83-2):

- oral: NOAEL = 150 mg/kg bw/day (Wistar rats, systemic effects, OECD 422, gavage)

- oral: NOAEL = 15 mg/kg bw/day (Wistar rats, local effects, OECD 422, gavage)

- inhalation: LOAEC = 5 ppm corresponding to approx. 0.027 mg/L (Sprague-Dawley rats, local effects, no guideline, 28 days, vapour)

- inhalation: NOAEC = 5 ppm corresponding to approx. 0.027 mg/L (Swiss-Webster mice, local effects, no guideline, 28 days, vapour)

- inhalation: LOAEC = 5 ppm corresponding to approx. 0.027 mg/L (New Zealand White rabbits, local effects, no guideline, 28 days, vapour)

- inhalation: LOAEC = 5 ppm corresponding to approx. 0.027 mg/L (Beagle dogs, local effects, no guideline, 28 days, vapour)

- dermal: no data

Data from the structural analogue n-butyl acrylate (CAS No. 141-32-2):

- oral: NOAEL = 84 mg/kg bw/day for males (DowChemicalCo, rats, OECD 408, 13 weeks, drinking water)

- oral: NOAEL = 111 mg/kg bw/day for females (DowChemicalCo, rats, OECD 408, 13 weeks, drinking water)

- inhalation: NOAEC = 108 ppm (BASF, Sprague-Dawley rats, local effects, OECD 413, 13 weeks, vapour)

- inhalation: LOAEC = 211 ppm (BASF, Sprague-Dawley rats, local effects, OECD 413, 13 weeks, vapour)

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:

02-16-2021 to 20-07-2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Principles of method if other than guideline:

The duration of treatment covered a 14 weeks in-life period in the males including premat-ing, mating (mating pairs were from the same test group) and postmating period; a 10-weeks premating period, 3 days mating period, the entire gestation and approximately 4 weeks of lactation period in the females, approximately 3 weeks in-life period in the male rearing ani-mals and 8 days in-life period in the female rearing animals. In addition groups of 10 male and 10 female Wistar rats (F0 parental animals) and groups of 10 male and 10 female rearing animals, were treated with the test substance by gavage at doses of 12, 40 and 120 mg/kg body weight/day (mg/kg bw/d).

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Details on species / strain selection:

The test guideline requires the rat to be used as the animal species. This rat strain was selected since extensive historical control data are available for Wistar rats.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: about 36+/+ 1 days
- Weight at study initiation: weight variation did not exceed 20 percent of the mean weight
- Housing: During the pretreatment, premating, mating and postmating period of the study, the rats were housed together (up to 5 (pretreatment) and 2 animals (premating) per sex and cage and 2 animals (males only during mating and postmating) per cage, respectively) in Polysulfonate cages Typ 2000P (H-Temp) supplied by TECNIPLAST, Hohenpeißenberg, Germany. During the mating, gestation and lactation period and after weaning the female rats were housed individually in Polycarbonate cages type III supplied by TECNIPLAST, Hohen-peißenberg, Germany and Becker & Co., Castrop-Rauxel, Germany, with the following ex-ceptions: During overnight matings, male and female mating partners were housed together in Polycarbonate cages type III. Pregnant animals and their litters were housed together until PND 21 in Polycar-bonate cages type III.
- Diet (e.g. ad libitum): ad libitum (Mouse and rat maintenance diet "GLP", Granovit AG, Switzerland)
- Water (e.g. ad libitum): ad libitum (drinking water)
- Acclimation period: 8 days

DETAILS OF FOOD AND WATER QUALITY:
The food used in the study will be assayed for chemical and microbial contaminants. Fed. Reg. Vol. 44, No. 91 (09 May 1979), p 27354 (EPA), will serve as the guideline for maximum tolerable contaminants. Additionally the levels of phytoestrogens should not exceed 350 µg of genistein equivalents/gram. According to recommendations of the GV-SOLAS, the total amount of bacteria must not exceed 1*105 per g food.
Drinking water analysis: The drinking water is regularly assayed for chemical contaminants both by the municipal authorities of Frankenthal and by the Environmental Analytics Water/Steam Monitoring Department of BASF SE as well as for bacteria by a contract laboratory. The Drinking Water Regulation will serve as the guideline for maximum tolerable contaminants

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 45-65
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Details on route of administration:

The oral administration of a test substance has been proved useful worldwide in numerous studies for discovering a potential toxicological profile.

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
For the test substance preparation, the specific amount of test substance will be weighed, topped up with drinking water in a graduated flask and intensely mixed with a magnetic stirrer until it is completely dissolved.
The test substance preparations will be prepared at intervals which guarantee that the test substance concentrations in the vehicle will remain stable.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical verifications of the stability of the test substance in drinking water for a period of 7 days at room temperature was verified before the start of the study in a similar batch. At the beginning of administration, towards the middle and towards the end of administration each 1 sample was taken from the low, mid and high concentration for a concentration con-trol analysis. All test samples, plus a duplicate set of reserve samples, were withdrawn by staff of the Laboratory Reproduction Toxicology.
The reserve samples were stored at the Laboratory Reproduction Toxicology frozen (at -20 °C) Analysis of these samples were performed in case of equivocal analytical results with the original samples or after loss of/damage to original samples after agreement by the Study Director.

Duration of treatment / exposure:

The duration of treatment covered a 14 weeks in-life period in the males including premat-ing, mating (mating pairs were from the same test group) and postmating period; a 10-weeks premating period, 3 days mating period, the entire gestation and approximately 4 weeks of lactation period in the females, approximately 3 weeks in-life period in the male rearing ani-mals and 8 days in-life period in the female rearing animals.

Frequency of treatment:

once daily, 7 days per week (exception: no administration to animals being in labor)

Dose / conc.:

0 mg/kg bw/day (nominal)

Dose / conc.:

12 mg/kg bw/day (nominal)

Dose / conc.:

40 mg/kg bw/day (nominal)

Dose / conc.:

120 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 animals

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on dose-range-finding studies

Positive control:

No positive control conducted.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- A cageside examination was conducted at least daily for any signs of morbidity, pertinent behavioral changes and signs of overt toxicity before the administration as well as within 2 hours and between 2 and 5 hours after the administration. Abnormalities and changes were documented daily for each animal. Individual data of daily observations can be found in the raw data. The parturition and lactation behavior of the dams was generally evaluated in the mornings in combination with the daily clinical inspection of the dams. Only particular findings (e.g. inability to deliver) were documented on an individual dam basis. On weekdays (except Saturday, Sunday and public holidays) the parturition behavior of the dams was inspected in the afternoons in addition to the evaluations in the mornings.

DETAILED CLINICAL OBSERVATIONS: Yes
- Detailed clinical observations (DCO) were performed in all animals once prior to the first ad-ministration (day 0) and at weekly intervals during the administration period. The examinations started in the morning.
- Detailed clinical observations checked in table No. 1 were included.

BODY WEIGHT: Yes
- body weight of the male and female parental animals and F1 rearing animals was deter-mined once a week at the same time of the day (in the morning) until sacrifice. The body weight change of the animals was calculated from these results. During the mating period the parental females were weighed on the day of positive evi-dence of sperm (GD 0) and on GD 7, 14 and 20. Females with litter were weighed on the day of parturition (PND 0) and on PND 1, 4, 7, 10, 13, 17 and 21. Females without positive evidence of sperm, without litter and females after weaning (PND 21) were weighed weekly.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- food consumption was determined once a week for male and female parental animals and F1 rearing animals, with the following exceptions: Food consumption was not determined after the 10nd premating week (male parental an-imals) and during the mating period (male and female parental animals). Food consumption of the females with evidence of sperm was determined on GD 0-7, 7-14 and 14-20. Food consumption of the females which gave birth to a litter was determined on PND 1-4, 4-7, 7-10, 10-13, 13-17 and 17-21. Food consumption was not determined in females without positive evidence of sperm during the mating and the gestation period and in females without litter during the lactation period.

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 / No / Not specified

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- water consumption was determined once a week (over a period of 3 days) for the male and female parental animals and F1 rearing animals, with the following exceptions: Water consumption was not determined after the 10nd premating week (male parental animals) and during the mating period (male and female parental animals); Water consumption of the females with evidence of sperm was determined for GD 0-1, 7-8, 13-14 and 19-20; Water consumption of the females, which gave birth to a litter was determined for PND 1-2, 3-4, 6-7, 9-10, 12-13, 16-17 and 20-21.
Water consumption was not determined in the females without positive evidence of sperm during mating and gestation periods and in the females without litter during lactation period.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Blood samples from all dams at PND 14 and all F0 males at termination were taken by punc-turing the retrobulbar venous plexus under isoflurane anesthesia for hormone measure-ment.
- examinations were performed in 5 F0 animals per sex and group towards the end of the ad-ministration period
- parameters checked in table No. 5 were examined.

CLINICAL CHEMISTRY: Yes
- Blood samples from all dams at PND 14 and all F0 males at termination were taken by punc-turing the retrobulbar venous plexus under isoflurane anesthesia for hormone measure-ment.
- examinations were performed in 5 F0 animals per sex and group towards the end of the ad-ministration period
- parameters checked in table No. 6 were examined.

URINALYSIS: Yes

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations:
end of administration period
- Dose groups that were examined:
all, first 5 surviving male and the first 5 surviving female animals with litter per group (in order of delivery)
- Battery of functions tested are checked int table No. 2-4: home cage observeratin; open field observation, sensory-motoric test; motor activity

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
The animals will be sacrificed by decapitation under isoflurane anesthesia. The exsanguinated animals will be necropsied and assessed by gross pathology.
Organ weights: Were determinded as listed in table No.7

HISTOPATHOLOGY: Yes
The organs or tissues will be fixed in 4% neutral buffered formaldehyde solution or in modified Davidson's solution as listed in table No. 8

Statistics:

Means and standard deviations were calculated. Further statisctis were performed as listed in table No. 9

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All high-and several mid-dose males showed salivation during the entire study. Salivation was also observed in all high-dose females during the premating, gestation and lactation period, in two high-dose females during the mating period and in some mid-dose females during premating, gestation and lactation periods. The temporary salivation was considered to be test substance-induced.
No other clinical signs or changes of general behavior, which may be attributed to the test substance, were detected in any of the male and female F0 parental animals in any of the test groups (01 - 03; 12, 40 and 120 mg/kg bw/d) during the study.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

There were no test substance-related mortalities in any of the groups.
One female animal of test group 02 (40 mg/kg bw/d) was found dead during blood sampling on the day of scheduled sacrifice.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Mean body weights and body weight change of all male and all female parental animals in all test substance-treated groups were comparable to the concurrent control values during the entire study. Mean body weight change of the high-dose parental males was statistically significantly below the concurrent control values during in-life days 42 - 49 and in the high-dose females during PND 1 - 4 (about 32%, respectively). As these changes lack consistence they were considered to be incidental findings

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Food consumption of all male and all female animals of all test substance-treated groups was comparable to the concurrent control values throughout the entire study.

Food efficiency:

not examined

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

no effects observed

Description (incidence and severity):

Water consumption of all male and female animals of all test substance-treated groups was largely comparable to the concurrent control throughout the entire study. Water consumption of the high-dose females was statistically significantly below the concur-rent control values during GD 13 - 14 (about 16%). As this decrease was not consistent, this is considered to be an incidental finding.

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

After three months of administration, in males of test group 3 (120 mg/kg bw/d) prothrombin time (Hepatoquick’s test, HQT) was significantly reduced. The values were below the historical control range (males, HQT 34.4-42.3 sec). Therefore, this alteration was regarded as treatment related and adverse.

In addition, in males of test group 3 mean corpuscular hemoglobin concentration (MCHC) was significantly decreased whereas absolute reticulocyte counts were significantly increased. The measured red blood cell parameters (i.e., red blood cell (RBC) counts, hemoglobin and hematocrit values) were not altered. Absolute reticulocyte counts were within the historical control range (males, absolute reticulocytes 116.2-162.9 Giga/L). Therefore, MCHC decrease and reticulocyte count increase in males of test group 3 were regarded as incidental and not treatment related.

In dams at lactational day 14 (LD14) in test group 2 (40 mg/kg bw/d) relative monocyte counts were significantly decreased, but this change was not dose dependent. Therefore, this change was regarded as incidental and not treatment related.

After four months of administration, in F0 females of test group 3 (120 mg/kg bw/d) red blood cell (RBC) counts were significantly decreased. The mean RBC counts was 5% lower compared to study controls. No other red blood cell parameter was changed. Therefore, this isolated alteration was regarded as maybe treatment related but non adverse (ECETOC Technical Report No. 85, 2002).

In females of test group 3 relative basophil counts were significantly increased, but the values were within the historical control range (females, relative basophils 0.1-0.7 %). In females of test group 1 (12 mg/kg bw/d) relative lymphocyte counts were significantly lower whereas relative monocyte counts were significantly higher compared to controls, but both changes were not dose dependent. Therefore, the changes in this chapter were regarded as incidental and not treatment related.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

After three months of administration, in males of test group 3 (120 mg/kg bw/d) LDL-cholesterol levels were significantly decreased whereas inorganic phosphate levels were significantly increased. Both parameters were outside historical control ranges (males, LDL-cholesterol, 0.17-0.27 mmol/L, inorganic phosphate 1.42-1.79 mmol/L). Therefore, these alterations were regarded as treatment related and adverse.

After four months of administration, in females of test group 3 total cholesterol and HDL-cholesterol levels were significantly increased. Total cholesterol levels were within the historical control range, HDL-cholesterol values were marginal above this range (females, cholesterol 1.02-2.14 mmol/L, HDL-cholesterol 1.07-1.26 mmol/L). However, these changes were regarded if ever treatment related as non-adverse. Additionally, in females of test groups 1, 2 and 3 (12, 40 and 120 mg/kg bw/d) total bilirubin values were significantly higher compared to controls. However, all values were within the historical control range (females, total bilirubin 1.38-2.36 µmol/L). Therefore, this change was regarded as incidental and not treatment related.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment-related changes among urinalysis parameters were observed in F0 males and females.

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Home cage observations: No test substance-related or spontaneous findings were observed in male and female ani-mals of all test groups during the home cage observation.
Open field observations: The open field observations did not reveal any test substance-related findings in male and female animals of all test groups.
Sensorimotor tests/reflexes: There were no test substance-related findings in male and female animals of all test groups.
Quantitative Parameters: No test substance-related impaired parameters were observed in male and female animals of all test groups. The statistically significantly lower value of landing foot-splay test in males of test group 02 was considered as spontaneous in nature and not treatment-related, as there was no dose-response.
Motor activity measurement: No treatment-related, adverse changes on motor activity data (summation of all intervals) was observed in the male and female animals of all test substance-treated groups in com-parison to the concurrent control values. The statistically significantly decreased number of beam interrupts in the low-dose males during interval 8 was considered to be spontaneous in nature and not treatment related since there was no relation to dose.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The significantly increased absolute and relative liver weight in males and the significantly increased relative liver weight in females in test group 03 (120 mg/kg bw/day) were regarded to be treatment-related. The still significantly increased relative liver weight of test group 02 males (40 mg/kg bw/day) were inside historical control values and therefore not regarded to be adverse.
In females of test group 02 and 03 (40 and 120 mg/kg bw/day) the reduced absolute adrenal gland weights were regarded to be unrelated to treatment as no dose-response relationship was present nor the relative organ weights were significantly altered, and the organ weights were within historical control values.
The relative increase of relative kidney weight in females of test group 03 (120 mg/kg bw/day) were minimally outside historical control values but were regarded to be unrelated to treatment as no histopathologic finding was observed that could explain the weight increase.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

At 120 mg/kg bw d the foci and the thickened margo plicatus in the forestomach were regarded to be treatment-related.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Forestomach:
In the forestomach, two females of test group 03 (120 mg/kg bw/day) showed erosion/ulcer. One male animal of the same test group revealed a moderate edema and severe focal hyperplasia of the squamous epithelium. This is a well-known secondary finding seen with erosion/ulcer. Therefore, in this animal an erosion/ulcer is most likely, although not observed on the slide investigated.
Four male and four female animals revealed focal hyperplasia of the margo plicatus. All these above-mentioned findings were regarded to be treatment-related.

Liver:
In the periportal area of the liver of males of test group 03 (120 mg/kg bw/day) microvesicular vacuolation of the hepatocytes was observed. A special stain for neutral fat (Oil Red O stain) was performed and showed a positive result.

All other findings occurred either individually or were biologically equally distributed over control and treatment groups. They were considered to be incidental or spontaneous in origin and without any relation to treatment.


The stages of spermatogenesis in the testes of males of the high dose test group were comparable to those of the controls. In high dose females the different stages of functional bodies in the ovaries were present and comparable to the control animals.
 

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Thyroid hormones:
After three months of administration in males of test group 3 (120 mg/kg bw/d) T4 values were significantly increased. The mean value was also above the historical control range (males, T4 44.65-73.22 nmol/L). T3 values and TSH values were not altered and neither any weight change nor any histopathologic finding was observed among these individuals. Therefore, the isolated increase of T4 values of males in test group 3 was regarded as non-adverse if at all treatment related.

After four months of administration, in females of test groups 1, 2 and 3 (12, 40 and 120 mg/kg bw/d) T4 values were significantly higher compared to controls. However, all values were within the historical control range (females, T4 26.66 60.54 nmol/L). T3 and TSH values were not changed. Therefore, this alteration was regarded as incidental and not treatment related.

At PND13, in F1 pups of test groups 1, 2 and 3 (12, 40 and 120 mg/kg bw/d) no changes of serum T4 and TSH levels were observed.

Dose descriptor:

NOAEL

Effect level:

40 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

histopathology: non-neoplastic

Critical effects observed:

no

Discussion:

In an OECD 422 study, the test substance 4 -Hydroxybutyl Acrylate was administered daily as an aqueous solution to groups of 10 male and 10 female Wistar rats (F0 parental animals) and groups of 10 male and 10 female rearing animals by gavage at doses of 12, 40 and 120 mg/kg body weight/day (mg/kg bw/d)to screen for potential systemic, reproductive and developmental toxicity.Control animals (10 male and 10 female Wistar rats (F0 parental animals and F1 rearing animals) were dosed daily with the vehicle only (drinking water). The duration of treatment covered a 14 weeks in-life period in the males including premating, mating (mating pairs were from the same test group) and postmating period; a 10-weeks premating period, 3 days mating period, the entire gestation and approximately 4 weeks of lactation period in the females, approximately 3 weeks in-life period in the male rearing animals and 8 days in-life period in the female rearing animals.

The stability of these preparations was demonstrated over a period of 7 days under ambient conditions. Analyses confirmed the overall accuracy of the prepared concentrations of the test substance in the vehicle. 

Regarding clinical examinations, no test substance related, adverse signs of systemic toxicity were observed up to a dose of 120 mg/ kg bw/d. 

Transient salivation during a short time period after gavage dosing was noted for nearly all high-dose and some mid-dose male and female animals (F0 parents and F1 offspring) during all sections of the study. It is likely, that this temporary finding was induced by a local affection of the upper digestive tract, considering the evident histopathological signs of irritation found in the forestomach and the transition zone between fore- and glandular stomach of some high-dose animals. Salivation is not an adverse effect by itself, but at least for the high-dose group it can be considered as an outward sign reflecting adverse pathological findings in the stomach.

Neither water and food consumption nor body weight/body weight gain were adversely affected in any of the tested dose groups. 

Regarding clinical pathology, in males of test group 3 (120 mg/kg bw/d) prothrombin time was reduced which was most probably due to an increased synthesis of coagulation factors by liver cells. Additional lower LDL-cholesterol values in males of this test group may be also due to an increased uptake of LDL-cholesterol in the liver cells.

Regarding pathology, the forestomach and the liver were target organs. In the forestomach, one male and two females, all of test group 3 (120 mg/kg bw/day), revealed erosion/ulcer which corresponded to the macroscopic observation “focus”. The margo plicatus in the forestomach was macroscopically thickened in all males and four females of test group 3 (120 mg/kg bw/day). This was correlated to the histopathologic observation “hyperplasia, squamous epithelium”. Both findings were regarded to be treatment-related and locally adverse caused by the irritating effect of the test substance. 

The liver weight increase in males and females of test group 3 (120 mg/kg bw/day) were both regarded to be treatment-related. Males of this test group revealed an increase of periportal vacuolation of hepatocytes. These vacuoles were positive (neutral fat) in the ORO stain. Therefore, the liver findings in males of test group 3 (120 mg/kg bw/day) were in combination with findings in clinical pathology regarded to be treatment-related and adverse.

In females, there was no histopathologic finding that could explain the weight increase. As no adverse findings in females of test group 3(120 mg/kg bw/day) in clinical pathology were observed, the weight increase of the liver was assessed to be not adverse. 

All other findings occurred either individually or were biologically equally distributed over control and treatment groups. They were considered to be incidental or spontaneous in origin and without any relation to treatment.

Regarding fertility and reproductive performance, no signs of toxicity were observed in male or female parental animals of all test groups during the entire study. All F0 parental animals proved to be fertile. Mating behavior, conception, implantation and parturition were not affected. 

Regarding developmental toxicity, no signs of developmental toxicity were noted in any of the treated groups. Pup status, viability, survival and growth, as well as timing of puberty showed no treatment-related, adverse findings.

Conclusions:

Under the conditions of the present OECD 422 combined repeated dose tox-icity study with the reproductive/developmental screening test in Wistar rats the oral admin-istration of 4-Hydroxybutyl Acrylate by gavage to male and female Wistar rats resulted in signs of systemic toxicity at a dose of 120 mg/kg bw/d, considering clinical pathological and pathological findings. Thus, the no observed adverse effect level (NOAEL) for general systemic toxicity was the mid dose of 40 mg/kg bw/d for male and female Wistar rats.

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please see for more information the read-across justification in Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Remarks:

rat, 100 days, feed

Effect level:

>= 196 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Dose descriptor:

NOAEL

Remarks:

rat, 100 days, feed

Effect level:

>= 305 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Dose descriptor:

NOAEL

Remarks:

dog, 97 days, feed

Effect level:

125 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Dose descriptor:

NOAEL

Remarks:

dog, 97 days, feed

Effect level:

131 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Dose descriptor:

NOAEL

Remarks:

rat, 90 days, drinking water

Effect level:

5 other: mg/kg

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed

Remarks on result:

other: Result read-across CAS No. 96-33-3

Dose descriptor:

LOAEL

Remarks:

rat, 90 days, drinking water

Effect level:

20 other: mg/kg

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Remarks on result:

other: Result read-across CAS No. 96-33-3

Dose descriptor:

NOAEL

Remarks:

rat, 97 days, drinking water

Effect level:

84 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 141-32-2

Dose descriptor:

NOAEL

Remarks:

rat, 97 days, drinking water

Effect level:

111 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 141-32-2

Dose descriptor:

NOAEL

Remarks:

rat, OECD 422, gavage

Effect level:

150 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: general systemic toxicity: no adverse effects observed

Remarks on result:

other: Result read-across CAS No. 25584-83-2

Dose descriptor:

NOAEL

Remarks:

rat, OECD 422, gavage

Effect level:

15 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: local effects: irritation in forestomach and duodenum

Remarks on result:

other: Result read-across CAS No. 25584-83-2

Key result

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

40 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: inhalation

Remarks:

chronic and sub-acute toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please see for more information the read-across justification in Section 13.

Reason / purpose for cross-reference:

read-across source

Dose descriptor:

NOAEC

Remarks:

local effects / rat, 2 years

Effect level:

0.024 mg/L air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Key result

Dose descriptor:

NOAEC

Remarks:

systemic effects / rat, 2 years

Effect level:

0.024 mg/L air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Key result

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

2.4 mg/m³

Study duration:

chronic

Species:

rat

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

Please see for more information the read-across justification in Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Dose descriptor:

NOAEC

Remarks:

systemic effects / rat, 28 days

Effect level:

ca. 0.12 mg/L air (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Key result

Dose descriptor:

LOAEC

Remarks:

local effects / rat, 28 days

Effect level:

ca. 0.024 mg/L air (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other: Result read-across CAS No. 818-61-1

Remarks:

Correction for molecular weight not required.

Dose descriptor:

LOAEC

Remarks:

local effects / rat, dog, rabbit, 28 days

Effect level:

0.027 mg/L air (analytical)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: Local effects on the nasal mucosa and upper respiratory system.

Remarks on result:

other: Result read-across source CAS No. 25584-83-2.

Remarks:

Correction for molecular weight is not required.

Dose descriptor:

NOAEC

Remarks:

systemic effects / rat, dog, rabbit, 28 days

Effect level:

0.053 mg/L air (analytical)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: high dose

Remarks on result:

other: Result read-across source CAS No. 25584-83-2

Remarks:

Correction for molecular weight not required

Dose descriptor:

NOAEC

Remarks:

local effects / mouse, 28 days

Effect level:

0.027 mg/L air (analytical)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: eye irritation

Remarks on result:

other: Result read-across source CAS No. 25584-83-2.

Remarks:

Correction for molecular weight is not required.

Dose descriptor:

NOAEC

Remarks:

systemic effects / mouse, 28 days

Effect level:

0.027 mg/L air (analytical)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

Remarks on result:

other: Result read-across source CAS No. 25584-83-2.

Remarks:

Correction for molecular weight is not required.

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

24 mg/m³

Study duration:

subacute

Species:

rat

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

Data for 4-hydroxybutyl acrylate (4-HBA) and data from the structural analogues 2-hydroxyethyl acrylate (HEA, CAS No. 818-61-1) and hydroxypropyl acrylate (HPA, CAS No. 25584-83-2) are considered appropriate for the assessment.

Data for 4 -HBA CAS No. 2478 -10 -6 (combined OECD 408/422 by oral gavage):

4-HBA was administered daily as an aqueous solution to groups of 10 male and 10 female Wistar rats (F0 parental animals) and groups of 10 male and 10 female rearing animals by gavage at doses of 12, 40 and 120 mg/kg body weight/day (mg/kg bw/d). Control animals (10 male and 10 female Wistar rats (F0 parental animals and F1 rearing animals) were dosed daily with the vehicle only (drinking water). The dose selection was based on the results of 14 d range-finding studies (0; 50; 150; 200 and 600 mg/kg bw/d), the animals of the 600 mg/kg bw/d were sacrificed moribund / died prematurely, therefore, organ weights were not recorded. Significantly increased absolute and relative liver weights were described at 150 mg/kg bw/d and 200 mg/kg bw/d, dose-dependent adverse local effects to forestomach and stomach occurred at 150 mg/kg bw/d and higher.

The duration of treatment covered a 14 weeks in-life period in the males including premating, mating (mating pairs were from the same test group) and postmating period; a 10-weeks premating period, 3 days mating period, the entire gestation and approximately 4 weeks of lactation period in the females, approximately 3 weeks in-life period in the male rearing animals and 8 days in-life period in the female rearing animals.

After 10 weeks of premating treatment the F0 animals were mated to produce F1 generation pups. Mating pairs were from the same test group. Mating was discontinued as soon as sperm were detected in the vaginal smear. F0 animals were examined for their reproductive performance including determination of the number of implantation sites and the calculation of postimplantation loss for all F0 females.

A detailed clinical observation (DCO) was performed in all F0 animals before the start of the administration period and, as a rule, thereafter at weekly intervals for the F0 animals and F1 rearing animals. Water consumption of the F0 parents during premating and F1 rearing animals was determined once a week (over a period of 3 days). However, during gestation and lactation water consumption of the F0 females were determined on gestation days (GD) 0-1, 7-8, 13-14, and 19-20 and on postnatal days (PND) 1-2, 3-4, 6-7, 9-10, 12-13, 16-17 and 20-21. Food consumption of the F0 parents during premating and F1 rearing animals was determined once weekly. In dams food consumption was determined for GD 0-7, 7-14, 14-20 and PND 1-4, 4-7, 7-10, 10-13, 13-17 and 17-21. In general, body weights of F0 parents and F1 rearing animals were determined once weekly. However, during gestation and lactation F0 females were weighed on GD 0, 7, 14 and 20 and on PND 0, 1, 4, 7, 10, 13, 17 and 21. Estrous cycle data were evaluated for F0 generation females over a three weeks period prior to mating until evidence of mating occurred. Moreover, the estrous stage of each female was determined on the day of scheduled sacrifice. The pups were sexed and examined for macroscopically evident changes on PND 0. They were weighed on PND 1, 4, 7, 13 and 21. Their viability was recorded. At necropsy, all pups were sacrificed with CO₂under isoflurane anesthesia (except the selected pups for blood sampling) and examined macroscopically for external and visceral findings.

Anogenital distance (defined as the distance from the anus [center of the anal opening] to the base of the genital tubercle) measurements were conducted in a blind randomized fashion, using a measuring ocular on all live male and female pups on PND 1.All surviving male pups were examined for the presence or absence of nipple/areola anlagen on PND 12. If nipple/areola anlagen were recorded, all surviving male pups were carefully re-examined one day prior to necropsy (PND 20).

Blood samples were taken from all surplus pups at PND 4 as well as one male and one female pup per litter at PND 13 by decapitation under isoflurane anesthesia for hormone measurement. Clinico-chemical and hematological examinations were performed in 5 F0 animals per sex and group towards the end of the administration period. Blood samples from all dams at PND 14 and all F0 males at termination were taken by puncturing the retrobulbar venous plexus under isoflurane anesthesia for hormone measurement. Urine samples for clinical pathological investigations were withdrawn from all F0 parents. At the end of the administration period a functional observational battery was performed and motor activity was measured in 5 parental males and females per group. Various sperm parameters (motility, sperm head count, morphology) were assessed in the male F0 parental animals at scheduled sacrifice or after appropriate staining. All F0 parental animals were sacrificed by decapitation, under isoflurane anesthesia, and were assessed by gross pathology. Weights of selected organs were recorded and a histopathological examination was performed.

 

The following test substance-related relevant effects/findings were noted in the F0 parental animals at 120 mg/kg bw/d:

• Salivation after gavage dosing in all male animals during the entire study and in all female animals during premating, gestation and lactation period, and in 2 females during mating period
• Reduced prothrombin time in F0 males
• Decreased LDL-cholesterol in F0 males
• Increased inorganic phosphate values in males
• signs of erosion/ulcer in the forestomach one male and two females
• focal hyperplasia of the margo plicatus of four males and four females
• vacuolation of the hepatocytes in the periportal area of the liver of males

 

No test substance-related, adverse findings (also including macroscopically for external and visceral findings) were observed at F1 pups and rearing animals at 120 mg/kg bw/d. No test substance-related, adverse findings were observed in the F0 animals and F1 pups and rearing animals at 15 and 40 mg/kg bw/d.

 

In conclusion, under the conditions of the present OECD 408/422 combined repeated dose toxicity study with the reproductive/developmental screening test in Wistar rats the oral administration of 4HBA by gavage to male and female Wistar rats resulted in signs of systemic toxicity at a dose of 120 mg/kg bw/d, considering clinical pathological and pathological findings.

Thus, the no observed adverse effect level (NOAEL) for general systemic toxicity was the mid dose of 40 mg/kg bw/d for male and female Wistar rats. The NOAEL for fertility and reproductive performance was 120 mg/kg bw/d for male and female Wistar rats. The NOAEL for developmental toxicity was 120 mg/kg bw/d (BASF, 2022)

Data from the structural analogue 2-hydroxyethyl acrylate (HEA, CAS 818-61-1):

Repeated dose toxicity: Oral route  

A study according to OECD TG 422 for HEA is available(HARTF 2020b).

In this study HEA was administered daily to groups of 10 male and 10 female Wistar rats (F0 animals) by gavage at doses of 12, 40 and 120 mg/kg body weight/day (mg/kg bw/day, test groups 1-3, respectively) to screen for potential systemic, reproductive and developmental toxicity the substance administration resulted in signs of parental toxicity at the mid- and high-dose of 40 and 120 mg/kg bw/day, such as a combination of clinical signs and gastrointestinal pathology, being the consequence of the irritating properties of the test item. Thus, the NOAEL for general systemic toxicity was 40 mg/kg bw/day for male and female Wistar rats based on the reduced food consuption (lactation phase) and the significant increased liver weights and the NOAEL for local effects (gastrointestinal pathology) was 12 mg/kg bw/day. The NOAEL for reproductive performance and fertility was set to 120 mg/kg bw/day for male and female Wistar rats. The NOAEL for developmental toxicity was 120 mg/kg bw/day.

Groups of male and female Sherman strain rats (10/sex/group) were maintained for 100 days on a diet containing 0, 0.03. 0.1 or 0.3 % HEA (equivalent to doses of 0, 20, 65, and 196 mg/kg body weight/day for males and 0, 30, 102, and 305 mg/kg body weight/day for females) (Dow Chemical Co., 1967).  

Treatment did not cause any adverse effects as judged by general appearance and behaviour, growth, food consumption, serum, urea, nitrogen and alkaline phosphatase determinations, final average body and organ weights, organ/body weight ratios, and gross and microscopic examination of tissues. The NOAEL (systemic effects) for male and female rats was approx. 196 – 305 mg/kg bw/d (Dow Chemical Co., 1967). Groups of male and female Beagle dogs (2/sex/group) were maintained for 97 days on a diet containing 0.06, 0.2, or 0.4 % HEA in diet (equivalent to doses of 21, 60 and 125 and 22, 63 and 131 mg/kg body weight/day for males and females respectively). There was no evidence of adverse effects as judged by general appearance and behavior, weight gain, food consumption, hematological values, examination of bone marrow, urea nitrogen content and alkaline phosphatase activity in the serum, serum bromsulfophthalein, serum glutamic oxalacetic transaminase and serum glutamic pyruvic transaminase tests, final average body and organ weights, and gross and microscopic examination of tissues. The NOAEL (systemic effects) was approx. 125 -131 mg/kg bw/d.

Repeated dose toxicity: Inhalation route  

In a 4-week inhalation study (Dow Chem. Co., 1970) 15 to 20 male Sherman rats per group were exposed for 7 hours/day, 5 days/week to HEA vapours at concentrations of 0, 5, 10 or 25 ppm (corresponding to approx. 0.024, 0.048, and 0.120 mg/L) . Mean analytical concentrations were: 4.5 ± 1.1 ppm, 10.6 ± 1.4 ppm, and 22.5 ± 3.9 ppm. The duration of exposures was seven hours per day, five days per week for a total of twenty exposures. Interim sacrifices were performed on the 5 and 10 ppm groups after 2 weeks of exposure and on the 25 ppm animals after one week of exposure. All animals were subjected to a gross and microscopic examination irrespective of whether they died during treatment or were sacrificed at termination of treatment. Clinical signs of mild nasal irritation were observed at 10 ppm; concentrations of 25 ppm produced dyspnea and abdominal bloating which became more severe as the number of exposures increased. Histopathological examination found ulcerative keratitis (superficial loss of cornea with inflammation) in all groups exposed to HEA. Ulcerative keratitis appeared to be an HEA dose-related lesion with lesions in 14, 6, and 3 animals at levels of 25 ppm, 10 ppm and 5 ppm, respectively. Twenty exposures produced a higher incidence of corneal ulcers than 8 or 9 exposures at the 10 ppm and 5 ppm level. Focal ulcerative rhinitis (superficial loss of nasal epithelial tissue with inflammation) was observed in 7 and 4 rats in the 25 and 10 ppm exposure groups, respectively. This lesion was not present in the 14 days recovery rats on the above doses or in any 5 ppm and control rats.The higher incidence of chronic-active laryngitis in the HEA-exposed rats was interpreted as being compound-related at the 25 ppm and 10 ppm levels as was the chronic-active tracheitis at the 25 ppm, 10 ppm, and 5 ppm levels.There were 17 spontaneous deaths in the 25 ppm treatment group. Unfortunately due to the high incidence of chronic murine pneumonia in all groups (not treatment-related) it was impossible to characterize any lung pathology which might have been caused by exposure to HEA. At termination, mean body weights of rats exposed to 10 ppm for 20 days were significantly lower than controls. Relative weights of livers were higher for rats that were exposed to 10 and 5 ppm, relative kidney weight was increased at 10 ppm only. Testicular atrophy was observed histopathologically in one of 9 rats exposed to 10 ppm HEA for 20 exposures but was judged not to be treatment-related. No testicular atrophy was found in the highest exposure group. The lowest observed adverse effect concentration (LOAEC), based on severe local irritation effects (ulcerative keratitis and chronic-active tracheitis), was 5 ppm. No NOAEC was derived in this study.  

In a chronic inhalation study (Dow Chemical Co., 1979), male and female Sprague-Dawley rats (99 or 100 animals/ sex/dose group) were exposed to atmospheres containing 0 ppm (controls), 5.0 ppm (0.024 mg/L) or 0.5 ppm (0.0024 mg/L) 2-hydroxyethyl acrylate (HEA) for 6 hours/day, 5 days/week over an 18 month period, and subsequently held for a post-exposure period of 5 months (males) and 6 months (females). The study included 12-month interim sacrifices for pathologic and cytogenetic examinations. Haematology, blood chemistry and urine analysis were measured prior to the scheduled 12-month interim sacrifice, and again after 5 months of the post-exposure observation period. Histopathological examination was carried out for the all available tissues of the control and 5 ppm groups at interim and terminal sacrifice, and at 0.5 ppm terminal sacrifice limited evaluations were performed. Body weights, terminal organ weights and cumulative mortality, urinalysis, clinical chemistry and haematology did not appear to be altered by chronic HEA exposure. Overall treatment was not associated with adverse effects except that the rats in the 5 ppm treatment group developed yellow staining of the fur and a marginal increase in Mycoplasma-induced chronic murine pneumonia which was interpreted as being treatment-related. No treatment-related effects were seen in the 0.5 ppm group. Overall chronic inhalation exposure to HEA at a dose of 5 ppm caused only a minimal toxicological effect while no toxicity was seen at 0.5 ppm. Gross and histopathological examination of tissues showed no indication of significant chronic toxicity or a carcinogenic effect in either the 5 or 0.5 ppm treatment groups (Dow Chemical Co., 1979). The NOAEC was set at 0.0024 mg/L (nominal) based on an increased incidence, increased severity, and earlier onset of the lesions associated with the chronic murine pneumonia observed at the high dose level.    

Data from the structural analogue Methyl acrylate (MA, CAS 96-33-3):

Repeated dose toxicity: Oral route

Following a 3-month oral administration of methyl acrylate to the F344 rat in drinking water (0; 1, 5 and 20 mg/kg bw/d) slight decreases in body weight gain and water consumption were noted in both sexes receiving the highest dose. Also observed in the female rats at the highest dose was an increase in urinary specific gravity, probably as a result of decreased water intake and a slight but statistically significant increase in the mean relative kidney weight. All alterations seen in histology were typical of those occurring spontaneously in rats of this age and strain. The kidneys of male rats at the highest dose showed an increase in severity of a spontaneous renal disease normally seen in F344 rats. This alteration characterized by dilated renal tubules and eosinophilic cast formation, was observed in six of 10 males examined from the 20 mg/kg bw/day dose and in two of 10 male controls. This observation was also noted in 2 of 10 females at the highest dose and in none of the female controls. The increase in relative organ weights and the histopathological observations indicate that the highest dose may have had a slight effect on the kidneys. No other histopathological effects were seen, including the sex organs. The No Observed Adverse Effect Level (NOAEL) based on the effects seen at 20 mg/kg bw/day in this study was determined to be 5 mg/kg bw/day for male and female CDF Fischer 344 rats and the Lowest Observed Adverse Effect Level was 20 mg/kg bw/day (Dow 1981).

Repeated dose toxicity: Inhalation route

Ten Sprague Dawley rats/sex/group were exposed to 23, 124, 242 and 626 ppm; (0.082, 0.44, 0.86 and 2.24 mg/L) for 12 weeks, 5 day a week, 6 hours per day. The No Observed Adverse Effect Concentration (NOAEC) was 23 ppm (0.082 mg/L) (no clinical/chemical/haematological effect, no effect on body weight, organ weight and histology) and the Lowest Observed Adverse Effect Concentration (LOAEC) was 124 ppm (0.44 mg/L) (reduced body weight, reduced organ weights). At 242 ppm (0.860 mg/L), methyl acrylate caused transient respiratory and eye irritation at the beginning of exposure. At 626 ppm (2.24 mg/L), the animals exhibited laboured breathing, irritation of the mucosa, and hemorrhagic discharge from the eyes and nose that became increasingly severe. All animals of this dose group died during the first half of the study due to strong irritation (hyperemia in the trachea and lungs along with bronchopneumonia). Reduced body weight gain was seen to be treatment related in the 124-626 ppm groups (0.440 –2.24 mg/L). Increased relative lung and relative liver weights were observed in the 242 ppm group, and in the females of the 124 ppm group without detectable microscopic changes in these organs. Absolute organ weights of heart, liver, kidney and spleen were decreased in males of the 242 ppm dose group, absolute spleen weight of males was also reduced in the 124 ppm group. Keratinisation of the transition epithelium between respiratory and olfactory epithelium was observed, as well as degeneration and vacuolization of the olfactory epithelium at the histological examination of the 242 ppm and 626 ppm groups, but not in the 124 ppm group. No changes in blood chemistry were found, apart from a rise in sodium values and a drop in potassium values in the 242 ppm group (the 626 ppm group was not evaluated for blood chemistry due to lethality) (BASF AG 1978, 1980).

The test result from the sub-acute study is supported by data from the structural analogue hydroxypropyl acrylate (HPA, CAS 25584-83-2):  

Repeated dose toxicity: Oral route

Hydroxypropylacrylate was administered daily as an aqueous preparation to groups of 10 male and 10 female Wistar rats (F0 animals) by gavage at doses of 15, 50 and 150 mg/kg body weight/day (mg/kg bw/d). Control animals (10 male and 10 female Wistar rats) were dosed daily with the vehicle only (drinking water). The duration of treatment covered a 2-week premating and a mating period for both sexes, approximately 2 days post-mating in males, as well as gestation and lactation in females.

The following adverse treatment-related findings were noted at 150 mg/kg bw/d. Decreased food consumption in the females during the entire premating period (up to 7% below control). Minimal to slight thickening of the mucosa of the duodenum correlating to the macroscopically observed dilation in all male and 9/10 females. Focal hyperplasia of the duodenal mucosa in 1/10 female animals. Diffuse squamous hyperplasia of the forestomach in all male animals (graded slight or moderate) and in 7/10 female animals (graded minimal or moderate). Erosion/ulcer in the cranial part of the forestomach in 6/10 male and 2/10 female animals. At 50 mg/kg bw/d minimal thickening of the wall of the duodenum correlating to the macroscopically observed dilation in 2/10 male animals. Minimal diffuse squamous hyperplasia of the forestomach in 6/10 male and female animals. At 15 mg/kg bw/d no test substance-related adverse findings were observed. No test substance-related adverse findings were observed for the F1 generation.

Under the conditions of the present OECD 422 combined repeated dose toxicity study with the reproductive/developmental screening test in Wistar rats, the NOAEL (no observed adverse effect level) for general, systemic toxicity of Hydroxypropylacrylate was 150 mg/kg bw/d for male and female rats. Based on pathological findings characteristic of irritation in forestomach and duodenum in F0 parental rats of both sexes at 150 and 50 mg/kg as well as corresponding temporary reductions of food consumption in F0 females at 150 mg/kg bw/d a NOAEL of 15 mg/kg bw/d was determined for local effects in the gastrointestinal tract.

Repeated dose toxicity: Inhalation route

An inhalation study with rats, mice, rabbits and dogs was conducted with test substance (Dow Chemical Company 1983). Three groups of animals per species, consisting of 10 male Sprague-Dawley rats, 20 male Swiss-Webster mice, 4 malewhite rabbits, or 2 male beagle dogs, were used in the study. The animals were exposed (whole body) to test substance vapours at 0 (unexposed control), 5 ppm (0.027 mg/L) or 10 ppm (0.053 mg/L). Exposures were 6 hours/day, 5 days/week for a total of 21 exposures for the rats and mice and 20 exposures for rabbits and dogs. In the rat study, no mortality was observed. Five of 10 rats exposed to 10 ppm developed slight cloudiness of the cornea. No treatment-related decreases in mean body weights were found, and the absolute and relative organ weights were not affected. No treatment-related effects on the haematological measurements, the clinical chemistry measurements, or the urinalysis parameters were identified. At necropsy, focal corneal cloudiness was noted in 8 of 10 rats from the high exposure group suggesting an irritant effect. Histologically, a small increase in the number of animals with changes in the lungs at 10 ppm (subacute pneumonitis) and the nasal mucosa (both concentrations) was observed. No other treatment-related effects in the examined tissues were observed and no systemic toxicity was identified. The LOAEC was 5 ppm (0.027 mg/L) based on the local effects in the nasal mucosa. In the mouse study, no mortality was observed. Three of 20 mice exposed to 10 ppm, but none exposed to 5 ppm showed signs of eye irritation. No compound-related, statistically significant effects on mean body weights were found. However, the high dose mice showed slightly lower body weights during weeks 1, 3 and 4 of exposure (up to 4.5 % lower in week 1) which recovered during the weekend without treatment. No gross or histopathological changes related to exposure were observed. The NOAEC was 5 ppm (0.027 mg/L) based on the eye irritation observed at 10 ppm. In the rabbit study, no mortality was observed. All rabbits exposed to 10 ppm and 2 of 4 animals exposed to 5 ppm developed slight rhinitis and eye irritation (moderate conjunctivitis). No treatment-related effects on mean body weight were observed and all groups gained a similar amount of weight during the study. The absolute and relative organ weights were not affected. No treatment-related effects on the haematological measurements, or the clinical chemistry measurements were identified. Gross and histopathological changes related to exposure were found in the upper respiratory system (rhinitis, squamous metaplasia, and ulcerations), trachea and lungs (bronchitis, focal pneumonitis) of both hydroxypropyl acrylate exposure groups. The tracheal changes varied from no effect in some low dose animals to focal ulceration, squamous metaplasia and tracheitis in the high dose group. The most marked effects were seen in the upper respiratory system of all rabbits, especially those in the 10 ppm group that were characterized by mucopurulent rhinitis with squamous metaplasia and ulceration of the nasal turbinate mucosa. The LOAEC was 5 ppm (0.027 mg/L) based on effects on the upper respiratory system. In the dog study, no mortality was observed. During the exposures, both dogs exposed to 10 ppm lost body weight (from 2 to 10 %) and exhibited nasal irritation (exudative rhinitis) and eye irritation (bilateral corneal cloudiness, slight corneal edema, and bilateral suppurative conjunctivitis). The body weights showed some recovery during the weekends when no exposures occurred. One dog exposed to 5 ppm exhibited exudative rhinitis approximately half way through the study. At necropsy, exudative rhinitis, tracheitis, and suppurative bronchopneumonia were observed in all hydroxypropyl acrylate-exposed dogs. Microscopic lesions included suppurative rhinitis, squamous metaplasia and hyperplasia of the lining epithelium and focal area of ulceration in the mucosa of the nasal turbinates. These lesions extended to the trachea and lungs of the high exposure group resulting in bronchopneumonia. The LOAEC was 5 ppm (0.027 mg/L) based on effects on the upper respiratory system.

Data from the structural analogue n-butyl acrylate (n-BA, CAS 141-32-2):

Repeated dose toxicity: Oral route  

In a 13 week-study, F344-rats (15 animals per sex and dose) received butyl acrylate via drinking water in concentrations of 0, 0.015, 0.09 and 0.15 % (0, 12, 73, 84 mg/kg body weight per day for males and 0, 15, 91, 111 mg/kg body weight per day for females). A satellite group (5 male and 5 female rats) was given 150 mg/kg bw butyl acrylate (in corn oil) via gavage 5 days a week for 13 weeks (Dow Chemical 1980). The only effects reported were a slight reduction in water consumption, which occurred in all dose groups, and a decrease in weight gain for male rats in the highest dose group. No abnormal haematology, clinical chemistry, urinalysis, or histopathology findings were reported. In the gavage satellite group, the only effect observed was a slight increase in relative liver weight. The highest level administered in drinking water approaches the maximum solubility limit of butyl acrylate in water and thus was the highest concentration that could be reasonably given.The NOAEL for the drinking water study is 84 (male) and 111 (female) mg/kg body weight per day. 

Repeated dose toxicity: Inhalation route

Sprague Dawley rats (20 animals per sex and dose) were exposed by inhalation to measured concentrations of 0, 21, 108, 211 and 546 ppm (corresponding to approx. 0, 0.11, 0.57, 1.11, 2.86 mg/L) for 6 hours per day, 5 days/week for 13 weeks (BASF AG 1979, 1980). Clinical, clinico-chemical, haematological, gross-pathological, and histopathological examinations revealed no substance-related effects in the 21 and 108 ppm dose groups. At 211 ppm, the test substance caused eye irritation and irritation of the nasal mucosa. Significant reductions in body weight changes (13.3 %) were observed. In clinico-chemical examinations of females, decreased potassium values and an increase in alkaline phosphatase activity were observed. In the 546 ppm dose group, 31 of 40 animals (77 %) died. Hemorrhagic discharge from eyes and noses and severe dyspnoea were observed, which became constantly more severe. Many clinico-chemical and haematological parameters were affected in animals of this dose group. The animals died during exposure due to strong irritation of the respiratory tract. Metaplasia of the respiratory epithelium as far as the terminal bronchioles and proliferation of the bronchoalveolar epithelium could be detected in histopathological examinations.

The NOAEC for this study is 108 ppm (0.57 mg/L/day) and the LOAEC is 211 ppm (1.11 mg/L/day) based on body weight decrease, clinico-chemical changes, and changed organ weights. The NOAEC for local effects (histological changes in the nasal mucosa and olfactory epithelium) is 21 ppm (0.11 mg/L/day) and the LOAEC is 108 ppm (0.57 mg/L/day).

 

Repeated dose toxicity: Dermal route  

There are no experimental data available on subchronic and chronic toxicity of 4-hydroxybutyl acrylate and its structural analogues by the dermal route of exposure. But due to animal welfare reasons and since the substances are corrosive and moderate to strong skin sensitizers, no long-term testing by the dermal route is planned.    

Justification for classification or non-classification

Based on the available data, the test substance is not classified in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.