Acrylic acid

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1991

Reference 3

Reference Type:

secondary source

Title:

Chemical Hazards of the Workplace, Second Edition.

Author:

Proctor NH et al.

Year:

1988

Bibliographic source:

Science Information Resource Center, J. B. Lippincott Compagny

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Acrylic acid

EC Number:

201-177-9

EC Name:

Acrylic acid

Cas Number:

79-10-7

Molecular formula:

C3H4O2

IUPAC Name:

prop-2-enoic acid

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid, pure
- Analytical purity: 99.74%
- Impurities (identity and concentrations): Diacrylic acid 0.22%, Acetic acid 0.12%, Propionic acid 0.12%, the concentrations of other imputies were < 0.02%
- Test substance No.: 80/386

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Wiga GmbH, D-Sulzfeld
- Age at study initiation: 10 weeks old
- Weight at study initiation: mean weight 215 g
- Housing: Single in Makrolon/wire cages (type MD III supplied by Becker & Co., Castrop-Rauxel)
- Diet (ad libitum): SSNIFF R meal, Ssniff Versuchstierdiaeten GmbH, CH-Soest
- Water (ad libitum): Tap water

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 55 ± 5
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

Exposures were conducted using a continuous infusion pump (type Infu 362). Acrylic acid was metered into the inner coil of a glass evaporator heated by hot water. The acrylic acid vapours were diluted with a flow of fresh conditioned air with a flow meter. This mixture of acrylic acid vapour and air was passed through a glass cooler, thermostated cold water at 8-10°C being passed through its inner coil. The mixture of acrylic acid vapour and air was thus cooled to 23°C and passed to the exposure chambers (made of glass and steel, volume about 500 liters). The following amounts of test substance were used: 1.15 ml/h (study group 1, 40 ppm), 3.4 ml/h (study group 2, 120 ppm), 10.2 ml/h (study group 3, 360 ppm). The temperature in all exposure chambers was continuously monitored using NTC sensors and the measured values were recorded using a 12-channel printer.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration of acrylic acid in the exposure chambers was determined using a continuously operating total hydrocarbons analyzer equipped with a flame ionization detector.
Nominal concentrations (ppm): 40.7, 120.3, 361
Analytical concentrations (ppm): 39.4, 114.0, 356.2

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: 15.5 hours
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

from day 6 to day 15 of gestation

Frequency of treatment:

6 hours/day

Duration of test:

until day 20 of gestation

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

40 ppm

Remarks:

corresponding to approx. 0.12 mg/L. Recalculation based on the equation c(mg/m3) = molar mass (g) / molar volume (L) x c(mL/m3) with molecular weight (72.06 g/mol) and molar volume (24.1 L at 20 °C and 1013 hPa) [DFG, 2005]

Doses / concentrations 2

Dose / conc.:

120 ppm

Remarks:

corresponding to approx. 0.36 mg/L. Recalculation based on the equation c(mg/m3) = molar mass (g) / molar volume (L) x c(mL/m3) with molecular weight (72.06 g/mol) and molar volume (24.1 L at 20 °C and 1013 hPa) [DFG, 2005]

Doses / concentrations 3

Dose / conc.:

360 ppm

Remarks:

corresponding to approx. 1.08 mg/L. Recalculation based on the equation c(mg/m3) = molar mass (g) / molar volume (L) x c(mL/m3) with molecular weight (72.06 g/mol) and molar volume (24.1 L at 20 °C and 1013 hPa) [DFG, 2005]

No. of animals per sex per dose:

30

Control animals:

yes, sham-exposed

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: not specified

DETAILED CLINICAL OBSERVATIONS: Yes
Prior to the exposure period, animals were observed for clinical signs once daily. Preceding and following each exposure, individual does were observed for clinical signs of toxicity.

BODY WEIGHT: Yes
- Time schedule for examinations: On gestation day 0, 3, 6 9 12, 15, 18 and 20

FOOD CONSUMPTION: Yes
- The feed consumption by each animal was determined on gestation day 0, 3, 6 9 12, 15, 18 and 20

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: The uteri and ovaries were removed. The uteri were weighed. The number of corpora lutea, implantation sites for each hern of the uterus, dead and live implatations and fetuses were determined.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

Living fetuses were weighed, sexed, and examined for externally detectable changes. In addition, attention was paid to the viability of the fetuses, the length of the umbilical cord and the condition of the fetal membranes and amniotic fluid. One-third of the fetuses of each dam were fixed in Bouin's solution and examined for internal soft tissue changes. In order to assess the skeletal system, two-thirds of the living fetuses of each dam were initially fixed in 96% alcohol, then clarified with potassium hydroxide solution and stained with Alizarin red S. The fetuses were stored in 100% glycerol.

- External examinations: Yes: all per dam
- Soft tissue examinations: Yes: one-third per dam
- Skeletal examinations: Yes: two-thirds per dam

Statistics:

Quantitative continuous random variables, eg. body weight data or food consumption data, were examined with the Williams test. Discrete random variables, eg. number of corpora lutea, number of implantations, or percentage values, such as live fetuses as a percentage of total implantations, fetuses with anomalies (or variations, retardations) as a percentage of total fetuses investigated, were examined with a linear rank test of Krauth. The Fisher test was used for the comparison of frequencies, eg. number of litters with anomalies (or variations, retardations) in relation to the number of litters investigated. All tests were performed with type I error of = 0.05 and = 0.01. The linear rank test and the Fisher test were carried out with a Bonferroni correction, but including additional information. If the Bonferroni corrected test did not show any significance for = 0.05, the comparison was calculated with uncorrected = 0.05. The linear rank test and the Fisher test were calculated by counting all possible permutations.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

The animals in groups 0, 1 and 2 showed no signs of behavior differing from normal during the period of exposure. Starting with the 1st exposure, the animals in group 3 showed pronounced watery discharge from the eyes and nose, and there was occasional wiping of their snouts and restless behavior. The signs disappeared rapidly after each exposure so that the animals were normal again after 1 - 2 hours.

Mortality:

no mortality observed

Description (incidence):

No animal died in any group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weights and the body weight gains of the pregnant animals in groups 1 and 2 (40 ppm and 120 ppm) show, compared to the control group, no relevant differences which could be attributed to an effect of the substance.
An effect of the substance of the nature of a significantly (99% significance) Lower body weight, and an appropriate adverse effect on the body weight gain, was noticeable in group 3 (360 ppm) during the exposure period (6th - 15th day of gestation). After the end of the period of exposure to acrylic acid, the pregnant animals in all groups increased in weight to the same extent (no adverse effect on the body weight gain), but the body weights of the animals in group 3 (360 ppm) remained significantly (99% significance) Lower than in the control group up to the Last day of the observation period (20th day of gestation). Thus, a marked toxic effect on the dams due to inhalation of acrylic acid was demonstrated in the group at the highest concentration (360 ppm).

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

The feed consumption of the animals in groups 1 and 2 (40 ppm and 120 ppm) did not differ from the control group over the entire period of the study. A marked effect of exposure to acrylic acid was detected at the highest concentration (360 ppm) in group 3. The feed consumption was lower, with 99% significance, during the exposure period (6th - 15th day of gestation), but no effect of this type was detectable in the follow up observation period.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

At the highest dose group smaller difference between body weight and uterus weight was reported.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No pathological changes which could be attributed to the inhaled substance were found on macroscopic examination of the internal organs of the animals.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

no effects observed

Details on maternal toxic effects:

Indications of a toxic effect on the dams emerged at 120 ppm (decreased consumption of feed during the exposure phase and a smaller difference between the body weight and uterus weight after necropsy). A marked toxicity on the pregnant animals was detected at 360 ppm (lower body weight, body weight gain slowed down, decreased consumption of feed, smaller difference between body weight and uterus weight, and clinical signs of an irritant effect caused by acrylic acid vapours).

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEC

Effect level:

0.12 mg/L air (nominal)

Basis for effect level:

other: maternal toxicity

2

Key result

Dose descriptor:

LOAEC

Effect level:

0.36 mg/L air (nominal)

Basis for effect level:

other: maternal toxicity

Maternal abnormalities

Key result

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Although the dams lost weight, no negative effect on the fetal weight was seen. In fact, the fetuses in the 120 ppm and 360 ppm groups were heavier, but this is very probably an incidental finding.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

not examined

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No significant difference between the groups was found.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No significant difference between the groups was found.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No significant difference between the groups was found.

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEC

Remarks:

teratogenicity

Effect level:

>= 1.08 mg/L air (nominal)

Basis for effect level:

other: highest dose tested

Fetal abnormalities

Key result

Abnormalities:

no effects observed

Overall developmental toxicity

Key result

Developmental effects observed:

no

Any other information on results incl. tables

ANlMALS WITH CESAREAN SECTION

	Group 0 0 PPM	Group 1 40 PPM	Group 2 120 PPM	Group 3 360 PPM
Number of Animals	25	27	26	25
CORPORA LUTEA
Total	424	430	437	410
M	16.96	15.93	16.81	16.40
ME	16.00	16.00	16.00	17.00
QD	2.00	2.00	1.63	1.50
K (A)
IMPLANTATIONS
Total	324	337	324	310
M	12.96	12.48	12.46	12.40
ME	14.00	14.00	13.50	14.00
QD	3.00	2.00	2.63	2.50
K (A)
LIVE FETUSES
Total	298	319	309	292
M	11.92	11.81	11.88	11.68
% IMPLANTATIONS/P.ANIMAL
M	93.10	93.21	95.66	90.70
ME	100.00	100.00	100.00	93.33
QD	6.97	3.85	3.39	4.55
K (A)
DEAD IMPLANTATIONS
Total	26	18	15	18
M	1.04	0.67	0.58	0.72
% IMPLANTATIONS/P.ANIMAL
M	6.90	6.79	4.34	9.30
ME	0.0	0.0	0.0	6.67
QD	6.97	3.85	3.39	4.55
K (A)
Resorptions Early (Salewski)	0	0	0	0
Resorptions Early	24	14	13	17
Resorptions Intermediate	1	3	2	0
Resorptions Late	1	1	0	0
Dead Fetuses	0	0	0	0

 Symbols

+/++ = Level of Significance 5%/1% in Relation to group 0

Uterus an Body weight of Pregnant Animals

		Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Uterus	N	25.00	27.00	26.00	25.00
	MV	64.40	65.74	67.54	65.32
	SD	18.76	25.51	23.61	21.14
	SE	3.75	4.91	4.63	4.23
BWS	N	25.00	27.00	26.00	25.00
	MV	216.38	216.00	213.82	215.24
	SD	9.36	11.34	7.70	9.85
	SE	1.87	2.18	1.51	1.97
BWE	N	25.00	27.00	26.00	25.00
	MV	354.33	348.90	345.93	332.61
					**
	SD	19.94	33.27	26.98	26.08
	SE	3.99	6.40	5.29	5.22
BWE-Uterus	N	25.00	27.00	26.00	25.00
	MV	289.93	283.15	278.39	267.30
				**	**
	SD	12.03	17.77	16.57	13.36
	SE	2.41	3.42	3.25	2.67
BWE-BWS-Uterus	N	25.00	27.00	26.00	25.00
	MV	73.56	67.15	64.57	52.06
			*	**	**
	SD	11.45	11.18	13.06	9.54
	SE	2.29	2.15	2.56	1.91

 Key                             Test Group      Significance 95 %        Significance 99%

Analysis of Trend                    0                                 *                                 **

Uterus an Body weight of Non-Pregnant Animals

		Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Uterus	N	5.00	3.00	3.00	4.00
	MV	1.00	1.00	1.00	1.50
	SD	0.0	0.0	0.0	0.0
	SE	0.0	0.0	0.0	0.5
BWS	N	5.00	3.00	3.00	4.00
	MV	214.50	208.57	213.67	217.10
	SD	4.25	15.31	6.70	3.52
	SE	1.90	8.84	3.87	1.76
BWE	N	5.00	3.00	3.00	4.00
	MV	255.88	242.70	247.00	251.02
	SD	20.93	10.91	3.96	7.94
	SE	9.36	6.30	2.29	3.97
BWE-Uterus	N	5.00	3.00	3.00	4.00
	MV	254.88	241.70	246.00	249.52
	SD	20.93	10.91	3.96	7.11
	SE	9.36	6.30	2.29	3.56
BWE-BWS-Uterus	N	5.00	3.00	3.00	4.00
	MV	40.38	33.13	32.33	32.42
	SD	18.43	6.95	7.92	7.05
	SE	8.24	4.01	4.57	3.52

 Key                             Test Group      Significance 95 %        Significance 99%

Analysis of Trend                    0                                 *                                 **

Findings in Fetuses: Cesarean Section

	Group 0 0 PPM	Group 1 40 PPM	Group 2 120 PPM	Group 3 360 PPM
Fetuses Investigates	298	319	309	292
Litters Investigated	25	27	26	24
Anomalies
Litters	0	1	0	0
(% Litters)	0.0	3.70	0.0	0.0
F (E)
Fetuses	0	1	0	0
(% Fetuses / Litter)
M	0.0	0.25	0.0	0.0
ME	0.0	0.0	0.0	0.0
QD	0.0	0.0	0.0	0.0
K (E)
Variations
Litters	0	0	0	0
(% Litters)	0.0	0.0	0.0	0.0
F (E)
Fetuses	0	0	0	1
(% Fetuses / Litter)
M	0.0	0.0	0.0	0.42
ME	0.0	0.0	0.0	0.0
QD	0.0	0.0	0.0	0.0
K (E)
Retardations
Litters	0	0	0	0
(% Litters)	0.0	0.0	0.0	0.0
F (E)
Fetuses	0	0	0	0
(% Fetuses / Litter)
M	0.0	0.0	0.0	0.0
ME	0.0	0.0	0.0	0.0
QD	0.0	0.0	0.0	0.0
K (E)	0.0	0.0	0.0	0.0

 Symbols

+/++ = Level of Significance 5%/1% in Relation to group 0

 

Findings in Fetuses: Cesarean Section

Anomalies

		Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Litters		25	27	26	24
Fetus Investigated		298	319	309	292
Head	BI		1

 

Findings in Fetuses: Cesarean Section

Variations

		Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Litters		25	27	26	24
Fetus Investigated		298	319	309	292
LIMBS	PAB				1

 

 

Findings in Fetuses: Cesarean Section

Retardations

	Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Litters	25	27	26	24
Fetus Investigated	298	319	309	292

 

Mean Litter Data

			Test Group 0 0 PPM	Test Group 1 40 PPM	Test Group 2 120 PPM	Test Group 3 360 PPM
Fetuses Males			145.00	140.00	149.00	133.00
Fetuses Females			153.00	179.00	160.00	159.00
Fetuses Total			298.00	319.00	309.00	292.00
Weight	Males	N	24.00	26.00	25.00	24.00
		MV	3.60	3.77	3.83	3.83
					*	*
		SD	0.29	0.25	0.45	0.28
		SE	0.06	0.05	0.09	0.06
	Females	N	25.00	27.00	24.00	24.00
		MV	3.42	3.51	3.62	3.70
					*	**
		SD	0.26	0.27	0.30	0.26
		SE	0.05	0.05	0.06	0.05
	Total	N	25.00	27.00	26.00	24.00
		MV	3.51	3.63	3.77	3.76
					**	**
		SD	0.27	0.23	0.46	0.26
		SE	0.05	0.04	0.09	0.05
Runts	Total		3.00	1.00	2.00	0.0

 Key                             Test Group      Significance 95 %        Significance 99%

Analysis of Trend                    0                                 *                                 **