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Description of key information

An LD50 of 2996 mg/kg bw was estimated for acute toxicity via the oral route following a 15-day in vivo study in rats administered 2-butoxyethyl methacrylate at a dose range of 1000 - 8000 mg/kg bw. Mortality at 10, 50, 70, and 90 % was reported for 1000, 3000, 5000, and 8000 mg/kg bw respectively. Considerable change to rat behaviour and outward appearance was recorded at all doses as well as internal macroscopic organ change from 3000 mg/kg bw 2-butoxyethyl methacrylate.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 10, 1984
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
Version: May 12, 1981; Guideline 401 removed on December 17, 2002
GLP compliance:
(See Bundesanzeiger Nr. 42a, March 2, 1983, FRG)
Test type:
standard acute method
Limit test:
Specific details on test material used for the study:
- Expiration date of the lot/batch: September 1984
-Stability of test material in dilution: more than 2 hours

KFM-Han (outbred, SPF-Quality)
Details on test animals and environmental conditions:
- Source: Wistar rats (20 males and 20 females per group) were obtained from Kleintierfarm Madoerin AG, CH 4414 Fuellinsdorf / Switzerland
- Age at study initiation: 8 - 11 weeks at experiment start
- Weight at study initiation: Males: 166 - 247 g; Females 159 - 185 g
- Housing: Groups of five in Makrolon type-3 cages with standard softwood bedding ("Lignocel", Schill AG, Switzerland)
- Diet: Pelleted standard Kliba 343, Batch No. 4/84 and 98/84 rat maintenance diet ('Kliba', Klingentalmuehle AG, Switzerland) ad libitum
- Water: Community tap water from Itingen ad libitum
- Acclimation period: At least five days under test conditions, after veterinary examination
- Randomisation: Computer-generated random algorithm

- Temperature (°C): 22 ± 2 °C
- Relative humidity (%): 55 ± 10 %
- Air changes (per hr): Air-conditioned with 10 - 15 air changes / hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light / 12 hours dark and at least 8 hours music/light period
- Other: Hourly monitored environment
Route of administration:
oral: gavage
CMC (carboxymethyl cellulose)
(2 % solution of CMC, visc. 100 CPS, Fluka AG, Buchs / Switzerland in distilled water)
Details on oral exposure:
- Concentration in vehicle (application volume / kg body weight): 10 ml at 1000 mg/kg bw; 20 ml at 3000 mg/kg bw; 20 ml at 5000 mg/kg bw; 20 ml at 8000 mg/kg bw

DOSAGE PREPARATION: The test article was placed into a glass beaker on a tared Mettler PK 4800 balance and the vehicle (2 % solution of CMC, carboxymethylcellulose natriumsalt purum, visc. 100 CPS, Fluka AG, Buchs / Switzerland in distilled water) was added. A weight by volume suspension was prepared using a homogeniser (Ultra-Turrax, Janke and Kunkel, Staufen, FRG). Homogeneity of the test article in the vehicle was maintained during treated using a magnetic stirrer (Auer-Bittmann, Switzerland). The preparations were made immediately prior to each dosing

10 ml at 1000 mg/kg bw, 20 ml at 3000 mg/kg bw, 20 ml at 5000 mg/kg bw, and 20 ml at 8000 mg/kg bw via oral gavage after being fasted for 12 - 18 hours (access to water was not interrupted)
No. of animals per sex per dose:
5 males and 5 females per group
Control animals:
Details on study design:
- Duration of observation period post-administration: Observation period of 15 days
- Frequency of observations and weighing: Mortality, viability and any change in appearance and general behaviour were recorded four times during test day 1 and daily during days 2 - 15. Specifically, animals were checked for symptoms related to general behaviour, respiration, the eyes, the nose, motility, body position, motor susceptibility, the skin, and various other (e.g. emaciation, salivation)
- Necropsy of survivors performed: All animals were necropsied following anesthetisation by intraperitoneal injection of sodium pentobarbital and death by exsanguination
- Other examinations performed: Body weight observed on days 1 (pre-administration) and 8 and 15
The LOGIT-Model (COX, Analysis of Binary Data, London 1977) was applied to estimate the LD50 value. Additionally, the 90, 95, and 99 % confidence intervals for the LD50 for each sex and the slope of the concentration response line was estimated.
Key result
Dose descriptor:
Effect level:
2 996 mg/kg bw
Based on:
other: Logit estimation
Dose descriptor:
Effect level:
1 505 mg/kg bw
Based on:
other: Logit estimation
Dose descriptor:
Effect level:
5 697 mg/kg bw
Based on:
other: Logit estimation
1000 mg/kg: 1 female (day 6); 3000 mg/kg: 5 females (day 2 - 4); 5000 mg/kg: 2 males (day 3 - 5) and 5 females (day 2 - 5); 8000 mg/kg: 4 males (day 2) and 5 females (day 2 - 3)
Clinical signs:
1000 mg/kg: Sedation, dyspnea, curved body position, ruffled fur, reddened urine (females);
3000 mg/kg: Sedation, dyspnea, ataxia, ventral body position, latero-abdominal position, curved body position, ruffled fur, pallor, reddened urine;
5000 mg/kg: Sedation, coma (males), dyspnea, chromodacryorrhea, ataxia, ventral body position, latero-abdominal position, curved body position, ruffled fur, pallor, reddened urine;
8000 mg/kg: Sedation, dyspnea, exophthalmos, ataxia, ventral body position, latero-abdominal position, curved body position; ruffled fur, pallor (males), reddened urine
Body weight:
1000 mg/kg: No loss of weight in males; weight loss in 1 female
3000 mg/kg: Weight loss in 3 males; All females dead
5000 mg/kg: Loss of weight in all surviving males; All females dead
8000 mg/kg: Loss of weight in all surviving males; All females dead
Gross pathology:
Changes reported for deceased rats (all killed rats exhibited no macroscopic change):
1000 mg/kg: Death due to cannibalism;
2000 mg/kg: Liver light discoloured (1), liver pale (3), intestines reddened (1), small intestines reddish discoloured (3), urine reddened, severe (1), urinary bladder filled with brown to red fluid (3), severe autolysis (1);
3000 mg/kg: Lung mottled, slight (2), lung mottled (1), liver mottled, slight (3), liver light discoloured (3), liver light discoloured, partly black (1), intestines reddish discoloured (3), intestines reddish (1), intestines reddened, slight (1), intestines, meteorism, filled with reddish fluid (1), stomach/intestines, meteorism, partly, filled with reddish fluid (1), urine dark-red discoloured, severe (3), urine red (1), urine reddened, slight (1), testes whitish (1);
8000 mg/kg: Lung mottled, slight (9), liver light, discoloured (1), intestines reddish discoloured, filled with dark-red contents (9), urine, severe dark-red (9)
Interpretation of results:
GHS criteria not met
An in vivo study was performed to determine the oral toxicity of 2-butoxyethyl methacrylate in rats at doses of 1000, 3000, 5000, and 8000 mg/kg bw. Exposure resulted in mortalities of 10, 50, 70, and 90 %, respectively. Considerable clinical symptoms, namely to outward appearance and behaviour, and to internal organs (following necropsy) were reported during the 15-day observation period. An LD50 of 2996 mg/kg bw was estimated for both sexes using the Logit Model.
Executive summary:

To determine the acute toxicity of 2-butoxyethyl methacrylate via the oral route, a 15-day experiment was conducted according to Good Laboratory Practise (GLP) and OECD Guideline 401 (Acute Oral Toxicity).

2-butoxyethyl methacrylate was administered to Wistar rats (half male, half female) by oral gavage at a single dose of 1000, 3000, 5000, or 8000 mg/kg bw after being fasted for a 12 - 18-hour period. The test article was delivered in a vehicle of 2 % solution of carboxymethylcellulose natrium salt purum in distilled water (10 ml at 1000 mg/kg bw; 20 ml at 3000, 5000, and 8000 mg/kg bw), which was prepared immediately prior to each dosing. Observations of mortality / viability and change in behaviour and appearance were made at four points on day 1 and daily from days 2 - 15. Body weight was recorded on day 1 (pre-administration) and on day 8 and 15. All animals were necropsied to establish whether any internal organ alteration had occurred at the macroscopic level.

A number of toxicity symptoms related to appearance and behaviour were evident at all doses, including (but not limited to) sedation, ataxia, altered body position, weight loss, and reddened urine. Macroscopic organ changes were apparent at 3000 - 8000 mg/kg bw following necropsy, particularly with regards to discolouration of the urine and the liver, intestines, and bladder (reddish to dark-red). Mortality rates of 10 % at 1000 mg/kg bw, 50 % at 3000 mg/kg bw, 70 % at 5000 mg/kg bw, and 90 % at 8000 mg/kg bw were observed. Logit estimation was used to calculate an LD50 of 2996 mg/kg bw for 2-butoxyethyl methacrylate. A separate LD50 of 5697 and 1505 mg/kg bw was determined for males and females respectively. Although the mixed sex LD50 is greater than the 2000 mg/kw bw threshold outlined in CLP Regulation (EC) No. 1272/2008 for Category 4, the registered substance should be regarded as having relatively low acute toxicity with the potential to cause harm to a vulnerable portion of the population under certain conditions. 2-butoxyethyl methacrylate has been classified as a Category 5 acutely toxic substance under GHS (2011) criteria.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
2 996 mg/kg bw

Additional information

The endpoint conclusion established for acute oral toxicity was obtained in a key study undertaken in line with Good Laboratory Practise (GLP) and OECD Guideline 401 (Acute Oral Toxicity) and it has been regarded as a suitable basis for human risk assessment.

Justification for classification or non-classification