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EC number: 215-304-0 | CAS number: 1320-51-0
There are Klimisch 1 validity studies for skin and eye irritation, both of which showed mild irritation, which in the skin was despite the use of a protocol with 24 hour occluded exposure rather than the 4 hour period typically. There is no specific testing for respiratory irritation but there is an acute inhalation toxicity study.
Table 1: Individual scoring for 100% test material (containing 57.58% hydroxyethyl urea) tested on intact skin
Scoring interval after patch removal
The skin irritation potential of the test substance EXP 3982 N-2-hydroxyethylurea containing 57.58% of the active ingredient hydroxyethyl urea was studied under GLP in accordance with OECD TG 404. Six healthy male rabbits of the New Zealand White strain (11 to 12 weeks old, weighing 2.4 to 2.7 kg) were used in the study. The treatment area was clipped 24 hours prior to the start of the experiment. The pure test substance (57.58% hydroxyethyl urea) and a 52% aqueous solution (30% hydroxyethyl urea) were applied topically on areas of intact and abraded skin under occlusion for a duration of 24 hours, which is longer than the normal exposure duration of 4 hours given in the guideline. Each animal was treated on four sites. The skin surface area treated per site was approximately 6.5 cm2. The patches were removed after 24 hours and remaining test material was wiped off. Scoring of the skin reaction according to Draize (1959) was performed 1, 24, 48 and 72 hours and up to 10 days after removal of the patches. The scores of individual animals for erythema/eschar and oedema were up to 1 at individual ratings 24, 48 and 72 hours after patch removal. All skin reactions were fully reversible within 10 days. The test substance was non-corrosive. No other effects related to treatment were observed. Hydroxyethyl urea is not classified as a skin irritant based on GHS criteria.
Individual scores at 1 h
Cornea score: 0 for all animals
Iris score: 0 in three males, 1 in three females
Conjunctivae score: 1 in all animals
Chemosis score: 1 in all animals
Individal mean scores at 24, 48 and 72 h
Iris score: 0 in three males and two females, 1/3 in one female
Conjunctivae score: 1/3 in two males and one female, 2/3 in two females, 1 in one male
Chemosis score: 0 in one male and one female, 1/3 in two males and two females
The potential irritant and/or corrosive effects of the aqueous solution EXP 3982 N-2-hydroxyethylurea containing 57.58 % of the active ingredient hydroxyethyl urea were evaluated under GLP on the eyes of New Zealand White rabbits in accordance with OECD TG 405. Each of six rabbits received a 0.1 mL dose of the aqueous solution in the conjunctival sac of the right eye. The contralateral eye of each animal remained untreated and served as a control. Test and control eyes were examined for signs of irritation for up to 7 days following dosing.
Exposure to the test article produced iritis in 3/6 test eyes at the 1-hour socring interval which resolved completely in all test eyes by the 48-hour scoring interval. Effects on the conjunctivae (redness, swelling and/or discharge) were noted in 6/6 test eyes at the 1-hour scoring interval. The conjunctival irritation resolved completely in all test eyes by study day 7.
EXP 3982 N-2-hydroxyethylurea is considered to be a mild irritant to the ocular tissue of the rabbit. It does not have to be classified for eye irritation according to Regulation (EC) 1272/2008 (CLP) /GHS.
The available information for skin and eye irritation in rabbits indicates that hydroxyethyl urea is a mild irritant to eyes and to skin with prolonged exposure. We have no test specifically for irritation of the respiratory tract; the acute inhalation toxicity test in rats did not indicate any specific symptoms of respiratory irritation. Some red foci were observed in the lungs of some animals at all treatment levels, by when examined histologically on the third phase of the experiment they were not haemorrhages and not confirmed as related to treatment. They are therefore not necessarily an indication of irritation. The limited information from the acute inhalation toxicity study in rats does not report any specific signs of respiratory irritation, in a study which has the complication of a the presence of ca. 1.5% of ammonium lactate in the solution which is not present in the test substance used in the other toxicology studies.
The rabbit skin and eye irritations studies only showed mild irritation even after prolonged skin contact. The available information on respiratory irritation from the acute inhalation study does not indicate any serious irritation. Based on these studies there is no requirement to classify hydroxyethyl urea for skin or eye irritation according to the EU CLP criteria.
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