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DL-LACTONE CAS N°:79-50-5 - page 76 / 113

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OECD SIDS 5. TOXICITY

76

DL-LACTONE

ID: 79-50-5 DATE: 18.01.2006

considered, but a negative test result was anticipated that still would have to be confirmed in an in-vivo study. Since no severe harm for the animals was to be expected, this in-vivo skin irritation study was performed and was started by treatment of a single rabbit (sentinel). The two other animals were treated in a similar manner three weeks later, after considering the degree of skin irritation observed in the first animal. Approximately 24 hours before treatment, the dorsal fur was clipped with electric clippers, exposing an area of approximately 150 square centimeters (10x15 cm²). Whenever considered necessary the treated skin areas were re-clipped at least 3 hours before the observations, to facilitate scoring. A health inspection was performed prior to the commencement of treatment, to ensure that the animals were in a good state of health. Special attention was paid to the skin to be treated, which was intact and free from abnormalities. Each animal was treated by dermal application of 0.5 grams of the test substance. The test substance was moistened with 0.1 ml of the vehicle and applied to the skin of one flank, using a Metalline (Lohmann GmbH, Neuwied, Germany) patch of 2x3 cm. The patch was mounted on Micropore (3M, St. Paul, Minnesota, USA) tape, which was wrapped around the abdomen and secured with Coban (3M, St. Paul, Minnesota, USA) elastic bandage. Four hours after the application, the dressing was removed and the skin cleaned of residual test substance using water.

Observations Mortality/viability: Twice daily. Signs of overt toxicity: At least once daily. Body Weight: Day of treatment (prior to application) and at termination. Irritation: The skin reactions were assessed at approximately 1, 24, 48 and 72 hours after the removal of the dressings and test substance. The irritation scores and a description of all other (local) effects were recorded. Adjacent areas of the untreated skin of each animal served as controls. The irritation was assessed according to the following numerical scoring system. At each observation, the highest scores given

were recorded: Erythema and eschar formation: No erythema.............................

......0

Very slight erythema (barely perceptible).....1 Well-defined erythema.........................2 Moderate to severe erythema...................3 Severe erythema (beet redness)................4 (Where signs of necrosis or corrosion (injuries in depth) prevent erythema scoring, the maximum grade for erythema (= 4)

is given.) Oedema formation: No oedema.......................

..............0

Very slight oedema (barely perceptible).......1 Slight oedema (edges of area well-defined by

definite raising).

............................2

Moderate oedema (raised approximately 1 millimeter).................................3 Severe oedema (raised more than 1 millimeter and extending beyond the area of exposure)....4

Histopathology

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