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Evaluation of acute immunotoxicity of alachlor in male F344/N rats.
Henningsen-GM; Biagini-RE; MacKenzie-BA; Sanderson-WT; Robertson-SK; Baumgardner-ES
Toxicologist 1992 Feb; 12(1):178
Alachlor (2-chloro-2', 6' -diethyl-N-[methoxymethyI] acetanilide) is one of the most commonly used herbicides in the United States for pre-emergence control of broadleaf weeds and grass. The EPA classifies alachlor as a suspected human carcinogen due to sufficient evidence of cancer in exposed laboratory animals. Epidemiological evidence of carcinogenicity and data on potential immunotoxic effects of alachlor in animal models do not exist. Since chemical-induced immune dysfunction has been associated with increased cancers and/or infectious diseases in laboratory animals, the potential immunotoxicity of alachlor was studied with a multiple immunoassay model in 9-week old male F344/N rats. Evaluations were made of humoral immunity, cell-mediated immunity, natural killer cell activity, and hematologic and immunopathologic effects. Groups of rats [9-12 per group) were injected (ip) on days -1, 6 and 13 of the 14-day multiple-assay study. Group 1 (vehicle control) received 10 ml/kg propylene glycol; groups 2-4 (test treatments) received alachlor in 10 ml/kg propylene glycol at 1.25, 2.5 or 3.75 mg/kg; group 5 (positive control) received dexamethazone in 10ml/kg physiological saline (PS) at 1 mg/kg; and group 6 (PS control) received 10ml/kg PS. The results showed that alachlor had no statistically significant toxic effects (compared to the vehicle controls) for any of the immunologic, hematologic, or pathologic endpoints evaluated. Minor vehicle-related effects occurred. Doses used in this study were 25%, 50% and 75% of the acute (4-hr) LD100 dose of 5 mg/kg reported for Wistar rats receiving single ip injections (in propylene glycol). These findings suggest that alachlor has minimal potential to cause immunotoxicologic effects which could contribute to alachlor's carcinogenic effects in F344 rats.
Immunotoxins; Immune-reaction; Cancer; Cancer-rates; Animal-studies; Animals; Carcinogenicity; Carcinogens; Immune-system-disorders; Chemical-reactions; Cellular-reactions; Immune-system; Dose-response; Herbicides; Laboratory-animals
Issue of Publication
The Toxicologist. Society of Toxicology 31st Annual Meeting, February 23-27,1992, Seattle, Washingtion