Evaluation of the carcinogenic risk of the phenoxyherbicide MCPA to an urodele amphibian.
To evaluate the carcinogenic potential of the phenoxyherbicide 2-methyl-4-chlorophenoxy-acetic acid (MCPA) in the crested newt, Triturus cristatus carnifex, a long-term study has been carried out exposing the animals by the percutaneous route. Two hundred adult newts were divided into one control and three experimental groups of 20 females and 30 males each. The control group was kept in tap water and the experimental groups were kept for 4 days a week in an aqueous solution of Agroxone 3, a commercial formulation of MCPA, at concentrations equivalent to 100, 200, and 400 ppm of the active ingredient. Treatment was continued for 1 year, after which all the animals were kept under observation for approximately another year. Surviving female newts were killed 22-24 months after the beginning of experimentation, whereas the male newts were killed after 28 months, at the end of 18 weeks of exposure to the tumour promoter 12-O-tetradecanoylphorbol-13-acetate. Under experimental conditions, there was no carcinogenic activity of MCPA. Putative preneoplastic nodules of the liver and tumor-like lesions of the lower jaw were occasionally observed among the animals that survived more than 22 months after the beginning of experimentation. However, no significant differences in frequency between control and experimental groups were found.
Zavanella
T
T
Department of Biology, University of Milan, Italy.
Pacces Zaffaroni
N
N
Arias
E
E
D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000633:toxicity*; D000818:Animals; D002273:Carcinogens; D005260:Female; D006016:Glycolates / Q000633:toxicity*; D008113:Liver Neoplasms / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D008339:Mandibular Neoplasms / Q000139:chemically induced* / Q000473:pathology; D009232:Myxoma / Q000139:chemically induced* / Q000473:pathology; D014319:Triturus / Q000502:physiology*
D002273:Carcinogens; D006016:Glycolates; D008456:2-Methyl-4-chlorophenoxyacetic Acid