Preliminary Study on the Carcinogenic Activity of the Fungicide Manganese Ethylenebisdithiocarbamate in the Adult Newt, Triturus Cristatus Carnifex

Percutaneous exposure of adult newts to the fungicide manganese ethylenebisdithiocarbamate (maneb) at 3 concentration levels (0.5, 2.5 and 5.0 ppm) for a total of 19-23 weeks did not result in the induction of any neoplasms.

Changes in catalase, glutathione peroxidase and glutathione-S-transferase activities in the liver of newts exposed to 2-methyl-4-chlorophenoxyacetic acid (MCPA)

Activities of catalase, glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) were measured in livers of the crested newt (Urodele Amphibian) after 16 days of percutaneous exposure to the herbicide Agroxone 3, a commercial formulation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) containing 25% MCPA as sodium salt and 75% wetting and dispersing ingredients. Animals of both sexes were exposed to 800 p.p.m. of the active ingredient. There was a three-fold increase in catalase and a clear enhancement of GSH-Px in the MCPA-exposed animals of both sexes. A sex-dependent effect of MCPA was observed on GST activity, which increased significantly in female newts only. Similar liver enzyme changes were observed in female newts, and not in males, given the hypolipidaemic drug clofibrate (13 mg/animal/day, by gavage, for 8 days), which is structurally related to phenoxyherbicides. These findings indicate that the crested newt is sensitive to the hepatic effects of the peroxisome proliferators.

Abnormal limb regeneration in adult newts exposed to the fungicide Maneb 80. A histological study

The effects of the fungicide Maneb 80 (manganese ethylenebisdithiocarbamate, 80% active ingredient) on the regenerating limb of the adult crested newt, Triturus cristatus carnifex, was studied. Female newts were exposed percutaneously to 5 ppm Maneb 80. One group of control newts was exposed to the inert ingredients of Maneb 80 (sodium lignin sulfonate and n-butylnaphthalene sulfonate), and another control group was kept in tap water. The limbs were examined histologically at weekly intervals throughout the regeneration period and at the end of the experiment (10-12 wk postamputation). The regenerating limbs of all the animals exposed to Maneb 80 showed growth retardation and skeletal abnormalities. Histological examination provided evidence that vascular disturbances are important for the genesis of the developmental abnormalities induced by Maneb 80. The inert ingredients had a promoting effect on limb growth and had no teratogenic effects under our experimental conditions. There were no histological differences between the two control groups.

Testing of the fungicide maneb for carcinogenicity in two populations of the European crested newt

The carcinogenic effects of the fungicide manganese ethylenebisdithiocarbamate (maneb) have been investigated in 2 populations of adult crested newt, which have different prevalences of spontaneous melanoma. Animals were exposed percutaneously to a 5 ppm solution of maneb 4 days a week for 37 weeks. No differences in tumor incidence were found between control and maneb-treated animals of either population. Most of the control and treated animals from Settala (Milan) died within 7 months because of the development of widely disseminated melanomas. Tumor incidence was 94% in controls and 98% in maneb-treated newts. In the population from Bagnaia (Perugia) the incidences of melanoma were 7% and 2%, respectively.