A review of perchloroethylene and rat mononuclear cell leukemia.

Mononuclear cell leukemia (MNCL) is an extremely common spontaneous disease of ageing F344 rats accompanied by splenomegaly, anemia, thrombocytopenia, and leukemic infiltration (initially of the spleen, liver, and lung). Rare in other rat strains, incidence in F344 rats is variable, has been increasing, and can exceed 70% in controls. MNCL cells possess natural killer (NK) cell characteristics and apparently, the neoplastic cells derive from large granular lymphocytes (LGL), hence the alternative name of LGL leukemia.

Dichlorvos--a comprehensive review of 11 rodent carcinogenicity studies.

Dichlorvos (DDVP) has been studied in 11 cancer bioassays. Only two studies, the National Toxicology Program (NTP) rat and mouse studies, show any indication of carcinogenic effects and these results, an increase in mononuclear cell leukemia in the rat and an increase in forestomach tumors in the mouse, appear to be related to the corn oil vehicle. The increase in mononuclear cell leukemia was confined to the male rat, was not dose-related, did not show an earlier onset than the controls, had no effect on survival, was within the range seen in historical controls, and was not confirmed in five other rat studies, four of which used higher doses.