[Use of the protozoan Tetrahymena pyriformis in testing for contamination of biological materials with organophosphates and carbamates].

The medium consisting of 1% protease-peptone with 0.2% yeast extract proved to be suitable for slant culture of the protozoon Tetrahymena pyriformis. PPY medium is optical for obtaining high cell densities under cultivation in Roux flasks. To evaluate the toxicity the cell number was determined by direct counting in Fuchs-Rosenthal chambers, following 24, 48 and 72-hr incubation period. LD50 for trichlorphon was determined up to 4.0 to 5.0 mg . 1(-1), LD100 within the range of 19.58 to 39.16 mg . 1(-1), LD50 for dichlorvos as 5.0 mg . 1(-1), LD100 as 19.58 to 39.16 mg . 1(-1), for model carbamate (eserine) LD50 was determined up to 25.0 to 50.0 mg . 1(-1), LD100 over 200.0 mg . 1(-1).