Variations in the lethal body burdens of organophosphorus compounds in the guppy

In the present investigation the influence of exposure duration and lipophilicity on the lethal body burdens (LBBs) of thirteen organophosphorus insecticides are investigated. The LBBs are found to differ widely between compounds, varying from 0.011 to 29 μmol•g−1 wet weight. Compounds of high hydrophobicity (log Kow > 4) tend to have high LBBs (2–29 μmol•g−1 wet weight) which are not dependent on exposure concentrations. Some, but not all, of the less hydrophobic compounds had lower LBBs which were dependent on the exposure concentration. The use of LBBs for the interpretation of aquatic toxicity data of specifically acting chemicals is discussed. The wide variation in the observed LBBs makes the solely use of LBBs for toxicity assessment far from straightforward for more specificically acting compounds.