Toxicity of the cyanobacterial toxin microcystin-LR to rats after 28 days intake with the drinking water

Humans may be exposed to low dosages of the cyanobacterial toxin microcystin-LR (MCLR) in the drinking water as a consequence of the lysis of cyanobacteria from contaminated lakes and reservoirs. At present there are no published animal experiments on the toxicity of chemically pure MCLR applied continuously in low concentrations in the drinking water. Data from such experiments are necessary to derive recommendations for drinking water guideline values. In the experiment described herein, daily intakes of approximately 50 and 150 μg/kg b.w. pure MCLR were administered to rats with the drinking water for 28 days. After this time, rats in both dose groups showed increased liver weight, altered serum enzyme activities, and histological injuries to the liver.