Effects of long-term lead exposure on monkey leukocyte chromosomes.

Cynomolgus monkeys (Macaca irus) received daily doses of 1 or 5 mg of lead for a period of 12 months. Samples of venous blood were taken at 0, 7, 9 and 12 months, and cultured lymphocytes were analysed for the presence of chromosome aberrations. A few severe chromosome aberrations, such as dicentrics or translocations, appeared in the control animals as well as in the lead-treated ones, during the course of the experiment. However, lead treatment increased significantly the frequency of chromosome and chromatid gaps, and this result is in agreement with other previous results.