Insecticides in human breast milk

Fifty samples of human breast milk were analysed by gas chromatography and thin layer chromatography for DDT (dichlordiphenyltrichloraethan), hexachlorobenzol, benezene-hexachlorides, dieldrin, aldrin and heptachlorepoxide. The three first substances were found in all samples in amounts varying from quite small up to eleven times the WHO recommended maximum for cow milk. The other substances were found in fewer milk samples, however, in some of these samples they were found in relatively high amounts. In Norway, only DDT has been investigated earlier (4), and compared to that study, there has been no significant change in the mean concentration of DDT in human breast milk during the last five years. The insecticide content was highest in colostrum and decreased with increasing duration of lactation. Considerable fluctuations in the content of insecticides were recorded in repeated milk samples collected from the same woman a few days apart. The percentage of samples with insecticide content higher than that permitted for cow's milk was greater in May/June (79%) than in early April (54%). The significance of these findings is discussed.