STUDY: Human Birth Defect Suspected from Malathion. Department of Clinical Genetics, Erasmus University, Rotterdam. Department of Child Neurology, University Hospital, Utrecht.

SOURCE: Teratology, 1987, vol.36, p.7 (3).

Malathion has been shown to cause birth defects in a variety of animals and at lower levels than other pesticides. Researchers suspect that Malathion caused the birth defect known as "amyoplasia", which is "a disorder characterized by almost total absence of skeletal muscle", in an infant girl who died soon after birth. The main researcher, Dr. D Lindhout, suspects this because "the mother used a malathion head lice shampoo during the 11th and 12th week of her pregnancy". Dr. Lindhout stated that malathion was a suspect in this birth defect because "when administered to adult animals, malathion and related thiophosphonates stimulate, and subsequently inhibit, the nicotinic sites in skeletal muscle, resulting in muscle weakness and paralysis. Neonates (newborn babies) are far more sensitive to these agents than adults, mainly because of a slower rate of detoxification of the metabolite (the metabolite in this case would be the liver breakdown of malathion which has been shown to be far more toxic than malathion itself)". Furthermore, "there was no genetic history of this problem in the mother or the father’s family and there was no evidence of drug use by the mother", except for the use of Malathion head lice shampoo during early pregnancy.

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