Dichlorodiphenyl trichloroethane (DDT) and its observed effects on body functions in vertebrates.

Objective: To review research findings on the effects of DDT on body functions in vertebrates.

Methods: The research was based on retrieval and critical review of relevant articles and abstracts cited in international and regional journals. The literature search was done on MedLine from the year 1975 to 2010. The analyses of published data on various vertebrates (birds, fish, mice, human, among others) were considered.

Results: The effect of DDT on body functions is purely dependent on the degree of exposure. Whereas mild exposure (1-5mg/kg) may not have significant effects, very high concentrations (>100mg/kg) of DDT generally adversely affect the reproductive functions of animals. Eggshell quality, egg hatch-ability and health of chicks are affected by high DDT exposure. Very high DDT levels may increase the chances of spontaneous abortion and preterm birth, which is one of the main causes of infant mortality in humans. The health of a growing foetus and infant may also be compromised by DDT transfer from an exposed mother through the placenta and breast milk. The DDT affects the estrous cycle of exposed animals by altering the hormonal functions. In male rats, DDT has been observed to alter spermatogenesis and reduce aggression behaviour. However the effect in higher male animals has not been clearly elucidated.

Conclusion: DDT exposure has drastic effects on reproductive functions in vertebrates, and safer alternatives should be considered rather than re-introducing DDT as a control agent for mosquitoes as has been suggested recently.