[Environmental pollutants with hormonal effects. Is estrogen theory a good model?]

Lately, a theory on possible oestrogenic effects of environmental contaminants like PCB, dioxin and some pesticides, has caused much concern. The "oestrogen theory" states that persistent, bioaccumulating chemicals affect foetal development by acting like oestrogens. This results in permanent changes, of the reproductive organs in particular, and leads to reduced reproductive success. The theory is based to a large degree on reports on animals from the Great Lakes region in North America, alligators from Florida and fish from rivers in Great Britain. Now that a decline in human semen quality over the last 50 years has been reported, the question has been raised as to whether this too may be a result of environmental oestrogens. The higher incidence of other diseases like hypospadia, cryptorchidism and testicular cancer also indicates that something may be affecting the reproductive health of the male. Whether the higher incidence of endometriosis and breast cancer can be explained by the hypothesis is questioned. That several environmental contaminants have oestrogenic effects, has been documented. Recent studies have shown that the contaminants have more general endocrine-disrupting effects, thereby indicating that the oestrogen model is too simple. It is a dilemma for environmental medicine whether the present knowledge gives sufficient reason to apply precautionary principle and demand specific regulations.