Aerial spraying of 2,4,5-T and human birth malformations: an epidemiological investigation.

An investigation of the rate of birth malformations in the Northland region of New Zealand provides no evidence to associate spraying of 2,4,5-trichlorophenoxyacetic acid with the occurrence of any malformation of the central nervous system, including spina bifida. A statistically significant association between spray and malformation is found in the case of talipes. Whether this association indicates a causal relation remains to be established.