Worldwide trends in DDT levels in human breast milk.

BACKGROUND: Concern over human breast milk contamination with the pesticide DDT (1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane) has prompted numerous studies around the world during the last five decades. This article examines trends in reported DDT levels, and the apparent effect of restrictions on DDT use. METHODS: More than 130 published values for DDT in human milk since 1951 were compiled, and trend lines were fit for regions of the world. RESULTS: Population means have declined in much of the world, from 5000-10000 microg DDT/kg milk fat to around 1000 today in many areas. Although different regions have different means, the decline seen in various countries corresponds to their restricting DDT use. DISCUSSION: DDT concentrations in human milk have declined in most areas of the world, consistent with restrictions on its use. Nevertheless, levels can be high in areas still using DDT, even higher than the World Health Organization's recommended limit for infants. These results indicate that population averages can be reduced by a predictable amount as DDT use is restricted.