DDT environmental persistence from its use in a vector control program: a case study

Abstract

DDT contamination was investigated in soil, sediment, and chicken eggs from an endemic leishmaniasis area located in Rio de Janeiro City, Brazil. The last DDT application in this area was in 1990, for sand-fly vector control. Sampling campaigns were conducted in 1997 and 1999. DDT was extracted by use of a modified soxhlet apparatus and analysis was performed by gas chromatography with electron capture detector. The results show that, in 1997, soil samples contained up to 351 microg x kg(-1) x d x w. of summation operator DDT near the insecticide-sprayed sites. In 1999, the soil concentration decreased to 112 microg x kg(-1) x d x w. of summation operator DDT. Sediments from small creeks also showed low concentrations (up to 32.9 microg x kg(-1) x d x w. of summation operator DDT). Chicken eggs had, on average, 1.98 mg x kg(-1) summation operator DDT (twice FAO's maximum residue limit), comprising 82% of p,p'-DDE. Taking into account the egg results, DDT bioaccumulation is a question of concern. Considering just the egg consumption, it was estimated that DDT intake in the study area is 0.38x10(-4) mg x kg(-1) body weight x day(-1) whereas the reference maximum dose (US EPA) is 5x10(-4) mg x kg(-1) body weight x day(-1). This approach can be used to estimate DDT exposure in other places where DDT contamination may be of concern, especially in places where locally produced animals and eggs are a significant portion of the diet.