EVOLUTION OF DDT RESIDUES IN ALL SAINTS BAY, BRAZIL, 1985-1994

摘要

Use of organochlorine insecticides has been prohibited in Brazil since 1976. However, later use of existing stock and smuggled parcels are partially responsible for their incomplete elimination. Extended, official use of DDT took place over the entire country at the end of 1984 to eradicate malaria. In 1985, a cross-sectional survey was conducted for DDE at nine intertidal sites of All Saints Bay using local mussels. In 1994, the study was repeated in 19 sites utilizing four selected species of mussel and the same analytical methodology as previously applied. The DDT residues (as ng/g of DDE, wet weight) varied between 0.24 and 5.1 for Anomalocardia brasiliana, 2.1 and 44.0 for Brachidontes exustus, < 0.33 and 15.8 for Macoma constricta, and < 0.31 and 1.36 for Littorina spp. No samples were found that exceeded the various action limits. The highest concentrations were detected on the coastline of Salvador City, in the Aratu Industrial Centre area, in the Subae estuary and in the Itaparica channel. From 1985 to 1994, increases were observed at all the sites, except for Mataripe, where an oil refinery operates on a large restricted area. Increases of up to 15 fold were observed in the Salvador and Aratu areas. Prohibited use of DDT, together with the carry over of the DDT used in the malaria campaign, seem to be the reasons for these increases.