Pesticide levels in ground and surface waters of Primavera do Leste Region, Mato Grosso, Brazil.

Residues of the herbicides simazine, metribuzin, metolachlor, trifluralin, atrazine, and two metabolites of atrazine, deisopropylatrazine (DIA) and deethylatrazine (DEA), are surveyed in the surface and groundwater of the Primavera do Leste region, Mato Grosso, Brazil during September and December 1998 and April 1999. Different water source sampling stations of groundwater (irrigation water well, drinking water well, and water hole) and surface water (dam and river) are set up based on agricultural land use. A solid-phase extraction procedure followed by gas chromatography-nitrogen-phosphorus detection is used for the determination of these compounds. All compounds are detected at least once in water samples. A temporal trend of pesticide contamination is observed, with the highest contamination frequency occurring in December during the main application season. Metribuzin shows the highest individual detection frequencies throughout the monitoring period, followed by metolachlor, simazine, and DEA. The maximum mean concentrations of pesticides in this study are in the range from 0.14 to 1.7 microg/L. We deduct that the contamination of water resources is predominantly caused by non-point pollution of pesticides used in intensive cash-crop cultures of the Cerrado area. Therefore, a continuous monitoring of pesticide concentrations in water resources of this tropical region is necessary to detect the longer term contamination trends and developing health risks.

Dissipation of DDT in a heavily contaminated soil in Mato Grosso, Brazil.

After the prohibition of organochlorine-pesticide use in Brazil for controlling insect vector diseases, Mato Grosso State gathered the exceeding DDT and stored it irregularly in an open air area that belongs to the National Health Foundation, causing soil contamination. This study aimed to evaluate the contamination level and dissipation of p,p'-DDT and p,p'-DDE in this area. For that, surface soil samples were collected on 19 September 2000, 15 December 2000, 4 April 2001 and soil samples 30-40 cm; 60-70 cm and 90-100 cm deep were taken from five points in the studied area on 17 July 2001. The contaminants were determined by a small scale method which consists on extraction and clean-up steps combined into one step by transferring soil samples mixed with neutral alumina to a chromatographic column prepacked with neutral alumina and elution with hexane:dichloromethane (7:3 v:v). The eluate was concentrated and the analytes were quantified by gas chromatography with an electron-capture detector. p,p'-DDT at surface soil ranged from 3,800 to 7,300 mg kg(-1). 30-40 cm deep soil sample concentrations varied from 0.036 to 440 mg kg(-1) while 90-100 cm deep samples varied from 0.069 to 180 mg kg(-1). Volatilization is probably the main dissipation process. The p,p'-DDT is moving slowly downward in the soil profile, however, the levels of this contaminant are high enough to present risk to underground waters.

Serum DDT in malaria vector control sprayers in Mato Grosso State, Brazil.

DDT was used intensively in vector control programs in Mato Grosso State until 1997. The present study aimed to determine DDT concentrations in blood samples from Brazilian National Health Foundation workers in Mato Grosso. Blood samples were analyzed from 41 sprayers, 20 drivers, and 14 unexposed workers, collected in June 1999 and October 2000 in two regions of the State (Sinop and C ceres). Sprayers and drivers were occupationally exposed, and no significant differences were found in serum DDT levels between these two groups in either region. Likewise, no significant differences were found in p,p'DDE and total DDT levels between C ceres and Sinop. However, p,p'DDT levels were higher in Sinop due to the intensive use of this insecticide in the region in recent years. The two regions together showed the following results: total DDT ranging from 7.50 micro g/L to 875.5 micro g/L (median = 135.5 micro g/L) for sprayers; from 34.5 micro g/L to 562.3 micro g/L (median = 147.7 micro g/L) for drivers; and from undetected to 94.8 micro g/L (median = 22.5 micro g/L) for unexposed workers.

Acetamiprid, carbendazim, diuron and thiamethoxam sorption in two Brazilian tropical soils.

Sorption of acetamiprid ((E)-N1-[(6-chloro-3-pyridyl)methyl]-N2-cyano-N1-methylacetamidine), carbendazim (methyl benzimidazol-2-ylcarbamate), diuron (N-(3,4-dichlorophenyl)-N, N-dimethyl urea) and thiamethoxam (3-(2-chloro-thiazol-5-ylmethyl)-5-methyl-[1,3,5]oxadiazinan-4-ylidene-N-nitroamine) was evaluated in two Brazilian tropical soils, Oxisol and Entisol, from Primavera do Leste region, Mato Grosso State, Brazil. To describe the sorption process, batch experiments were carried out. Linear and Freundlich isotherm models were used to calculate the K(d) and K(f) coefficients from experimental data. The K(d) values were utilized to calculate the partition coefficient normalized to soil organic carbon (K(oc)). For the pesticides acetamiprid, carbendazim, diuron and thiamenthoxan the K(oc) (mL g(- 1)) values ranged in both soils from 98 - 3235, 1024 - 2644, 145 - 2631 and 104 - 2877, respectively. From the studied pesticides, only carbendazim presented correlation (r(2) = 0.82 and p < 0.01) with soil organic carbon (OC) content. Acetamiprid and thiamethoxam showed low sorption coefficients, representing a high risk of surface and ground water contamination.

Serum DDT in malaria vector control sprayers in Mato Grosso State, Brazil

DDT was used intensively in vector control programs in Mato Grosso State until 1997. The present study aimed to determine DDT concentrations in blood samples from Brazilian National Health Foundation workers in Mato Grosso. Blood samples were analyzed from 41 sprayers, 20 drivers, and 14 unexposed workers, collected in June 1999 and October 2000 in two regions of the State (Sinop and Cáceres). Sprayers and drivers were occupationally exposed, and no significant differences were found in serum DDT levels between these two groups in either region. Likewise, no significant differences were found in p,p'DDE and total DDT levels between Cáceres and Sinop. However, p,p'DDT levels were higher in Sinop due to the intensive use of this insecticide in the region in recent years. The two regions together showed the following results: total DDT ranging from 7.50µg/L to 875.5µg/L (median = 135.5µg/L) for sprayers; from 34.5µg/L to 562.3µg/L (median = 147.7µg/L) for drivers; and from undetected to 94.8µg/L (median = 22.5µg/L) for unexposed workers