PURPOSE: To determine whether weight at birth is related to prenatal exposure to persistent organochlorine compounds.
METHODS: Birth weight was obtained for 197 singleton infants drawn from the ...general population born in two cities in Ukraine in 1993 to 1994. Concentrations of seven organochlorine pesticides (p,p′-DDT, p,p′-DDE, β-hexachlorocyclohexane, hexachlorobenzene, trans-nonachlor, oxychlordane, heptachlor epoxide) and 11 polychlorinated biphenyl congeners measured in maternal milk taken at four or five days after birth were used as an index of prenatal exposure.
RESULTS: The greatest differences were seen for β-hexachlorocyclohexane, with a pattern not suggestive of dose–response; infants in the lowest tertile were small, those in the central tertile were large, and those in the upper tertile were average. Adjustment for gestational age and other potential confounders had little effect on these patterns. Infants in the two upper tertiles for p,p′-DDE were larger than those in the lower tertile, with the effect being more striking after adjustment for gestational age. Adjustment for potential confounders made the pattern disappear. Other chemicals showed no convincing evidence of effects.
CONCLUSIONS: Prenatal exposure to the chemicals studied, at concentrations currently seen in this population, does not impact weight at birth.
Objetivos. Evaluar el estado de susceptibilidad a insecticidas piretroides deltametrina y lambdacialotrina y al organoclorado DDT, e identificar los mecanismos bioquimicos asociados con resistencia ...en 13 poblaciones naturales de Aedes aegypti recolectadas en localidades de Colombia donde el dengue es un grave problema de salud publica. Metodos. Se recolectaron y criaron en condiciones controladas formas inmaduras de diferentes criaderos naturales del vector para cada localidad. Con la generacion F2 se realizaron bioensayos utilizando las metodologias OMS 1981 (papeles impregnados) y CDC 1998 (botellas impregnadas). En las poblaciones con mortalidades compatibles con disminucion de la susceptibilidad, se midieron los niveles de esterasas no especificas (ENE), oxidasas de funcion mixta (OFM) y acetilcolinesterasa modificada (ACEM) mediante pruebas colorimetricas. Resultados. Todas las poblaciones del mosquito evaluadas evidenciaron resistencia al organoclorado DDT. En cuanto a los piretroides, se encontro resistencia generalizada a lambdacialotrina pero no a deltametrina. Los mecanismos bioquimicos de resistencia evaluados permitieron encontrar 7 de 11 poblaciones con ENE elevadas y una poblacion con OFM incrementadas. Conclusiones. Se descarta la resistencia cruzada de tipo fisiologico entre el DDT y lambdacialotrina en las poblaciones de A. aegypti evaluadas. La resistencia fisiologica a lambdacialotrina parece asociarse con el incremento de las ENE. El comportamiento diferencial en los niveles de susceptibilidad y los valores enzimaticos entre poblaciones se asociaron con la variabilidad genetica y presion de seleccion quimica a nivel local. Palabras clave Aedes; DDT; dengue; insecticidas; mosquito; insecticidas organoclorados; resistencia a los insecticidas; Colombia. Objectives. To assess the susceptibility status of 13 natural populations of Aedes aegypti (collected from sites in Colombia where dengue is a serious public health problem) to the pyrethroids, deltamethrin and lambda-cyhalothrin, and to the organochlorine, DDT, and to identify any biochemical mechanisms associated with resistance. Methods. Immature forms of the vector were collected from natural breeding spots at each site and then raised under controlled conditions. Using the F2 generation, bioassays were performed using the World Health Organization's 1981 methodology (impregnated paper) and United States Centers for Disease Control and Prevention's 1998 methodology (impregnated bottles). In populations where mortality rates were consistent with decreased susceptibility, levels of nonspecific esterases (NSE), mixed-function oxidases (MFO), and acetylcholinesterase (AChE) were measured using colorimetric tests. Results. All of the mosquito populations that were tested showed resistance to the organochlorine DDT. In the case of the pyrethroids, widespread resistance to lambdacyhalothrin was found, but not to deltamethrin. Assessing the biochemical resistance mechanisms showed that 7 of the 11 populations had elevated NSE, and one population, increased MFO. Conclusions. Physiological cross-resistance between DDT and lambda-cyhalothrin in the A. aegypti populations tested was dismissed. Physiological resistance to lambdacyhalothrin appears to be associated with increased NSE. The differences in susceptibility levels and enzyme values among the populations were associated with genetic variations and chemicals in use locally. Key words Aedes; DDT; dengue; insecticides; mosquito control; insecticides, organochlorine; insecticide resistance; Colombia.
OBJETIVO: Estimar o grau de exposição interna aos praguicidas organoclorados (POP) dos moradores de um atêrro a céu aberto. MÉTODOS: Estudo observacional, de aferição simultânea e controlado, cujo ...fator de estudo foi residir em área contaminada por POP e o efeito foi a concentração sanguínea dessas substâncias. A população de estudo foi de 238 pessoas residentes em um aterro a céu aberto (Pilões), no município de Cubatão, SP; e a população de controle ficou dimensionada em 258 pessoas, também residentes no mesmo município (Cota 200). Foram analisados os praguicidas HCB, p-p'DDT, p-p'DDE, p-p'DDD, o-p'DDT, a HCH; b HCH; g HCH; Aldrin; Dieldrin; Endrin; Heptaclor; Heptaclor-epoxi e Mirex. RESULTADOS: Os teores médios sangüíneos de HCB em Pilões foram de 4,66 µg/L, 155 vezes maior que a média na Cota 200 (0,03 µg/L). Em Pilões, os teores médios de DDT total foram de 3,71 µg/L, duas vezes maior do que na Cota 200 (1,85 µg/L) e o HCH total apresentou concentrações sangüíneas seis vezes maiores em Pilões, 0,84 µg/L, contra 0,13 µg/L. CONCLUSÕES: Evidenciou-se associação positiva entre residir em Pilões e apresentar teores sangüíneos de POP, com risco muitas vezes maior quando comparado a localidades sem a presença desses contaminantes.
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