Inter-individual Differences in the Effects of Aircraft Noise on Sleep Fragmentation.

STUDY OBJECTIVES: Environmental noise exposure disturbs sleep and impairs recuperation, and may contribute to the increased risk for (cardiovascular) disease. Noise policy and regulation are usually based on average responses despite potentially large inter-individual differences in the effects of traffic noise on sleep. In this analysis, we investigated what percentage of the total variance in noise-induced awakening reactions can be explained by stable inter-individual differences. METHODS: We investigated 69 healthy subjects polysomnographically (mean ± standard deviation 40 ± 13 years, range 18-68 years, 32 male) in this randomized, balanced, double-blind, repeated measures laboratory study. This study included one adaptation night, 9 nights with exposure to 40, 80, or 120 road, rail, and/or air traffic noise events (including one noise-free control night), and one recovery night. RESULTS: Mixed-effects models of variance controlling for reaction probability in noise-free control nights, age, sex, number of noise events, and study night showed that 40.5% of the total variance in awakening probability and 52.0% of the total variance in EEG arousal probability were explained by inter-individual differences. If the data set was restricted to nights (4 exposure nights with 80 noise events per night), 46.7% of the total variance in awakening probability and 57.9% of the total variance in EEG arousal probability were explained by inter-individual differences. The results thus demonstrate that, even in this relatively homogeneous, healthy, adult study population, a considerable amount of the variance observed in noise-induced sleep disturbance can be explained by inter-individual differences that cannot be explained by age, gender, or specific study design aspects. CONCLUSIONS: It will be important to identify those at higher risk for noise induced sleep disturbance. Furthermore, the custom to base noise policy and legislation on average responses should be re-assessed based on these findings.

Residuos de plaguicidas organoclorados en leche vacuna, Nicaragua / Organochlorine pesticide residues in cowá milk in Nicaragua

El presente trabajo constituye un estudio preliminar hecho en Nicaragua para eleborar un perfil de contaminacion de la leche de vaca con 10 plaguicidas organoclorados y hacer recomendaciones pertinentes. Entre diciembre de 1993 y marzo de 1994, se tomaron muestras de leche de 48 lugares diferentes del pais. Se analizo el contenido de residuos de hexaclorobenceno (HCB), a-BHC, lindano, aldrina, dieldrina,oxiclordano, heptacloro epoxido y metabolitos principales de DDT (p,p'-TDE, p,p'-DDE y p,p' -DDT) en las muestras mediante el metodo de la extraccion de la grasa de leche en fase solida, seguida de una determinacion cuantitativa usando cromatografia de gases con un detector de captura de electrones. Se recomienda investigar y estimar el riesgo de posible contaminacion de otros alimentos y proteger la salud publica mediante un control estricto de la produccion o importacion, almacenamiento, venta y uso de plaguicidas organoclorados