Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14755

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Field testing passive air samplers for current use pesticides in a tropical environment
(Universidad Nacional, Costa Rica., 2008) Gouin, Todd; Wania, Frank; Ruepert, Clemens; Castillo, Luisa E.
Air was sampled for one year in the central valley of Costa Rica using an active high-volume sampler as well as passive samplers (PAS) based on polyurethane foam (PUF) disks and XAD-resin filled mesh cylinders. Extracts were analyzed for pesticides that are either banned or currently used in Costa Rican agriculture. Sampling rates for PUF-based passive air samplers, determined from the loss of depuration compounds spiked on the disks prior to deployment, averaged 5.9 +- 0.9 m3 · d-1 and were higher during the windier dry seasonthan duringthe rainy season. Sampling ratesforthe XADbased passive sampler were determined from the slopes of linear relationships that were observed between the amount of pesticide sequestered in the resin and the length of deployment, which varied from 4 months to 1 year. Those sampling rates increased with decreasing molecular size of a pesticide, and their average of 2.1 +- 1.5 m3 · d-1 is higher than rates previously reported for temperate and polar sampling sites. Eventhoughthetrends ofthe sampling rate with molecular size and temperature are consistent with the hypothesis that molecular diffusion controls uptake in passive samplers, the trends are much more pronounced than a direct proportionality between sampling rate and molecular diffusivity would suggest. Air concentrations derived by the three sampling methods are within a factor of 2 of each other, suggesting that properly calibrated PAS can be effective tools for monitoring levels of pesticides in the tropical atmosphere. In particular, HiVol samplers, PUF-disk samplers, and XADbased passive samplers are suitable for obtaining information on air concentration variability on the time scale of days, seasons and years, respectively. This study represents the first calibration study for the uptake of current use pesticides by passive air samplers.
Maternal blood and hair manganese concentrations, fetal growth, and length of gestation in the ISA cohort in Costa Rica
(Environmental Research, 2015-01) Mora, Ana Maria; van Wendel de Joode, Berna; Mergler, Donna; Cordoba, Leonel; Cano, Camilo; Quesada, Rosario; Smith, Donald R.; Menezes-Filho, José; Eskenazi, Brenda
Background: Animal studies have shown that both deficiency and excess manganese (Mn) may result in decreased fetal size and weight, but human studies have reported inconsistent results. Methods: We examined the association of blood and hair Mn concentrations measured at different times during pregnancy with fetal growth among term births and length of gestation in a cohort of 380 mother-infant pairs living near banana plantations aerially sprayed with Mn-containing fungicides in Costa Rica. We used linear regression and generalized additive models to test for linear and nonlinear associations. Results: Mean (± SD) blood Mn concentration was 24.4±6.6μg/L and geometric mean (geometric SD) hair Mn concentration was 1.8 (3.2) μg/g. Hair Mn concentrations during the second and third trimesters of gestation were positively related to infant chest circumference (β for 10-fold increase=0.62cm; 95% CI: 0.16, 1.08; and β=0.55cm; 95% CI: -0.16, 1.26, respectively). Similarly, average maternal hair Mn concentrations during pregnancy were associated with increased chest circumference (β for 10-fold increase=1.19cm; 95% CI: 0.43, 1.95) in infants whose mothers did not have gestational anemia, but not in infants of mothers who had gestational anemia (β=0.39cm; 95% CI: -0.32, 1.10; pINT=0.14). All these associations were linear. Blood Mn concentrations did not show consistent linear nor nonlinear relationships with any of the birth outcomes. Conclusions: Mn plays an important role in fetal development, but the extent to which environmental exposures may cause adverse health effects to the developing fetus is not well understood. Among women living near banana plantations in Costa Rica, we did not observe linear or nonlinear associations of Mn concentrations with lowered birth weight or head circumference, as reported in previous studies. However, we did find positive linear associations between maternal hair Mn concentrations during pregnancy and infant chest circumference

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