Metal exposure and reproductive disorders in indigenous communities living along the Pilcomayo River, Bolivia.

BACKGROUND: The Pilcomayo River is polluted by tailings and effluents from upstream mining activities, which contain high levels of metals. The Weenhayek live along this river and are likely to have elevated exposure. OBJECTIVES: To assess whether the Weenhayek have increased risk of reproductive and developmental disorders related to elevated metal exposure in comparison with a reference population. METHODS: We assessed reproductive and developmental outcomes, i.e. fertility, fetal loss, congenital anomalies, and walking onset by means of structured interviews. We sampled hair, water and fish to assess the relative exposure of the Weenhayek. Samples were analyzed for Pb and Cd with ICP-MS techniques. RESULTS: The Weenhayek communities studied had a higher prevalence of small families (OR 2.7, 95% CI 1.3-6.0) and delayed walking onset (OR 2.7, 95% CI 1.4-5.1) than the reference population. Median Pb levels in Weenhayek hair were 2-5 times higher than in the reference population, while Cd levels were not elevated. In water and fish, both Pb and Cd levels were increased in the Weenhayek area. CONCLUSIONS: We found indications for increased risks of small families and delayed walking onset among the Weenhayek living along the Pilcomayo River. Lactants form a high risk group for lead exposure.

Population dynamics of the migratory fish Prochilodus lineatus in a neotropical river: the relationships with river discharge, flood pulse, El Niño and fluvial megafan behaviour

The relative importance of flood pulse dynamics and megafan behaviour for the Sábalo (Prochilodus lineatus) catches in the neotropical Pilcomayo River is studied. The Sábalo catches can mainly be explained by decreased river discharges in the preceding years resulting in smaller inundated areas during rainy season floods and thereby in a decreased area of feeding grounds for the fishes. The decreased river discharges and the related decline of Sábalo catches in the 1990's can be linked to the 90-95 El Niño event. In 2007 the Sábalo catches were comparable to the catches before the "El Niño" event. The connectivity (continuity) between the main river and flood plain areas, which is influenced by sedimentation processes, is also of great importance and very probably plays a more important role since the late 1990's.

Se ha estudiado la importancia relativa de la dinámica del pulso de inundación y el comportamiento del sistema megafan para las capturas del Sábalo (Prochilodus lineatus) en el río Pilcomayo. Las capturas del Sábalo puede explicarse fundamentalmente por los bajos caudales del río en los años anteriores, resultando en menores superficies de las zonas inundadas durante la temporada de lluvia y por lo tanto en una área menor de alimentación para los peces. La disminución del caudal del río y la declinación relativa de capturas de Sábalo en los años 1990 pueden estar relacionadas con el 90-95 evento de El Niño. En 2007, la captura de Sábalo fue comparable a las capturas antes del evento de "El Niño". La conectividad (continuidad) entre el río principal y las llanuras aluviales, que son influenciadas por los procesos de sedimentación, son también de gran importancia y muy probablemente juegan un papel muy importante desde finales de los años '90.