Sociodemographic and nutritional correlates of neurobehavioral development: a study of young children in a rural region of Ecuador

To identify and describe the sociodemographic and nutritional characteristics associated with neurobehavioral development among young children living in three communities in the northeastern Andean region of Cayambe-Tabacundo, Ecuador. Women in the study communities who had a child 3 to 61 months of age completed a questionnaire about maternal and child health and sociodemographic characteristics. The Ages and Stages Questionnaire (ASQ) was directly administered to 283 children by two trained interviewers. Growth measurements and a hemoglobin finger-prick blood test were obtained in 2003–2004. Prevalence of developmental delay was calculated, and associations between child development and maternal, child, and household characteristics were explored. High frequencies of developmental delay were observed. Children 3 to 23 months old displayed delay in gross motor skills (30.1%), and children 48 to 61 months old displayed delay in problem-solving skills (73.4%) and fine motor skills (28.1%). A high frequency of both anemia (60.4%) and stunting (53.4%) was observed for all age groups. Maternal educational level was positively associated with communication and problem-solving skills, and monthly household income was positively associated with communication, gross motor, and problem-solving skills. The results suggest a high prevalence of developmental delay and poor child health in this population. Child health status and the child’s environment may contribute to developmental delay in this region of Ecuador, but sociodemographic factors affecting opportunities for stimulation may also play a role. Research is needed to identify what is causing high percentages of neurobehavioral developmental delay in this region of Ecuador.

Pb-210-Ra-226 and Ra-228-Th-232 systematics in young arc lavas: implications for magma degassing and ascent rates

New data show that island arc rocks have (Pb-210/Ra-226)(o) ratios which range from as low as 0.24 up to 2.88. In contrast, (Ra-22S/Th-232) appears always within error of I suggesting that the large Ra-226-excesses observed in arc rocks were generated more than 30 years ago. This places a maximum estimate on melt ascent velocities of around 4000 m/year and provides further confidence that the Ra-226 excesses reflect deep (source) processes rather than shallow level alteration or seawater contamination. Conversely, partial melting must have occurred more than 30 years prior to eruption. The Pb-210 deficits are most readily explained by protracted magma degassing. Using published numerical models, the data suggest that degassing occurred continuously for periods up to several decades just prior to eruption but no link with eruption periodicity was found. Longer periods are required if degassing is discontinuous, less than 100% efficient or if magma is recharged or stored after degassing. The long durations suggest much of this degassing occurs at depth with implications for the formation of hydrothermal and copper-porphyry systems. A suite of lavas erupted in 1985-1986 from Sangeang Api volcano in the Sunda arc are characterised by deficits of Pb-210 relative to Ra-226 from which 6-8 years of continuous Rn-222 degassing would be inferred from recent numerical models. These data also form a linear (Pb-210)/Pb-(Ra-226)/Pb array which might be interpreted as a 71-year isochron. However, the array passes through the origin suggesting displacement downwards from the equiline in response to degassing and so the slope of the array is inferred not to have any age significance. Simple modelling shows that the range of (Ra-226)/Pb ratios requires thousands of years to develop consistent with differentiation occurring in response to cooling at the base of the crust. Thus, degassing post-dated, and was not responsible for magma differentiation. The formation, migration and extraction of gas bubbles must be extremely efficient in mafic magma whereas the higher viscosity of more siliceous magmas retards the process and can lead to Pb-210 excesses. A possible negative correlation between (Pb-210/Ra-226)(o) and SO2 emission rate requires further testing but may have implications for future eruptions. (C) 2004 Elsevier B.V. All rights reserved.