Exploring Nonlinearity in the Association Between Birth Defect Rates and Agrichemicals in Groundwater in an Agricultural State

Background: Agricultural practices over the last 70 years have led to increased agrichemical contamination in some drinking water supplies. Studies report an elevated risk of birth defects associated with exposure to nitrate or atrazine, but little is known about effects of co-exposure. This ecological study evaluated the relationship between the concomitant presence of nitrate and atrazine in Nebraska drinking water supplies and risk for birth defects. Methods: County birth data were combined with water chemistry data retrieved from a state-sponsored agrichemical contaminant database. Segmented linear regression was used to examine associations between percentage of wells with nitrate and atrazine (separately and as a mixture), and the risk of birth defects. Results: When modeled for wells with nitrate-N concentrations \u3e 2 mg/L, the slope of the first regression segment was positive, increasing to 58% positive wells. After 58% positivity, the slope showed a negative association with birth defect rates. Adding atrazine to the model moved the changepoints to a lower percentage of wells positive for these agrichemicals in the association to birth defect rates. Models consistently showed this pattern of association with and without other nitrosatable compounds present. Conclusions: The results support an effect of nitrate and nitrosatable compounds on fetal development and suggest the relationship may be nonlinear. Exposure to nitrate and nitrosatable compounds as a mixture may have separate biological effects on reproductive outcomes when compared to the single compounds.https://digitalcommons.unmc.edu/chri_forum/1059/thumbnail.jp

The "three delays" as a framework for examining maternal mortality in Haiti

Haiti has one of the highest rates of maternal mortality in the Caribbean. The "Three Delays" model proposes that pregnancy-related mortality is overwhelmingly due to delays in: (1) deciding to seek appropriate medical help for an obstetric emergency; (2) reaching an appropriate obstetric facility; and (3) receiving adequate care when a facility is reached. This framework was used to analyze a sample of 12 maternal deaths that occurred in a longitudinal cohort of pregnant Haitian women. Because of political upheavals in Haiti during the survey, these deaths are an underestimate of all deaths that occurred in the cohort. Family and friend interviews were used to obtain details about the medical and social circumstances surrounding each death. A delayed decision to see medical care was noted in eight of the 12 cases, whereas delays in transportation only appeared to be significant in two. Inadequate care at a medical facility was a factor in seven cases. Multiple delays were relevant in the deaths of three women. Family and friend interviews suggest that a lack of confidence in available medical options was a crucial factor in delayed or never made decisions to seek care. Expanding the coverage of existing referral networks, improving community recognition of obstetric emergencies, and improving the ability of existing medical institutions to deliver quality obstetric care, are all necessary. However, services will continue to be under-utilized if they are perceived negatively by pregnant women and their families. The current data thus suggest that improvements to Haiti's maternity care system which focus on reducing the third delay--that is, improving the quality and scope of care available at existing medical facilities--will have the greatest impact in reducing needless maternal deaths.Haiti maternal mortality verbal autopsies maternity care