Maternal exposure to neighborhood soil Pb and eclampsia risk in new Orleans, Louisiana (USA): Evidence from a natural experiment in flooding

• Maternal eclampsia risk increases dose-responsively to neighborhood soil Pb content.
• Mothers are 4 X more likely to suffer eclampsia in high Pb areas than low Pb areas.
• Eclampsia risk declined in areas with reduced soil Pb following post-hurricane flooding .

BackgroundPrevious studies link maternal blood lead (Pb) levels and pregnancy-related hypertensive disorders.ObjectiveAssess the relationship between neighborhood soil Pb and maternal eclampsia risk.MethodsZip code summarized high density soil survey data of New Orleans collected before and after Hurricanes Katrina and Rita (HKR) were merged with pregnancy outcome data on 75,501 mothers from the Louisiana office of public health. Cross-sectional logistic regression analyses are performed testing the association between pre-HKR accumulation of Pb in soils in thirty-two neighborhoods and eclampsia risk. Then we examine whether measured declines in soil Pb following the flooding of the city resulted in corresponding reductions of eclampsia risk.ResultsCross-sectional analyses show that a one standard deviation increase in soil Pb increases the odds of eclampsia by a factor of 1.48 (95% CI: 1.31, 1.66). Mothers in zip code areas with soil Pb>333 mg/kg were 4.00 (95% CI: 3.00, 5.35) times more likely to experience eclampsia than mothers residing in neighborhoods with soil Pb<50 mg/kg. Difference-in-differences analyses capturing the exogenous reduction in soil Pb following the 2005 flooding of New Orleans indicate that mothers residing in zip codes experiencing decrease in soil Pb (−387.9 to −33.6 mg/kg) experienced a significant decline in eclampsia risk (OR=0.619; 95% CI: 0.397, 0.963).ConclusionsMothers residing in neighborhoods with high accumulation of Pb in soils are at heightened risk of experiencing eclampsia.

Odds ratios and 95% CI corresponding to conditional effect of soil Pb on eclampsia in New Orleans before Hurricanes Katrina and Rita, 1999 to August 2005 Figure optionsDownload as PowerPoint slide