Secular trends in blood lead concentrations of school-age children in Montevideo, Uruguay from 2009 to 2019

Lead exposure continues to be a public health problem globally, yet very few countries perform systematic biomonitoring or surveillance of children's blood lead levels (BLLs). Secular trends in children's BLLs have not been well characterized outside North America and Europe. In 2009-19, we conducted a series of non-representative cross-sectional surveys in Montevideo, Uruguay, enrolling children living in areas of the city with known or suspected lead contamination. Lead was measured with atomic absorption spectrometry on fasting venous blood samples. Of the 856 children representing independent (non-sibling) observations, 759 had BLL measures. Other missing data were imputed. Using linear and logistic regression models, we estimated the covariate-adjusted year to year difference in mean BLL and the likelihood of having BLL >= 5 and BLL >= 3.5 mu g/dL. At the start of the study, mean +/- SD BLL was 4.8 +/- 2.6 mu g/dL, and at the end 1.4 +/- 1.4 mu g/dL. The prevalence of BLL >= 5 and BLL >= 3.5 mu g/dL also differed markedly between 2009 and 2019 (30.8% vs. 2.7% and 53.8% vs. 5.8%). Similarly, where 80.8% of children had BLL >= 2 mu g/dL in 2011, in 2019 that number was 19.3%. The estimated year to year difference in BLL was similar to 0.3 mu g/dL. Despite this progress, pediatric lead exposure remains a problem in Montevideo. In years 2015-19, between 19 and 48% of school children had BLL >= 2 mu g/dL, a level at which adverse neurobehavioral outcomes continue to be reported in the literature. Continued prevention and risk-reduction efforts are needed in Montevideo, including systematic surveillance of BLLs in all children.