Association between self-reported length of time in the USA and blood lead levels: National Health and Nutrition Examination Survey 2013-2016

Objectives The aim of this study is to determine the association between length of time in the USA with blood lead (BPb). Design Population-based cross-sectional study using data from the 2013-2016 National Health and Nutrition Examination Survey. Setting USA. Participants 5933 men and women (>= 15 years); subgroups of men only (n=2867), women only (n=3064) and women of childbearing age (15-45 years) (n=1580). Primary and secondary outcomes The primary outcome was BPb concentration. The main exposure variable was self-reported number of years spent in the USA, categorised as: born in the USA; 0-4 years; 5-9 years; 10-19 years and >= 20 years. We used linear regression models adjusted for race/ethnicity, education, blood cotinine, age, sex (as appropriate) and accounted for complex survey design. Results Women of childbearing age who have lived 0-4 years in the USA have, on average, a 54% (95% CI 36% to 75%) higher BPb compared with women born in the USA. Corresponding results for all women, men and the entire population were 49% (95% CI 34% to 66%), 49% (95% CI 28% to 75%) and 49% (95% CI 33% to 66%), respectively. Similar, statistically significant, results were observed for other time periods (5-9 years, 10-19 years and >= 20 years); the magnitude of the association decreased with increasing time in the USA. Conclusions This study provides additional evidence that newcomers to the USA may be a population at higher risk of elevated BPb.