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.