Health Disparities
Lead exposure as a contributor to the Black-White racial disparity in blood pressure: evidence from NHANES 1988-1994 and 2017-2020 Mia Zhu* Mia Zhu Hannah Van Wyk Sung Kyun Park
Background: In the United States (US), racial disparities in blood pressure have persisted with Black people experiencing a greater risk of hypertension compared to White people. While disparities in lead exposure may explain some of this disparity, little is known about the mediating role of lead in racial disparities in blood pressure.
Methods: We used national-level, cross-sectional data of noninstitutionalized US adults aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES), III (1988-1994) (n = 10,570) and 2017-2020 (n = 4,536). We examined the extent to which racial disparities in blood pressure were explained by disparities in blood lead in these two NHANES cycles using causal mediation analysis. We estimated natural direct and indirect effects and considered potential interaction between race and blood lead using 4-way decomposition.
Results: In NHANES-III, Black participants would have a 5.74 (95% CI: 4.94, 6.54) mmHg higher mean systolic blood pressure (SBP) compared to White participants if all adjusted covariates were held equal to that of the White population; 10% of this disparity was explained by differences in blood lead levels between Black and White participants. Similar trends were observed with hypertension. In NHANES 2017-2020, similar overall trends were observed. However, the proportion of racial disparities mediated by differences in blood lead between Black and White individuals reduced from 10% to 5%.
Conclusions: These findings suggest that racial differences in lead exposure may explain racial disparities in blood pressure, but the mediating role of blood lead has decreased since the 1980s.
