Naphthalene exposure and relationship with hemoglobin and hematocrit in White, Black, and Hispanic adults: Results from the 2003-2004 National Health and Nutrition Examination Survey

Introduction: Naphthalene is an important contaminant in indoor and outdoor air. Acute overexposure can have toxic effects, resulting in hemolysis. We examined 1- and 2-hydroxynaphthalene urinary metabolites (NAP1 and NAP2) in White, Black and Hispanic U.S. adults, and their relationship with hemoglobin (HGB) and hematocrit (HCT). Methods: Using the 2003-2004 National Health and Nutrition Examination Survey data, weighted generalized linear regression analyses were used to examine the association between HGB (g/dL) and HCT (%) with NAP1 and NAP2 (per 100,000 ng/L). Beta coefficients ± SE are reported. Results: NAP1 and NAP2 were highest in Blacks, followed by Whites, and lowest in Hispanics. There was a positive association between NAP1 and HGB (0.39±0.11, p=0.0034) and HCT (1.14±0.28, p=0.0009) after adjusting for age, gender, race, education, and smoking. Stratified analysis by smoking showed similar results with the association being stronger for smokers (HGB 0.63±0.23, p=0.02; HCT 1.43±0.79, p=0.09) than non-smokers (HGB 0.34±0.14, p=0.03; HCT 1.08±0.42, p=0.02). The association was also stronger for Blacks (HGB 0.54±0.20, p=0.02; HCT 1.43±0.55, p=0.02) than for Whites (HGB 0.37±0.18, p=0.06; HCT 1.20±0.51, p=0.03) and was not significant for Hispanics (HGB 0.30±1.7, p=0.10; HCT 0.99±0.52, p=0.08). NAP2 was not significantly associated with HGB or HCT. Conclusion: The observed disparity in NAP1 and NAP2 levels by race-ethnicity is consistent with the literature, and may in part be related to mothball use differences. The positive association between NAP1 with HCT and HGB is an unexpected finding. Further research is needed to understand the possible biological mechanisms for this association.