Seafood intake and urine concentrations of total arsenic, dimethylarsinate and arsenobetaine in the US population

Background: Seafood is the main source of organic arsenic exposure (arsenobetaine, arsenosugars and arsenolipids) in the population. Arsenosugars and arsenolipids are metabolized to several species including dimethylarsinate (DMA). Objective: Evaluate the association of seafood intake with spot urine arsenic concentrations in the 2003-2006 National Health Nutrition and Examination Survey (NHANES). Methods: We studied 4276 participants ≥6 years. Total arsenic was measured using inductively coupled plasma dynamic reaction cell mass spectrometry (ICPMS). Urine DMA and arsenobetaine were measured by high-performance liquid chromatography coupled with ICPMS. Results: Participants reporting seafood in the past 24-h had higher urine concentrations of total arsenic (median 24.5 vs. 7.3 γg/L), DMA (6.0 vs. 3.5 γg/L), arsenobetaine (10.2 vs. 0.9 γg/L) and total arsenic minus arsenobetaine (11.0 vs. 5.5 γg/L). Participants reporting seafood ≥2/wk vs. never during the past year had 2.3 (95% confidence interval 1.9, 2.7), 1.4 (1.2, 1.6), 6.0 (4.6, 7.8) and 1.7 (1.4, 2.0) times higher (p-trend <0.001) concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine, respectively. In participants without detectable arsenobetaine and in analyses adjusted for arsenobetaine, seafood consumption in the past year was not associated with total arsenic or DMA concentrations in urine. Conclusion: Seafood intake was a major determinant of increased urine concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine in the US population. Epidemiologic studies that use total arsenic, DMA, the sum of inorganic arsenic, methylarsonate and DMA, and total arsenic minus arsenobetaine as markers of inorganic arsenic exposure and/or metabolism need to address seafood intake.