Evaluation of mercury in urine as an indicator of exposure to low levels of mercury vapor.

Abstract

We conducted a pooled analysis to investigate the relationship between exposure to elemental mercury in air and resulting urinary mercury levels, specifically at lower air levels relevant for environmental exposures and public health goals (i.e., < 50 microg/m3 down to 1.0 microg/m3). Ten studies reporting paired air and urine mercury data (149 samples total) met criteria for data quality and sufficiency. The log-transformed data set showed a strong correlation between mercury in air and in urine (r = 0.774), although the relationship was best fit by a series of parallel lines with different intercepts for each study R2 = 0.807). Predicted ratios of air to urine mercury levels at 50 microg/m3 air concentration ranged from 1:1 to 1:3, based on the regression line for the studies. Toward the lower end of the data set (i.e., 10 microg/m3), predicted urinary mercury levels encompassed two distinct ranges: values on the order of 20 microg/L and 30-60 microg/L. Extrapolation to 1 microg/m3 resulted in predicted urinary levels of 4-5 and 6-13 microg/L. Higher predicted levels were associated with use of static area air samplers by some studies rather than more accurate personal air samplers. Urinary mercury predictions based primarily on personal air samplers at 1 and 10 microg/m3 are consistent with reported mean (4 microg/L) and upper-bound (20 microg/L) background levels, respectively. Thus, although mercury levels in air and urine are correlated below 50 microg/m3, the impact of airborne mercury levels below 10 microg/m3 is likely to be indistinguishable from background urinary mercury levels.

High exposure of Chinese mercury mine workers to elemental mercury vapor and increased methylmercury levels in their hair

“…Urine and serum or plasma THg concentrations are good biomarkers of level of exposure to Hg 0 vapor or divalent Hg (6,9,10). In this study, THg concentration in urine was measured to assess the level of exposure of mine workers to Hg 0 vapor, because urine samples from the mine workers were easy to obtain.…”

“…Therefore, the central nervous system (CNS) and kidneys are the two target organs of Hg 0 exposure (6). For the assessment of the level of human exposure to Hg 0 vapor, urine and serum total mercury (THg) concentrations are used as biomarkers (6,9,10). Many studies have shown a significant correlation between Hg concentrations in urine and serum and the Hg 0 concentration in air when exposure levels are high (6,(11)(12)(13).…”

Mercury Exposure in Young Children Living in New York City

“…26 The paper suggests that when mercury exposure is at or below the ATSDR's 1-μg/m action level for mercury vapor relative to background levels of urinary mercury, 3 the contribution of mercury vapor exposure to measurable urine mercury levels may be negligible. Therefore, if mercury vapor was present in a child's environment at or below the residential action levels, it may not have been measurable in urine.…”

Exposure assessment of young children living in Chicago communities with historic reports of ritualistic use of mercury

“…The anonymous urines samples did not significantly differ from the enrolled population. Lastly, a recent article (26) suggests that the contribution of mercury vapor exposure to measurable urine mercury levels may be negligible relative to background levels of urinary mercury when the exposure is at or below the Agency for Toxic Substances and Disease Registry (ATSDR) action level for mercury vapor (1 μg/m3). If mercury vapor was present in a child's environment at or below the residential action levels, it may not have been measurable in urine.…”