revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 452
5. POTENTIAL FOR HUMAN EXPOSURE
Naleway et al. (1991) reported results of a screening study conducted in 1985 and 1986 by the American
Dental Association to analyze urinary mercury concentrations in dentists and identify those individuals with
elevated urinary mercury levels. In 1985, 1,042 U.S. dentists were screened, and a mean urinary mercury
level of 5.8 µg/L (ppb) (maximum 84 µg/L) was reported. In 1986, 772 dentists screened had a mean
urinary level of 7.6 µg/L (ppb) (maximum 115 µg/L). Their mean urinary mercury levels were substantially
lower than pooled data (mean, 14.2 µg/L) from dentists participating in the screening program from
1975–1983 (Naleway et al. 1985). The authors noted a substantial decline, particularly during the last 5
years (1982–1986), which was attributed to better mercury hygiene and the reduced use of amalgam
restorations. This study also evaluated responses from a questionnaire survey of 480 dentists. The results
indicated that those dentists reporting skin contact with mercury amalgam had mean urinary mercury levels
of 10.4 µg/L (ppb), compared to 6.3 µg/L (ppb) in dentists reporting no skin contact; this difference was
found to be statistically significant. Similarly, the mean urinary mercury level in dentists reporting mercury
spills in the office was 7.8 µg/L (ppb), compared to 6.0 µg/L (ppb) for those reporting no mercury spills.
Again, the difference was significant. Additionally, the number of hours practiced per week was found to
weakly correlate with urinary mercury concentrations (Naleway et al. 1991).
Painters are another group that may be occupationally exposed to mercury vapors from volatilization of
mercury during application of paint containing phenylmercuric acetate. Hefflin et al. (1993) studied the
extent of mercury exposure from the application of exterior latex paints. These authors compared the air and
urinary mercury concentrations of 13 professional male painters with those of 29 men having other
occupations (nonpainters). The painters applied 2 brands of exterior latex paint that contained mercury; the
median concentration was 570 mg/L (ppm). The median air mercury concentration was higher for painters
(1.0 µg/m 3 ; range, non-detectable to 4 µg/m3 ) than for nonpainters (non-detected; range, not detected to
3 µg/m3 ). The median urinary mercury concentration was nearly twice as high for painters (9.7 µg/L [ppb];
range, 5.9–20.4 µg/L) as for nonpainters (5.0 µg/L [ppb]); range, 2.6–11.6 µg/L [ppb]) (p=0.0001). The
normal range of urinary mercury is