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

MERCURY 475
5. POTENTIAL FOR HUMAN EXPOSURE
candles, ammonia, or camphor. Any of these practices can liberate mercury vapor into the room air exposing
the occupants to unnecessarily elevated levels of mercury vapors (ATSDR 1997; Wendroff 1990, 1991).
The issuance of cautionary notices by health departments to members of these user populations may be
appropriate. While some medicinal and pharmaceutical uses of mercury compounds have been replaced in
recent years, individuals in some religious and ethnic groups may still use mercury in various rituals. This
use of mercury can contaminate the dwelling if the mercury is not removed from flooring, carpeting, and
woodwork in an appropriate manner.
Individuals Living in Homes Where Mercury-containing Latex Paints Have Been Used. Prior
to 1991, phenylmercuric compounds were used as biocides in 25–30% of interior and exterior latex paints;
however, this use of mercury was voluntarily discontinued for interior paint in 1990 and for exterior paint in
1991 (Hefflin et al. 1993; Reese 1990). This use of phenylmercury resulted in the exposure of house
painters and residents to elemental mercury vapors in homes where interior or exterior latex paint was
applied. The concentration of mercury in interior paints was less than 200 ppm; however, the atmospheric
concentrations of elemental mercury vapor were found to be as high as 200 µg/m 3 less than 6 hours after
painting, 10 µg/m3 at 24 hours, and 6 µg/m3 after 1 month. Although the use of mercury biocides in latex
paint has been discontinued, it is possible that people who use old latex paint in their homes will be exposed
to mercury for a considerable time (Blondell and Knott 1993). Furthermore, although phenylmercury use in
exterior latex paints was discontinued in 1991, paint companies were allowed to continue to produce and sell
paint containing phenylmercury until the existing stocks of phenylmercury were exhausted. Paint produced
after 1990 containing phenylmercury must be so labeled. Exterior latex paints may have contained
phenylmercury at concentrations of up to 1,500 ppm, and their use has been shown to result in elevated
mercury levels in painters (see Section 5.5) (Hefflin et al. 1993). However, each year many homeowners
(66%) repaint their own homes, rather than employing professional painters; therefore, these individuals may
also be exposed (Hefflin et al. 1993). In addition, consumers can mistakenly use exterior paints indoors,
which may produce higher exposures to mercury than when the paints are used outdoors. Blondell and
Knott (1993) estimated that approximately 13 million people could be exposed to mercury through painting,
assuming the interior of houses were painted once every 5 years, that 78% of the interior paint used is latex,
and that one-third of the interior latex paint contained mercury. These authors emphasize that key
populations at risk include the painters, residents in the painted homes and children living in those homes.