Mercury vapor in residential building common areas in communities where mercury is used for cultural purposes versus a reference community

Abstract

Background: Exposure to elemental mercury (Hg0) in residential buildings can occur from accidental spills, broken objects (thermometers, fluorescent fixtures, thermostats), and deliberate introduction, one mode of which involves cultural practices by individuals who believe dispersal of mercury in a residence will bring luck, enhance health or ward off harm.

Objectives: To determine whether mercury vapor levels in common areas of residential buildings is higher in a community where cultural uses are likely (study areas S1, S2) than in a reference community (C1) where cultural use is unlikely, and whether levels can serve as a signal of significant cultural mercury use.

Methods: We monitored Hg0 vapor with a portable spectrophotometer in the three communities. We randomly selected sites in S1 and C1 community, and also include sites in S2 specified by local health officials who suspected cultural mercury use. We evaluated 122 multifamily buildings and 116 outdoor locations.

Findings: We found >25 ng/m3 Hg0 in 14% of buildings in study areas compared to only one reference building. In the latter we identified an accidental mercury spill from a bottle that had been brought into the building. Both the mean and maximum indoor mercury vapor levels were greater in the study communities than in the reference community. In all communities, we observed mean indoor Hg0 vapor concentration greater than outdoors, although in two-thirds of buildings, indoor levels did not exceed the area-specific outdoor upper-limit concentration.

Conclusion: After controlling for factors that might influence Hg0 vapor levels, the most plausible explanation for greater Hg0 levels in the study area is a relationship to cultural use of mercury. None of the measured levels exceeded the ATSDR minimum risk level for residences of 200 ng/m3 Hg0 although levels in living quarters might be greater than those in the common areas.

Fig. 1

Foreground left: amalgam icon — Parad Shivling. This item weighed 10 g and emitted 0.3 μg/h Hg⁰ vapor at 24 °C. Foreground right: gelatin capsules containing Hg⁰. The clear capsule contains 9 g Hg⁰ and was purchased in the study area for $1.00. We purchased the colored capsules in the Dominican Republic at a similar cost. Rear left: bottle of elemental mercury. This bottle contains approximately 2 kg Hg⁰ and was the source of spilled Hg in the reference community (C1). Rear center and right: Agua de Florida, and 7 Escencias. We purchased these items in the Dominican Republic also. The store clerk suggested we mix these items with mercury from the capsules and apply the mixture to floors in the home twice per week. These products typically contain water, alcohol, and essential oils. We do not believe they contain mercury though we did not analyze them.

Fig. 2

Cumulative probability plot of maximum Hg⁰ concentration in building common areas (n=122). ◆ Reference community (C1), ◻ study communities (S1, S2).