ASSESSMENT OF AIRBORNE HEXAVALENT CHROMIUM IN THE HOME FOLLOWING USE OF CONTAMINATED TAPWATER

Field studies were conducted to estimate the plausible uptake of hexav alent chromium [Cr(VI)] aerosols inhaled during indoor residential use of a shower or an evaporative cooler supplied with water containing C r(VI). In the evaporative cooler study, water concentrations of 20 mg Cr(Vl)/L did not produce an increased concentration of airborne Cr(VI) . The indoor air concentration of Cr(VI), measured over 24 hours of us e, was 0.3-2.7 ng/m(3), about the same as the concurrent outdoor conce ntrations. In the shower study, the average airborne concentrations of Cr(VI) aerosols at breathing-zone height ranged from 87 to 324 ng Cr( VI)/m(3) when the water concentration of Cr(VI) was 0.89 to 11.5 mg/L. The Cr(VI) concentration in air was correlated directly to water conc entration. The lifetime average daily doses and incremental cancer ris k estimates corresponding to 30-year residential exposures were calcul ated using the measurements in this study and published exposure guide lines. The plausible upperbound lifetime cancer risk associated with c ontinuous exposure to ''background'' Cr(VI) in outdoor air was estimat ed at 6.9 per million for a person exposed during ages 0-30, and 4.0 p er million for ages 30-60. Similarly estimated upperbound cancer risks due to inhalation of shower aerosols from water containing 2-10 mg Cr (VI)/L over the same exposure period ranged from 0.9 to 5.5 per millio n. Our calculations demonstrate that shower aerosols do not contribute appreciably to background Cr(VI) exposures and risks, even at concent rations exceeding 2 mg Cr(VI)/L, which exhibit a discernible and unaes thetic yellow color that may limit the potential for long-term exposur es of this type. We conclude that exposure to indoor aerosols from wat er containing Cr(VI) is unlikely to create a health hazard at concentr ations up to IO mg Cr(VI)/L. Furthermore, these aerosol measurements m ay be relevant to estimating airborne exposures to other nonvolatile c hemicals.