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

MERCURY 395
5. POTENTIAL FOR HUMAN EXPOSURE
1991). Mercury may also be released to surface waters in effluents from a number of industrial processes,
including chloralkali production, mining operations and ore processing, metallurgy and electroplating,
chemical manufacturing, ink manufacturing, pulp and paper mills, leather tanning, pharmaceutical
production, and textile manufacture (Dean et al. 1972; EPA 1971c). Discharges from a regional
wastewater treatment facility on the St. Louis River that received primarily municipal wastes contained
0.364 µg/L (ppb) of mercury, resulting in concentrations in the adjacent sediment of up to 5.07 µg/g (ppm)
(Glass et al. 1990). Industrial effluents from a chemical manufacturing plant on the NPL (Stauffer
Chemical’s LeMoyne, Alabama site) contained more than 10 ppm of mercury; these effluents had
contaminated an adjacent swamp and watershed with mercury concentrations in the sediments ranging
from 4.3 to 316 ppm (Hayes and Rodenbeck 1992). Effluent monitoring data collected under the National
Pollutant Discharge Elimination System (NPDES) Program were used to estimate pollutant loadings from
effluent discharges to the San Francisco Bay Estuary between 1984 and 1987 (Davis et al. 1992). Of the
1,030 samples of industrial effluents monitored entering the San Francisco Estuary during this period, 39%
were found to contain mercury (Davis et al. 1992). Although these authors did not specify the limits of
detection for mercury and did not provide quantitative information on the concentrations detected, they did
indicate that measurements for most of the priority pollutants including mercury were at or below the
detection limit. This precluded quantitative assessment of spatial and temporal trends in calculating
loadings to the estuary for all but four metals (Davis et al. 1992).
According to the most recent Toxics Release Inventory, in 1996, the estimated releases of 541 pounds of
mercury to water from 31 large processing facilities accounted for about 0.64% of total environmental
releases for this element (TRI96 1998). An addition 15 pounds of mercury were released indirectly to
POTWs, and some of this volume ultimately may have been released to surface waters. This is
approximately 215 pounds more mercury than was released to water directly or indirectly via POTWs in
1994 (TRI94 1996), but 445 pounds less than that released to water either directly (144 pounds) or
indirectly via POTWs (301 pounds) in 1991 (TRI91 1993). The TRI data listed in Tables 5-1 and 5-2
should be used with some caution, since only certain types of facilities are required to report (EPA 1996f).
This is not an exhaustive list.
Mercury has been identified in surface water, groundwater, and leachate samples collected at 197, 395, and
58 sites, respectively, of the 714 NPL hazardous waste sites where it has been detected in some
environmental media (HazDat 1998).