Air
Human exposure to copper in air comes from both natural and anthropogenic sources. For the general
population, exposures to copper concentrations in air average between 5 and 200 ng/m3. The
concentrations of copper in air can be higher in the proximity of major sources such as smelters, mining
operations, and combustion sources (e.g., power plants, incinerators, automobiles, etc.). The results of
COPPER 159
6. POTENTIAL FOR HUMAN EXPOSURE
several studies in which concentrations of copper in air were reported and described below and are
summarized in Table 6-8
According to the EPA's National Air Surveillance Network report for the years 1977, 1978, and 1979,
median copper concentrations were 133, 138, and 96 ng/m3, respectively, for urban samples and 120, 179,
and 76 ng/m3 for nonurban samples, respectively (Evans et al. 1984). In this study, 10,769 urban and
1,402 nonurban air samples collected for 24 hours were analyzed. For 1977, 1978, and 1979, 1% of
urban samples exceeded 1,156, 975, and 843 ng/m3, respectively, and 1% of nonurban samples exceeded
1,065, 1,396, and 645 ng/m3, respectively. The maximum urban and nonurban copper concentrations
reported were 4,625 and 4,003 ng/m3, respectively. Davies and Bennett (1985) reported average
atmospheric copper concentrations of 5–50 ng/m3 in rural areas and 20–200 ng/m3 in urban locations.
The concentrations in rural areas are considerably lower than those reported in the EPA survey. Data
from many urban locations in the United States show concentrations of copper associated with particulate
matter ranging from 3 to 5,140 ng/m3 (Schroeder et al. 1987). Remote and rural areas have
concentrations of 0.029–12 and 3–280 ng/m3, respectively. The levels reported by Schroeder et al. (1987)
are consistent with those obtained in a study of airborne trace elements in national parks (Davidson et al.
1985). In the Smokey Mountain National Park, the copper concentration in air was 1.6 ng/m3, while in
the Olympic National Park, where several locations were monitored, 3.3–6.7 ng/m3 of copper was
measured in the atmosphere. The lower copper concentrations found in Smokey Mountain Park
compared with those in the Olympic National Park have been attributed to greater vegetative cover and
higher moisture in the former and larger amounts of exposed rock and soil in the latter. Average copper
crustal enrichment factors (the concentration of copper in air compared with the average concentration in
the earth's crust) were 31 and 76, respectively.
As part of the Airborne Toxic Element and Organic Substances (ATEOS) project for determining patterns
of toxic elements in different settings, three urban areas (Camden, Elizabeth, and Newark) and one rural
site (Ringwood) in New Jersey were studied during two summers and winters between 1981 and 1983
(Lioy et al. 1987). Each site was sampled every 24 hours for 39 consecutive days. As an example, the
geometric mean copper concentrations in the summer of 1983 were 16.0, 21.0, 21.0, and 6.0 ng/m3 for
Camden, Elizabeth, Newark, and Ringwood, respectively. In the winter of 1983, the mean copper
concentrations were slightly higher with values of 21.0, 36.0, 33.0, and 63.0 ng/m3, respectively. The
levels of copper measured in these industrial urban areas are considerably higher than the mean values
reported in the National Air Surveillance survey where arithmetic means of 0.201 and 0.259 ng/m3 for
copper in air were obtained in1978 and 1979, respectively (Evans et al. 1984). Summer and winter
maxima in the four ATEOS study areas were: 100.0 and 131.0 ng/m3 in Camden, 231.0 and 493.0 ng/m
in Elizabeth, 131.0 and 380.0 ng/m3 in Newark, and 77.0 and 29.0 ng/m3 in Ringwood, respectively.
Copper follows the same pattern as other heavy metals, in that increased copper levels are present in
winter in urban areas and in summer in rural areas. No explanation for this pattern has been offered.
Anderson et al. (1988) performed a study of the atmospheric aerosols collected at a site in Chandler,
Arizona, over a 12-day period in February and March 1982. Several major copper smelters are located
~120 km to the southeast, which were upwind of the sampling site during approximately 50% of the study
period. Particles containing >0.5% Cu were termed 'Cu-bearing' particles; 5.6% of the fine (0.4 to ~2 µm)
particles collected were in this category. The most abundant type of Cu-bearing particle, representing
74% of the total, was associated with sulfur. However, the analysis was not able to specify the form of
sulfur present. These particles were often associated with Zn, Fe, Pb, As, and Ca. Sixteen percent of the
Cu-bearing particles were associated with silicon and 4% were associated with chloride. The
concentration of Cu-S particles was highest when the surface and upper level winds were from the
southeast to the east, and reached a maximum 1–2 days after the winds began to blow. Therefore, the
smelters to the southeast appear to be the probable source. The particles associated with silicon and
chlorine did not show any apparent correlation with wind and were either from a diffuse regional source
or a local source.
Mine waste dump sites are a source of airborne copper carried in dust (Table 6-9). Particle size
distribution and the concentration of copper in particle size ranges differ depending on the mine waste site
(Mullins and Norman 1994). For example, the mean concentrations (ppm, w/w) of copper in dust
(<10 µm particle size range) collected at four mine waste dump sites in Butte, Montana, were 3,370 (Gray
Rock), 1,950 (Corra), 1,960 (Late Acquisition), and 2,570 (Railroad Bed).
Mean concentration ranges of copper in remote (any area of lowest copper concentration such as the
Antarctic or Arctic) and rural (any site that represents a regional background that is not directly
influenced by local anthropogenic emissions) precipitation ranges were 0.013–1.83 and 0.68–1.5 ppb,
respectively, based on a weight per unit volume basis (Barrie et al. 1987). Although an earlier survey
referred to by these investigators (Galloway et al. 1982) yielded much higher values, 0.060 and 5.4 ppb,
these were ascribed to sample contamination. The mean concentration of copper in rain reported in an
extensive study in southern Ontario, Canada, was 1.57 (0.36 standard deviation) ppb during 1982 (Chan
et al. 1986). These concentrations showed little spatial variability. Concentration of copper n cloud water over Olympic Peninsula in Washington State has been measured at 1.7±1.6 µg/L (airequivalent mean concentration of 0.5 ng/m3) (Vong et al. 1997).
The concentration of copper in rain samples taken within 2–15 km downwind of the Claremont, New
Hampshire, municipal waste incinerator was found to range from 0.11 to 2.12 µg/L with a mean
concentration of 0.87 µg/L. The total mean deposition rate of airborne copper from rain was measured to
be 4.0 µg/m2/day for the eight sampling sites used in the study (Feng et al. 2000). However, copper
deposition from automobile emissions, as measured by the concentration of copper in snow, did not vary
significantly as a function of distance (15–150 meters) from an expressway in Montreal, Canada. Mean
concentrations of copper in the snow (expressed as mg/L [and standard deviations]) were measured as
0.051 (0.073), 0.065 (0.127), 0.034 (0.027), and 0.044 (0.051) at 15, 20, 15, and 150 meters, respectively
(Loranger et al. 1996).
Airborne concentrations of copper in the indoor atmosphere within homes located in Suffolk and
Onondaga counties in New York average between 8 and 12 ng/m3 (Koutrakis et al. 1992). The
concentration was significantly affected by the use of kerosene heaters, which were found to emit copper
into the indoor air at a rate of 15,630 ng/hour (Koutrakis et al. 1992).
Elevated levels of copper in fog water have been observed 3 km downwind from a refuse incinerator in
Switzerland (Johnson et al. 1987). High concentrations of copper were associated with low pH. The
maximum concentration, 673 ppb, occurred at pH 1.94; levels >127 ppb were associated with pH values
<3.6. Copper(II) concentrations in fog water from the central valley of California ranged from 1.7 to
388 ppb (Miller et al. 1987). The source of the copper was not investigated. The highest values were
recorded just as the fog was dissipating.
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