REVIEW ARTICLE
Widespread Arsenic Contamination of Soils in Residential Areas and Public Spaces: An Emerging Regulatory or Medical Crisis? D. A. Belluck,1 S. L. Benjamin,1 P. Baveye,2 J. Sampson,3 and B. Johnson3 1
Riskwriters, Ltd., Minneapolis, Minnesota, USA Laboratory of Geoenvironmental Science and Engineering, Bradfield Hall, Cornell University, Ithaca, New York, USA 3 Minnesota Department of Transportation, Office of Environmental Services, St. Paul, Minnesota, USA 2
A critical review finds government agencies allow, permit, license, or ignore arsenic releases to surface soils. Release rates are controlled or evaluated using risk-based soil contaminant numerical limits employing standardized risk algorithms, chemicalspecific and default input values. United States arsenic residential soil limits, ∼0.4–∼40 ppm, generally correspond to a one-in-onemillion to a one-in-ten-thousand incremental cancer risk range via ingestion of or direct contact with contaminated residential soils. Background arsenic surface soil levels often exceed applicable limits. Arsenic releases to surface soils (via, e.g., air emissions, waste recycling, soil amendments, direct pesticide application, and chromated copper arsenic (CCA)-treated wood) can result in greatly elevated arsenic levels, sometimes one to two orders of magnitude greater than applicable numerical limits. CCA-treated wood, a heavily used infrastructure material at residences and public spaces, can release sufficient arsenic to result in surface soil concentrations that exceed numerical limits by one or two orders of magnitude. Although significant exceedence of arsenic surface soil numerical limits would normally result in regulatory actions at industrial or hazardous waste sites, no such pattern is seen at residential and public spaces. Given the current risk assessment paradigm, measured or expected elevated surface soil arsenic levels at residential and public spaces suggest that a regulatory health crisis of sizeable magnitude is imminent. In contrast, available literature and a survey of government agencies conducted for this paper finds no verified cases of human morbidity or mortality resulting from
Received 19 August 2002; accepted 7 November 2002. Disclaimer. The views expressed in this paper do not necessarily represent the parent institutions of the authors. The authors express thanks to all reviewers of this manuscript and to medical and environmental agency personnel who kindly responded to the survey on morbidity and mortality from exposure to arsenic in soils. Address correspondence to D. A. Belluck, Risk Writers, Ltd., 3108 46th Avenue South, Minneapolis, MN 55406, USA. E-mail:
[email protected] International Journal of Toxicology, 22:109–128, 2003 c 2003 American College of Toxicology Copyright ° 1091-5818/03 $12.00 + .00 DOI: 10.1080/10915810390198311
exposure to elevated levels of arsenic in surface soils. This concomitance of an emerging regulatory health crisis in the absence of a medical crisis is arguably partly attributable to inadequate government and private party attention to the issue. Keywords
Arsenic, CCA-Treated Wood, Morbidity, Mortality, Soils
Arsenic, released to the atmosphere by natural processes (∼60%) (Cullen and Reimer 1989) and anthropogenic activities (∼40%) (Ayres and Ayres 1999; Cullen and Reimer 1989) returns to earth via precipitation and dry fallout (Cullen and Reimer 1989). Since recovery of arsenic from nonferrous smelters in the United States ceased, arsenic is imported at estimated levels of 27,000 metric tons in 1998 (90% for chromated copper arsenic [CCA]-treated wood) (Bleiwas 2000), and 24,000 metric tons in 2000 (Reese 2000). Since 1975, it is estimated that more than 300,000 metric tons of inorganic arsenic has been used in CCA-treated wood; most remains in service (Bleiwas 2000). CCA-treated wood is often light green in color, but may be factory dyed to various shades of brown (Lebow and Tippie 2001). This paper will integrate data on arsenic exposure, toxicology, natural and anthropogenic releases to soils, concentrations in background and contaminated soils, and regulatory toxicology to provide context for the following general questions: 1. Do arsenic levels in surface soils constitute a significant health risk? 2. Do commonly found elevated levels of arsenic in surface soils, primarily those caused by CCA-treated wood release of arsenic, constitute an emerging regulatory health crisis? 3. If there is an emerging regulatory health crisis, is there a concomitant medical crisis?
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To better answer question 3, a survey conducted by the authors of United States and international health and environmental departments will be presented that asks whether they have records of any cases of morbidity or mortality in humans exposed to elevated arsenic levels in surface soils. General Arsenic Exposure Estimates of human exposure to arsenic from ingestion, inhalation, and dermal routes are variable. United States adult estimated daily average uptake/unusual uptake of inorganic arsenic is estimated at 4.5/90 µg/day for water, 0.05/27–41 µg/day for air, 11–14/∼18 for food, 0.14 (assumes 7.2 ppm in soil)/2 (assumes 100 ppm in soil) µg/day for soil, no data/1.8–5.4 µg/day for smoking, and 16–19/138–156 µg/day for total absorbed (Valberg et al. 1997). Ingestion of drinking water and food appears to be the primary exposure route in the United States with soil a small component, less than 1% of intake (ODHS 2002; Valberg et al. 1997). Arsenic concentrations of 1, 2, 5, 10, 20, and 50 ppb were exceeded in groundwater in 36%, 25%, 14%, 8%, 3%, and 1% respectively of all United States public water-supply systems evaluated (Focazio et al. 1999). About 40% of both large and small regulated water supplies using groundwater have arsenic concentrations greater than 1 ppb (Welch et al. 1999). Estimated average daily intake of inorganic arsenic by Canadian adults in the general population/living near point sources (µg/kg·body weight [bw]/day) include: water, 0.1/
