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PUBLIC HEALTH ASSESSMENT ADDENDUM

AMERICAN SMELTING AND REFINING COMPANY
TACOMA, PIERCE COUNTY, WASHINGTON


PURPOSE

The Agency for Toxic Substances and Disease Registry (ATSDR) prepared a Preliminary Health Assessment for the American Smelting and Refining Company (ASARCO) site on January 2, 1989. Since that time, we have received two additional reports on the site – the Endangerment Assessment (1) and the Engineering Evaluation/Cost Analysis of Removal Action Alternatives (2). This addendum will specifically address public health concerns related to the contamination of off-site soils with arsenic.


DISCUSSION

In 1988, soil samples were collected from "high use" and residential locations surrounding the ASARCO site. High use areas included parks, playgrounds, school yards, and vacant lots with open access to children and other residents.

Analyses of soil samples from these areas indicated a trend in which the concentrations of arsenic in soil decreased as the distance from the site increased. Within a one-half mile radius of the smelter, the maximum soil concentration of arsenic in a high use area was 3,000 ppm. The geometric mean concentration of arsenic in 37 soil samples from high use areas was 515 ppm. In residential areas within a one--half mile radius of the site, the maximum soil arsenic concentration was 1,660 ppm; the geometric mean arsenic concentration in 71 residential soil samples was 277 ppm.

Residents living near the site could ingest small amounts of soil as the result of hand-mouth contact while working or playing outdoors. Larger amounts of soil could be ingested by children who exhibit pica. Pica is the ingestion of non-food items, such as soil, and occurs commonly in children aged 6 months to 3 years. Opportunities for soil ingestion would be most likely to occur in bare areas that have little or no vegetative cover. Additional exposure to arsenic could occur indoors from the ingestion of arsenic contaminated dusts.

The generation of dusts in work or play areas could also result in the inhalation of arsenic contaminated dust. However, the dose derived from dust inhalation would likely be much less than the dose derived from oral ingestion.

In 1987, the Tacoma-Pierce County Health Department tested children living within one-half mile of the site for urinary arsenic levels. It was reported that the urinary arsenic concentrations were less than the concentrations detected in previous studies (1). However, some of the children tested still showed elevated urine arsenic concentrations (greater than 40 ug/l). The source of arsenic exposure in the children with elevated urinary arsenic levels has not been established. However, other studies have shown that living in an area with arsenic contaminated soils can significantly increase urinary arsenic levels. In an earlier study at another site, ATSDR determined that urinary arsenic concentrations were elevated in children who lived in areas containing elevated soil arsenic concentrations (150-1,950 ppm) (3).

Chronic human exposure to arsenic by the ingestion of arsenic contaminated water has been associated with hyperkeratosis (overgrowth of the horny layer of the skin) and hyperpigmentation (abnormal deposits of dark pigment in the skin). Chronic oral ingestion of arsenic has also been associated with an increased incidence of skin cancer, particularly squamous cell carcinomas. It has been suggested that these squamous cell carcinomas arise from hyperkeratotic lesions.

Exposure to high doses of arsenic can also cause other noncarcinogenic toxic effects, such as neurotoxicity, gastrointestinal distress, and hematologic abnormalities. The dose levels of arsenic that cause these effects have not been well defined, but in general, they appear to exceed the dose levels which cause dermal toxicity (4).


CONCLUSIONS

The presence of elevated concentrations of arsenic in soil samples from areas surrounding the ASARCO facility poses a public health concern. Children living in the area are particularly at risk because:
(1) Children are more likely to frequent playgrounds, school yards, and other areas where high soil concentrations of arsenic were detected, and
(2) Soil ingestion by children, especially those with pica, would be greater than for adults.

Long-term exposure to arsenic could significantly increase an individuals risk of developing skin lesions, including skin cancer. The likelihood of arsenic exposures causing other noncarcinogenic effects cannot be assessed because of the lack of adequate dose-response relationships for these other toxic effects.


RECOMMENDATIONS

Suitable action should be taken to reduce human exposure to arsenic contaminated soils. In order to reduce such exposures, the U.S. Environmental Protection Agency has proposed remedial activities that would include the excavation and removal of soils contaminated with arsenic at concentrations in excess of 250 ppm. Such actions should be effective in reducing arsenic exposures and the resulting risk to human health. These actions should be implemented in a timely fashion in order to reduce further exposures to environmental arsenic contamination.


PREPARER OF REPORT

Kenneth G. Orloff, Ph.D.
Senior Toxicologist
Health Sciences Branch

REGIONAL REPRESENTATIVE

Greg D. Thomas
Public Health Advisor
Field Operations Branch
ATSDR Region X


REFERENCES

  1. Black and Veatch, Final Endangerment Assessment, Rushton/Vashon Area, September, 1988.

  2. Black and Veatch, Engineering/Cost Analysis of Removal Action Alternatives, Rushton/Vashon Area, 1988.

  3. Suzanne Binder, Dave Forney, Wendy Kaye, and Dan Paschal, Arsenic Exposure in Children Living Near a Former Copper Smelter, Bull. Environ. Contain. Toxicol. 39 114-121 (1987).

  4. Agency for Toxic Substances and Disease Registry, Toxicological Profile for Arsenic, ATSDR/TP-88/02, 1988.


Table of Contents

  
 
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