Environmental News Arsenic in old herbicides comes back to haunt Denver A crabgrass killer used on residential properties in the 1950s and 1960s has been linked to arsenic concentrations ranging between several hundred and several thousand parts per million in upper soil layers in the Denver area. The finding raises questions of whether other arsenical herbicides and pesticides commonly used nationwide from the 1930s through the 1960s for agricultural purposes remain in soils that are now being developed into residential areas and whether that contamination can or has affected human health In the Denver case, the suspected culprit, which was banned for use in and around homes un-
der the Federal Insecticide, Fungicide, and Rodenticide Act in 1968, contained 25.11% arsenic trioxide and 8.25% lead arsenate in its formulation, says David Folkes of EnviroGroup Limited, an environmental consulting firm in Englewood, CO. Folkes presented his findings at the International Conference on Arsenic Exposure and Health Effects in San Diego in June. Because of Denver's semi-arid climate, the arsenic in the herbicide did not leach away over the years, and now "fairly high arsenic concentrations are potentially impacting thousands of residential properties in Denver and other cities" where the herbicide
Mysterious arsenic concentrations stump researchers Cadmium concentrations decrease with distance from a smelter site (top graph), but arsenic concentrations do not follow this pattern (bottom graph), leading researchers to suspect another contaminant source.
Source: David Folkes, EnviroGroup Limited.
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was sold, Folkes says. Although medical monitoring has shown no evidence of significant biouptake or health impacts, the levels are high enough that U.S. EPA has conducted some "emergency removals" on 18 residential properties—digging up the soil down to 1 ft and replacing it with clean soil, according to Barry Levine, director of EPA's Region 8 Superfund program. Another batch of 14-15 more yard cleanups was expected to follow in August and September. Initially, nobody was looking at pesticides as the source of the arsenic contamination. As the result of a natural resource damages lawsuit filed by the state of Colorado against Asarco, Inc., in 1983, the company was required to investigate and clean up soil contamination around a smelter that it has owned and operated for more than a century over W\Q years, it served 3.S 3. lead smelter, an arsenic trioxide refinery, a. cadmium refinery, and since 1993, as a high-purity metals facility. The lawsuit settlement required Asarco to sample properties around the plant continuing outward in all directions until metals concentrations fell below 70 ppm Normally, contamination from airborne emissions decreases fairly rapidly with distance from the source, which was exactly what happened with metals like cadmium, Folkes says. Testing soils on neighboring properties showed that the cadmium approached background levels about a half mile or so from the plant (see figure). Arsenic was another story. Instead of going down, "we began finding random, spuriously high arsenic levels the further we got from the plant and continuing for miles that did not fit the normal pattern," Folkes says. Similar findings turned up in subsequent random samplings carried out by Colorado's Department of Public Health and Environment (DPHE) in other areas of Denver, as well
as by EPA, including some individual samples as high as 10,000 ppm. "It's so sporadic that one property can show screaming high levels, and right next door, it's really clean," says DPHE's Mark Rudolph. Because they expected the arsenic and cadmium would behave similarly and decrease with distance, Folkes' group started investigating other possible sources, including airborne emissions from other nearby smelters, spills, contaminated fill, and arsenical pesticides. "One of the first things we looked at was the effect of land use on the arsenic concentrations," Folkes says. It turned out that arsenic levels found on developed properties were distinctly different from undeveloped properties, not following the classic airborne dispersion pattern. Another correlation was found between high arsenic concentrations and areas that had well-kept lawns back in the 1950s; arsenic speciation showed that the arsenic in residential areas was predominanuy in the form of arsenic trioxide crystals as opposed to the metal phases found at the Asarco plant and in nearby soils A further analysis of arsenic concentration and soil depth turned up a smooth profile from the surface down to a few centimeters indicating the arsenic was aDDlied at the ground surface Finally historians on the nroject team were able to idpntifv an actual nroduct sold wiriplv in thp Dpnvpr arpa in thp 11^0 d 1 Qfifl th t inpH a ratio of arsenic trioxide and lead arsenic identical to that found in the soils of a number of residential properties. The presence of perhte, a filler material used in the product, also was found to correlate with high arsenic concentrations. "One of the questions we were asked early on in our study was 'if this is from a residential pesticide, then why don't we see this elsewhere?'" Folkes notes. The answer: "nobody bothered to test for it before, and now that we are, we're finding it." EPA now is conducting tests on pesticides mat contained arsenic, hoping to eventually fin-
gerprint where soils around Denver became contaminated from pesticides and where smelters were the cause, Levine says. "The bottom line is that if this is a pesticide problem, it could be nationwide." The state of Colorado has required Asarco to clean up arsenic concentrations exceeding 70 ppm, as well as concentrations exceeding 28 ppm if a homeowner requests mis action, in areas affected by its plant. The cutoff point for EPA's emergency soil removals at other sites in Denver where it has done testing stands at 400 ppm, but the final cleanup level will depend on
the results of a risk assessment that EPA plans to release for public comment in October. "The concern is really for kids," Levine says. Although EPA did not find any arsenic in areas where children tend to aggregate such as gardens, schoolyards, and playgrounds, "we have found some concentrations in people's homes from dust being tracked in," Levine says. The U.S. Agency for Toxic Substances and Disease Registry is currently evaluating the public health implications related to arsenic exposure. —KRIS CHRISTEN
Obituary Remembering Alvin Alm We are sorry to note the passing of Alvin Aim, a business executive and senior government official who helped shape environmental and energy policy over a 40-year career. During the height of his career, Aim contributed to ES&Tas both an Editorial Advisory Board Member (from 1993 to 1995) and as a monthly columnist (from 1989 to 1993), analyzing topics ranging from an as-yet developed international agreement to stem global warming to Vice President Al Gore's book "Earth in the Balance." "Al Aim made outstanding contributions to environmental protection in this country and to the environmental profession," says ES&T Editor William Glaze. "I was honored to know and work with him. His "Regulatory Focus" column was one of our most popular features." Aim died of natural causes in Washington, DC, on July 24. With experience in budgeting, economics, and regulation. Aim was twice tapped by government leaders to take on tough jobs. In his last government post, Aim served as the U.S. Department of Energy's Assistant Secretary for environmental management where he engineered a more efficient but controversial plan to clean the military's nuclear waste dumps, designed to cut in half the estimated $350 billion price tag. In his second stint at the U.S. EPA in 1983, then-EPA Administrator William Ruckelshaus relied on Aim to help boost the reputation of the agency, battered following the tenure of Administrator Anne Gorsuch who resigned under pressure due to her handling of the Superfund and other programs. Born in Denver, he began his career with the Atomic Energy Commission, then served in the Bureau of the Budget. By 1970, Aim was the staff director of the newly created Council on Environmental Quality, a White House advisory agency where he helped write the 1972 Clean Water Act. He moved to EPA in 1973, focusing on providing grants to municipalities to improve wastewater treatment plants. He later coordinated the development of President Jimmy Carter's energy plan. His successes in business include serving as chair and CEO of Thermal Analytical Corp.; CEO of Alliance Technologies Corp.; and senior vice president of Science Applications International Corp. At the time of his death, Aim was president of Chambers Associates Inc., a public policy consulting firm.
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