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Congressional Testimony
ATSDR: Public Health Actions and Findings

Testimony by
Barry L. Johnson, Ph.D.
Assistant Surgeon General
Assistant Administrator
Agency for Toxic Substances and Disease Registry
Public Health Service
U. S. Department of Health and Human Services

Before the
Subcommittee on Commerce, Trade, and Hazardous Materials
Committee on Commerce
U.S. House of Representatives

May 23, 1995

Good morning. I am Barry Johnson, Ph.D., Assistant Administrator of the Agency for Toxic Substances and Disease Registry (ATSDR). I have served as Assistant Administrator since 1986, and my professional background is in toxicology and environmental health. I welcome this opportunity to brief you on ATSDR's public health actions and findings under the Comprehensive Environmental Response, Compensation, and Liability Act, as amended (CERCLA, or Superfund).

My testimony today will describe ATSDR's principal CERCLA responsibilities and our key administrative relationships with the Environmental Protection Agency (EPA). Our testimony is organized around what we, and others, have found about associations between uncontrolled releases of hazardous substances and the impact on human health. For the purposes of this testimony, we have given emphasis to uncontrolled hazardous waste sites.

CERCLA mandates of ATSDR a broad, national program of Superfund site health assessments, health investigations, surveillance and registries, applied research, emergency response, health education, and toxicological database development. Our work is conducted in close collaboration with the Environmental Protection Agency (EPA), state health departments, and local health agencies.

As preface, the American public remains quite concerned about the potential impacts of Superfund sites on public health. Since 1991, ATSDR has received more than 4,000 requests for assistance from concerned citizens potentially affected by more than 1,000 sites. Additionally, since February first of this year, we have received more than 45,000 requests for information via the Internet. ATSDR has had direct contact since 1991 with more than 300,000 citizens concerned about Superfund and hazardous substances issues through our public meetings and other site-specific activities.

The following statements capsulize our findings to date related to the impact on public health of hazardous waste sites and emergencies related to unplanned releases of hazardous substances:

• Although epidemiologic findings are still unfolding, when evaluated in aggregate (i.e., by combining health data from many Superfund sites), proximity to hazardous waste sites seems to be associated with a small to moderate increased risk of some kinds of birth defects and, less well documented, some specific cancers.

• Health investigations of communities around some individual hazardous waste sites have found increases in the risk of birth defects, neurotoxic disorders, dermatitis, leukemia, cardiovascular abnormalities, respiratory dysfunction, and immune disorders.

• Site remediation doesn't necessarily resolve all public health concerns. An increasing body of scientific evidence indicates that past exposures to hazardous substances can cause latent adverse health effects. Recent findings from the ATSDR exposure registry of approximately 5,000 persons exposed in the past to trichloroethylene (TCE) in drinking water showed adult registrants reporting elevated rates of stroke, liver problems, anemia, diabetes, kidney disease, and skin rashes; speech and hearing impairments were increased in young children. These findings highlight the need for continuing surveillance of populations exposed to hazard substances.

• From what we have learned about 1,309 sites assessed by ATSDR from 1987 through December 1994, completed exposure pathways (i.e., people were in the path of substances released from sites) were identified at about 40% of sites. About 60% of EPA National Priorities List (NPL) sites assessed by ATSDR in fiscal years 1993 and 1994 were found to have completed exposure pathways.

• ATSDR has issued 21 major health advisories on sites considered imminent and urgent threats to public health and those advisories have led to removal actions under EPA's authorities. Seven sites have been placed on the NPL because ATSDR issued a health advisory.

• Of the 136 sites for which public health assessments were conducted and advisories were issued in fiscal years 1993 and 1994, ATSDR classified 54% as health hazards. Ten percent of sites were classified as no apparent public health hazard, 2% of sites were classified as no public health hazard, and 34% could not be determined. Historically, 23% of 1,719 public health assessments for more than 1,300 Superfund sites represented a health hazard, according to ATSDR's criteria. These figures should be cited with caution, however, because of limitations in our contaminant and human exposure databases.

• ATSDR has completed an analysis of the demographic characteristics of populations around 93% of the current 1,286 NPL sites. Our data, which are based on 1990 census information, indicate that about 11 million people, whose health is potentially affected by exposure to hazardous substances at the site, reside within 1 mile of these sites' borders.

• At more than 50% of sites where people are known to be exposed to a contaminant from the site, lead or trichloroethylene, or both, were identified as hazards. At more than one third of these sites, levels of concern of chromium, benzene, arsenic, tetrachloroethylene, cadmium, methylene chloride, toluene, or 1,1,1-trichloroethane were also found. All but the last two of these substances are known carcinogens or are reasonably anticipated to be carcinogens, according to EPA.

• 60% of ATSDR's public health assessments include recommendations to EPA and states to interdict or reduce current, ongoing exposures to hazardous substances.

• From data reported by 11 state health departments for 1993 from almost 4,000 emergency events where hazardous substances were released, there were 16 deaths, 4,063 separate injuries sustained by 2,269 victims, and 496 evacuations of people. The most frequent victims were responders to the event and employees working at a facility.

• Serious gaps exist in scientific knowledge about the toxicity, bioavailability, exposure, and human health effects of individual hazardous substances and mixtures of substances released from Superfund sites and during emergency releases. There is a particular need for data on levels of exposure to hazardous substances in community populations.

• Physicians and other health care providers in communities around Superfund sites continue to express a significant need for training and technical assistance in matters of hazardous substances.

ATSDR was created by CERCLA. We therefore work closely with EPA and states in the conduct of our health-based responsibilities. ATSDR is not a regulatory agency. We advise EPA and states on health hazards associated with Superfund sites, but any risk management actions rest with EPA and others. For example, we can advise EPA to provide alternate drinking water to a community, but any actual provision of water is up to EPA's determination. ATSDR interacts with EPA in several ways. Our public health advisories inform EPA of imminent hazards to public health. There have been 21 public health advisories to date. In our experience, EPA has acted promptly on every advisory. We also provide a large amount of consultation on a daily basis to EPA regions on site- specific matters of human health. When requested, we provide health-based advice on matters of site remediation. Over the last 3 years, ATSDR has received approximately 3,000 requests from the EPA regions.

One of ATSDR's most substantive relationships with EPA concerns the conduct of ATSDR's public health assessments of NPL sites and sites where ATSDR has been petitioned to conduct a health assessment. For the NPL sites, ATSDR uses Remedial Investigation environmental contamination data collected by EPA as one key database for ATSDR's site-specific health assessments. ATSDR's health assessment reports are provided to EPA, states, and local communities. These documents state the level of human health hazard assessed by ATSDR. Each report contains individual recommendations to EPA, states/tribes, and ATSDR itself. ATSDR monitors the outcome of each report's recommendations. By our count, EPA implements about 95% of our recommendations.

For some sites, ATSDR measures exposure levels of site-related toxicants in community residents. This exposure information is provided to EPA for use in any removal or other risk management action.

Other key partners are state and local health departments. One main purpose of our support to state and local health departments is to improve their capacity to respond to community health concerns. I refer to communities around Superfund sites and other areas of environmental contamination. These communities' legitimate health concerns need the coordinated response of government at all levels.

In 1986 when Congress reauthorized Superfund, it was clear that they strengthened the statute's health section, and it was equally clear to ATSDR that Congress envisioned a partnership between states and ATSDR in implementing these health provisions. In 1987, the Agency committed itself to a goal of building or enhancing state health departments' capacity in environmental health. From fiscal year 1987 through 1994, we have provided about $62,600,000 in funds to 36 states through a series of cooperative agreement programs. This figure represents approximately 18% of ATSDR's total budget during this period, a substantial figure given other budgetary demands on the Agency.

I'll now discuss details of ATSDR's CERCLA mandates and key findings.

Public Health Assessments

Since 1986, the Agency has completed more than 1,700 public health assessments of communities around Superfund sites. The 1986 CERCLA amendments require that ATSDR: a) conduct, within 1 year, a public health assessment of every site placed, or proposed for placement, on the NPL, and b) respond to petitions for health assessments from individuals. The NPL currently numbers 1,296 sites, including 162 federal government sites or facilities.

Public health assessments are ATSDR's principal device for identifying communities that need public health followup. Our public health assessments are conducted using environmental contamination data provided primarily by EPA; health outcome data (e.g., birth defects), which states supply when available; and community-reported health concerns.

Many of ATSDR's public health assessments are conducted, after appropriate training by ATSDR, by state health departments under cooperative agreements with ATSDR. Currently, ATSDR funds 22 states (encompassing approximately 80% of all NPL sites) to draft public health assessments that are then reviewed and approved by ATSDR staff.

The Agency's public health assessments currently place sites in specific categories of public health concern. Data from the 136 sites assessed in fiscal years 1993 and 1994 indicate that about 5% of sites presented an Imminent and Urgent Public Health Hazard. ATSDR classified 49% of sites as Public Health Hazards, 34% as Indeterminate (sites where key environmental data are lacking to adequately determine if persons are being exposed), 10% as No Apparent Public Health Hazard (sites where past and current exposures have been indicated but where current data indicate those exposures are no longer of public health concern), and 2% as No Public Health Hazard. Ranking and classification of sites are not precise sciences; as databases have improved in quality, so has the ranking and categorization of sites.

ATSDR has compiled the information from its 1,700 public health assessments, 2,500 consultations, and other documents into a unique integrated database, called HazDat. ATSDR has used this database to identify a number of characteristics about Superfund NPL sites. An analysis of 1,309 sites assessed through December 1994 found that pathways of human exposure to hazardous substances were completed at about 40% of sites. For fiscal years 1993 and 1994, this figure increased to 60%, primarily because of improvements in contaminant databases and other types of information.

ATSDR also has been able to make important observations about the types of contaminants released from Superfund sites; the environmental media that are most affected by those contaminants; and the pathways by which people are exposed to contaminants. The top 10 contaminants of concern identified at sites with a completed exposure pathway were these: lead (59% of sites), trichloroethylene (TCE) (53%), chromium (47%), benzene (46%), arsenic (45%), tetrachloroethylene (PCE) (41%), cadmium (39%), toluene (39%), 1,1,1-trichloroethane (32%), and methylene chloride (31%). All but two of these substances are known carcinogens or are reasonably anticipated to be carcinogens.

Contaminants released from sites were most frequently identified in groundwater, followed by subsurface soil, sediment, and surface water.

Using ATSDR's HazDat database, we have found that a hundred or more different toxic chemicals can be found at a single waste site. These chemicals can be found in widely varying combinations in water, soil, and air, and some of the combinations may be much more hazardous than any of the individual chemicals. Therefore, ATSDR is examining the combinations of chemicals that exist at waste sites to identify chemical mixtures that should be studied. As an example of what we have learned from this analysis, we have found that soil with levels of concern for copper, chromium, arsenic, cadmium, or mercury almost always also has lead in high levels (more than 80% of the time). This kind of information is important for designing human epidemiologic investigations and relevant laboratory studies. The National Research Council, using EPA data, estimated in 1991 that about 41 million people reside within 4-mile radii of 1,134 NPL sites. ATSDR has completed an analysis of the demographic characteristics of persons residing around 93% of the current 1,296 NPL sites. We find that 11 million people live within 1 mile of these sites' borders. These people are potentially at risk from exposure to hazardous substances at these sites.

In fiscal years 1993 and 1994, sufficient data were available to indicate the need for health investigations at about 35% of sites, including sites where concern was for current or past exposures to hazardous substances released from the sites. The investigations are examining human exposure and health effects. ATSDR has a backlog of health followups; approximately 15% of followups can currently be completed each year.

As I mentioned, ATSDR can be petitioned by an individual to conduct a public health assessment of a site. The Agency has received 394 petitions to date, representing 323 individual sites. An average of 80 petitions are received annually. We are currently accepting about 75% of petitions for conduct of public health assessments or health consultations. About 55% of petitions come from individual or community groups; about 8% come from members of Congress. The large number of petitions received annually is a demanding workload for ATSDR; to put these 80 into perspective, EPA added 23 sites to the NPL in 1991, 30 in 1992.

Health Effects Investigations

Another of the CERCLA mandates requires that we conduct studies of the adverse health effects of exposure to hazardous substances from waste sites. Epidemiologic studies conducted by ATSDR, state health departments, and academic institutions are of two types: a) studies that examine the health of persons around individual sites and b) studies that combine populations around sites and their data for aggregate analysis.

Health investigations help identify persons for whom exposures can be interdicted, add important information about risk factors for diseases and illnesses, identify vulnerable populations on whom to focus prevention activities, determine relationships between exposure and adverse health effects, and help determine or evaluate measures to prevent or mitigate adverse health conditions. Findings from human health studies are also significant material for inclusion in site-specific risk assessments.

Aggregated Site Studies

Investigating the broad picture of the association between hazardous waste sites and public health impact requires combining site populations with common environmental characteristics, thereby increasing the size of the human populations investigated. This aggregating of sites has been used as an investigative method by researchers examining the association between cancer and birth defects rates in areas around hazardous waste sites.

Two sets of investigators have reported an increased frequency of cancers in counties surrounding hazardous waste sites. In 1983, the New Jersey Health Department reported that age-adjusted gastrointestinal (GI) cancer mortality rates (all sites combined) were higher in 20 of New Jersey's 21 counties than national rates. Within specific sex and race groups, cancer mortality rates in the state during the period 1968-1977 significantly exceeded national rates for cancers of the esophagus, stomach, colon, and rectum. The environmental variables most frequently associated with GI cancer mortality rates were population density, degree of urbanization, and presence of toxic waste disposal sites. Similarly, an EPA study was conducted of 593 hazardous waste sites in 339 U.S. counties of 49 states where analytic evidence showed contaminated groundwater as the sole source of drinking water supply. For each identified county, age-adjusted, site-specific cancer mortality rates for 13 major cancer sites (anatomic) were extracted from U.S. Cancer Mortality and Trends (1950-1979) for white males and females during the decade 1970-1979. Statistically significant associations between excess deaths and all counties with hazardous waste sites, when compared to all counties without hazardous waste sites, were shown for cancers of the lung, bladder, esophagus, stomach, large intestine, and rectum for white males; and for cancers of the lung, breast, bladder, stomach, large intestine, and rectum for white females. Neither the EPA nor the New Jersey studies reported any data bearing on the levels of exposure of these residents, which is a significant limitation.

A New York State Health Department study examined the association between congenital malformations in children and maternal proximity to hazardous waste sites in the state. The study included data for 9,313 newborns with congenital malformations, as recorded in the New York State Congenital Malformations Registry, and 17,802 healthy comparison children. A total of 590 hazardous waste sites in 20 New York counties were selected for analysis of the incidence of malformations. (Waste sites in New York City were excluded, given what were presumed unique sociodemographic and geographic characteristics compared with the rest of the state.) An exposure risk index was created for each respondent within a 1-mile radius of the birth residence. Through statistical analysis, the investigators controlled for several possible confounding variables, including maternal age, race, education, complications during pregnancy, birth weight, length of gestation, and sex of child. It is important to note that other possible confounding factors, such as smoking and alcohol history, maternal and paternal occupational exposures, and maternal nutritional status were not evaluated because of lack of data. Results indicated that maternal proximity to hazardous waste sites may carry an additional risk of approximately 12% of bearing children with congenital malformations. Higher malformation rates were associated with both a higher exposure risk (63% increase in risk) and documentation of off-site chemical leaks (17% increased risk). These results are the subject of follow-up investigation by ATSDR and the New York State Health Department.

ATSDR funded an additional birth defects study by the California Department of Health Services. The department conducted a study investigating the relationship between maternal residence and the presence of hazardous waste sites for the risk of congenital malformations. The study evaluated births between 1983 and 1985; 5,617 births with congenital malformations were evaluated. The study concluded that maternal residence at the time of the child's birth in a census tract with a hazardous waste site, significantly increased the risk of giving birth to an infant with malformations of the heart and circulatory system.

Studies by ATSDR and other researchers indicate that adverse reproductive outcomes may be related to consumption of contaminated drinking water or living in proximity to hazardous waste sites. For example, birth defects and developmental disabilities were evaluated by ATSDR-funded surveillance systems in Iowa, New Jersey, and Washington. These states used birth defects registries and birth records to assess populations potentially exposed to hazardous substances in specific geographic areas. In Iowa, investigators found an association between herbicides in public drinking water and urogenital and limb reduction birth defects and small babies for their gestational age. In New Jersey, investigators found links between solvents in public drinking water and excess small babies for their gestational age, and cardiac, oral clefts, and central nervous system birth defects. Data on birth defects from these state surveillance systems will be the subject of additional epidemiologic studies to clarify any associations with hazardous waste sites.

ATSDR has adopted the approach of aggregating sites for the purpose of health evaluation. This approach was outlined in a 1992 report to Congress entitled, The Feasibility and Value of Performing Multisite Epidemiologic Studies for Superfund Sites. An example of this approach is an ATSDR study conducted in four separate geographic areas near mining and smelting sites in Illinois, Kansas, Missouri, and Pennsylvania involving more than 2,200 people. It was found that the blood lead levels in children living near the sites were strongly associated with soil lead levels. This demonstrates that the lead contamination in soil was an important contributor to the lead in children's blood. As you know, lead has been shown to be particularly harmful to the developing brain and nervous system of young children. Efforts are underway to reduce children's exposure to lead.

Adverse health effects in persons who in the past were exposed to hazardous substances are suggested by findings from ATSDR's National Exposure Registry. Included in the registry are approximately 5,000 individuals with documented exposure to trichlorethylene (TCE). The 5,000 registrants come from 15 sites in Michigan, Indiana, Illinois, Arizona and Pennsylvania; 11 of the sites are on the NPL. TCE levels in drinking water ranged from 1 part per billion (ppb) to 19,380 ppb. (The Maximum Contaminant Level for TCE is 5 ppb.) Exposure durations ranged up to 18 years. For essentially all persons on the registry, TCE exposure has stopped following provision of uncontaminated water. Registrants report (through a structured health survey) more health problems compared to respondents to other national health surveys. Some of these problems were reported only by males, some only by females, and some only by specific age groups. The health problems reported in excess of those reported by the general U.S. population included anemia and other blood disorders, diabetes, hearing impairments, kidney disease, skin rashes, speech impairments, stroke, liver problems and urinary tract disorders. Some of the health problems reported by registrants are consistent with the toxicology of TCE. However, caution must be exercised when interpreting these health findings. Medical validation studies currently are being conducted of a sample of the 5,000 registry cohort.

Health Studies at Individual Sites

A considerable number of studies have been conducted by Federal, State, and local governments, universities, and private investigators regarding health effects in communities around individual hazardous waste sites. Some recently completed site investigations conducted by ATSDR or state health departments with ATSDR support reported the following results:

• Respiratory Illness
  • At the Brio NPL site in Friendswood, Texas, a study of 744 current or former residents showed increased reports of respiratory and skin problems.

  • A 1995 study among residents of Forest City and Glover, Missouri, who lived near operating smelters showed an increase in reports of respiratory problems and decreased pulmonary function, especially among nonsmoking women.

  • Findings from an ATSDR study of residents living near a former hazardous waste incinerator in Caldwell County, North Carolina, show an increased prevalence of respiratory disease in the target population. Follow-up biomarker testing that found decreased pulmonary function among residents living near the site verifies these symptoms.

• Cancer and Immune System Function
  • Blood samples from approximately 6,000 persons who live near 10 hazardous waste sites showed an increased rate of an unusual production of abnormal blood cells that has been associated with chronic lymphocytic leukemia. Thus far these observations have been predominantly among people who were potentially exposed to volatile organic compounds.

  • Findings from an ATSDR cross-sectional, symptom- and disease-prevalence study of 700 persons in Tucson, Arizona, exposed to volatile organic compounds in drinking water reveal an increased prevalence of the debilitating disease erythematosus lupus.

• Birth Defects and Reproductive Disorders
  • A study among Texarkana, Texas, residents showed that persons living near an abandoned wood treatment facility reported more difficulty becoming pregnant and had fewer pregnancies than a comparison population not living near the site.

  • In an ATSDR-funded study, investigators reported the increased occurrence of birth defects in the children of women living near 600 hazardous waste sites in California. Analysis shows that children of women living near sites where exposure to the solvents toluene and xylene was likely had greater than twice the typical rate of neural tube birth defects, such as spina bifida and anencephaly.

  • Findings from an ATSDR-funded study of minority women living near sites in California where exposure to semi- volatile organic chemicals, pesticides, and heavy metals was likely shows elevated rates of limb reduction defects, central nervous system defects, and heart defects in their children compared to the rates of such defects in the children of minority women not living near hazardous waste sites.

  • Near the Lipari NPL site in New Jersey, a study by the New Jersey State Health Department (funded by ATSDR) showed babies that were small for their gestational age born to women living near the site, particularly during the years 1970-1975, when hazardous substance releases peaked. These differences abated when site releases were contained.

• Neurologic Problems
  • An ATSDR study of residents living near a former hazardous waste incinerator in Caldwell County, North Carolina, found increased neurologic symptoms in residents living near the incinerator site.

  • When compared with the expected rates of illness among the U.S. population, children from ATSDR's National Exposure Registry who were exposed to trichloroethylene through contaminated drinking water had higher rates of speech and hearing impairment.

A comprehensive review of the published literature on the public health implications of hazardous waste was conducted in 1991 by the National Research Council. This review concluded: In spite of the complex limitations of epidemiologic studies of hazardous- waste sites, several investigations at specific sites have documented a variety of symptoms of ill health in exposed persons, including low birth weight, cardiac anomalies, headache, fatigue, and a constellation of neurobehavioral problems. It is less clear whether outcomes with a long delay between exposure and disease also have occurred, because of complex methodological problems in assessing these outcomes. However, some studies have detected excesses of cancer in residents exposed to compounds, such as those that occur at hazardous waste sites. A more recent study of the scientific literature concerning hazardous waste and human health effects was sponsored by the Chemical Manufacturers Association (CMA) this year. That study identifies a number of shortcomings in the studies reviewed. The principal shortcoming identified by the CMA reviewers was too limited knowledge about levels of exposure of community residents to substances released from waste sites. ATSDR's experience shows that adverse health effects of hazardous substances released from sites have occurred in some communities. The prevalence of adverse effects is unknown because of limitations in toxicologic knowledge, environmental databases, and environmental epidemiology practices.

Health Studies of Remediation Workers

In addition to concern for the health of communities potentially affected by the release of substances from hazardous waste sites, care must be exercised that the workers who remediate (i.e., clean up) the sites are not harmed by their work. The removal of soil or water contaminated with toxic substances clearly presents the potential for adversely affecting the health of clean- up workers if the necessary precautions are not taken.

As an industry, cleanup of hazardous waste sites is relatively new in the United States, but one that involves large numbers of workers. Given the recent introduction of site-specific work, there is only a very limited scientific database on any potential health effects associated with such work. According to one source, clinical and research findings from clinical centers performing health surveillance examinations on hazardous waste workers have not shown remarkable health abnormalities related to the workers' activities. From a public health perspective, this is a very desirable outcome. However, the investigators caution that the lack of any health problems in hazardous waste workers may be due to the fact that most of the workers examined had performed feasibility (i.e., inspection and assessment) work, not actual remediation of sites.

I am pleased to note that ATSDR and the Health and Safety Fund, which is a joint project between the Laborers International Union of North America and site remediation contractors, have jointly developed a health surveillance program for hazardous waste remediation workers. This system will eventually contain medical information on about 5,000 remediation workers. The data will be evaluated periodically for any evidence of adverse health effects in groups of workers.

Exposure Studies

Concern for public health effects of hazardous substances occurs when exposure in humans exceeds safe levels. A series of studies conducted by ATSDR has documented human exposure to contaminants at some Superfund sites, but no exposure at other sites. This human exposure information is critical, and can best be verified through biologic sampling.

Examples of ATSDR-conducted studies that document human exposure to contaminants from waste sites include these:

• The importance, and difficulty, of relating environmental contamination levels with human exposure levels is exemplified by the work ATSDR has done in conjunction with the Centers for Disease Control and Prevention (CDC) and the Panhandle Health District in Idaho to conduct blood lead surveillance of children exposed to lead from a smelter. The smelter closed in 1982 and the area around it is an NPL site. Lead in soil and dust were the principal exposure routes. Through surveillance and intervention efforts, children's mean blood levels have declined steadily since 1974. However, in 1994, blood lead levels in about 17% of children still exceeded 10 µg/dL. Efforts are ongoing to reduce all children's blood lead levels to below 10 µg/dL, the current CDC action level for lead.

• A study of the Mohawk Tribe in New York documented that women who consumed local fish from polychlorinated biphenyl (PCB)-contaminated waters had significantly higher concentrations of PCBs in their breast milk.

• In Fond du Lac, Minnesota, Native Americans who consumed fish from water contaminated with mercury were found to have higher levels of mercury in their blood than people who did not consume fish.

• Exposure studies conducted in Park City, Utah, among residents near Prospector Square mine tailings and by the New Mexico Department of Health among residents near the Billing Mine Superfund site in Socorro, found higher blood lead levels in persons living near the site. Although the mean blood lead levels were less than 10 µg/dL, these studies once again demonstrate that lead in soil does constitute exposure risks for children.

• The results of biologic testing of residents living near the ASARCO Smelter site in Everett, Washington, showed that the vast majority of participants in the study did not have current exposure to arsenic. This study, done in cooperation with the Washington State Department of Ecology and the EPA, supported the conclusion that some of the interim actions for reducing exposure at the site had been effective, and that relocation of residents was unnecessary.

• An ATSDR study of human exposure to PCBs in Monroe County, Indiana, found that in spite of the potential for exposure to PCB-contaminated media, the results of their serum PCB tests showed that individuals living in the community were generally not at risk of current exposure to PCBs.

• A study of people who were exposed to contaminated drinking water in communities surrounding the Rocky Mountain Arsenal NPL site in Colorado showed no significant increases in levels of mercury and arsenic in urine.

Emergency Response and Consultations

I turn now to what we have learned about the other type of site addressed under Superfund the emergency release of hazardous substances. ATSDR has implemented an active state-based hazardous substances emergency events surveillance system to describe the public health consequences associated with hazardous substance releases. As a result of our activities, the ability of participating states to respond to an emergency involving hazardous substances has been significantly improved.

Fourteen states are collecting data on the nature and impact of emergency releases of hazardous substances. Information reported by 11 of these states on nearly 4,000 events in 1993 indicates the following trends:

• 12% of all emergency events involving exposure to hazardous substances resulted in injuries.

• 4,063 separate injuries (including 16 deaths) were sustained by 2,269 victims.

• The most frequently reported injuries were respiratory irritation, eye irritation, nausea, and headache, followed by chemical burns and trauma. The most frequent victims were responders to the event and employees working at a facility.

• 496 emergency events required the evacuation of people living nearby.

A special kind of health consultation is the Public Health Advisory. It is a statement of concern from the ATSDR Administrator to the EPA Administrator. ATSDR has issued 21 public health advisories, leading to placement of 7 sites on the NPL.

As examples of health advisories, in November 1990, ATSDR issued a public health advisory informing EPA, the Navajo Nation, the Indian Health Service, and other federal and New Mexico state agencies of a potential significant environmental hazard to human health on Navajo land near Bluewater, New Mexico. ATSDR was concerned that the presence of uranium-containing radioactive mine wastes, areas potentially contaminated with heavy metals, and many physical hazards could result in adverse human health effects in residents of the areas. Potentially affected persons included 25 individuals in 2 extended families living in the immediate vicinity and approximately 100 additional persons within a 3-mile radius. As a result of this public health advisory, EPA completed an emergency removal of uranium-containing waste ore from the site, reducing radiation exposure by about 80%.

As a second example, in 1991, ATSDR, in support of EPA, issued a public health advisory on a potential significant environmental hazard to human health in the vicinity of Austin Avenue, Lansdowne, Pennsylvania. The contaminants of concern included radium, radon, and asbestos in a warehouse and residence. In conjunction with the release of the public health advisory, EPA, at the advice of ATSDR, relocated two families and initiated whole body radiation counts on them to determine if they had been internally contaminated by radium at the sites. As a result of this public health advisory, EPA surveyed an area extending in a 2-mile radius from the Austin Avenue site (encompassing more than 12 square miles of metropolitan Philadelphia, Pennsylvania) and identified 21 additional sites with elevated radiation readings. In 1993, ATSDR issued a public health advisory concerning an area of Stratford, Connecticut. City and state authorities had found widespread contamination of school play areas and residential properties because contaminated soil had been used as fill material. The contaminated soils contained large concentrations of lead, PCBs, and asbestos. ATSDR, working with EPA and state and local health and environmental agencies, implemented a number of public health interventions in 1994. These included a voluntary blood lead testing program, in-home dust sampling, physician education on hazardous substances, and EPA's proposed placement of the Stratford site on the NPL.

Toxicological Databases and Data Gaps

The 1986 CERCLA amendments [§104(i)(2)] require ATSDR and EPA to jointly rank, in order of health importance, hazardous substances released from waste sites. The agencies have agreed on a list of 275 Superfund Priority Hazardous Substances. The first 10 substances on the list are lead, arsenic, mercury, vinyl chloride, benzene, cadmium, PCBs, chloroform, benzo(a)pyrene, and trichloroethylene.

ATSDR is directed by CERCLA [§104(i)(3)] to prepare a Toxicological Profile for each Priority Hazardous Substance. We have developed 200 profiles to date; these profiles are up-to-date compilations of all that is known about the health effects of these substances.

These profiles also identify key data gaps in scientific knowledge about hazardous substances. For example, exposure to what levels of mercury will result in an acute health effect? Does drinking benzene-contaminated water cause birth defects? Does eating fish contaminated with PCBs cause illness? Does long-term exposure to zinc cause cancer?

As directed by CERCLA [§104(i)(5)], ATSDR, in cooperation with EPA and the National Toxicology Program must evaluate the adequacy of scientific data for each of the 275 prioritized substances. Key gaps in scientific knowledge are to be filled through referral to EPA's authorities under the Toxic Substances Control Act and other mechanisms. The 117 key data gaps for the first 38 substances on the Priority List of Hazardous Substances were published in 1992. CERCLA directs that ATSDR work with EPA, National Toxicology Program, and industry to assure the initiation of applied research to fill identified data gaps. ATSDR has referred 60 key data gaps to EPA for handling under its Toxic Substances Control Act authorities. Some key data gaps are being filled by funding from ATSDR, as directed by Congress, through research grants to academic institutions in the Association of Minority Health Professions Schools and to academic and state health departments in support of health research mandated by the Great Lakes Critical Programs Act. Some data gaps will be filled voluntarily by private industry through arrangements with ATSDR.

Health Education

Turning to another of our mandates, CERCLA [§104(i)14] directs ATSDR to develop educational materials and provide training for medical colleges, physicians, and other health professionals. To this end, we have developed a series of monographs entitled Case Studies in Environmental Medicine to inform health care professionals of health effects caused by hazardous substances in the environment. Twenty documents are currently available; another 15 are in various stages of development. These self-instructional exercises in environmental medicine are designed to guide primary care practitioners through the diagnosis and treatment of illness in persons exposed to hazardous substances in the environment. The documents are prepared and peer reviewed with the assistance of physicians and other health care professionals, including representatives of a number of professional medical societies and associations.

Since 1986, as part of our educational efforts, we have:

• provided training to more than 30,000 health professionals,

• distributed more than 140,000 copies of the Case Studies,

• provided training to more than 400 minority health professionals, and

• distributed to physicians and hospitals more than 60,000 copies of medical management guidelines for use in responding to emergency events.

Mr. Chairman, this concludes my testimony. I will be pleased to answer questions.

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