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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 Superfund, Recycling, and
Solid Waste Management
United States Senate

May 6, 1993

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 I am a 30-year career public health officer and scientist. 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). ATSDR is one of the 8 agencies that comprise the Public Health Service; we are the principal federal public health agency involved with hazardous waste issues. As such, we will provide the committee with what we, and others, have found about associations between human health and hazardous wastes and the prevention of adverse human health effects that result from exposure to such wastes. I must emphasize association does not necessarily mean causation.

As background, ATSDR was created by the CERCLA legislation in 1980. We draw our budget and principal authorities from CERCLA [§104 (i)]. Our understanding of Congressional intent in creating ATSDR was to establish a federal public health resource that would work with EPA and other federal agencies, the States, local governments, and the public, on health and science matters concerning the human health hazards associated with Superfund sites and emergencies resulting from the unplanned releases of hazardous substances. The 1980 CERCLA mandated ATSDR to: 1) establish a National Exposure and Disease registry, 2) create an inventory of health information on hazardous substances, 3) create a listing of areas closed or restricted to access, 4) provide medical assistance during public health emergencies, and 5) determine the relationship between human exposure to hazardous substances and illness.

The 1986 Superfund Amendments considerably expanded the Agency's responsibilities. We were mandated to conduct health assessments (i.e., ATSDR's Public Health Assessments) of all National Priorities List (NPL) sites and to respond to petitions from individuals seeking health assessments, with the added provision for follow-up health activities, as needed, such as health studies, health surveillance, and exposure registries. We were also given responsibility for ranking which hazardous substances posed the greatest human health hazard at NPL sites, preparing toxicological profiles for each of those substances, and determining key data gaps for each substance. Identified key data gaps are to be filled through directed research, coordinated with EPA. ATSDR was also tasked to develop educational materials for health professionals, primarily physicians, concerning the diagnosis and treatment of patients exposed to toxic substances.

In short, CERCLA, as amended, mandates of ATSDR a broad, national program of Superfund site health assessments, health investigations, surveillance and registries, applied research, emergency responding, health education, and toxicological database development.

What have ATSDR and others determined about the impact on public health of hazardous waste sites and emergencies from the unplanned releases of hazardous substances? The following statements capsulize our findings to date:

• Though 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 associated with a small to moderate increased risk of some kinds of birth defects and, less well documented, some specific cancers.

• Although presenting great difficulty in study design to environmental epidemiologists, health investigations of communities around some individual hazardous waste sites have found increases in the risk of birth defects, neurotoxic disorders, leukemia, cardiovascular abnormalities, respiratory and sensory irritation, and dermatitis. However, no adverse health findings have been reported in many studies. These apparent discrepancies may be due to factors such as limitations inherent to epidemiologic methods, differences in environmental conditions in the communities investigated, and the small number of persons evaluated at some sites.

• Site remediation doesn't necessarily resolve all public health concerns. An increasing body of scientific evidence indicates 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 registrants reporting elevated rates of diabetes, stroke, elevated blood pressure, and neurologic problems. Followup research will attempt to determine to what extent these conditions are related to TCE.

• Human exposure to releases from hazardous waste sites has been documented at about 40% of sites; potential exposure could occur at another 40%. The actual levels of human exposure vary greatly from site to site and within groups at sites; each site is different. Measured levels of hazardous substances range from quite low to levels of health concern. ATSDR has found elevated exposure levels for lead, PCBs, arsenic, cadmium, chlordane, mercury, and a herbicide in persons at 12 sites.

• About 2% of sites present an Imminent and Urgent Public Health Hazard. (Such sites have been referred to EPA in accordance with normal procedure for actions under its emergency removal authority. Since 1989, ATSDR has issued 11 major health advisories on sites that were considered as imminent and urgent threats to public health.) ATSDR classifies 35% of sites as being Public Health Hazards, 40% as Indeterminate (these are sites where key environmental data are lacking to adequately determine if persons are being exposed), 20% as No Apparent Public Health Hazard (these are sites where past and current exposures have been indicated but where, based on current data, those exposures are no longer of public health concern), and 2% as No Public Health Hazard.

• Enough environmental data are available to support health investigations in communities living near 35% of the sites evaluated by public health assessments. There is insufficient environmental data to determine if health investigations should be conducted at approximately 40% of the sites which have had health assessments.

• The National Research Council, using EPA data, estimates about 41,000,000 people reside within 4-mile radii of 1,134 NPL sites, and about 3,325 persons reside, on the average, within 1 mile-radii of NPL sites.

• According to data collected for ATSDR since 1985 by the National Governors' Association, the number of areas closed to the public or with restricted access has increased from 1,637 in 1985 to 2,302 in 1991.

• The public, particularly communities living around hazardous waste sites, continue to express concern for the health effects of hazardous substances released from waste sites and other sources. ATSDR has received 251 petitions for public health assessments of sites of concern to petitioners; 80 petitions are being received annually.

• A hundred or more different toxic chemicals can be found at a single waste site in widely varying combinations; such mixtures may be much more toxic than any of the individual chemicals. The top 10 specific contaminants of concern identified at sites with a completed exposure pathway (those categorized as urgent public health hazards or public health hazards) were: lead (79% of sites), trichloroethylene (TCE) (66%), benzene (64%), arsenic (60%), chromium (57%), cadmium (52%), tetrachloroethylene (PCE) (49%), toluene (45%), di(2-ethylhexyl)phthalate (43%), and vinyl chloride (41.5%). The most common media in which those contaminants were identified were groundwater and soil.

• 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. ATSDR and EPA jointly identified 117 key data gaps for the first 38 top ranked hazardous substances found released from Superfund sites.

• Based on data from 5 state health departments, unplanned releases of hazardous substances from fixed and mobile sources present a health risk to workers (64% of injuries reported), emergency responders (14%), and community residents (22%).

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

Turning now to more detail on these points, perhaps the most pressing of the mandates given us dealt with conducting public health assessments at abandoned hazardous waste sites.

Since 1986 the Agency has completed more than 1,500 public health assessments. The 1986 CERCLA amendments require ATSDR: a) to conduct, within 1 year, a public health assessment of every site placed, or proposed for placement, on the NPL, and b) to respond to petitions for health assessments from individuals. The NPL currently numbers 1,331 sites, including 98 Department of Defense sites and 18 Department of Energy sites. ATSDR's public health assessments are an evaluation of data and information on the release of hazardous substances into the environment to:

• assess any current or future impact on public health,

• develop health advisories or other health recommendations, and

• identify studies or actions needed to evaluate and mitigate or prevent adverse human health effects.

Public health assessments are ATSDR's principal device to identify those communities that require public health followups. Our public health assessments are conducted using environmental contamination data provided primarily by EPA; health outcome data (e.g., birth defects) are supplied, when available, by states; and ATSDR staff seek to identify community-based health concerns. Many of ATSDR's public health assessments are performed under cooperative agreements by state health departments. Currently, ATSDR funds 22 states (covering approximately 80% of all NPL sites) to draft public health assessments which are then reviewed and approved by Agency staff.

The Agency's public health assessments currently place sites within specific categories of public health concern. About 2% of sites present an Imminent and Urgent Public Health Hazard. (Such sites are referred to EPA for actions under its emergency removal authority. Since 1989, ATSDR has issued 11 major health advisories on sites that were considered as imminent and urgent threats to public health.) ATSDR classifies 35% of sites being Public Health Hazards, 40% as Indeterminate (these are sites where key environmental data are lacking to adequately determine if persons are being exposed), 20% as No Apparent Public Health Hazard (these are sites where past and current exposures have been indicated but where, based on current data, those exposures are no longer of public health concern), and 2% as No Public Health Hazard. Site ranking and site classification is not a precise science; as databases improve in quality, so will ranking and categorizations of sites.

ATSDR has integrated all the information from its 1,500 public health assessments into an integrated database, called HazDat. Using this database, ATSDR can draw a number of characteristics about Superfund NPL sites. An analysis of public health assessments conducted last year found that human exposure to hazardous substances occurred at about 40% of sites. These figures have remained consistent with health assessments conducted over the past six years.

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 three classes of contaminants of concern identified in the fiscal year 1992 public health assessments, and the frequency with which they occurred at sites, were:

• volatile organic compounds (solvents) (87% of sites),

• inorganic compounds (87%), and

• halogenated pesticides (50%).

The top 10 specific contaminants of concern identified at sites with a completed exposure pathway (i.e., those categorized as urgent public health hazards or public health hazards) were: lead (79% of sites), trichloroethylene (TCE) (66%), benzene (64%), arsenic (60%), chromium (57%), cadmium (52%), tetrachloroethylene (PCE) (49%), toluene (45%), di(2-ethylhexyl)phthalate (43%), and vinyl chloride (41.5%).

For the most part, these classes of contaminants 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 has lead in high levels too (more than 80% of the time). This kind of information is important for designing human epidemiological investigations.

The National Research Council, using EPA data, estimates about 41,000,000 people reside within 4-mile radii of 1,134 NPL sites, and about 3,325 persons reside, on the average, within 1 mile-radii of NPL sites. ATSDR is obtaining demographics data on the communities around NPL sites, and in 1994 will conclude an analysis of their ethnic and racial composition as part of the Agency's Minority Health Program.

ATSDR's public health assessments are reviewed by a multidisciplinary staff of physicians, epidemiologists, toxicologists, and engineers to determine what follow-up actions should be undertaken at individual Superfund sites. In fiscal year 1992, sufficient data were available to indicate the need for health investigations at about 35% of sites, including sites where concern was for current and/or past exposures to hazardous substances released from the sites. The health investigations consist of human exposure studies and health effects investigations. ATSDR is backlogged in conducting these health followups; approximately 15% of followups can currently be serviced each year.

As I mentioned, ATSDR can be petitioned by an individual to conduct a health assessment of a site of concern to the petitioner. The Agency has received 251 petitions to date, a large figure that shows the public's health concerns. An average of 80 petitions are received annually. We are currently accepting about 75% of petitions as requiring public health assessments or health consultations. About 55% of petitions come from individual or community groups; 8% from members of Congress. The large number of petitions received annually is a demanding workload on ATSDR; to put these 80 into perspective, EPA added 23 sites to the NPL during 1991 and 30 in fiscal year 1992.

CERCLA [§104(i)(1)(C)] requires ATSDR "in cooperation with the States, and other agencies of the Federal Government, establish and maintain a complete listing of areas closed to the public or otherwise restricted in use because of toxic substance contamination." The National Governors' Association, under funding from ATSDR, has maintained the subject list. In 1985 there were 1,637 areas closed, which grew to 2,302 in 1991. The greatest number of areas closed or restricted to access occurred because of contamination of organic chemicals (73% of all areas). The bulk (78%) of sites closed or restricted are in states east of the Mississippi River. Data available to ATSDR do not indicate the reasons for the increased number of sites closed or restricted to access.

Another of our CERCLA mandates requires that we conduct studies of the adverse health effects of exposure to hazardous substances from waste sites. Epidemiological studies by ATSDR, state health departments, and academic institutions can be grouped into studies of a) the health of persons around individual sites and b) studies that combine populations around sites and their data for aggregate analysis.

Health investigations are important in a public health sense for identifying: persons for whom exposures must be interdicted and adverse health conditions that should be brought to the attention of persons found at increased risk of adverse health effects and medical and health authorities.

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 who have examined the association of 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. A 1983 study 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 significantly1 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 (Najem et al., 1983).2 Similarly, a study was conducted of 593 hazardous waste sites (HWS) in 339 U.S. counties of 49 states where analytic evidence showed contaminated ground drinking water as the sole source of water supply (Griffith et al., 1989). For each identified county, age-adjusted, site-specific cancer mortality rates for 13 major cancer sites were extracted from U.S. Cancer Mortality and Trends 1950-1979 for white males and females in the decade 1970-1979. Significant associations between excess deaths and all HWS counties, when compared to all non-HWS counties, 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.

A particularly important study examined the association between congenital malformations in children and maternal proximity to hazardous waste sites in the state of New York (Geschwind, et al., 1992). The study consisted of a total of 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 in comparison to the rest of the state.) A coordinate mapping procedure was used to match all case and comparison geographic coordinates to the hazardous waste coordinates. 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 confounds like smoking and alcohol history, maternal and paternal occupational exposures, and maternal nutritional status were not evaluated due to 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).

ATSDR funded a study conducted by the New Jersey Department of Health of reproductive outcomes associated with contaminated drinking water (Bove, 1992). Public drinking water systems serving 75 towns in northern New Jersey were evaluated. Hazardous waste sites were thought to have been among several sources of contaminants in the water supplies. All live births and stillbirths (excluding chromosomal defects and plural births) born during the period 1985 through 1988 to residents of the 75 towns were included in the study. The towns selected were not known to have excessive health problems. Information on birth outcome status and maternal risk factors was obtained from vital records and the New Jersey Department of Health Birth Defects Registry. Exposures during each month of pregnancy to drinking water contaminants were estimated for all births in the study using sample data for the public water system serving the town of maternal residence at time of birth. Contaminants evaluated included total trihalomethanes; trichloroethylene; tetrachloroethylene; total dichloroethylenes; carbon tetrachloride; and 1,2-dichloroethane. Although some water systems had levels of certain contaminants above federal standards at the time of the study, the study area was not considered to have contamination levels that were atypical of other areas in the U.S. Significant associations were found for the following: (1) Total trihalomethanes were associated with term low birth weight, intrauterine growth retardation, central nervous system defects, and major cardiac defects. (2) Trichloroethylene was associated with neural tube defects and oral cleft defects. (3) Carbon tetrachloride was associated with term low birth weight, intrauterine growth retardation, central nervous system defects, and oral cleft defects. (4) Tetrachloroethylene was associated with oral cleft defects. (5) Dichloroethylenes were associated with central nervous system defects. (6) Dichloroethane was associated with major cardiac defects.

ATSDR supported an additional birth defects study by the California Department of Health Services. They conducted a study to investigate 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. During this study 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 infants with malformations of the heart and circulatory system.

Studies done both by ATSDR and other researchers indicate that adverse reproductive outcomes may be related to consumption of contaminated drinking water or living in proximity of 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 in geographic areas potentially exposed to hazardous substances. Excess stillbirths, prematurity, low birth weight, cardiac defects, urogenital defects, limb reductions, clubfoot, oral clefts and neural tube defects may be related to exposures to hazardous substances through contaminated drinking water. Birth defects data from these state surveillance systems will be the subject of additional epidemiologic studies to clarify any associations with hazardous waste sites.

Latent 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 14 sites in Michigan, Indiana, Illinois, and Pennsylvania; 10 of the sites are on the NPL. TCE levels in drinking water ranged from 1 part per billion (ppb) to 19,380 ppm. (The Maximum Contaminate Level for TCE is 5 ppb.) Exposure durations ranged up to 18 years. For essentially all persons on the registry, TCE exposure has ceased due to provision of uncontaminated water. People on the registry report (through a structured health survey) more health problems when compared to national survey data. Some of these problems appear in only males, some in only females, and some in only specific age groups. The health problems which were reported in excess of those reported by the general population included anemia and other blood disorders, diabetes, hearing impairments, heart disease, hypertension, kidney disease, skin rashes, speech impairments, stroke, 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 until medical validation studies are conducted of a sample of the 5,000 registry cohort.

Several investigators have reported adverse health effects associated with specific hazardous waste sites. The principal health findings include: a) significantly shorter height by age for children at a waste site than for comparison children (Paigen et al., 1987); b) a higher prevalence in birth defects and liver diseases among persons living near a thorium waste disposal site than compared to persons living a greater distance from the waste site (Najem and Voyce, 1990); c) lower birthweight and more birth defects in census tracts where exposure to waste site occurs (ATSDR, 1990); d) hepatomegaly and abnormal liver function tests in residents exposed to leachate from a toxic waste dump (Meyer, 1983); e) dermatitis, respiratory irritation, neurologic symptoms, and pancreatic cancer at 7 sites (ATSDR); and f) in residents around a Superfund mining site, illness rates for chronic kidney disease, stroke, hypertension, heart disease, skin cancer, and anemia showed significant elevations (Neuberger et al., 1990). Though none of these studies measured exposure levels to hazardous substances, they add to the scientific database on waste sites and public health.

As an example of an individual site study, a study of a leukemia cluster in children living in Woburn, Massachusetts, found a confirmed increase in incidence, distributed uniformly over an 11-year period (Cutler et al., 1986). The investigators found no leukemia sufferer who had contact with a hazardous waste site, but could not rule out exposure to contaminated water (chloroform, trichloroethylene, tetrachloroethylene) as a factor. Studies of this kind cannot prove causality between incidence of adverse health effects and releases of hazardous substances from waste sites; however, they raise serious questions that should be elaborated through more precise investigation.

Some investigators have examined the kind and frequency of symptoms reported by persons living near hazardous waste sites (Hertzman, et al., 1987). Results from another study indicated that the group exposed to airborne hazardous waste was higher in self reported complaints referable to the respiratory system, constitutional ills, sensory irritation, and irregular heart beat than a comparison group from an nearby area (Ozonoff, et al., 1987). Similarly, when compared to a reference community, a health survey of persons near a large Superfund site found elevated odds ratios for 23 symptoms, and 8 symptoms had odds ratios greater than 1.5: blurred vision, pain in ears, daily cough for more than one month, nausea, frequent diarrhea, unsteady gait, and frequent urination (Baker, et al., 1988). Another study indicated excess symptom reporting among "exposed" community residents, (i.e., persons living near hazardous waste sites) compared with "unexposed" persons. Symptom reporting was strongly associated with "environmental worry" (Lipscomb, 1989).

In other studies, a) the proportion of cases of congenital heart disease among live births was significantly greater when parents had first trimester residential exposure to trichloroethylene and dichloroethylene-contaminated water, than for the comparison group (Goldberg, et al., 1990); b) when compared to controls, findings from a case-control study showed the frequency of spontaneous abortion was associated with detectable levels of mercury, high levels of arsenic, potassium, and silica, among other factors (Aschengrau, et al., 1989); and c) conduction latency of the blink reflex was lengthened in persons with alleged chronic exposure to trichloroethylene in well water when compared with latencies from laboratory controls (Feldman, et al., 1988).

A considerable number of studies have been conducted to investigate health effects in communities around hazardous waste sites. Many of these studies are negative in the sense that statistically significant increases in adverse health effects were not found (Grisham, 1986; Upton, 1989). Although such findings may represent the true health status of the communities due to limited or no exposure to hazardous substances, negative results can also occur from: inadequate sample sizes, inadequate information about exposure to hazardous substances, poor selection of sites studied, or inappropriate health effects studied for the toxicology of the specific substances found at a given waste site.

A comprehensive review of the published literature on public health implications of hazardous waste was conducted by the National Research Council (NRC, 1991b). 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".

As research proceeds, it is prudent to consider each waste site as a potential source for the release of substances into environmental media that can adversely affect human health. Because of this concern, ATSDR has developed a list of seven priority health conditions to 1) assist in evaluating potential health risks to persons living near these sites and 2) determine program and applied human health research activities involving hazardous substances identified at the sites (MMWR, 1992). To arrive at the priority health conditions shown in Table 1, ATSDR evaluated the toxicological and human health effects data for 50 of the 275 priority hazardous substances identified as being released from Superfund sites. In addition, ATSDR drew heavily on the findings from approximately 1,200 public health assessments conducted by the Agency for Superfund sites. These Superfund Priority Health Condition provide ATSDR and others with a framework for conducting health investigations around aggregated waste sites.

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.

Specific regulations for hazardous waste site remediation workers have been developed and promulgated by the Occupational Safety and Health Administration as a mandate in CERCLA, as amended. These regulations, which are contained in 29 CFR 1910.120, require the employer of remediation workers to develop and implement a comprehensive safety and health program for workers involved in hazardous waste operations. A significant requirement of the regulations is periodic medical surveillance of hazardous waste site workers (Melius, 1990). Additionally, worker training grants administered by the National Institute of Environmental Health Sciences provide essential training in protecting workers against the hazards of site remediation.

As an industry, clean up of hazardous waste sites is relatively new in the U.S., but one that involves large numbers of workers. Given the recency 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 (Favata, et al., 1990). 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 of the Laborers International Union of North American, in consultation with CDC's National Institute for Occupational Safety and Health, have jointly developed a health surveillance program for hazardous waste remediation workers. This system will eventually contain the medical information of about 10,000 remediation workers. The data will be evaluated periodically for any evidence of adverse health effects in groups of workers.

Concern for public health effects of hazardous substances occur when levels of exposure in humans exceed safe levels. A series of studies conducted by the Agency has documented exposure at some Superfund sites to heavy metals, volatile organic chemicals and/or polychlorinated biphenyls which could put affected residents at increased risk of developmental disabilities, growth retardation, kidney, liver and blood disorders, hypertension or birth defects.For example, the mean blood lead level for children living near the California Gulch site in Colorado was almost twice that predicted by a biokinetics uptake model (CHD, 1990). In addition to lead, increased exposure to arsenic has been reported in children living near waste sites in Montana, Washington, and Utah (ATSDR, 1986; ATSDR, 1987; ATSDR, 1988b; Binder, et al., 1987); elevated serum levels of polychlorinated biphenyls were found in some people at two waste sites (Stehr-Green, et al., 1988), although not at most sites surveyed; and 1,1,2,2-tetrachloroethylene was noted in the breath of persons whose homes were situated near a former chemical waste dump (Monster and Smolders, 1984). Twelve exposure studies conducted by ATSDR found elevated biological levels of hazardous substances of concern. The substances included lead, mercury, PCBs, chlordane, arsenic, and a herbicide.

The importance, and difficulties, of relating environmental contamination levels with human exposure levels is exemplified by the work ATSDR has conducted on persons exposed to lead. In one long-term investigation, ATSDR has worked 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 operations in 1982 and the area around it is an NPL site. Lead in soil and dust constituted the principal exposure routes. Through surveillance and intervention efforts, children's mean blood levels have declined steadily from 1974. However, in 1992 about 26% of children still exceeded 10 ug/dl. (The current CDC action level for children's blood lead levels is 10 ug/dl.) Efforts are on-going to reduce all children's blood lead levels to below 10 ug/dl.

Other studies of blood lead and soil lead associations have shown quite differing results. In studies at the Smugglers' Mountain NPL site in Colorado, quite high soil lead levels did not result in children's blood lead levels of health concern. ATSDR is currently concluding the data analysis of a study of 2,500 persons potentially exposed to lead in soil. From this study should come a better understanding of the relationship between lead in soil and lead in people.

I would like to turn now to what we have learned about the other kind of site addressed under Superfund -- the emergency release of hazardous substances.

In order to supplement information needed but not provided by the traditional national emergency response databases such as the National Response Center Database, the Hazardous Materials Information System, and the Acute Hazardous Events Database, 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.

Five states (Michigan, Iowa, Colorado, New Hampshire, and Wisconsin) collected data during the first two years of the project. These states reported a total of 1,249 events to the hazardous substances emergency events surveillance system. Seventy-two percent were fixed-facility and 28% transportation-related events. Twenty-eight percent of the events occurred in residential areas.

Respiratory irritation and eye irritation were the most frequently reported health effects, followed by nausea. This holds true for both fixed-facility and transportation events. In transportation events, the victims also commonly received trauma injuries and chemical burns. In all events combined, victims were most frequently employees (64%), followed by the general public (22%), and first responders such as fire fighters or police officers (14%). In transportation-related events, fewer (10%) of the victims were from the general public. The data derived from these initial five states clearly have major import for directing the nation's emergency response and prevention efforts.

To deal with hazardous substance emergencies, ATSDR has emergency response coordinators with immediate access to a wide variety of experts, including physicians, chemists, toxicologists, environmental scientists, and health care professionals. Between October 1985 and October 1992, approximately 6300 health consultations were conducted. Approximately 10% of those were provided during responses to acute release events.

During this past fiscal year, at the request of EPA regional offices, other federal agencies, and state and local agencies, ATSDR emergency response personnel made five on-site emergency responses, and responded to requests for information related to 83 other acute events. ATSDR's role during these emergencies focused on assisting first responders in addressing the public health needs of the approximately 140 people who were injured as a result of those acute events, and another 92,000 people (range: 1 to 50,000 per event) who were potentially affected.

Besides on-site emergency responses, ATSDR may prepare a health consultation or provide technical assistance in response to requests for information about health risks posed by a specific site, chemical release, or hazardous material. Health consultations can be written or oral; they provide a site-specific answer to a specific question. Consultations are also timely; an oral consultation may be provided on the same day a request is received. Approximately 43% of ATSDR's emergency event consultations provided medical guidance and treatment information for requestors.

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. As an example, in November of 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 to the residents of those areas. Potentially affected persons included 25 individuals in two extended families living in the immediate vicinity and approximately 100 additional persons within a three-mile radius. As a result of this public health advisory, EPA completed an emergency removal of uranium-containing waste ore from the site, thereby 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 both a warehouse and residential structure. 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 the families 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 two-mile radius from the Austin Avenue site (encompassing more than 12 square miles of metropolitan Philadelphia, Pennsylvania). Using a specially equipped radiation monitoring van, EPA scanned more than 60,000 homes and identified 21 additional sites with elevated radiation readings. Those sites included single-family dwellings, multi-family units, and a residential care facility.

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 ten 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 176 profiles to date which are up-to-date compilations of all that is known about the health effects of these substances. Over 1 million of these profiles have been distributed and we are told that the Toxicological Profiles are extremely useful to government agencies, private industry, and concerned community groups.

These profiles also serve the function of identifying key data gaps in scientific knowledge about these 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 PCB's 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 Toxic Substances Control Act authorities 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 initiate applied research to fill identified data gaps. ATSDR has referred 60 key data gaps to EPA for handling under their 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 Protection Act. It is also possible that some data gaps will be filled voluntarily by private industry, though that has yet to be realized.

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, with another 15 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:

• trained over 20,000 health professionals,

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

• trained more than 250 minority health professionals.

Preliminary feedback indicates that communication between physician and patient about the health effects of exposure to hazardous substances has improved, and that physicians, in some instances, are actually changing their practice in some communities where we have provided training.

Our key partners in conducting our work are EPA and state/local health departments. One main purpose of our support to state and local health departments is to improve the ability of health agencies to respond to community health concerns. I refer to communities around Superfund sites and other areas of pollution. Their 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 1992 we provided about $40,000,000 in funds to states through a series of cooperative agreement programs. This figure represents approximately 15% of ATSDR's total budget during this period, a substantial figure, given other budgetary demands on the Agency.

We have also continued to strengthen our focus on community involvement as an integral part of conducting our activities. During the past year, Agency personnel made approximately 8,000 personal contacts with members of communities near hazardous waste sites.

Community Assistance Panels have been found to be an effective means of fostering communication between ATSDR and site communities. A community assistance panel has three primary purposes: 1) to facilitate communication between ATSDR and the affected community; 2) to provide an ongoing series of community-based meetings to ensure community involvement throughout the public health assessment process; and 3) to provide information to ATSDR on the community's health concerns for inclusion in the public health assessment.

ATSDR also is increasing its use of public availability sessions-informal, drop-by meetings at which community members can meet one-on-one with ATSDR staff to discuss health and site concerns. Other site-specific community involvement activities that we have found useful include small group briefings for key community leaders, a practice that enables ATSDR to solicit information from grassroots leaders about how best to interact with their constituents and to address their concerns, and to provide up-to-date information about ATSDR activities in their community.

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1 The word significantly is used to mean statistical significance, according to some test used by the investigator whose results are being described.

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

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