Females exposed to certain hazardous substances report more adverse health outcomes than national norms, and in some cases more than similarly exposed males, according to data from the National Exposure Registry of the Agency for Toxic Substances and Disease Registry (ATSDR).

The registry currently consists of subregistries for benzene, trichloroethylene (TCE), trichloroethane (TCA), and dioxin. The purpose of the registry is to assess the potential long-term health impact on the general population of exposures to environmental hazards, such as those at Superfund sites.

Female and male registrants of at least one subregistry have reported significantly more anemia and other blood disorders, skin rashes, and strokes compared to national norms provided by the National Health Interview Survey. Registrants also reported a greater amount of diabetes, kidney and liver problems, and urinary tract disorders, but rates for females were typically greater than those of males exposed to the same substances. Results that differed significantly compared to national norms for females by health outcome and subregistry are illustrated in Table 1.

The data indicate that the adverse health outcomes experienced by these women might be associated with exposure to low-level hazardous substances over extended periods, said Je Anne Burg, PhD, chief, ATSDR Exposure and Disease Registry Branch (EDRB), and Ginger Gist, PhD, senior environmental health scientist, EDRB, in their 1997 paper "The Potential Impact on Women from Environmental Exposures" (Journal of Women's Health 6[2]:159-161).

This data is particularly important because there is a need for information about the impact of exposures on certain subpopulations, including women.

"Most information on the health effects of exposure to hazardous substances comes from occupational studies of healthy males and toxicologic studies in which such low-level, long-term exposures cannot be duplicated," the researchers said.

"Women as a whole have typically been underrepresented in these types of studies," said Dr. Gist. "The information we hope to develop from the National Exposure Registry should allow researchers to focus on women as a susceptible population for certain chemical exposures. More importantly, however, this information will make women more aware of their potential health problems related to exposure to these substances and, in turn, allow them to assist in their own health maintenance."

The registry has longitudinal data on approximately 5,000 female registrants, ranging in age from infants to the elderly; there are approximately 10,000 registrants in all. Data on demographics, smoking, occupational and reproductive histories, and 25 general health conditions are collected at baseline and in biennial followups. ATSDR researchers compare the rates of reported health conditions with national norms and use the results to generate hypotheses and conduct more in-depth studies.

ATSDR researchers plan to use this data and that from biennial followups to conduct a more definitive assessment of the association between women's health outcomes and exposures to these substances, the researchers said.

ATSDR researchers are currently assessing reproductive outcomes reported in the registry, Dr. Gist said. Under a cooperative agreement with ATSDR, the University of South Carolina School of Public Health is conducting research concerning speech and hearing deficits in registrants who were 0-9 years of age at baseline. ATSDR researchers have also proposed a study verifying the rates of anemia, diabetes, and cancer for the volatile organic chemical registries (i.e., benzene, TCE, and TCA). Once these tasks have been accomplished, the researchers can begin more focused studies of the health outcomes.

Some registry data (without personal identifiers) is available from ATSDR. For more information on the registry, contact Je Anne Burg, PhD, ATSDR, 1600 Clifton Rd, NE, MS E31, Atlanta, GA 30333; telephone (404) 639-6202; fax (404) 639-6219; e-mail jrb3@cdc.gov.

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Agency for Toxic Substances and Disease Registry (ATSDR) researchers are using computational models to refine reconstruction of past exposures to hazardous substances through environmental pathways and water distribution systems.

One goal of ATSDR's exposure assessment studies is to identify links between environmental hazards and increased risks to human health. Often, there is not enough information available about past exposures to estimate health risks; therefore, researchers have to reconstruct levels of hazardous substances that people may have been exposed to and length of time they were exposed.

"The use of a computational model provides health scientists and public health professionals with a refined methodology that allows them to quantify areas of past exposure and possible public health concern rigorously," said Morris Maslia, PE, a research hydrologist in ATSDR's Division of Health Assessment and Consultation (DHAC).

ATSDR researchers and others can use computational models to test a variety of exposure scenarios and hypotheses and to reconstruct exposure estimates and make recommendations based on scientifically accepted techniques and procedures, he said.

In April 1997, Maslia and colleagues published the paper "Exposure Assessment Using Analytical and Numerical Models: Case Study" (Pract. Period. Hazard., Toxic, Radioact. Waste Manage 1[2]:50-60). The paper describes application of computational models to estimate exposure of residents of a Somers, Connecticut, neighborhood to tetrachloroethylene (also known as perchloroethylene or PCE), a volatile organic compound, detected in groundwater supplies.

Maslia's colleagues were Robert Williams, PE, DEE, of ATSDR, and Mustafa Aral, PhD, PE, of the Georgia Institute of Technology (Georgia Tech).

Obtaining a reliable result hinged on simulating the behavior of the groundwater system and PCE migration and concentration over time. The researchers used simplified one-dimensional analytical and two-dimensional numerical fate and transport models to (1) determine the vertical migration of PCE through overlying glacial till, (2) characterize groundwater flow in the bedrock aquifer, and (3) reconstruct historical PCE concentrations in the bedrock aquifer. The researchers calibrated the models to available field data. They obtained PCE concentrations profiles for 9 scenarios using a 30-year (1963 to 1994) simulation for each one.

The researchers also conducted a Monte Carlo analysis of parameter uncertainty for the one-dimensional analysis. Implementation of analytical tools in analysis of groundwater media requires many input parameters, including source-, media-, and chemical-specific variables.

"It is often more appropriate to express these parameter values in terms of a probability distribution rather than a single deterministic value and to use an uncertainty propagation model to assess the effect of the variability on the output of the models," the researchers said in their paper.

The study indicated that (1) although the glacial till was expected to be a barrier to PCE movement, contaminated groundwater was moving rapidly through the glacial till overlying the bedrock aquifer; (2) residents have probably been exposed to PCE-contaminated groundwater for at least 16 years; (3) contaminated groundwater in the bedrock aquifer is a consequence of a PCE source in the sand filter bed; (4) the highest measured and simulated concentrations of PCE-contaminated groundwater occurred in the 3rd quarter of 1993; (5) it is unlikely that past consumption of the most highly contaminated well water would have resulted in any acute toxic effects; and (6) no long-term adverse human health effects, including cancer, are likely to occur as a result of past PCE exposures, Maslia said.

As a result of the rigorous modeling, the researchers were able to quantify exposure for citizens; assess potential health risks; and provide information to the Connecticut attorney general for resolving litigation issues, Maslia said.

In another ATSDR-Georgia Tech study using computational modeling, Aral, Maslia, and several other colleagues were able to show that many past assumptions about exposures through water systems do not hold up ("Estimating Exposure to Volatile Organic Compounds from Municipal Water-Supply Systems: Use of Better computational Model," Arch Environ Health 51[4]:300-309).

Past approaches to exposure-dose reconstruction were carried out under at least one of the following assumptions: (1) every person served by the system has been exposed; (2) all contamination has been significantly diluted and has not caused appreciable exposure; (3) every person within a 1/2-, 1-, or 2-mile radius has received the same exposure, Maslia said.

The researchers integrated and modeled the following in their study: groundwater hydraulics; fate and transport of groundwater contaminants; hydraulics of water distribution systems; chemical fate and transport within water distribution systems; demographic analysis; and spatial analysis techniques. In addition to using environmental and health data, they used geographic information systems coupled with census information and spatial environmental analysis techniques to assess the size and demographic characteristics of the population.

The researchers found that (1) exposure to volatile organic compounds in the water system can exhibit significant spatial variation from one census block to another; (2) the maximum contamination of the wells under conditions of maximum groundwater pumping [peak demand] does not yield the expected maximum spatial distribution of exposed census block areas and population; (3) the use of a computational model to estimate the concentration of contaminated water within each census block provides a more refined approach than applying a commonly used "1-mile radius" approach that may incorrectly identify exposed census block areas and population; (4) hydraulic and chemical fate modeling of water distribution systems, such as the one in this study, require a rigorous analysis and cannot be conducted by solving mathematical equations that describe a simplified pipe geometry and network; and (5) although water from contaminated wells is mixed with water from uncontaminated wells and distributed throughout the water distribution system, only some pipe sections and hydrants may actually become contaminated, Maslia said.

For more information, contact Morris Maslia, PE, ATSDR/DHAC, 1600 Clifton Rd, NE, MS E32, Atlanta, GA 30333; telephone (404) 639-0674; fax (404) 639-0656; e-mail mfm4@cdc.gov.

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The Agency for Toxic Substances and Disease Registry (ATSDR) is not only working to protect public health from hazardous substances at Superfund sites, but is making sure that it is prepared to help respond to terrorist acts involving hazardous substances.

ATSDR staff members have participated with other federal, state, and local agency staff members in a number of counter-terrorism preparedness activities. These activities have included participation in simulated responses to simulated terrorist attacks; development of detectors for chemical weapons; and meetings to identify shortfalls in community preparedness and subsequent corrective actions.

ATSDR's focus is on preparing for and responding to terrorist attacks involving hazardous substances related to bombing, arson, military chemical agents, common industrial chemicals, and toxins.

Federal Bureau of Investigation (FBI) and U.S. State Department reports indicate that several incidents of terrorism in the United States and abroad have involved intentional releases of hazardous substances into the environment. One of the more highly publicized incidents was release of the nerve agent Sarin into the Tokyo subway system in 1995. Other incidents include the attaching of pipe bombs to chemical plants in Norfolk, Virginia, in 1991; the attempt to use cyanide during the World Trade Center bombing in 1992; and several releases of hazardous substances into the food chain by terrorists during the past 3 years. FBI and U.S. State Department reports warn that the threat of chemical terrorism is expected to grow significantly in the future.

The response simulations have given approximately 50 local, state, and federal agencies an opportunity to interact in a safe setting and in a manner similar to how they might act in an actual incident. These interactions have also resulted in relationships that will increase the likelihood that ATSDR will be consulted during events involving hazardous substances and potential human exposures, according to ATSDR Division of Toxicology (DT) staff. ATSDR involvement, in turn, increases the likelihood that adverse health effects will be prevented.

"One of ATSDR's roles in response to terroristic chemical attacks is serving as a resource and building communities' capacity for effective responses before incidents happen," said Joseph Hughart, MPH, RHSP, deputy director, ATSDR's Office of Federal Programs (OFP).

ATSDR is receiving funding from the U.S. Department of Health and Human Services Office of Emergency Preparedness and the U.S. Department of Defense (DOD), Defense Special Weapons Agency, to develop resources for communities to address the threat of toxic terrorism. These resources include information on toxic substances related to terrorism; guidance on how to establish a registry of terrorism victims; and a guide for communities and commanders on how to evaluate and prepare for incidents of terrorism involving hazardous substances.

ATSDR's OFP and DT staff members have also conducted training sessions for local, state, and federal first responders in the southwestern states to assist them in preparing to respond to incidents of terrorism involving hazardous substances. These training sessions are being conducted in cooperation with the Nevada Department of Motor Vehicles and HazMat Training Center. To date, more than 380 emergency responders have been trained. An additional 100 state and local public health staff members will be trained in October 1997. The State of Arizona has also requested this training, and plans are being made to respond to that request.

ATSDR's OFP staff members have provided, and continue to provide, extensive assistance to the DOD Joint Staff on potential hazards posed by chemical terrorism to U.S. military personnel involved in peacekeeping and nation-building activities overseas. They have also participated in U.S. State Department policy development and training courses on international terrorism related to peacekeeping and nation-building activities.

Communities can use many of the documents already prepared by ATSDR to address health hazards posed by releases of hazardous substances from Superfund sites in preparing to respond to chemical terrorism incidents. These documents include Case Studies in Environmental Medicine on a number of hazardous substances; shelter-in-place protective measures; contaminated patient handling; and risk assessment. In addition, ATSDR's Emergency Response Section is available at (404) 639-0615 to assist first responders in addressing health hazards posed by chemical terrorism.

For more information on ATSDR's programs related to terrorism, contact Joseph Hughart, MPH, RHSP, deputy director, ATSDR/OFP, 1600 Clifton Rd, NE, MS E28, Atlanta, GA 30333; telephone (404) 639-0730; fax (404) 639-0750; e-mail jxh8@cdc.gov.

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Children and the Environment

First Steps: Tool Developed To Ensure Children Considered in Health Programs

A tool is now available to Agency for Toxic Substances and Disease Registry (ATSDR) staff members and others to ensure that children's health issues are considered in all agency projects.

In 1996, ATSDR started its Child Health Initiative. The initiative's goals are to (1) promote child health practices in all of ATSDR's programs and activities; (2) identify opportunities for new projects that benefit infants, children, and youth; and (3) solicit input and disseminate information through a network of extramural partnerships. ATSDR established a Child Health Workgroup, composed of nationally recognized experts in child health and environmental medicine, to guide it in this effort.

One of the workgroup's first steps was to assess current ATSDR programs and products and suggest changes for improving the quality of data, the pediatric impact of prevention, and the future benefit of ATSDR's activities for the children being served.

The workgroup developed a tool--a set of questions to be applied to programs and products--to ensure consideration of child health issues in all activities (Figure 1). This tool can be applied and adapted to other environmental and public health programs.

Figure 1

Questions To Ask To Ensure Consideration of Children* in Environmental Health Programs

• Are children exposed to potentially harmful substances?
• Are any exposure pathways unique to children?
• Do children differ from adults in their weight-adjusted intake of toxicants?
• Do pharmokinetic or pharmacodynamic parameters of adults and children differ?
• What are the effects of multiple and cumulative exposures?
• Are latent or delayed effects of early exposure possible?
• At what stage of development is the child exposed?
• Could any development processes be altered by the toxicant?
• Are there adequate animal models for exposure after birth?
• What do these models indicate about adverse effects on exposed children?
• Are effects seen in more than one generation of a family?
• Are there ethical and cultural consequences unique to children?
• If children are not included in an agency activity, why are they excluded?

* The term "child" refers to infants, children, and adolescents, and, when appropriate, the entire gestational period.

It is beneficial to ask these questions because they (1) help ensure that the issues addressed will not be overlooked in program planning or implementation; (2) refocus activities to include children; (3) result in data being collected and analyzed on the basis of children's exposures and not extrapolated from adult data; and (4) might lead to identification of unique, child-oriented priority data needs.

"These questions help ATSDR consider children systematically whenever new projects are planned," said Robert W. Amler, MD, MS, chief medical officer at ATSDR. "The workgroup found that, previously, most ATSDR programs involved children, but they also found some missed opportunities. Now any project planner can find the child-health component if there is one."

The full text of the workgroup's recommendations to ATSDR for integrating child health into its programs "Healthy Children--Toxic Environments, Acting on the Unique Vulnerability of Children Who Dwell Near Hazardous Waste Sites" is available on ATSDR's web site at www.atsdr.cdc.gov/child/chw497.html or by contacting the ATSDR Information Center at 1600 Clifton Rd, NE, MS E57, Atlanta, GA 30333; telephone (404) 639-6357; fax (404) 639-6359; e-mail atsdric@cdc.gov. More information on ATSDR's Child Health Initiative is available through ATSDR's Child Health Home Page at ww.atsdr.cdc.gov/child/ or by contacting Robert W. Amler, MD, MS, ATSDR Chief Medical Officer, at ATSDR, 1600 Clifton Rd, NE, MS E28, Atlanta, GA 30333; e-mail to rwa1@cdc.gov.

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This page last updated on October 24, 2003
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