Future Directions

In the process of developing this report, we identified a number of limitations to the most readily available data and the methods used to collect and present them. This section discusses recommended improvements to the measures in the report and improvements to the data sources used to calculate the measures. We also include a discussion of tracking systems for childhood diseases.

There are many important measures that we would like to include in future reports; our discussion here is focused on those of greatest importance, which were identified through discussion with experts in the field.

Characteristics of Ideal Measures

Ideally, measures would be available to reflect all important factors in each of the three parts of this report.

For environmental contaminants, ideal measures would reflect concentrations in the environment of all of the chemical and biological agents that are important for children. The measures would reflect the potential for children to be exposed to these pollutants.

For concentrations of contaminants measured in children, ideal measures would reflect concentrations of the key pollutants that tend to accumulate in children and that pose high risks of health effects.

For childhood diseases, ideal measures would reflect all the important childhood diseases that may be caused by or exacerbated in part by environmental factors.

Ideally, for measures in all three parts of the report, data sources would provide information for all of the nation's children. Data also would be available for 10 years or more to provide information about changes over time. Information would be available on differences among geographic areas, differences among racial-ethnic groups, and differences by various social and economic status factors.

Data for Existing and New Measures

In the sections below, we outline potential improvements to the existing measures and describe other data that we would like to include in future reports. As future editions of this report are developed, we will continue to review and assess data sources that are available. This review and assessment will be an ongoing process as new sources of data are identified and, we hope, existing sources of data are improved.

Environmental Contaminants

Our goal is to have nationally representative measurements of concentrations of environmental contaminants that could affect children's health in air, water, food, and soil.

Common Air Pollutants

The measures used for criteria air pollutants are based on two kinds of data: exceedances of national standards and the reports of daily air quality generated through the Air Quality Index.

To further develop measures in this area, the first priority is to obtain data on measured concentrations of air pollutants in all counties. These data would allow for a more detailed assessment of the severity of pollution, both in terms of the numbers of days in which standards are exceeded and the actual concentrations of pollutants. The data also would allow better assessment of the measure's completeness.

As noted in Part I of the report, the information about exceedances of standards shows only whether air quality, at any point during a year, exceeds a standard. It does not allow any analysis of how often such exceedances occur. On the other hand, it does provide disaggregation of the data separately for each pollutant.

Measures based on actual concentrations may better capture the potential health risks to children. Such measures could portray the combined pollution burden from multiple pollutants on any single day as well as the full duration of concentrations at various levels.

Hazardous Air Pollutants

The measures in this report for hazardous air pollutants (air toxics) are based on data from the year 1990 only. Work is underway to produce measures that will reflect trends over time in ambient concentrations of hazardous air pollutants. Estimates of ambient concentrations in 1996 are expected to be completed within the coming year and will be incorporated into next year's report. Estimates will be updated every three years thereafter.

Data from air toxics monitoring programs also could be considered for inclusion in future editions of this report. Currently, national data on air toxics monitoring are limited and much of the monitoring and data collection are performed at the state level.

The air toxics measures presented in this report do not distinguish between situations in which many hazardous air pollutants exceed health benchmarks and those in which only one exceeds the benchmarks. Measures accounting for the number of hazardous air pollutants exceeding health benchmarks may provide a fuller picture of the potential risks to children. To develop these measures further, the authors will consider monitoring information and updated modeling data.

The hazardous air pollutants measures in this report are further limited because they represents only the presence of these pollutants in ambient air. For certain hazardous air pollutants that are persistent in the environment, greater exposures occur in food. These pollutants settle out of the air onto land and into bodies of water, and then are taken up in the food chain. Future work on measures of food contaminants will consider this pathway of exposure (see the section on food contaminants below).

Indoor Air Pollutants

Indoor air contaminants are represented by a surrogate measure reflecting the percentage of homes where people smoke. The most important improvement to this measure would be to add data for other sources of indoor air pollutants, such as consumer products, gas stoves, and furnishings, for both homes and schools. We have not identified any nationally representative data on air contaminants for homes, schools, and other indoor environments in which children may spend large amounts of time, but we will continue to explore possible measures in this area.

Drinking Water Contaminants

The measures for contaminants in drinking water reflect violations of national standards. These measures share the limitations of the criteria air pollutant measures, as described above, in that they do not distinguish among the impacts of various concentrations of contaminants. The data on drinking water contaminants are less complete than those used for the air measures because less reporting of water contaminants occurs at the national level. In addition, the drinking water contaminant measures in this report rely on the Maximum Contaminant Level (MCL) standards, which are based partly on health considerations but also take into account technical feasibility. Each MCL also has a corresponding Maximum Contaminant Level Goal (MCLG), which is based only on health considerations. The MCLG could be considered for measures in future reports.

Actual measured contaminant concentrations would provide the most relevant measures of potential risks to children. The most complete data are collected at the state level; information from the states would need to be compiled nationally to improve the measures for drinking water. Another problem with the data on drinking water is that many water systems do not adequately monitor for contaminants, so we have no information about potential risks to children in those areas. Future reports will consider data collected at the state level.

Since 1999, EPA has required water suppliers to send annual reports on drinking water quality to their customers. These reports contain information on the drinking water source and the level, or range of levels, of contaminants found in local drinking water. These data also will be considered along with state data in future reports.

Information on sources of contamination to ground water and surface water sources that supply water to public water systems is important for identifying the key contributors to drinking water contamination. EPA now requires states to assess all the ground water and surface water sources that supply water to public water systems. These assessments will identify the major potential sources of contamination to drinking water supplies, and will help officials determine the water systems' susceptibility to contamination. Information from state assessments will be considered for future reports.

Surface Water Contaminants

In future reports we hope to characterize the risks to children posed by the consumption of fish contaminated with mercury, PCBs, and other toxicants that affect neurological development. Many states target their warnings on the consumption of fish from contaminated water to pregnant women and children. We also would like to characterize the risks posed to children by swimming in waters with bacterial contamination. Children are at greater risk of illness while swimming than adults are because of their longer exposure times and more frequent accidental ingestion of water.

On October 10, 2000 the Beaches Environmental Assessment and Coastal Health Act was signed into law. This new amendment to the Clean Water Act requires nationally consistent bacterial standards for recreational waters in all coastal and Great Lakes beaches, and provides grants for states and tribes to conduct beach monitoring and notification programs. Data generated under this provision, when available, may be useful for constructing measures for future reports.

Pesticide Residues and Other Food Contaminants

Contaminants in food are represented in this report by a measure of the frequency with which pesticides are detected in tested samples of produce. This measure does not distinguish among differing levels of contamination. Furthermore, the detection limits do not provide a health-based point of comparison, as they are not equivalent to levels of concern for children's health.

For future reports we will consider improved measures for pesticides that incorporate the actual measured levels of pesticide residues, along with children's food consumption rates that are available from surveys conducted by the U.S. Department of Agriculture.

The Food Quality Protection Act (FQPA) of 1996 established a single, health-based safety standard for new and existing pesticides and their residues in raw and processed food. EPA now routinely considers the combined effects of pesticide exposure from food, drinking water, and other non-work related uses, as well as the effects of pesticides that act in the same way in the body. We will consider new data, standards and analytical techniques developed in the implementation of FQPA in developing measures for future versions of this report.

We also will examine the available data on the presence of other types of contaminants in foods. As noted above, some hazardous air pollutants find their way into the food chain after being deposited from the atmosphere, and their presence in food can pose more of a risk to children than their presence in the air. In addition, children are exposed in utero and nursing infants may be exposed to persistent contaminants in breast milk. We will explore the feasibility of preparing measures of these other food contaminants for future reports.

Finally, some children may be exposed to particularly elevated levels of contaminants in food, including children in homes where much of the diet comes from subsistence fishing or subsistence farming. We will explore the availability of suitable data regarding such differential exposures for future reports.

Land Contaminants

For contaminants in soil, this report includes a measure of the percentage of children living in counties that have a Superfund site. This measure will be refined for future reports by considering whether children live in close proximity to one of these sites (e.g., within one mile), rather than whether they live anywhere in the same county. A measure of children living in proximity to brownfield sites also will be considered for future reports. We are not aware of nationally representative databases of contaminants in soil. Measures for soil contaminants will focus on proximity to sites found to have high levels of contamination or other surrogates.

Other Contaminated Media

Key additional data needs focus on exposure pathways and environments that are particularly important for children. A number of contaminants may gather on household surfaces, including those found in indoor air, contaminants in soil that are tracked into the home, and those from the workplace that inadvertently are brought into the home on the parents' clothes or body. Young children may be frequently exposed to environmental contaminants that gather on floors and other surfaces in the home through hand-to-mouth and object-to-mouth contact. Data available for these exposure scenarios are limited.

Biomonitoring

Currently, nationally representative biomonitoring data are available for concentrations of lead in blood. Data are needed on concentrations of other contaminants in children?s bodies.

The Centers for Disease Control and Prevention (CDC) currently are collecting additional biomonitoring data for an annual National Exposure Report Card. The report card is intended to provide concentrations of toxic substances present in the U.S. population, from measurements in samples of blood and urine. CDC?s sampling process will provide some measurements for children. The 25 substances to be included in the first report card will include heavy metals, cotinine, nonpersistent pesticides, and phthalates. We will develop new biomonitoring measures for future versions of this report as the CDC data become available.

Childhood Diseases and Tracking

The childhood diseases in this report were selected using several criteria: The data had to be nationally representative and readily available; some proportion of the observed effects should be caused, or suspected to be caused, by environmental contaminants; and the diseases must be important to children. The current report includes measures for respiratory related diseases, with an emphasis on asthma, and measures for childhood cancer. Other measures of severity for repiratory effects will be considered for future reports, including emergency room visits and deaths. Several additional respiratory conditions, such as lung function, are influenced by environmental factors but are not included in this report. Future work will focus on identifying appropriate data sources for these measures.

A number of additional types of childhood diseases, such as birth defects and water-borne diseases, may be environmentally mediated, but we do not have consistent nationally representative data for them. For other important effects, such as learning and neurological disorders, identifying appropriate data sources may be difficult. Future work will focus on identifying important childhood diseases for which existing data sources may be used for tracking.

Tracking systems are important for following trends in diseases that may be important in children. These systems can help researchers and health officials identify progress toward reducing diseases and areas that require research and interventions. Some childhood diseases are tracked at the state level. Examples of tracking systems include cancer registries in some states, which collect data on all the reported cancers in those states. Measures of the extent to which we track these important diseases could be added to future editions of this report. For example, the percentage of states that have tracking systems for certain types of important childhood diseases could be included as a measure in next year's report. Suggested topics include birth defects, asthma, and learning disorders.