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8 Risk-Management Recommendations and Research Priorities Chapters 6 and 7 describe a framework for developing policy options to reduce exposure of dioxins and dioxin-like compounds (referred to collectively as DLCs) through food, and they illustrate how the framework might be applied to a broad range of specific risk-management interventions. As the committee emphasized in those chapters, there are substantial gaps in the data needed to adopt many of the possible interventions that were identified, particularly regula- tory interventions based on the government's food safety regulatory authority. Tolerances were not recommended not only because of the paucity of data on which to establish limits, but also because the committee recognized the signifi- cant ramifications of such actions without substantive evidence to support them. The committee considered both the scientific uncertainties in risk at current levels of exposure and the concern within the general population about exposure to DLCs. It further recognized that there are substantial gaps in the data that have to be filled before many of the identified policy options can be adopted. Based on the analysis of current data and deliberations concerning the strategic options available to the government, the committee recommended some risk-manage- ment actions. The committee' s recommendations are qualitative rather than quan- titative in light of the paucity of data to support specific reduction goals, and they fall into four categories: (1) general strategic recommendations, (2) high-priority risk-management interventions, (3) other risk-management interventions that de- serve consideration, and (4) research and technology development to support risk management. 202
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 203 GENERAL STRATEGIC RECOMMENDATIONS DLCs have been the object of concern and activity on the part of federal regulatory agencies for many years, prompted by the large volume of evidence demonstrating the toxicity of DLCs at low levels of exposure in animals and suggesting the potential for DLCs to pose significant risks to humans. Important progress has been made in reducing new environmental discharges of DLCs. With respect to the problem of DLC exposures through food, however, most of the efforts have focused on assessment of the potential risks of DLCs, as dis- cussed in Chapter 2. This has included substantial investments in toxicity testing and extended interagency efforts to refine and reach agreement on DLC risk assessments. This effort has been worthwhile. Risk assessment provides the es- sential starting point for risk management and, for any important problem, it is desirable to have the most definitive assessment of risk that available data and understanding will permit. Uncertainty is, however, inherent in risk assessment generally, and uncertainties in assessment of the risks posed by exposure to DLCs through food will persist for the foreseeable future. These uncertainties are not, however, an obstacle to sound and effective risk management. Given that the risk assessments that have been conducted have raised con- cerns about the health impacts of DLCs, and that there is no benefit but possible harm from DLC exposure through foods, the committee considers it appropriate for the federal government to focus its efforts on exposure reduction strategies. To move effectively toward reducing human exposure to DLCs through foods, the federal government should begin by pursuing the following strategic courses of action: (1) establish an integrated risk-management strategy and action plan, (2) foster collaboration between the government and the private sector to reduce DLCs, and (3) invest in the data required for effective risk management. Develop an Integrated Risk-Management Strategy and Action Plan Justification DLC exposure through food is a widely shared problem in the food system. It results not from the actions of any one segment of the food system, but from the complex interaction of widespread environmental contamination and the estab- lished practices and behaviors of animal producers, food processors, and con- sumers. Its solution requires action across the system, based on consideration of all the factors that contribute to exposure and all the possibilities for reducing exposure. At the federal level, regulatory responsibility for DLCs in food is shared by three agencies: the U.S. Department of Health and Human Services' Food and Drug Administration (FDA), the U.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS), and the U.S. Environmental Protection Agency (EPA), and by multiple other program offices. For example, FDA's
204 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY Center for Food Safety and Applied Nutrition is responsible for setting regulatory limits on the levels of DLCs that may lawfully be present in human food and for regulating the practices of food processors. However, FDA's Center for Veteri- nary Medicine is responsible for regulating DLCs in animal feeds. A third orga- nizational component of FDA, the Office of Regulatory Affairs, manages the field function of the agency, which involves conducting inspections, product sampling, and enforcement, and often requires balancing, in the face of scarce resources, the food-related functions of FDA with the agency's responsibilities for drugs and other medical products. FSIS has jurisdiction over the safety of meat and poultry, which would include enforcement of any regulatory restric- tions that might be placed on the level of DLCs in these products. EPA sets limits on permissible discharges of DLCs into waterways based on assessments of the resulting impact of DLCs on the safety of fish. At the state and local level, multiple health, agriculture, and natural resource agencies can be involved in issuing and enforcing advisories and regulatory restrictions on the harvesting and consumption of fish from contaminated waters. In addition to these regulatory agencies, a wider set of federal agencies would be involved in devising and implementing any DLC risk-management interventions that involve changing food-consumption patterns or conducting research. For example, multiple agencies within USDA and the U.S. Department of Health and Human Services collaborate in developing the government's Di- etary Guidelines for Americans, and both departments have nutrition education programs. In addition, the Food and Nutrition Service within USDA sets policy for the National School Lunch Program and other government feeding programs, while USDA's Agricultural Marketing Service acts as the government's purchas- ing agent for these programs. Most of the regulatory agencies have food safety research programs that could contribute to the development of risk-management interventions, but so also do USDA's Agricultural Research Service and its Co- operative State, Research, Education and Extension Service, the Centers for Dis- ease Control and Prevention, and other federal agencies. Recommendation The committee recommends that the sponsoring agencies empower an interagency coordination group with the authority and mandate to develop and to implement a single, integrated risk-management strategy and action plan. No one agency has the mandate, resources, expertise, or authority to ad- dress DLC exposure through food on a system-wide basis. With an integrated, comprehensive, and system-wide approach however, it will be possible to set achievable and widely shared goals for DLC exposure reduction, to identify optimal risk-management interventions, to set priorities, and to make the best use of available government resources. An integrated approach on the part of the federal government would also help to ensure effective interaction and collabora-
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 205 tion between the public and private sectors and help to minimize private sector disruptions and costs. The committee recognizes the difficulty of working across agency lines on a problem of this complexity. There will be a need to establish clearly defined leadership for the effort, accountability for results, and mechanisms for on-going collaboration and coordination. Foster Collaboration Between the Government and the Private Sector to Reduce DLCs in the Food Supply Justification No one desires the presence of DLCs in food, and no one set of participants in the food system can fairly be assigned sole responsibility and accountability for their presence or for actions needed to reduce foodborne exposure to DLCs. DLC exposure through food is a shared problem requiring shared, collaborative solutions. This does not preclude the possibility that regulatory interventions will play a role at some point in reducing DLC exposure, but, as discussed in Chapters 6 and 7, the committee sees no immediate regulatory solutions. There is instead a need, among other things, to generate data and develop practices in the food- production and processing systems that will reduce DLC levels and resulting exposures over time. This will require active collaboration between the federal government and the private sector. Recommendation The committee recommends that, as part of the process of developing an integrated risk-management strategy and action plan, the federal govern- ment, through an interagency coordination group, create an atmosphere and program of collaboration with the private sector. This recommendation is premised on both the government and industry being willing to define and ac- tively approach the problem of DLC exposure through food as a shared problem. If that willingness exists, the government should establish an organizational focal point and define processes through which government and the private sector could collaborate in developing and implementing the integrated strategy and action plan for reducing DLC exposure through food. Invest in the Data Required for Effective Risk Management Justification As discussed in Chapters 6 and 7, there are significant gaps in the data required to devise, implement, and evaluate risk-management interventions to
206 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY reduce DLC exposure through food. The lack of data is most glaring with respect to consideration of options to reduce DLC levels at the animal production stage and in human food. To target and prioritize efforts to reduce DLCs at these stages and to determine what reductions are desirable and feasible, the critical starting point is good information on the current levels of DLCs in forage, feeds, and feed components, across geographical regions, and in the array of human foods in which DLCs are found. As discussed in Chapters 4 and 5, however, the available data on these points are very limited. A reliable, reasonably complete picture of the current levels and distribution of DLCs in animal feeds and human food is lacking. There is also insufficient data on the levels and distribution of DLC body burdens in the general population and among sensitive and highly exposed sub- groups. Body burden data are a prerequisite for evaluating the effectiveness of efforts to reduce DLC exposure through food. Recommendation The committee recommends that a commitment of resources by all spon- soring agencies for data collection be a central element of any risk-manage- ment strategy and action plan for reducing DLC exposure through food. The committee recognizes that DLC analysis is expensive and that expense has been a limiting factor in data-collection efforts to date. In the committee's judgment, however, a commitment to risk management to reduce DLC exposure necessi- tates a commitment to data collection. As discussed below, the committee recom- mends, as one of its research priorities, an effort to develop less costly analytical methods for DLCs in feeds and food. HIGH-PRIORITY RISK-MANAGEMENT INTERVENTIONS The committee has identified two areas that it believes deserve high-priority attention as part of any risk-management strategy for reducing DLC exposure through food. The committee recommends that the government focus its initial risk-management interventions on: (1) interrupting the cycling of DLCs through forage, animal feeds, and food-producing animals, and (2) reducing DLC expo- sure in girls and young women in order to protect fetuses and breastfeeding infants from exposure to DLCs. Interrupt the Cycling of DLCs Through Forage, Animal Feeds, and Food-Producing Animals Justification As discussed in Chapter 4, animal forage and feeds are primary pathways for DLC contamination of the human food supply. This occurs as a result of the
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 207 direct contamination of forage and plants used for animal feeds, typically by airborne deposition of DLCs. When animals consume contaminated forage and feeds, DLCs are stored in their fat and subsequently enter the human food supply. In addition, several billion pounds of rendered animal fat are used annually as a component of animal feeds, which results in the recycling of DLCs back through the feed and the possibility of increasing levels of DLCs in meat and other animal-derived food products (see Figure 4-1~. Recommendations The committee recommends that the government's risk-management strategy for DLCs give high-priority attention to reducing the contamina- tion of animal forage and feeds and interrupting the recycling of DLCs that results from the use of animal fat in animal feeds. The committee considers the animal feed and animal production stages of the food system to be key leverage points for reducing DLC exposure through food because it stops DLCs at their primary point of entry into the human food supply. This is the only available means the committee could identify for preventing DLC contamination of human food. At subsequent stages human exposure can be reduced only by discarding or otherwise avoiding consumption of DLC-contaminated food. While FDA has the authority to set legally binding limits (i.e., tolerances) on the levels of DLCs in animal feeds, the committee is not recommending such regulatory action at this time. This is due to the current lack of data to support binding tolerances, the consequences of trying to establish limits without ad- equate supportive evidence, and the committee's belief that there is a need for collaboration between the government and the animal production industry to develop alternative feeding practices and to overcome other practical obstacles to reducing DLCs in animal forage and feeds that may obviate the need for regula- tory action in the future. As an initial step, the government, in collaboration with the animal production and feed industries, and directed by an interagency coordination group, should establish a nationwide data-collection effort and data reposi- tory on the levels of DLCs in animal forage and feeds, which should be accessible for both public and private use. An expanded data-collection effort by the government and industry and the pooling of the data would provide a better understanding of current DLC levels in forage and feeds, including their sources and geographic distribution. This would in turn provide a basis for devis- ing and targeting specific interventions to reduce DLCs in forage and feeds. The government and industry should also begin collaborating immedi- ately to define voluntary guidelines for good animal feeding and production practices that would reduce DLC levels in forage and feeds and would mini- mize other potential sources of DLC exposure in animal production. Such guidelines could include avoiding forage or feeds obtained from areas known to
208 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY have high levels of DLC contamination. They could also include criteria for the use of animal fat in animal feeds, which would result in reducing DLC levels in the finished feeds, and criteria for the use of non-DLC containing materials in animal enclosures and in feed packaging and transportation. The use of "cleaner" (i.e., uncontaminated) fats is not a practical alternative at the present time because of the high cost of analysis that would be needed to implement widespread testing. The committee further recommends that the government, in collabora- tion with the animal production industry, identify means to achieve the reduction or elimination of DLC-containing animal fat as a component of animal feeds. This would require, among other things, the development of crite- ria for determining what constitutes an acceptable use of animal fat and economi- cally feasible analytical methods for distinguishing acceptable from unacceptable animal fat. It would also require the development of alternative uses or acceptable disposal methods for the large quantity of animal fat now used in animal feeds. However, the committee recognizes that reducing or eliminating the use of ani- mal fat as a component of animal feeds could have unintended negative conse- quences: (1) increased cost of food, (2) problems of animal waste disposal, (3) increased food spoilage, and (4) changes in the taste of food that consumers find unacceptable. Only when more complete data are generated on DLC levels in forage and feeds, and a better understanding is developed of how DLC contamina- tion can be avoided, should the government consider setting legally binding limits on DLCs in forage and feeds. Reducing DLC Exposure in Girls and Young Women Justification As discussed in Chapter 2, fetuses and breastfeeding infants may be at par- ticular risk from exposure to DLCs. This is due to the potential for DLCs to cause adverse neurodevelopmental, neurobehavioral, and immune system effects in developing systems, combined with the potential for in utero exposure of the fetus to DLCs and exposure of breastfeeding infants to relatively high levels of DLCs in breast milk. These exposures are a result of the body burden of DLCs that girls and young women accumulate during their childhood, adolescence, and young adult years. Data suggest that, due to the bioaccumulation phenomenon, reduction of DLC intake during pregnancy has no significant impact on the mother's body burden or on the baby's exposure in utero or through breastfeeding. The committee recommends the following options as ways to reach a broad number of individuals with the least potential undesired outcomes.
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 209 Recommendations The committee recommends that the government place a high public health priority on reducing DLC intakes by girls and young women in the years well before pregnancy is likely to occur. Such reductions can be achieved by reducing the intake of animal fat among this population. The committee therefore recommends, as an immediate in- tervention, that the government take steps to increase the availability of foods low in animal fat in government-sponsored school breakfast and lunch programs and in child- and adult-care food programs. Specifically, the com- mittee recommends that the National School Lunch Program increase the availability of low-fat (1 percent) and skim milk and have the option of offering other milks. Because the current law (Richard B. Russell National School Lunch Act, amended Dec. 8, 2000, §9~2~) favors the provision of whole milk, it should be amended to require that schools offer low-fat and skim milk and have the option of offering reduced-fat (2 percent fat) or whole (3.5 percent fat) milk. The committee further recommends that participants in the Spe- cial Supplemental Nutrition Program for Women, Infants and Children be encouraged, except for children under 2 years of age, to choose low-fat or skim milk and low-fat versions of other animal-derived foods in their food packages. In addition, to reduce other sources of animal fat, the committee recom- mends that USDA's Economic Research Service undertake detailed analyses of the feasibility of and barriers to setting limits on the amount of saturated fat that can be present in individual meals in the National School Lunch Program. There are insufficient data to establish limits on saturated fat in school lunch and breakfast meals to reduce DLC exposure. Detailed analyses are needed to determine an appropriate level of saturated fat to reduce DLC exposure and to promote and maintain good nutrition habits. Although data are insufficient to set limits on saturated fat intake to reduce DLC exposure, there is a strong body of evidence to support the benefit of reducing saturated fat intake to reduce the risk of chronic disease. The Dietary Guidelines for Americans recommend that less than 10 percent of calories should be derived from saturated fat. School lunches are currently required to provide less than this level when the fat content of the meals is averaged over a week. There is currently no saturated fat guideline for individual meals. If a limit were established for saturated fat in individual meals served in the National School Lunch Program, more lean meat, poultry, and seafood products would be used in place of high-fat versions of these foods, which would lower levels of animal fat (and thus DLCs) in school lunches. While potential changes in the school lunch program are being considered, there should be ongoing educational efforts aimed at reducing the consumption of animal fat by girls and young women.
210 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY As discussed in Chapter 5, substituting low-fat or skim milk for whole milk, especially when coupled with other substitutions of foods lower in animal fat such as selecting lean cuts of meat, poultry, low-fat fish, and low-fat cheeses, could significantly reduce DLC intakes and resulting body burdens of DLCs in girls and young women in the crucial years preceding pregnancy. Reducing DLC intakes in this way is the only practicable intervention the committee could identify that would, in the relatively near term, reduce DLC exposure to fetuses and breastfeeding infants, which appear to be the populations most vulnerable to the toxicity of DLCs. OTHER RISK-MANAGEMENT INTERVENTIONS THAT DESERVE CONSIDERATION Although more data are needed, there are several other specific interventions that could be considered as part of an integrated risk-management strategy and action plan for reducing DLC exposure through food. These include: (1) reducing DLC discharge sources in animal production areas, (2) removing DLC residues from foods during processing, (3) providing advisories and education to highly exposed populations, and (4) educating the general population about strategies for DLC exposure reduction. Reducing DLC-Discharge Sources in Animal Production Areas Justification As discussed in Chapter 3, the largest quantifiable source of new DLC for- mation in the United States is the backyard burning of yard, home, and farm waste. To the extent this occurs in animal production areas or in areas where animal feed is produced, it is potentially an important pathway for DLC contami- nation of food and resulting human exposure. Recommendation The committee recommends that the government consider, as part of an integrated risk-management strategy, a focused effort to reduce unregulated (e.g., backyard) burning, especially in animal production areas. This could be pursued initially as an element of the collaborative effort with the animal produc- tion industry to reduce DLC contamination of animal forage and feeds. The committee has not examined whether there are practicable regulatory interven- tions to address this potential source of DLCs in the environment.
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 211 Removing DLC Residues from Foods During Processing Justification DLCs can directly contaminate human foods through airborne deposition on food plants and soils. As discussed in Chapter 4, as much as 25 percent of DLC exposure through foods may come from this source. In such cases, the DLCs and DLC-contaminated soils typically adhere to the external surfaces of the plant and its edible portion, including vegetables, fruits, and grains. These DLCs can, to a significant extent, be prevented from entering the food supply at the food-pro- cessing stage through readily available cleaning and processing measures and by peeling root and waxy-coated vegetables. In addition, the physical removal of fat from meat products through trimming prevents DLCs from entering the human food supply. Recommendation The committee recommends that the government explore, with the food industry, practicable steps to reduce, during processing, the DLC contami- nation of food. This effort could result in the development of voluntary good manufacturing practices for reducing DLCs in food. Consideration and adoption of regulatory measures in this area would require more data than currently exist on the magnitude of the DLC reductions that could be achieved through process- ing, as well as on the feasibility and cost of achieving these reductions. Providing Advisories and Education to Highly Exposed Populations Justification As discussed in Chapter 5, there are population groups that for economic, cultural, or other reasons consume large amounts of fish and marine mammals that tend to be high in DLCs. These highly exposed groups, and in particular sensitive members of these groups (such as developing fetuses and breastfeeding infants), may be at higher risk of adverse health effects from DLCs than the general population. Currently, EPA and some state and local agencies issue advi- sories on the consumption of fish caught in highly contaminated areas. Recommendation The committee recommends that the government continue collaborat- ing with state and local officials to provide up-to-date fishing advisories on waters that are highly contaminated with DLCs. In addition, the committee recommends that the government work with highly exposed populations to de-
212 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY velop information and education programs about the potential risks of DLCs and offer practical ideas for reducing DLC exposure, taking into account each group's economic and cultural situation. Educating the General Population About Strategies for Reducing Exposure to DLCs Justification Within the general population there is much that could be done at the indi- vidual and household levels to reduce exposure to DLCs through food. The intervention that could be the most immediate and could have the most impact is for individuals to reduce their intake of animal fat. This could be done by reduc- ing the consumption of fat from meat, poultry, and fish (e.g., by trimming and discarding their excess fat) and by choosing lower-fat versions of these foods. Individuals could reduce DLC intakes by washing and, as appropriate, peeling root and waxy-coated vegetables prior to consumption. Achieving changes in dietary patterns and food preparation practices is diffi- cult. The government has been communicating the fat reduction message, based on the U.S. Dietary Guidelines, for a number of years. While fat intake has declined as a percentage of calories, it has remained fairly constant in absolute terms while total calorie intake has risen. The communication of the fat-reduction message is further complicated in the case of DLCs since one of the major sources of DLCs in the diet fish has nutritional advantages as a source of protein and potentially "healthy" fats, such as the omega-3 fatty acids. Further- more, while it may seem that the provision of information about DLCs on food labels would be an alternative educational approach, the limited range of foods tested and the complexities of the toxicity equivalents measurement system and its interpretation could mislead consumers about the DLC content in food. Recommendations The committee recommends that the government continue (and explore ways to enhance) its promotion of the U.S. Dietary Guidelines, including the message to limit intake of saturated fat. This message has the potential to produce health benefits that go well beyond the reduction of DLC exposure, including reductions in the risk of cardiovascular disease and cancer. The com- mittee further recommends that the government consider linking, in its Di- etary Guidelines and associated information campaigns, the saturated fat reduction message based on cardiovascular disease and cancer with the mes- sage that reducing saturated fat has the added benefit of reducing exposure to DLCs and other lipophilic contaminants. The committee recognizes that
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 213 communicating clear and effective messages on this complex subject is difficult, and that great care must be exercised in crafting messages that do not mislead or confuse consumers by making the messages ineffective for their intended pur- poses or by causing dietary changes that could be detrimental. As discussed below, behavioral research may be needed to craft effective messages. RESEARCH AND TECHNOLOGY DEVELOPMENT TO SUPPORT RISK MANAGEMENT As one of its general strategic recommendations, the committee recommends above that the government focus its efforts on exposure-reduction strategies and that it invest in data collection to support risk management. There is also a need, in the committee's judgment, for a broader research and technology development agenda to support risk management. Among the many possible subjects for such efforts, the committee recommends that the government consider placing a prior- ity on the following: (1) low-cost analytical methods development and toxicity equivalents review, (2) research to support removal of DLCs from animal feeds, (3) expansion of the National Health and Nutrition Examination Survey's (NHANES) data collection on DLC body burdens, (4) research on the effects of dietary DLCs on fetuses and breastfeeding infants, (5) behavioral research on achieving dietary change, and (6) predictive modeling studies on DLCs in the food supply. Analytical Methods Development and Toxicity Equivalents Review Justification As discussed in Chapter 2, the analysis of forage, feeds, and food commodi- ties for DLC contamination is expensive, and this expense has been a limiting factor in the collection of data to design and evaluate risk-management interven- tions. In addition, accuracy and reproducibility in DLC measurements are often compromised by analytical variances and measurement bias. Recommendation The committee recommends that the government invest in the develop- ment of cost-effective analytical methods that will make possible a signifi- cantly larger volume of DLC testing to support risk management. As part of this effort, the committee recommends that the government review the current toxicity equivalents assessment standards to ensure that the standards accurately reflect the most current knowledge of the toxicity contribution of various DLC congeners, particularly for low-level exposures from foods.
214 Justification DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY Research to Support Removal of DLCs from Animal Feeds The committee has recommended reducing the contamination of animal for- age and feeds and reducing the recycling of DLCs that result from the use of animal fat in animal feeds as high-priority risk-management interventions. Achieving these goals may require significant adjustments in animal feeding practices and the development of alternative uses or acceptable disposal solutions for the several billion pounds of animal fat that are used annually in animal production systems. Recommendation The committee recommends that the government sponsor research on the economics of animal production and current animal feeding practices, with a view toward identifying economically feasible alternatives to current practices that will result in significant reductions in DLC contamination of animal forage and feeds. To complement the economic research, the committee recommends that the government sponsor research on disposal possibilities and alternative uses of animal fat, including use as a biofuel. Expansion of Data Collection on DLC Body Burdens Justification In 1999, NHANES began collecting measurements of serum dioxins from a subsample of the population examined in this large, recurring survey on diet and health. These measurements, if continued over time, will enable scientists to monitor trends in DLC body burdens. When these data are combined with data from FDA's Total Diet Study and the USDA Economic Research Service's food- consumption data as a component of the continuing NHANES, it will be possible to develop a more refined understanding of DLC exposure through food, includ- ing its geographic and population-group variability and its impact on body bur- dens among various components of the population. Such data will be essential to sound risk-management decision-making over the long term, including the con- sideration of possible regulatory interventions. Recommendations The committee recommends that the government expand data collection of DLC body burdens to expedite the development of a reasonably represen- tative and reliable database on DLC exposure patterns and body burdens.
RISK-MANAGEMENT RECOMMENDATIONS AND RESEARCH PRIORITIES 215 DLC analyses in human subjects are expensive and invasive to the subject, which makes the collection of new body burden data difficult. Thus, to supplement the NHANES data collection on DLC body burdens, the committee recommends that the government support continued and expanded DLC assays of tissues collected from existing cohorts and control groups, such as in the Ranch Hands study (discussed in Chapter 2), which has a large sample base of subjects with back- ground or low-level DLC exposures. Research on the Effects of Dietary DLCs on Fetuses and Breastfeeding Infants Justification From a public health perspective, the committee places its highest risk- management priority on reducing the DLC exposure of fetuses and breastfeeding infants. Recommendation To support and further focus risk-management initiatives in this area, the committee recommends that the government sponsor a prospective co- hort study (that includes monitoring breast-milk samples) to examine the health effects over time of pre- and postnatal DLC exposure of infants. The results of such a study would help public health officials and risk managers better understand the nature and severity of the risks posed by exposure to DLCs at this critical developmental phase of life, and thus help guide and set priorities for future risk-management initiatives. In addition, the committee recommends that breast-milk monitoring in sentinel populations be conducted to assess the magni- tude of exposure through this source. Behavioral Research on Achieving Dietary Change Justification and Recommendation To the extent that the government's risk-management strategy relies on achieving dietary changes to reduce DLC exposure, the committee recom- mends that it sponsor behavioral research to better understand how such changes can be brought about. It is clear from experience over the past decade that formulation and communication of a scientifically sound message about diet and health is not enough to change long-established dietary patterns. Dietary patterns are complex human behaviors that are affected by many factors and vary among individuals. Careful research is needed to better understand the phenom-
216 DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY enon and to develop educational and other techniques for improving dietary patterns. Predictive Modeling Studies on DLCs in the Food Supply Justification DLCs move through the atmospheric, terrestrial, and aquatic environments and into the human food supply in complex ways. In designing interventions to reduce DLC exposure through food, it is important to be able to model the movement of DLCs and their ultimate biomagnifications through the food chain, as well as to be able to predict how proposed interventions will affect levels in food and, in turn, human exposure and body burdens. Recommendation The committee recommends that the government sponsor research to develop improved predictive modeling tools and that it apply them in studies aimed at assessing the DLC-reduction effects of potential interventions. CONCLUSION DLCs are an undesirable contaminant in food, and there are good public health reasons for reducing DLC exposure through food, especially among highly exposed and sensitive populations. The committee recognizes there are serious limitations in the data available for managing the risks posed by DLCs in food and that, in light of these limitations and remaining uncertainties in risk assess- ments on DLCs, it is premature to recommend traditional food-safety regulatory remedies for the DLC problem. There are, however, a number of steps the gov- ernment could take to reduce DLC exposure among the most vulnerable popula- tion groups in the short term and to significantly reduce DLC exposure within the general population in the long term. These steps have been outlined in this con- cluding chapter.