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Executive Summary
Dioxins and chemically-related compounds (referred to collectively as DLCs)
occur as widespread, low-level contaminants in animal feeds and the human food
supply. Because dioxins accumulate in fatty tissues, consumption of animal fats
is thought to be the primary pathway for human exposure. In humans, dioxins are
metabolized slowly and accumulate in body fat over a lifetime. Dioxin toxicity
and its human health impact have been the subjects of recent re-evaluations by
the International Agency for Research on Cancer, the U.S. Agency for Toxic
Substances and Disease Registry, the National Institute of Environmental Health
Sciences, and the U.S. Environmental Protection Agency (EPA). Data indicate
declining levels of dioxin in the environment and in human tissues, although the
assessments prepared by the agencies differ and have not yet been reconciled.
Notwithstanding the declining overall levels, public concern about food
safety issues such as endocrine disrupters in the food supply and the effects of
dioxin-like compounds on children's health and development persists. Further,
special populations that consume large amounts of fish and wildlife for cultural
reasons (American Indian and Alaska Native tribes) and subsistence fishers have
eating patterns that place them at higher risk for exposure levels that may be
found to be dangerous.
Against this background, the National Science and Technology Council's
Interagency Working Group (IWO) on Dioxin anticipated the need to develop
policies to reduce dioxin exposure. IWG, with support from the U.S. Department
of Agriculture (USDA), the U.S. Department of Health and Human Services, and
other agencies and sponsors asked the National Academies to assist them by
identifying potential strategies to meet this need.
1
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2
DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY
The sponsors explicitly enjoined the committee from re-examining the ques-
tion of whether low doses of dioxin are toxic or to what degree in general or
specific populations. Separate scientific reviews have been initiated to reassess
and reconcile the different exposure analyses. However, the sponsors anticipated
that regulatory and other public health policies would likely be necessary to
reduce exposures, especially among vulnerable populations, and foresaw the need
to be prepared with evidence-based strategies.
The sponsors charged the Committee on the Implications of Dioxin in the
Food Supply to review the scientific evidence to identify potential ways to reduce
the levels of dioxin in food, taking into account the need to promote good nutri-
tion and health. Specifically, the committee was charged to:
.
Take into account the substantial body of data available in the EPA draft
reassessment and other reports on the pathways by which DLCs add to
the dioxin body burden by concentrating in food from sources such as
animal feeds that contain recycled animal fat or sources contaminated by
airborne DLCs, and through the intake of specific foods such as seafood,
foods of animal origin (e.g., eggs, dairy products, meat), and plant food-
stuffs,
Review the data on food-consumption patterns of various subgroups in
the population that appear to be at increased risk due to physiological
state, food practices, or geographic location,
Identify and describe possible risk-management options that could be
instituted to decrease the content of dioxins in food animals, seafood, and
other food products, and possible changes in food and/or nutrition poli-
cies that would decrease exposure, including, where possible, an assess-
ment of the net risk reduction afforded by a risk-management option,
including effects on nutrition, and
Identify and describe efforts in the United States and other countries to
decrease dioxin exposures of specific subgroups of the population through
public health or risk communication initiatives, and assess the extent to
which federal food and nutrition policies contribute to decreasing expo-
sure to dioxins.
The study sponsors recognized that the limited data available would likely
allow only qualitative estimates of net risk, descriptions of exposure reduction,
and identification of data needs. The committee did not make any judgments
about the risks of human exposure of DLCs through food. Rather, it offered
options available to the government to reduce this type of exposure and to in-
crease benefits to nutrition and health, while gathering the data needed to deter-
mine future action.
The committee concluded that although direct health effects currently cannot
be measured, animal and human epidemiological studies support exposure reduc-
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EXECUTIVE SUMMARY
3
tion while potential health risks are more fully studied. In its analysis, the com-
mittee developed and used a framework to identify and evaluate options to reduce
exposure and suggested actions that the government might take as it continues to
collect the data needed to devise a more comprehensive, long-term risk-manage-
ment strategy.
This report is organized around three specific pathways that lead to DLC
exposure through the food supply: (1) animal production systems, (2) human
foods, and (3) food-consumption patterns.
Animal Production Systems
DLCs enter the food chain when airborne contaminants that have been de-
posited on plants or in soil and sediment are taken up by food animals or fish
(e.g., through grazing or the direct consumption of feeds that contain DLC-
contaminated plant- and animal-based ingredients). Due to geographic variation
in DLC levels that may result from long-distance air transport and deposition,
naturally occurring and unintended contamination events, and different animal
husbandry practices, the exposure of food animals to DLCs in forage and feed
varies by region, differences in DLC levels in feed ingredients, and the combina-
tion of ingredients in different feeds. The resulting concentration of DLCs in food
animals is a consequence of accumulated exposure from these various sources as
the animals' body fat increases.
Human Foods
DLCs accumulate in human foods through the animal production systems
pathway. Levels of exposure through foods may vary regionally, depending on
the amount of locally produced food that is consumed. Most foods, except milk,
are processed in bulk and distributed widely, so that foods purchased by consum-
ers are less likely to reflect variable DLC levels. Thus, the exposure of the general
population through the food supply appears to be relatively uniform. On the other
hand, foods that are caught or harvested in the wild have levels of DLCs that
reflect those found in the local environment, so some populations that rely on
locally caught fish and wildlife for food may be at risk for higher exposure levels.
Food-Consumption Patterns
As a component of its data-gathering process, the committee commissioned
an analysis of the population's DLC intake from foods at current levels of con-
sumption. The analysis presented in this report was based on DLC values gath-
ered in the U.S. Food and Drug Administration's (FDA) Total Diet Study (a
market basket survey) and linked to the Continuing Survey of Food Intakes by
Individuals, which measures actual food intake. Dietary intake scenarios, based
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4
DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY
on the analysis, were used to predict the potential for reducing exposure to DLCs
by decreasing meat and fish intake and by substituting low-fat (1 percent fat) or
skim milk for whole (3.5 percent fat) milk. The scenarios indicated that the
greatest exposure to DLCs through food was from animal fats found in meats,
full-fat dairy products, and fatty fish.
FRAMEWORK FOR POLICY OPTIONS
The committee was charged by its sponsors to identify, evaluate, and recom-
mend policy options to reduce dietary exposure to DLCs, while taking into con-
sideration the need to maintain good nutrition and health. The committee was
also charged to evaluate the net exposure reduction afforded by various risk-
management options, including nutrition options, in light of efforts in the United
States and abroad to decrease the exposure of sensitive or otherwise vulnerable
populations.
The framework for risk-management options established a systematic ap-
proach to identify, evaluate, and recommend potential interventions to reduce the
exposure of humans to DLCs through the food supply. The committee approached
the development of options from the perspective of the three pathways discussed
above and it considered the potential nutritional consequences of dietary modifi-
cations to reduce DLC exposure through risk-relationship analysis. For each
option, the committee considered:
1. Alternate or interim actions,
2. Current barriers to implementation,
3. Anticipated DLC exposure reduction achievable through implementa-
tion, and
4. Risk relationships that included decreases (ancillary benefits) or increases
(countervailing risks) in other risks.
POLICY OPTIONS TO REDUCE EXPOSURE TO DLCs
THROUGH THE FOOD SUPPLY
The discussion of options to reduce DLC exposure through the food supply
must consider food safety statutes and other regulatory policies and procedures
that frame and constrain the adoption of exposure reduction options. Within the
federal government, FDA has the primary food safety regulatory jurisdiction over
DLCs in food. EPA considers food safety and acceptable levels of DLCs in fish
when setting acceptable air and water emission levels for DLCs. FDA is the
enforcement agency for DLCs in animal feed and human food, with the exception
of meat and poultry, which are under the jurisdiction of USDA's Food Safety and
Inspection Service (FSIS). FDA has broad authority to control DLCs in animal
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EXECUTIVE SUMMARY
s
feed and human food, constrained by the requirement to make factual showings
concerning DLCs and their risk in order to implement regulatory control.
The committee considered a range of possible interventions, but not all op-
tions were put forward as recommendations. Options considered to reduce DLC
exposure through animal production systems included:
Require testing for DLC levels in forage, feed, and feed ingredients,
Establish tolerance levels for DLCs in forage, feed, and feed ingredients,
Restrict the use of animal products, forage, feed, and feed ingredients that
originate from specific areas that are considered to be contaminated, and
Restrict the use of animal by-products in agriculture, animal husbandry,
and manufacturing processes.
eluded:
Options considered to reduce DLC exposure through the food supply in-
Require testing and publishing of data on DLC levels in the human food
supply, including food products, dietary supplements, and breast milk, to
use in establishing tolerance levels in foods,
Establish enforceable standards for DLC levels in processed foods and in
packaging that comes in direct contact with food, and
Require cleaning or washing practices for all vegetable, fruit, and grain
crops that potentially had contact with soil.
Options considered to reduce DLC exposure through food-consumption path-
ways included:
Increase the availability of low-fat and skim milk in federal feeding
programs targeted to children, which currently favor the provision of
whole milk (e.g., the National School Lunch Program),
Establish a maximum saturated fat content for meals served in schools
that participate in federal child nutrition programs, and
Promote changes in dietary-consumption patterns of the general popula-
tion that more closely conform to recommendations to reduce consump-
tion of animal fats, such as the recommendations of the Dietary Guide-
lines for Americans.
Consideration of Consequences of Actions to Reduce Exposure to DLCs
Through Dietary Intervention
Because of the persistent nature of DLCs and the uncertainty about their
toxic effects, almost any action taken to reduce their concentration in the food
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6
DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY
supply will have a long-term, rather than an immediate, impact on human health.
Such actions will, however, have an immediate impact on the food supply, which
could, in turn, have other health and nutritional effects.
With regard to the possible detrimental nutritional effects due to changes in
food-consumption patterns, the committee noted that current dietary recommen-
dations for the general population stress the benefits of a reduced intake of
saturated fats to decrease the risk of many chronic diseases. Thus, changes in
dietary patterns to reduce DLC exposure that involve a reduction of animal fats,
the primary source of saturated fats in our diet, would generally have beneficial
rather than detrimental nutritional effects.
Apart from the general population, the committee also took into account
DLC-sensitive population groups, such as developing fetuses and infants, that are
vulnerable due to developmental immaturity, and groups such as breastfeeding
infants, subsistence fishers, and American Indian and Alaska Native fish-eating
populations that receive higher-than-background levels of DLC exposure. A1-
though not a highly exposed population, preadolescent and teenage girls and
young women were of concern to the committee because they accumulate, over
time, body burdens of DLCs that can, when they enter their child-bearing years,
become a potential source of exposure for their developing infants in utero and
while breastfeeding.
Recommendations to reduce exposure were tailored to the particular con-
cerns of these groups, including weighing the benefits of breastfeeding against
the risks of DLC exposure for infants, early intervention to reduce lifetime body
burdens in children, especially girls, and cultural practices important to American
Indian and Alaska Native tribes and other groups.
RISK-MANAGEMENT RECOMMENDATIONS AND
RESEARCH PRIORITIES
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 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 avail-
able to the government, the committee recommended several risk-management
actions. The committee's recommendations are qualitative rather than quantita-
tive 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.
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EXECUTIVE SUMMARY
7
General Strategic Recommendations
Important progress has been made in reducing new discharges of DLCs into
the environment. With respect to DLC exposure through food, most of the effort
has focused on assessing the potential risks of DLCs. Given that the risk assess-
ments conducted have raised concerns about the health impacts of DLCs and that
there is no benefit, but possible harm, from DLC exposure through foods, the
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DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY
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 food, the federal government should begin by pursu-
ing the following strategic courses of action: (1) establish an integrated risk-
management strategy and action plan, (2) foster collaboration between the gov-
ernment and the private sector to reduce DLCs in the food supply, and (3) invest
in the data required for effective risk management.
Develop an Integrated Risk-Management Strategy and Action Plan
Considering the large number of federal agencies with responsibility for the
safety of food, reduction of DLCs in the food supply will require action across the
system. The committee recommends that, as an initial step, federal agencies
including FDA, FSIS, and EPA, create an interagency coordination group to
develop and implement a single, integrated risk-management strategy and action
plan.
Foster Collaboration Between the Government and the Private Sector to
Reduce DLCs in the Food Supply
DLC exposure through food is a shared problem that requires shared, col-
laborative solutions. The committee recommends that as part of the process of
developing an integrated risk-management strategy and action plan, the federal
government create an atmosphere and program of collaboration with the private
sector that involves agriculture, the food processing industry, health organiza-
tions, and consumers, which would include ongoing collection and re-evaluation
of data.
Invest in the Data Required for Effective Risk Management
There are significant gaps in the data required to devise, implement, and
evaluate risk-management interventions to reduce DLC exposure through food.
The cost of analyzing DLC congeners is extremely high and often creates an
impediment to effective data collection and analysis techniques. Research prior-
ity should be given to the development of less costly analytical methods for
determining the level of DLCs in animal feed and human food. The committee
recommends that the development of a plan and a commitment of resources for
data collection and analysis be a central element of the risk-management strategy
and action plan for reducing DLC exposure through food.
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EXECUTIVE SUMMARY
High - Priority Risk- Management Interventions
Interrupt the Cycle of DLCs Through Forage, Animal Feed, and Food-
Producing Animals
9
Findings. Animal forage and feed are primary pathways for DLC contamina-
tion of the human food supply. This typically occurs by airborne deposition of
DLCs on forage and plants used for animal feed. When animals consume con-
taminated forage and feed, DLCs are stored in their fat and subsequently enter the
human food supply. In addition to plant material used as animal feed that may
contain DLCs, several billion pounds of rendered animal fat are used annually as
a feed ingredient, which serves to recycle DLCs and leads to the possibility of
increasing levels of DLCs in meat and other animal-derived food products. The
committee considers the animal forage, feed, and production stage of the food
system to be a key leverage point for reducing DLC exposure through food
because it is the primary point of entry of these compounds into the human food
supply.
Recommendations. The committee recommends that the government's risk-
management strategy for DLCs give high-priority attention to reducing the con-
tamination of animal forage and feed and interrupting the recycling of DLCs that
result from the use of animal fat in animal feed.
As an initial step, the government, in collaboration with the animal produc-
tion and feed industries, should establish a nationwide data-collection effort and
a single data repository on the levels of DLCs in animal forage and feed, which
should be accessible for both public and private use. Government and industry
should also begin collaboration immediately to define voluntary guidelines for
good animal feeding and production practices that would reduce DLC levels in
forage and feed and minimize other potential sources of DLC exposure during
animal production.
The committee further recommends that the government, in collaboration
with the animal production industry, identify means to achieve the reduction or
elimination of DLC-containing animal fat as a component of animal feed. How-
ever, the committee recognizes that doing so could have unintended, negative
consequences: (1) increased cost of food, (2) problems of unused animal fat
disposal, (3) increased food spoilage, and (4) changes in the taste of food that
consumers find unacceptable. The government should consider setting legally
binding limits on DLCs in forage and feed only when more complete data are
generated and a better understanding is developed of how DLC contamination
can be avoided.
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DIOXINS AND DIOXIN-LIKE COMPOUNDS IN THE FOOD SUPPLY
Reducing DLC Exposure in Girls and Young Women
Findings. Fetuses and breastfeeding infants may be at particular risk from
exposure to DLCs due to their potential to cause adverse neurodevelopmental,
neurobehavioral, and immune system effects in developing systems, combined
with the potential for exposure of breastfeeding infants to comparitively high
levels of DLCs in breast milk. Data suggest that because DLCs accumulate in the
body over time, waiting until pregnancy to reduce DLC intake has no significant
impact on the mother's level or the baby's exposure in utero or through breast-
feeding. Therefore, intervention to reduce DLCs must occur in the years well
before pregnancy. Substituting low-fat or skim milk for whole milk, especially
when coupled with other substitutions of foods lower in animal fat by girls and
young women in the crucial years before pregnancy, could reduce DLC intakes
and resulting levels of DLCs during pregnancy.
Recommendations. In order to reduce DLC body burdens in the future for
women with child-bearing potential, the committee recommends, as an immedi-
ate intervention, 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 committee
recommends that low-fat and skim milk be made readily available in the National
School Lunch Program. In addition, the committee recommends that participants
in the Special 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 pack-
ages. Further, to reduce other sources of animal fat, the committee recommends
that USDA's Economic Research Service undertake a detailed analysis to deter-
mine the feasibility of and identify barriers to setting limits on the amount of
saturated fat that should be allowed in meals served under the National School
Lunch and Breakfast Programs.
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, particularly by the removal of fat from meat prod-
ucts through trimming, (3) providing advisories and education to highly exposed
populations, and (4) educating the general population about strategies for reduc-
ing exposure to DLCs.
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EXECUTIVE SUMMARY
Research and Technology Development to Support Risk Management
11
A broader research and technology agenda is needed to support risk-manage-
ment efforts to reduce exposure to DLCs through food. Among many possible
subjects for such efforts, the committee recommends that the government con-
sider placing a priority on:
1. Development of low-cost analytical methods and a review of toxicity
equivalents,
2. Research to support the removal of DLCs from animal feed,
3. Expansion of the National Health and Nutrition Examination Survey's
data collection on DLC body burdens,
4. Research on the effects of dietary DLCs on fetuses and breastfeeding
infants, and
5. Behavioral research on achieving dietary change and, where feasible,
predictive modeling studies on DLCs in the food supply.
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nutrition policies, particularly those related to public education and food assistance programs, on
the nutritional status and health of the population at large and to sensitive and highly exposed
groups.
THE COMMITTEE AND ITS CHARGE
i
Following a request by federal agencies to the National Academies, an expert committee was
appointed to review existing reports on the impact of DLCs on the safety of the food supply and
to offer options to further reduce exposure to these contaminants, while consicler~ng the need to
maintain health and optimize nutritional status, particularly with regard to sensitive and highly
exposed groups. The Food and Nutrition Board, in consultation with the Bo arc! on Agriculture
and Natural Resources and the Board on Environmental Studies and Toxicology, brought
together an ad hoc committee to study the implications of DLCs in the food supply.
The charge to the committee was to: (~) take into account the substantial bocly of data
available in the U.S. Environmental Protection Agency's draft reassessment (EPA, 2000) and
other reports on the pathways by which DLCs add to the dioxin body burden by concentrating in
foods fi om sources such as animal feed, and through intake of specific foods such as seafood,
foods of animal origin (e.g., eggs, dairy products, meats) and plant foodstuffs; (2) review the data
on food-consumption patterns of venous subgroups of the population that appear to be at
increased risk due to physiological state, food practices, or geographic location; (3) identify and
descnbe possible risk management options that could be instituted to decrease the content of
dioxins in food animals, seafood, and other food products, and possible changes in food ant!
nutrition policies that wouicl decrease exposure, inclu(ling, where possible, an assessment of the
net risk reduction afforded by a risk management option, including effects on nutrition; (4)
estimate uncertainty in net risk and identify key data needs; if the uncertainty is too great due to a
lack of data, provide a qualitative description of the potential for net risk reduction; (5) use
existing estimates of dioxin risk as much as possible; adjust chemical risk estimates derived
through upper bound method, if necessary, to allow comparison with nutrition benefits estimated
using central tendency methods; and (6) identify and describe efforts in the United States and
other countries to decrease dioxin exposures of specific subgroups of the population through
public health or risk communication initiatives, and assess the extent to which federal food and
nutrition policies contribute to decreasing exposure to dioxins.
The committee approached its charge by gathering information from existing literature ant!
from workshop presentations by recognized experts (see Appendix C for workshop agendas),
commissioning an analysis of DLC exposure through foods, deliberating on issues relevant to the
task, and formulating an approach to address the scope of work. Reports and other data releases,
such as the Centers for Disease Control and Prevention's Second National Report on Human
Exposure to Environmental Chemicals (NCEH, 2003), occurred subsequent to the committee's
deliberations. However, much of the information contained in these reports was provided, in
part, to the committee by agency representatives at the open sessions of the committee meetings.
The committee developed an analytical framework to identify, evaluate, and formulate
recommendations to reduce DLC exposure to the general population and to sensitive and highly
exposed subgroups. This analytical framework, described in Chapter 6, organizes a wide array of
policy options in the form of a matnx. Within the matrix, the committee developed a set of
general categories that allowed it to array and analyze options and to ask detailed questions about
1-2
Representative terms from entire chapter:
dlc exposure
