Assessing and Managing Health Risks from Chemical Constituents and Contaminants of Food

Transcription

1 16 17 September 2013 Assessing and Managing Health Risks from Chemical Constituents and Contaminants of Food Workshop on A Framework for Assessing the Health, Environmental and Social Effects of the Food System PRESENTED TO The Institute of Medicine PRESENTED BY Joseph V. Rodricks, PhD, DABT ENVIRON, Arlington, VA

2 Topics 1 Identifying and Assessing Risks 2 Assessing Safety 3 Risk Management 4 Contaminants 5 Risks and Benefits 6 Decision Frameworks 7 Emerging Issues 2

3 Risk Assessment Some Key Terms and Concepts 1 Virtually all chemicals can cause toxicity at sufficiently high doses 2 HAZARD: the term applied to those toxic properties 3 The rate of occurrence and severity of a chemical's hazards increase as exposure (dose) increases 4 RISK: the probability that a chemical s hazards will be expressed at specified doses. These same terms apply to all types of agents that can cause harm. 3

4 Potential Sources of Food-Related Risks SOURCE Natural constituents Nutrients Non-nutritive constituents NOTES Largest and chemically most diverse class Chemicals produced during food processing and preparation Reaction products from heating, irradiation, etc. Substances intentionally introduced Food additives, GRAS substances Substances intentionally used during production that may remain in finished foods Pesticides, biocides, veterinary drugs and feed additives Substances migrating from food contact surfaces Secondary direct, indirect additives Contaminants Dietary Supplements Substances not expected to be present, either chemical or biological Substances permitted under DSHEA to be sold as supplements 4

5 Conducting Risk Assessment: The Problem Epidemiological, experimental and clinical data are collected characterizing the toxic effects (hazards) of specific agents and their relationships to intake (dose). However How can the available data be used to assess the probability that the hazardous properties of these agents will occur in Other species? Other human populations? Under different exposure conditions? Requires extrapolation beyond data 5

6 Risk Assessment and its Relationship to Other Risk Analysis Activities NAS, 1983, 1994, 2008 RESEARCH/TESTING RISK ASSESSMENT RISK MANAGEMENT Clinical Studies, Epidemiology, Toxicology HAZARD EVALUATION What chemical? What toxic effects? Data on levels of chemicals in the environment and on rates of human contact with and exposure to those environments. DOSE-RESPONSE EVALUATION How does incidence and severity of toxic effect change with dose? HUMAN EXPOSURE ASSESSMENT What populations? What doses? Over what period of time? RISK CHARACTERIZATION Is there a risk to health? What is its magnitude? How well is it known? Are risks excessive? What are the risk control options? Are there offsetting benefits? How should risks be controlled? RISK COMMUNICATION Programs to describe for the public, regulators and customers the risk control activities and their bases. 6

7 Typical Dose-Response Relationship 7

8 The Standard Safety Model for Non-Carcinogens NOAEL UF s* = ADI (or TDI or RfD) Safety is assumed if human intakes fall below the ADI (Allowable Daily Intake) The model is based on the hypothesis that toxic effects occur only when a Threshold dose is exceeded. * Uncertainty factors to deal with interspecies and intraspecies variables and other uncertainties. 8

9 Carcinogens FDA/EPA introduced quantitative risk assessment in the 1970s. KEY ASSUMPTIONS: Carcinogens increase risk at all doses greater than zero (No threshold). In the low-dose region, risk increases in direct proportion to dose. Risks would be managed by restricting exposures to levels associated with very small probabilities of harm. 9

10 Risk Management: Some Approaches 1 Natural constituents Not regulated unless shown to be ordinarily injurious to health 2 Intentionally introduced substances Burden of proof of safety on industry Safety requirements must be satisfied No consideration of possible benefits 3 Contaminants Government must provide evidence of excessive risk Avoidability in food must be considered 4 Nutrients Recommendations regarding adequate and excessive intakes 10

11 Risk Management AVAILABLE TOOLS Enforceable standards/action levels Information labeling Warnings Educational materials HACCP 11

12 Chemical Contaminants of Food Some industrial chemicals are ubiquitous contaminants of the environment, and many degrade very slowly. Some arise from relatively localized industrial and waste sources. Some are of natural origin. Some have been known for many years while others are emerging. There is no up-to-date understanding of the human health risks associated with chemical contaminants of food. What s important? What s not? 12

13 Driving Forces 1 Growing scientific literature on the concentrations of many contaminants found in food. 2 Body burden surveys (CDC, etc.) increasing. 3 Growing scientific literature on toxic properties. New toxicity testing requirements being imposed on large numbers of industrial chemicals (EU s REACH Program). 4 Concerns for types of adverse health effects traditionally not associated with chemicals. 5 Concerns for health effects in susceptible subpopulations. 13

14 Some Important Chemical Contaminants of Food OLD DEPENDABLES Chlorinated pesticides PCBs Polychlorinated dioxins/furans Methyl mercury Lead, arsenic, cadmium Aflatoxins, other mycotoxins, marine toxins EMERGING Chromium VI, other metals Polybrominated diphenyl ethers Polyfluorinated carboxylates and sulfonates Perchlorate 14

15 Food Contaminants Risk management Challenge In many cases it is not possible to achieve risk-based safety limits without destroying food. Avoidability by good manufacturing practice is to be considered (Sec. 406). The decision framework presented in NRC s Science & Decisions (2008) could provide the guidance necessary to achieve a consistent approach to this problem. 15

16 Food-Related Health Risks and Benefits A food constituent increases health risk if at least a fraction of its range of human intake is associated with a known or expected increase in morbidity or mortality. A food constituent increases health benefits if at least a fraction of its range of human intake is associated with a known or expected decrease in morbidity or mortality. Scientific understanding of risks and benefits is severely hampered by the fact that patterns of food consumption and not simply the sum of the effects of all the individual constituents have powerful influences on net benefits and risks. 16

17 Risk assessment framework suitable for health benefits assessment Benefits = Reduced Risks Except for nutrients, current food laws do not permit balancing of risks and benefits. In the case of contaminants, risk reduction may be balanced against benefits of not having to destroy food. Methyl mercury in fish: FDA advice includes health benefit assessment. Little systematic study of natural constituents and chemicals introduced during processing/preparation. 17

18 A Uniform Framework for Risk Management NRC: Science & Decisions, 2008 Maximum scientific objectivity Due attention to the limits of science Thoroughness and balance Explicitness and clarity Maximum public health protection in most efficient way And benefits as well as risks! 18

19 Science & Decisions NRC, 2008 PHASE I: PROBLEM FORMULATION AND SCOPING PHASE II: PLANNING AND CONDUCT OF RISK ASSESSMENT PHASE III: RISK MANAGEMENT What problem(s) are associated with existing environmental conditions? If existing conditions appear to pose a threat to human or environmental health, what options exist for altering those conditions? Under the given decision context, what risk and other technical assessments are necessary to evaluate the possible risk management options? Stage 1: Planning For the given decision-context, what are the attributes of assessments necessary to characterize risks of existing conditions and the effects on risk of proposed options? What level of uncertainty and variability analysis is appropriate? Stage 2: Risk Assessment Hazard Identification What adverse health or environmental effects are associated with the agents of concern? Dose-Response Assessment For each determining adverse effect, what is the relationship between dose and the probability of the occurrence of the adverse effects in the range of doses identified in the exposure assessment? Exposure Assessment What exposures/doses are incurred by each population of interest under existing conditions? How does each option affect existing conditions and resulting exposures/doses? Risk Characterization What is the nature and magnitude of risk associated with existing conditions? What risk decreases (benefits) are associated with each of the options? Are any risks increased? What are the significant uncertainties? What are the relative health or environmental benefits of the proposed options? How are other decisionmaking factors (technologies, costs) affected by the proposed options? What is the decision, and its justification, in light of benefits, costs, and uncertainties in each? How should the decision be communicated? Is it necessary to evaluate the effectiveness of the decision? If so, how should this be done? Stage 3: Confirmation of Utility NO Does the assessment have the attributes called for in planning? Does the assessment provide sufficient information to discriminate among risk management options? Has the assessment been satisfactorily peer reviewed? YES FORMAL PROVISIONS FOR INTERNAL AND EXTERNAL STAKEHOLDER INVOLVEMENT AT ALL STAGES The involvement of decision-makers, technical specialists, and other stakeholders in all phases of the processes leading to decisions should in no way compromise the technical assessment of risk, which is carried out under its own standards and guidelines. 19

20 Some Unresolved and Emerging Scientific Issues Related to Chemicals Endocrine disrupting chemicals and non-monotonic doseresponse relationships Evolving, high-throughput toxicity testing methods Adequacy of toxicity and human intake data bases for additives/gras substances (PEW Foundation Studies) Non-traditional types of health hazards: diabetes, behavioral changes, obesity Vulnerable sub-populations Hazard vs. Risk based regulation 20