Environmental Pollutant Exposures and Public Health

R M Harrison

• Publisher: Royal Society of Chemistry
• Year: 2020
• ISBN:
  9781839160448
• Edition: 1
• Topic: Medicine
• Subtopic: Public Health, Administration & Care

Both genes and environment have profound effects upon our health. While some environmental factors such as polluted air are high in the public consciousness, there are many other pathways for people's exposure to toxic chemicals, such as through food, water and contaminated land. It is not only chemicals that can affect health; environmental radioactivity, pathogenic organisms and our changing climate also have implications for public health, and all contribute to the global burden of disease, leading to both disability and deaths of millions of people annually across the world. An understanding of the pathways of environmental exposure, and its effects upon health is key to developing regulations and behaviours that reduce or prevent exposure, and the consequent impacts upon health.

Covering topics from dietary exposure to chemicals through to the health effects of climate change, this book brings together contributors from around the world to highlight the latest science on the impacts of environmental pollutant exposure upon public health.

Risk Assessment of Chemicals in Food and Feed: Principles, Applications and Future Perspectives

L. Ingenbleek, L. S. Lautz, G. Dervilly, K. Darney, M. C. Astuto, J. Tarazona, A. K. D. Liem, G. E. N. Kass, J. C. Leblanc, P. Verger, B. Le Bizec and J. L. C. M. Dorne^*

^* Corresponding author.

ABSTRACT

In the modern world, chemicals are ubiquitous, and humans, animals and species in the environment are exposed to an increasing number, both of anthropogenic and natural origin. Chemical risk assessment in the food and feed safety areas involves a wide range of disciplines and research areas such as chemistry, biology, toxicology and epidemiology, biostatistics and modelling. The purpose of a chemical risk assessment is to quantify chemical exposures from relevant sources and routes of exposure (inhalation, oral, dermal through air, water/food, skin) for a given population or species (exposure assessment), determine safe levels for such chemicals (hazard identification and characterisation) and quantify the risk associated with such exposures (risk characterisation). This chapter aims to introduce the reader to the principles of risk assessment of chemicals in food and feed together with some examples and future perspectives to move towards holistic approaches. Exposure assessment aims to investigate how much of a chemical an organism is exposed to, through the detection and quantification of chemical residues in food and feed matrices (occurrence) and the level of food or feed consumption. Particular emphasis is placed on the need to consider the relevant analytical techniques available and food consumption databases. Hazard identification and characterisation requires the consideration of three key aspects with regards to chemical toxicity: (1) what the body does to a chemical (toxicokinetics), (2) what a chemical does to the body (toxicodynamics) and (3) approaches to derive safe levels of chemicals in humans and animal species. Risk characterisation brings the exposure and hazard dimensions together and provides means to quantify health risks for a given population or species after single and multiple chemical exposures (‘chemical mixtures’). Future perspectives are highlighted to move towards a One Health approach while considering humans, animal species and the environment in an integrated manner.

1 Introduction: Principles of Food and Feed Risk Assessment

Chemical risk assessment involves a vast range of disciplines and research areas including toxicology, chemistry, physiology, epidemiology, statistics and mathematical modelling, biochemistry, cellular biology, population biology to cite but a few. The purpose of chemical risk assessment is to quantify levels of chemical exposures (exposure assessment) for a given species or population from relevant sources and routes of exposure (inhalation, oral, dermal through air, water/food, skin), determine safe levels for such chemicals (hazard identification and characterisation) and quantify the risk associated with such exposures (risk characterisation). The diversity of chemicals that risk assessors deal with in the food and feed sectors is rather large and includes pesticides, biocides, food and feed additives, pharmaceuticals, air pollutants as well contaminants of anthropogenic (e.g. persistent organic pollutants, heavy metals, perfluoroalkyl substances, brominated flame retardants, dioxins etc.) or natural (marine biotoxins, mycotoxins etc.) origin.¹

Key actors include decision makers such as risk managers, national food safety agencies from member states, European and international scientific advisory bodies, academia, industry, non-governmental (NGOs) and consumer organisations. Key European agencies dealing with chemical risk assessment include the European Food Safety Authority (EFSA), the European Chemicals Agency (ECHA) within the REACH directive, and the European Medicines Agency (EMA) for pharmaceuticals. Key national and International scientific advisory bodies include the Food and Agriculture Organization FAO)/World Health Organization (WHO) joint expert committees on food additives (JECFA) and the joint meeting on pesticide residues (JMPR), the US Environmental Protection Agency (US-EPA), the US Food and Drug Administration (FDA), the Food Safety Commission of Japan and the Organisation for Economic Cooperation and Development (OECD) to cite but a few.² Over the past 60 years, these international and national bodies have performed risk assessment for thousands of substances in food, water, air or consumer products.

Prior to initiating a risk assessment, a problem formulation requires the framing of the scientific question for the substance(s) to be assessed. In the food and feed safety sectors, the problem formulation is generally posed by a decision maker such as risk managers from the European Commission or a national food safety authority. At this stage, the question(s) should fully address the issue(s) to be dealt with, expressed clearly and agreed prior to the start of the risk assessment.³ The WHO views problem formulation as an ‘iterative process involving risk assessors and risk managers to determine the need for and the extent of a risk assessment’.⁴ The US-EPA (2007)⁵ defines problem formulation as ‘a systematic planning step to identify the major factors to be considered in a particular assessment in relation to preliminary hypotheses with regards to hazard assessment (i.e. likelihood and severity of adverse effects which might occur or have occurred) and exposure assessment (i.e. likelihood and significance of exposure)’. In a food safety context, problem formulation typically includes description of a chemical hazard (e.g. a contaminant), the food commodities, the species or population to assess (e.g. humans, farm animals), and the potential consequences associated with the chemical hazard; consumer perception of associated hazards or risks; and the distribution of possible risks among different sub-populations (adults, children etc.). Desired outcomes of problem formulation include clear questions that need answering and identification of the resources and the timeframe needed for the assessment. With regards to the food and feed safety area in Europe as EFSA's remit, problem formulation is most often defined within the terms of reference provided by risk managers from the European Commission or a member state.⁶

The harmonised principles of human risk assessment of chemicals have been described in the WHO Environmental Health Criteria 240 ‘principles and methods for the risk assessment of chemicals in food’⁴ and in Regulation EC 178/2002, the founding regulation of EFSA.⁷ In short, risk assessment has been defined as ‘a scientifically based process consisting of four steps: exposure assessment, hazard identification and hazard characterisation, risk characterisation’.⁷ Ideally, risk assessment for a given chemical explores the quantitative translation of an external dose (exposure assessment) to an internal dose [toxicokinetics (TK)] to quantify toxic effects [toxicodynamics (TD)] and derive safe levels of exposure (hazard identification and characterisation). Exposure levels are then compared to the safe levels of exposure to conclude on health risks (risk characterisation).¹

For each of these steps, risk assessors use tiered approaches to produce fit for purpose risk assessments. Tiered approaches allow for simple and conservative approaches when time and resources are limited (low tiers), and more complex and precise approaches when needed (higher tiers).^3,8,9 Appropriate application of tiering must exhibit lower uncertainty of the risk assessment results (the lower the uncertainty for risk assessment, the higher the tier), so that predictions made at the highest tier will reduce uncertainty and resemble true exposures and impacts. Tiering implies that a risk assessment can be concluded as soon as there is clarity on sufficient protection for the exposed population defined in the problem formulation. Alternatively, one may progress to risk management (e.g. risk mitigation measures) or a higher tier when risk characterisation indicates insufficient protection. Because of the vast variety of problem formulations, approaches and data, the tiers are not prescribed nor does the tiering principle imply that assessments necessarily proceed from lower to higher tiers. For example, in many assessments of regulated products, the tier(s) applied will be predetermined by the available data, the problem formulation and/or the regulatory context. In practice, the tiers can be either qualified (low, intermediate or high) or classified using numerical attributes (0, 1, 2, 3, etc.). A low tier (tier 0) would typically describe a data poor situation, requiring conservative assumptions. At increasing tier – levels (1, 2 and 3) more data become available, allowing assessments to become more accurate, with a better characterisation of uncertainties and eventually making use whenever possible of quantitative methods such as probabilistic approaches including Bayesian methods. In practice, the tiers are defined in the problem formulation and these are not necessarily symmetrical for each step of the process (exposure assessment, hazard assessment and risk characterisation) because availability of data and regulatory requirements for these steps vary considerably.⁶ Hence, risk assessors cannot apply a “one size fits all” approach but rather require flexible approaches in relation to the risk assessment question, resources and data available.³

This chapter aims to introduce the reader to the principles of risk assessment of chemicals in food and feed together with some examples and future perspectives to move towards holistic approaches. Principles of exposure assessment are addressed in Section 2 to address the question of how much of a chemical is an organism exposed to. Particular emphasis is given to analytical techniques available for the detection and quantification of chemical residues in food and feed matrices (occurrence), food consumption with examples of available databases and methods for integrating occurrence and consumption for the quantification of chemical exposure levels. Section 3 provides a description of the hazard assessment process i.e. hazard identification and characterisation to investigate what the body does to a chemical (toxicokinetics), what a chemical does to the body (toxicodynamics), approaches to derive safe levels of chemicals and available toxicological databases. Section 4 briefly describes the final step of the risk assessment process: risk characterisation integrating exposure and hazard metrics to quantify health risks for a given population or species after single and multiple chemical exposures “chemical mixtures”. Finally, Section 5 provides future perspectives to move towards a One Health approach while considering humans, animal species and the environment in an integrated manner.

2 Exposure Assessment: How Much of a Chemical is an Organism Exposed to?

Five centuries ago, Paracelsus allegedly introduced the basic principle of toxicology: “Sola dosis facit venenum”.¹⁰ which means that only the dose makes that a substance becomes a poison. In order to weigh risks associated with the presence of chemical hazards in foods, assessors still extensively refer to this adage.

Exposure assessment is the component of risk assessment that determines how much of a chemical an organism is exposed to.

The dietary exposure results from the product of concentration of the chemical in a food with the quantity of food ingested daily, and ...

Table of contents

• Cover
• Halftitle
• Title
• Copyright
• Preface
• Contents
• Editor
• List of Contributors
• Risk Assessment of Chemicals in Food and Feed: Principles, Applications and Future Perspectives
• Chemical Pollution of the Aquatic Environment and Health
• Microbiological Contamination of Water and Health
• Outdoor and Indoor Air Pollutant Exposure
• The Effects of Air Pollution upon Public Health
• 2 Health Effects for Children
• Contaminated Land and Human Health
• Environmental Radiation and Health
• Endocrine-disrupting Chemicals and Their Effects on Reproductive and Neurobiological Health
• Consumer Products as a Source of Human Exposure to Chemicals
• Climate Change and Health
• Subject Index