An introduction to An introduction to Environmental health, Environmental health,

toxicology toxicology & risk assessment& risk assessment

Lecture 1

Contact me at:Office: 1st Floor Block 5 SHCVTel: 3620538Email: gracebao@uic.edu.hk

Lecture ObjectivesLecture Objectives

Define fundamental termsExplain the basic relationship

between the environment and healthExplain impact of environmental

factors on healthExplain risk assessmentConsider the risk management model

and process.

Content Content

Environmental healthToxicologyRisk assessment

HealthHealth

‘ Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity' (WHO, 1948)

健康是指生理、心理及社会适应三个方面全部良好的一种状况，而不仅仅是指没有生病或者体质健壮。

Human Health is affected byHuman Health is affected by

An individual genetic factors （遗传因素）determine an individual how to be affected

by environmental hazard.Exposed Environment （环境因素）

‘ that which is external to the individual human host.’

Physical, chemical, biological, social and cultural environment

HealthHealth

‘ Health is only possible where resources are available to meet human needs and where the living and working environment is protected from life-threatening and health threatening pollutants, pathogens and physical hazards.' (WHO, 1992)

Environmental healthEnvironmental health

Environmental health comprises those aspects of human health, including quality of life, that are determined by physical, chemical, biological, social and psychosocial factors in the environment.

It also refers to the theory and practice of assessing, correcting, controlling and preventing those factors in the environment that can potentially affect adversely the health of present and future generations.

(WHO, 1993)

Environmental healthEnvironmental health

Assesses environmental factors that influence human health and quality of life.

Seeks to prevent adverse effects on human health and ecological systems.

Contains environmental toxicology within its scope.

Basic Healthy EnvironmentBasic Healthy Environment

Clean AirSafe and sufficient waterAdequate and safe foodSafe and Peaceful Settlements （安定

生活） Stable Global Environment （稳定的全

球环境）

Health and environmentHealth and environment

‘ Genetics loads the gun…but the environment pulls the trigger. ’

Dr. Judith Stern (2009)Professor of Nutrition & Internal Medicine

Univ. of California, Davis

Environment and the EconomyEnvironment and the Economy

Environment is frequently sacrificed for the sake of the economy in our society. This policy is shortsighted because destruction of the environment undermines future economic resources.

China (nowadays) London (1952)

Which one is a developing Which one is a developing country?country?

Nelson's Column, London

Before and afterBefore and after

1952 nowadays

Flooding, New Orleans (2005)

Flooding, New Orleans

(2012)

Drought, China (2011)

Ice melting, Arctic Circle (2007)

Deforestation, Borneo (1950-2010)

…Drought, deforestation, flooding, hurricanes, ice melting, heat waves…

are these incidents above isolated?

Everything is linkedEverything is linked

ToxicologyToxicology

Toxicology = toxico + logy = poisons + study

Toxicology is traditionally defined as the study of the harmful effects of drugs, chemicals and chemical mixtures on living organisms.

Toxicology Toxicology

Toxicologists assess and compare toxic agents, or toxicants, for their toxicity, the degree of harm a substance can inflict.

Environmental toxicology focuses on effects of chemical poisons released into the environment.

Environmental toxicologyEnvironmental toxicology

Studies toxicants that come from or are discharged into the environment, and:Health effects on humansEffects on animalsEffects on ecosystems

Environmental toxicologyEnvironmental toxicology

Animals are studied:For their own welfareAs “canaries in a coal mine” to warn of

effects on humans

Silent SpringSilent Spring and Rachel Carson and Rachel Carson

Carson’s 1962 book alerted the public that DDT and other pesticides could be toxic to animals and people.

Further research led the EPA to ban DDT in 1973.

These developments were central to the modern environmental movement.

Download and listen to the eAudiobook of ‘Silent Spring’ in the ‘Reference’ section

Early Risk AssessmentEarly Risk Assessment

‘ What is food to one man may be fierce poison to others.’

Lucretius (c. 99 B.C.–c. 55 B.C.)

Which one is Risky?Which one is Risky?

Genetic Modified FoodsNuclear PowerMercury DioxinsPesticides in AgricultureX-RaysLandfill of Domestic Waste

Ranking!

HazardHazard

An event, or property, associated with an activity, product, process or site which has the potential to cause harm

Environmental health hazardsEnvironmental health hazards

Physical or climatic hazards (floods, heat wave, acid rain, UV exposure…)

Biological hazards (viruses, bacterial pathogens…)

Chemical hazards (Synthetic and natural toxicants…)

Cultural or lifestyle hazards (drinking, smoking, bad diet…)

RiskRisk

A combination of the probability, frequency, of occurrence of a defined hazard, and the magnitude (severity) of the consequence of the occurrence

Key Risk QuestionsKey Risk Questions

What are undesirable outcomes and who decides, what undesirable means?

Key Risk QuestionsKey Risk Questions

How can we specify, qualify and quantify the possibilities of undesirable outcomes?

Key Risk QuestionsKey Risk Questions

How do we aggregate different types of undesirable outcomes into a common concept which allows comparisons and priority setting?

HarmHarm

Harm to the health of living organisms or other interference with ecological systems of which they form a part and, in the case of man, includes offence caused to any of his senses or harm to his property

Tolerable RiskTolerable Risk

'Tolerability' does not mean 'acceptability'.

No risk is acceptable, only tolerable to the extent that there is some benefit arising from the activity and all possible controls are in place.

Tolerability of Risk

(HSE, 2010)

Risk assessmentRisk assessment

Analyses risks quantitativelyMeasures and compares risks

involved in different activities or substances

Helps identify and prioritise serious risks

Helps determine threats posed to humans, wildlife, ecosystems

Risk assessmentRisk assessment

Involves:Dose-response analysis or other tests of

toxicityAssessing likely exposure to the hazard

(concentration, time, frequency)Risk rating

Risk ratingRisk rating

Actual risk outcome

Risk ratingRisk rating

RISK LIKELIHOOD TABLE - Guidance

Five steps Five steps

http://www.hse.gov.uk/

RA Example RA Example

Scenario 1- Bitten by snakes when working outdoors

Risk managementRisk management

Consider risk assessments in light of social, economic, and political needs and values.

Weigh costs and benefits, given both scientific and nonscientific concerns.

Decide whether or not to reduce or eliminate risk.

The process of risk The process of risk managementmanagement

Four Simple StagesFour Simple Stages

What is the possible problem?

How big a problem might it be?

What will be the effect?

Does it matter?

Hazard Identification

Hazard Assessment

Risk Evaluation

Source-Pathway- ReceptorSource-Pathway- Receptor

Without a source or pathway or target there cannot be a risk. Therefore, determining the:

Source-pathway-Receptor relationship is the key to risk

assessment and management

Toxicants take many routes through the Toxicants take many routes through the environmentenvironment

Hazard IdentificationHazard Identification(What is the possible problem?)(What is the possible problem?)

Identify the chemicals, events,

releases, the pathways and targets

taking into account the environmental

setting and proposed activity

Hazard AssessmentHazard Assessment(How big a problem might it be?)(How big a problem might it be?)Understand potential exposure and

adverse effects based on fate and behaviour of chemicals in the environment

Screen to determine whether an identical frequency or dose might be significant

Risk EvaluationRisk Evaluation

Requires consideration of:The qualitative or quantitative

statements about risk derived from the risk estimation process

Other site-specific factors which may affect the risk

The uncertainties in the estimatesThe costs and benefits of taking action to

control or reduce unacceptable risksThe social pressures for action

Uncertainty/ComplexityUncertainty/Complexity

Sources: natural variability; people - poor data collection; models which do not reflect the real world; data manipulation & availability

Methods to manage: worst-case scenario; safety factors; collect more data

Case study Case study

Scenario 2 Your mom calls you to say that your little

cousin broke a thermometer and ate the silvery-grey material inside.

You know the silvery-grey material is mercury.

The FDA advises that pregnant women, women who may become pregnant, nursing mothers, and young children should avoid eating shark, swordfish, king mackerel and tilefish due to high levels of mercury in these fish.

Let’s consider a few questionsLet’s consider a few questions

Q1. Does this mean that eating the material from the thermometer is a serious problem?

Q2. With the mercury from the thermometer, what risks other than swallowing might be a problem?

Q3. Do you think there could be a difference in health effects depending on the route of exposure?

Q4. How else might the mercury be absorbed?

Q5. Do you think that the health risks from mercury in a thermometer might be different from the risks related to mercury in fish? What could be different?

Q6. Do you think there could be a difference in the effects of mercury on children, as opposed to adults?