Risk Assessment and Risk Managementold.iupac.org/publications/cd/essential_toxicology/IUPACTOX6.pdf · Risk Assessment and Risk Management ... Notes on Risk • Acceptability of

The Science of Chemical SafetyEssential Toxicology - 6

Risk Assessment and RiskManagement

John Duffus & Howard WorthIUPAC Educators’ Resource Material

©IUPAC

Duffus & Worth, ©IUPAC2

Background - 1

• No chemical, whether naturally occurring ormanufactured, is absolutely free from potentialtoxic effects

• The job of the toxicologist is to obtain the datarequired to define the potential of chemicalsfor toxicity (their intrinsic hazard), to assess itand to make this information available in acomprehensible form to the users of chemicals


Background - 2• Management in industry producing chemicals

and all people using chemicals should considerthe available information on their potentialtoxicity before making any decisions on use– Note: The potential toxicity ( hazard) is intrinsic to the

chemical and independent of how it is handled

• Managerial decisions should aim to minimizerisk (probability of exposure) associated withchemical use by handling appropriate to thetoxicity and other hazardous properties


Definitions - 1

• Risk - a measure of the probabilitythat a harmful event (death, injury orloss) arising from exposure to achemical or physical agent mayoccur under specific conditions ofmanufacture, use or disposal


Notes on Risk• Acceptability of risk may differ for different

people; the worker in industry may be preparedto accept certain risks as part of their job; thethe home user may wish as low a risk aspossible, especially where children areconcerned

• Risks to wild organisms in the naturalenvironment, especially plants and bacteria,may be accepted by people because they cannotsee the consequences for their own health


Definitions - 2

• Risk assessment - identificationand quantification of risk resultingfrom a specific use or occurrence ofa chemical or physical agent


Notes on Risk Assessment

• Risk assessment is concerned withdetermining those factors which areespecially dangerous and determining thelikelihood of unacceptable toxic exposure

• Risk should be assessed against definedlimits of exposure, established on the basisof toxicity tests under appropriateconditions


Definitions - 3

• Risk Management - decision-makingprocess to select the optimal steps forreducing a risk to an acceptable level


Notes on Risk Management

• Risk management involves considerationsof political, social, economic, andengineering factors

• In the industrial context, it consists of 3steps: risk assessment (evaluation),emission and exposure control, and riskmonitoring


Risk Perception

• Risk perception is the way in which wesee risk and determine its importance


Notes on Risk Perception• Risk perception by society and hence

regulatory authorities reflects the culture ofthe society and changes with time as moreinformation becomes available

• For example, the addition of tetra-ethyl leadto petrol was once regarded as acceptablebut now it is rejected because of thediscovery of harmful effects on children’sbrain function


Risk Management in Practice - 1• At the manufacturing level, consideration must

be given to the siting of factories, waste dumpsand other facilities, ensuring propercontainment of chemicals in order to reducethe exposure of workers and the surroundingpopulation to acceptable levels; this mayinvolve taking into account local geography,prevailing winds, etc.


Risk Management in Practice - 2

• At the domestic level, it must be recognisedthat the user often does not understand thepotential risk of misuse of a chemical

• Packaging and instructions for domestic usemust be designed so that precautions to betaken by the user are clear and legible


Risk Management in Practice - 3• Packaging of chemicals must ensure containment

and must take into account all possible misusethat the product may receive in the hands ofuninformed people

• Ultimately, risk management is the responsibilityof each individual using a chemical and reflectstheir relevant education or lack of it


Risk Management in Practice - 4

• Chemicals for household use may be processed toavoid possible misuse or accidents

• For example, a damping agent may be added topreparations of potassium chlorate sold as adomestic weed killer to prevent the possibility ofharm from its powerful oxidizing properties


The Risk Assessment Process

• 1. -The potentially toxic chemical (thehazard) must be identified– Exposure to potentially toxic chemicals usually

involves mixed exposures; in other words, theremay be more than one chemical in the process andthere may be more than one adverse effect

– At the domestic level, many preparations aremixtures of chemicals, each of which may have adifferent potentialfor harm (hazard)


Dose and Effect• 2.-The dose which will have a critical effect

must be identified– The relationship between dose and effect is very

different from one chemical to another (see Unit 4)

– The frequency of dosing may alter the effect

– In some cases a frequent, low dose exposure mayprovide a more severe effect than a less frequent buthigher dose


Exposure Assessment• 3.-An exposure assessment must be made from

the identification of the potentially toxicchemicals and knowledge of their properties anduse– Exposure falls into two main types, anticipatable and

accidental

– The main difference between anticipatable andaccidental exposure is that the first may be calculatedand the other may only be estimated approximately atbest


Anticipatable Exposure• Anticipatable exposure is that which is likely

to occur because of the procedures beingfollowed by the person using the chemical;for example, there will be human exposure todrugs, cosmetics, and food additives whichmay estimated even before these substancesare ever used

• Anticipatable exposure should be obvious inthat it must be an identifiable consequence ofa defined method of production or use


Accidental Exposure• Accidental exposure is that exposure which

results from an accident within a process usingchemicals or during transport, use and disposalof chemicals

• Maybe a chemical reaction goes out of control,or more commonly a spillage occurs; spillagemay result from a damaged pipe or otherequipment, a road tanker involved in anaccident, or a tanker at sea running agroundand sinking


ExposureAccidental Anticipatable

Majoraccident

Temporaryloss ofcontrol

Predictable butnot calculatable

Total riskassessment

Voluntarye.g. drugs,cosmetics,

foodadditives

Involuntary(due to

industrialprocesses)

Directe.g.

(occupationalor domestic)

Indirect(environmental)

Calculatable


Risk Assessment• Having determined the likely or actual

exposure, this value is divided by themaximum level of exposure regarded as safe,for example the TDI or RfD (see slide 5,Section 4); if the value obtained is more than 1,steps should be taken to reduce exposure belowthe reference value used

• The higher the value obtained from thiscalculation, the higher the risk and the moreurgent is the process of risk reduction


Risk Management - 1• If the result of risk assessment indicates that

the risk is too high, risk management must beundertaken with the aim of risk reduction.

• Risk management is a complex issue takinginto account many factors; these include awide range of scientific technical and legalconsiderations


Risk ManagementScientific and Technical

Considerations• The science relates to the chemical and physical

properties of the compounds and mixtures ofcompounds involved in the process and the endproduct

• The technical aspects relate to the processing,manufacture and presentation of the raw materialsand the end products


Inter-related factors in riskmanagement

Legal

Scientific(properties)

Technical(process)


Risk Management and Law - 1

• Risk management is often controlled bylegislation which lays down allowable limitsof exposure and puts specific duties onmanagement and workers

• Within the European Union, Directives andRegulations have been introduced toharmonise the legislation of the membercountries


Risk Management and Law - 2

• On a global basis, the OECD (the Organization forEconomic Co-operation and Development) hastaken the lead in standardizing toxicity testing

• The United Nations Environment Programme(UNEP) has compiled a legal file on control ofchemicals to assist countries in developingappropriate legislation


The Risk Management SystemChemical

considerations

Chemical/physicalproperties of reagents

and products

Physicalconsiderations

Plant, criteria, siting,design, prevailing

weather etc.

Risk management

Overlay of national and local legal infrastructure

Chemical Environmental

Risk assessment

Health and Safety

Toxicologicalconsiderations

Dose/effect,dose/response,

legislation


Risk Interactions

Workplace

Environment

Product


Acceptability of Risk - 1

• Risk management has to determine what levelof exposure is acceptable to people exposed: itis usually relatively easy to determine what arebroadly acceptable and unacceptable levels ofexposure but there is often a level of tolerableexposure lying between these



• Decisions on acceptability of exposure andtherefore of risk may take into account benefitsfrom the use of the potentially toxic chemicaland offset the benefits against the costs ofpossible harmful effects but those likely to beat risk of harm must be consulted and agree



Increasingrisk

Decreasingsafety

Acceptable

Tolerable

Unacceptable

Easy risk management decision

Difficult risk management decisionneeded to offset advantages againstrisk and disability - both health andenvironment

Easy risk management decision

Increasingsafety

Decreasingrisk


Risk Zones• The European Centre for Ecotoxicity and

Toxicity of Chemicals (ECETOC) definesfour risk zones: death or permanentincapacity, disability, discomfort, anddetectability

• Thus, risk management in industry should, atworst, ensure that exposure to a potentiallyharmful chemical lies in the area betweendisability and discomfort (Risk Zones 3 and4)


ECETOC Risk Zones• 1. DEATH OR PERMANENT INCAPACITY.

• This is the most severe category, death or permanentincapacity occurring immediately or shortly afterexposure. and includes severe effects. such aspermanent (unless surgically corrected) blindness.

• 2. DISABILITY.

• This includes individuals who are markedly helped byexternal assistance; treatment results in full recovery


ECETOC Risk Zones

• 3. DISCOMFORT.

• The discomfort category includes those for whom afull recovery is probable without external assistance,although systematic relief may be possible andreassurance desirable.

• 4. DETECTABILITY.

• This is a category where sensory irritation may occur(e.g. a substance detected by its unpleasant smell) butthere is no direct effect of exposure on health


Information on the Internet - 1• Cancer Information Service (U.S. National Cancer

Institute)– http://cis.nci.nih.gov/

• Cancer Research Campaign (U.K.)– http://www.crc.org.uk/

• Introduction to Applied Toxicology (Self StudyCourse)– http://www.agius.com/hew/resource/toxicol.htm

• IARC Monographs– http://193.51.164.11/default.html

• International Chemical Safety Cards (IPCS)– http://www.cdc.gov/niosh/ipcs/icstart.html

http://cis.nci.nih.gov/

http://www.crc.org.uk/

http://www.agius.com/hew/resource/toxicol.htm

http://193.51.164.11/default.html

http://www.cdc.gov/niosh/ipcs/icstart.html


Information on the Internet - 2

• Material Safety Data Sheets (Cornell University)– http://msds.pdc.cornell.edu/msdssrch.asp

• NIOSH Pocket Guide to Chemical Hazards (U.S.A.)– http://www.cdc.gov/niosh/npg/pgdstart.html

• Vermont SIRI Material safety Data Sheet Collection– http://hazard.com/msds/

• Where to find MSDS on the net– http://www.ilpi.com/msds/

http://msds.pdc.cornell.edu/msdssrch.asp

http://www.cdc.gov/niosh/npg/pgdstart.html

http://hazard.com/msds/

http://www.ilpi.com/msds/


Self Assessment - 6.1True or False?

• Hazard is a function of the way a chemical isproduced, used or discarded - see slide 2

• Risk perception is a function of our culturalbackground and our knowledge of toxicity -see slide 6

• Risk management is ultimately theresponsibility of the individual using achemical - see slide 8


Self Assessment - 6.2True or False?

• Labelling should be one of the best sourcesof information on toxicity - see slide 7

• Exposure assessment should always consideranticipatable exposures and possibleinteractions of hazardous chemicals - seeslides 11and 12

• Risk management must relate to anacceptable level of exposure for those likelyto be exposed and should take appropriatemeasures to achieve this - see slide 21


Self Assessment - 6.1Checklist

• Hazard is a function of the way a chemical isproduced, used or discarded - False– Note: this is true of “risk”

• Risk perception is a function of our culturalbackground and knowledge of toxicity - True

• Risk management is ultimately theresponsibility of the individual using achemical - True


Self Assessment - 6.2Checklist

• Labelling should be one of the best sources ofinformation on toxicity - True

• Exposure assessment should always consideranticipatable exposures and possibleinteractions of hazardous chemicals - True

• Risk management must relate to anacceptable level of exposure for those likelyto be exposed and should take appropriatemeasures to achieve this - True

Documents

Risk Assessment and Risk Managementold.iupac.org/publications/cd/essential_toxicology/IUPACTOX6.pdf · Risk Assessment and Risk Management ... Notes on Risk • Acceptability of