ja36 v1-0 13apr10 w501 final slides day 1

7/30/2019 JA36 v1-0 13Apr10 W501 Final Slides Day 1

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International Module W501

Measurement of Hazardous Substances

(including Risk Assessment)

Day 1


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Insert site Emergency procedures


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Insert Lecturer(s) Background


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Your Background?

Two (2) minute overview of your background


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Course Aims

To provide participants with a sound understandingof the techniques for assessing exposure tohazardous substances in the workplace

To understand how exposure information can beused to assess risk


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Course Learning Outcomes

Participants will be able to:

Describe the general approach to occupational health riskassessment including role of atmospheric monitoring

Select the appropriate equipment to measure specificairborne contaminants & devise a suitable samplingstrategy

Present the results in a useful form


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What is Required to Complete this Course

Ask questions as we go through the notes

Participate in the case study discussions

Participate in the practical exercises

Attempt the questions each night


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What is Occupational Hygiene ?

'Occupational Hygiene is the discipline of

anticipating, recognising, evaluating and

controllinghealth hazardsin the working

environment with the objective ofprotecting

worker healthand well-being and safeguarding

the community at large.'

(Source IOHA)


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Topics to be Discussed

Basic physiology & toxicology

Risk assessment

Hygiene standards

Air sampling theory & practice

Biological monitoring Sample analysis

Dusts, fumes & fibres

Vapours & gases

Presentation of results


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Todays Learning Outcomes

Physiology & toxicology

Understand and be aware of the features of theinteracting systems of the human body

Understand the routes of contaminant entry intothe human body and their target organs andsystems

Understand the concept of dose response


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Todays Learning Outcomes (cont)

Risk Assessment

Understand principles & processes of riskassessment

Be able to apply these principles & processes in aworkplace situation


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Todays Learning Outcomes (cont)

Hygiene standards

Understand the principles of setting hygiene

standards

Understand the application and limitations ofhygiene standards


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Work Groups

Each participant will be assigned a work group forthe duration of the course

The work groups are expected to work as a teamwhen evaluating cases studies and undertakingpractical sessions


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Introduction to Physiology & Toxicology


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Discussion Topics

The Human Body

Routes of Entry

Target Organs & Systems

Concept of Dose Response


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The Human Body

12 Interacting systems:

Cardiovascular Muscular

Digestive Nervous

Endocrine Reproductive

Immune Respiratory

Integumentary Skeletal

Lymphatic Urinary


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Cardiovascular System

Includes the heart, blood & the blood vessels(arteries, capillaries & veins)

Arteries bring oxygenated blood from heart to the

tissues

Veins bring deoxygenated blood back to the heart


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Digestive System

Takes in food, digests it & extracts energy &nutrients & expels the waste

Nutrients can be absorbed into blood & lymph

systems

Some used for energy, some for building tissues &

cells & some stored for future use


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Endocrine System

Control system of glands which secrete chemicalmessengers or hormones

Endocrine glands release hormones directly intobloodstream of the body

Regulate metabolism, growth & sexual development


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Immune System

Protects body from infection by creating &maintaining barriers to prevent that bacteria &viruses entering the body

e.g. hepatitis, influenza, cholera, typhoid & malaria


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Integumentary System

Comprises skin (cutaneous

membrane) & hair, nails &

endocrine glands

epidermis

dermis

subcutaneous tissue

Largest organ of body

interface with surroundings

Insulation & temp regulation

L h ti S t


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Lymphatic System

Major component of immune system

Complex system of lymphoid organs, lymph ducts &lymph vessels that produces & transport lymph fluid

from tissues to circulatory system

Removal of excess fluids from body tissues

Absorption of fatty acids & transport of fat tocirculatory system

Production of immune cells e.g. lymphocytes,monocytes & antibody producing plasma cells

M l S t


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Muscular System

Muscle attached to bone by tendons & other tissues

Exerts force by converting chemical energy into force

Nerves link muscle to CNS

Function

Produce movement

Maintain posture

Stabilise joints

N S t


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Nervous System

Electrical impulses carried along nerve cells

CNSbodys control centre

PNS all other nerves & neurons

Somatic :

bodys movement & conscious control

Autonomic:

Sympathetic responds to impending danger or stress

Parasympathetic evident when resting relaxed

Reprod cti e S stem


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Reproductive System

Produces offspring by fertilisation or fusion of asperm and one ovum and the subsequentdevelopment of the offspring

R i t S t


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Respiratory System

Responsible for carrying oxygen from inhaled air tothe bloodstream & expelling the waste product of

carbon dioxide

Skeletal System


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Skeletal System

206 bones joined by ligaments & tendons Protective & supportive framework for attached

muscles & soft underlying tissues

Produces red & white blood cells in bone marrow Bones store minerals eg calcium & can be

transported elsewhere

Urinary System


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Urinary System

The bodys filtering system via the kidneys which

reabsorb approx 99% of the fluid into the blood

Waste or urine passed to the bladder for excretion

Routes of Entry


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Routes of Entry

Inhalation

By far most common route of entry

Skin absorption

Via direct contact major source of entry oforganics eg solvents and pesticides

Routes of Entry (cont)


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Routes of Entry (cont)

Ingestion

Relatively minor route of accidental

ingestion or poor personal hygiene

Eye

Direct entry point for some solvents and also atrisk by direct contact



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Upon entry to the body contaminants can have anadverse effect on one or more organs (target organs)

Respiratory

Irritant & toxic gases eg Carbon monoxide &

sulphur dioxide Dusts & fibres eg silica & asbestos

Blood

Lead and mercury

Target Organs & Systems (cont)


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Central Nervous System Solvents eg toluene, xylene, MEK

Polycyclic and polyaromatic hydrocarbons

Liver

Alcohols & solvents

Kidneys

Selenium, alcohol & sodium compounds



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Brain

Mercury - as mad as a hatter

Urinary

Biological agents

Some metals

Reproductive

Lead, organic mercury



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Fatty tissues

Solvents

Skin

Acids, alkali

Epoxy resins

Skeletal

Lead

Benzene



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Endocrine Lead, cadmium

Carbon disulphide



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No substance is a poison by itself, it is the dose

that makes a substance a poison

Paracelsus 154

Dose Effect Relationship


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Dose Effect Relationship

For each chemical there is a dose-effect relationship

Acute (immediate) effects (Irritants, CO)

Chronic (long-term) effects (Benzene, Asbestos)

Local effects occur at point of contact

Systemic effects occur at distant target organs

Dose Effect relationship (cont)


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Dose Effect relationship (cont)

Factors effecting this relationship include

Physical state of the material

Concentration

Possible routes of entry to the body

Target organs

Dose Effect Relationship (cont)


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Dose Effect Relationship (cont)

Retention rate in the body

Human pre-disposition (pre-existing medicalcondition)

Individual sensitivity

Frequency & duration of exposure

Potency of compound

Synergistic effects with other compounds

(e.g. asbestos & smoking)

Key Factors


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ey acto s

Dose

Effect

Critical organ concentration

Dose


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The concentration of a substance at the site of effect

(regard being made for the time which substanceconcentration is maintained)

Dose = concentration x duration of exposure

Effect


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Any observable biological change associated with the

contaminant concerned:

Should be quantifiable

Does not need to be an adverse observable effect Certain effects can be beneficial and only become

adverse if the dose is excessive or remains for acritical period of time

Critical Organ Concentration


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g

That concentration beyond which organs exhibit

some effect

May not be organ of concentration (eg boneaccumulates lead but critical organ is bonemarrow)

Target Organs


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g g

Respiratory system

Skin

Eyes

Blood

Liver

Kidneys

Bladder

Nervous system

Dose Effect v Dose Response


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p

Dose effect: Correlation between dose and themagnitude of effect

Dose response: Correlation between response of anorgan with estimates of dose

Threshold


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The dividing line between no-effect and effect levelsof exposure

For each substance there is a threshold ofintoxication which is usually different for individualsubstances

Dose Response Curve


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p

Dose Response Curve

Source: Tranter 1999Reproduced with permission

Threshold of Intoxication


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For each substance, no matter how toxic, there existsa dose level called the threshold of intoxication,which the human body is capable of accepting anddetoxifying without injury to itself

Individual Susceptibility


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p y

Source: AIOH 2007-Reproduced with permission


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Risk Assessment

Definitions


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Hazard: potential for a substance to cause harm,injury etc

Exposure: the ability (or potential) for someone tocome into contact with a substance by breathing itin (inhalation), getting it onto the skin or into theeyes (absorption) or swallowing it (ingestion)

Definitions (cont)


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Risk: likelihood that the substance will causeinjury or illness in the conditions of its use

Note: the terms risk & hazard are treated solelin relation to chemical (substance) safety and notany broader concept

The Risk Assessment Process


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Risk management is used in all sectors of the

political, business & community environment

Part of our everyday activities (e.g. driving to work)

Central to OH&S legislation in many countries

Extends to occupational hygiene hazards (e.g.

conduct of RA for hazardous substances)

Key Steps to a Successful Risk Assessmen


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Identify substances in the workplace

Establish which are hazardous & obtain informationon their properties

Assess the exposure of workers

Key Steps to a Successful Risk Assessmen


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Evaluate the risks

Identify actions

Document & communicate outcomes to stakeholders

Information


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Primary sources of information:

Suppliers MSDS

Label fixed to product

What Does an MSDS Tell You?


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Product Name

Codes, Listings

Major Uses

Ingredients

Physical Characteristics

Precautions for Use

Safe Handling and Storage Information

First Aid/Emergency

To Be Useful, MSDSs, Must Have


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Issue Date

Company Details (Not O/Seas)

Substance Name

Health Effects/First Aid

Engineering Controls

Flammable/Fire & Explosion Hazards

Storage & Handling

Spills & Disposal

What Information Can You Obtain From a MSDS


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Toxic effects

Safe handling procedures

Exposure standards

Control technologies

Engineering

PPE

Reference to other analogous compounds

What Information Can You Obtain From a Label


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Much less detail than a MSDS but usually Name of compound

Safety phrases

Risk phrases

Pictograms

Suppliers details & emergency number

Examples of Risk Phrases


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R26 Very toxic by inhalation

R27 Very toxic in contact with skin

R34 Causes burns

R37 Irritating to respiratory system

R42 May cause sensitisation by inhalation

R45 May cause cancer

Examples of Safety Phrases


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S3 Keep in a cool place S8 Keep container dry

S15 Keep away from heat

S22 Do not breathe dust S23 Do not breathe vapour

S24 Avoid contact with skin

United Nations - GHS


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GHS - Globally harmonised system of classification an

labelling chemicals

Single international system

Currently being implemented by many countries as

part of national chemical regulations systems

Risk & safety phrases will be replaced by hazardstatements

Projected GHS Benefits


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Enhancement of the protection of human healthand the environment by providing aninternationally comprehensible system for hazardcommunication

Will provide a recognised framework for thosecountries without an existing system

Projected GHS Benefits (cont)


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Will reduce the need for testing and evaluation ofchemicals, and

Will facilitate international trade in chemicalswhose hazards have been properly assessed andidentified on an international basis

GHS Pictograms


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Source: ASCC information sheet

Other Sources of Information


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Collection Method

Type of Information

Interviews of workers,managers and engineers

TasksWork practicesHealth issuesProcesses

Exposure controlsMaintenanceEnvironmental agents

Other Sources of Information (cont)


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Interviews of medicaland safety staff

Health problemsPatterns of problemsWork practices

Exposure historyEnvironmental agents

Collection Method Type of Information



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Records:

Process standardsStandard operatingproceduresProduction

PersonnelMedicalEngineeringEnvironmental reportsProcess flow diagrams

Historic conditions

Chemical inventoriesUsage amountsTasksWork histories

Performance ofengineering controlsPast environmentalmonitoring resultsPast biological monitoringresults



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Governmental and non-

governmental standards

Literature

Current exposure limits

Proposed exposure limit

Epidemiological studiesToxicological studies

Emerging issues

Walkthrough Survey


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Can provide information that may not be otherwise

evident

Involves commencing at the starting point of aprocess and following the various components until

the end product is reached

To be useful must involve someone familiar with eacstep of the process

Basic Information From a Walkthrough Survey


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An understanding of the process

The number of workers involved

The materials (including quantities) used orhandled

Evidence of reactions and any materialtransformations

Engineering controls in place and theireffectiveness

Basic Information from a Walkthrough Survey (con


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Housekeeping standards

Visible conditions at the site (any dusts,mists, etc)

Possible routes of entry to the body

Personal protective equipment and its use

Generation of Hazardous Substances


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May be generated as a result of the process and notby any individual chemical

Process itself may change the form of a substancemaking it harmful

Fine dusts from solids Fumes from heating chemicals (ammonia

compounds)

Assessing the Risk


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Factors influencing the level of risk

How much a worker is exposed to a hazardoussubstance (exposure)

Route of entry to the body (inhalation, skin etc)

Severity of adverse health effects under conditionsof exposure (hazard)

Duration and frequency of exposure

Level of Risk


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As a result of using a hazardous substance without

controls the level of risk depends upon thecombination of the:

hazard of that substance under its condition of use

duration & frequency of exposure

i.e. Risk = combination of hazard and exposure

Types of Risk Analysis


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Qualitative analysis

Uses words to describe magnitude of potentialconsequences and likelihood that thoseconsequences will occur

Used as a screening activity, where basic analysisis appropriate for decisions or where numericaldata or resources are inadequate for a quantitativeanalysis

Types of Risk Analysis

Q tit ti l i


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Quantitative analysis

Uses numerical values for both consequences &likelihood

Quality of analysis depends on accuracy &completeness of numerical values and validity of

models used Consequences may be determined by modelling

the outcomes of events or extrapolation from paststudies or data

Process of Risk Analysis

Assessing the risk requires a judgment on the


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Assessing the risk requires a judgment on thelikelihood that a hazardous substance will effect

someones health

Ask yourself these questions

How much of the substance is used or produced &

how could workers be exposed ? Who could be exposed & how often ?

What are the routes of entry to the body ?

What are the consequences of exposure ?

Process of Risk Analysis (cont)


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Gathering information to answer previous questions

Monitor workplace (for quantitative analysis)

Determine level of risk

Non Monitoring Approaches


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HSE (UK) COSHH Essentials

ILO Chemical Control Tool kit

HSE (UK) COSHH Essentials


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Control banding tool for small to medium sizeenterprises to do risk assessments for chemicals &mixtures of chemicals

Required information

Type of task shoveling, drilling

Hazard classification (using risk & safety phrasesfrom MSDS )

Volatility or dustiness (from guidance material)

Amount used- kg,mg,litres,milliliters

HSE (UK) COSHH Essentials (cont)


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System identifies

Control band (control approach)

Produces advice on controlling risk from thechemical being used in the task

Provides written guidance & documentation

ILO Chemical Control Tool kit


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Very similar to COSHH Essentials

Does not apply to process dusts or fumes due to thefact that these are not classified by the supplier ofindividual chemicals

Has general application to many situations indeveloping countries but susceptible groups (childworkers & pregnant women) need to be considered

Stages of the ILO Chemical Control Toolkit


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Stage 1 Hazard Classification


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Stage 1 Hazard Classification (cont)


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Stage 2 How Much is Used


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Stage 3 - Dustiness


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Stage 3 Volatility


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Source: ILO toolkit

Stage 4 Control Approach


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Source: ILO toolkit

Stage 5 Task Specific Control Guidance Sheet


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Source: ILO tool



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Source: ILO toolkit



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Source: ILO toolkit

Outcomes of a Risk Assessment

Significant risk


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g

Exposure is high or the substance used is highlytoxic

A dangerous reaction with other substancespossible

Reasonably foreseeable that leaks or spills of ahazardous substance may occur

Not significant risk

Actions


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Process of risk evaluation provides a list of risks

requiring control, often with priorities

Need to identify a range of possible control options,evaluating them, selecting appropriate control

options and implementing them in the workplace Control options should be considered as part of

overall site or process risk management strategy

Actions (cont)

Possible control measures (Hierarchy of Control)


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Possible control measures (Hierarchy of Control)

Elimination of the substance

Substitution of the substance

Segregation of the substance from workers

Engineering methods

Administrative controls

Personnel protective equipment

Elimination

Difficult to achieve in practice


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Difficult to achieve in practice

production

quality

cost

Some examples preformed components (eliminating dust)

components that can be clipped, screwed or boltedtogether (eliminating adhesives)

Substitution


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Use a safer form of the same substance ( e.g. using a

substance in pellet rather than powder form)

Use a safer (less hazardous / less volatile) substance /product (e.g. use water based paint rather than oil basedpaint)

Process modification (e.g. applying a substance with a brushinstead of spraying the substance)

Segregation (Isolation)


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Can be achieved by separating people from a harmfulagent / process by:

distance

time

barriers

Engineering Controls

The use of equipment or processes, to prevent ori i i th l f h d h i l t


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minimise the release of hazardous chemical agents

Options include: automation / robots total enclosure / containment partial enclosure partial enclosure plus local exhaust ventilation local exhaust ventilation general (dilution) ventilation

Total Enclosure / Containment

The operator controls the process from outside thel d th h d i t i d It i d


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enclosure, and the hazard is contained. It is used

when working with; carcinogens

sensitisers

materials under high temperature or pressure

Examples include:

Pharmaceuticals, chemical plants and refineries

Closed loop sampling systems

Laboratory glove boxes

Partial Enclosure Plus LEV


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Common examples include:

welding and grinding benches,

spray paint booths and

fume cupboards

General Ventilation Compared to LEV

General Ventilation LEV


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Draws contaminant awayfrom source

Reduces level ofcontaminant inhaled by

employees

Very effective ifdesigned and usedcorrectly

Does not removecontaminant at source

Reduces backgroundlevels by addition of freshuncontaminated air

Administrative Controls

Safe systems of work rely heavily on:


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Safe systems of work rely heavily on:

good management / supervision employee engagement / behaviour

written rules and procedures

information, instruction and training

Simple instruction, allow to cool before opening

Administrative Controls (cont)

Formal standard operating procedure (in wriwhich if


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o a sta da d ope at g p ocedu e ( c

adopted ensures a task is undertaken the right wayevery time

task analysis,

in writing,

training / competence, supervision

Permit to work

confined space entry

Administrative Controls (cont)


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Reducing exposure time

Employee rotation

Work rest regimes

Personal Protective Equipment (PPE)

Head protection Body protection


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Head protection Body protection

Eye protection Hand protection

Ear protection Foot protection

Respiratory protection

Actions

Induction & training


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g

Extent will depend on level of risk Use the information on the hazards and controls obtained i

the risk assessment to prepare training materials

Ongoing workplace monitoring

Required where serious health effects may occur if controlfail

Statutory requirement for some substances

Useful to check effectiveness of control measures

Actions (cont)

Health surveillance


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May be required when there is an identifiable work relateddisease

Likely that disease or condition might occur underconditions of work

Valid techniques for early detection are available

Emergency procedures & first aid

Need to match level risk and address potentialconsequences of an uncontrolled release etc

Records

Documentation of risk assessments is a fundamentastep in the process


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step in the process

Needs to be given attention but in some cases isoverlooked once the risk level is established

Most organisations use the same format to documenrisks no matter their origins - brings familiarity to theprocess ensuring the level of detail required forongoing review is provided in the documentation

Reasons for Documentation (cont)

Communication with stakeholders


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Communication with stakeholders

Evidence of a systematic approach to riskidentification & analysis

For later review

Record of risk & develop the organisationsknowledge database

Reasons for Documentation (cont)

Documentation for managerial approval &


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Documentation for managerial approval &

implementation

To provide an accountability mechanism & tool

Audit trail

Share & communicate information

Management

The use of prescriptive legislation in many countriesis diminishing


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is diminishing

Most authorities have moved to a risk basedapproach where the onus is on the employer toestablish the level of risk and manage accordingly

Covers a broad range of issues including hazardoussubstances

Statutory authorities produce guidance materialwhich essentially defines minimum standards

Case Study 1 Risk Assessment

Super IH Paints


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Super IH Paints

Source: BP International

Case Study 1 Risk Assessment

Paint Manufacturer - vessel cleaning


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Paint Manufacturer - vessel cleaning

Case Study video together with backgroundinformation

Comment on what you see and hear. Ask questions

Determine the information you need to complete arisk assessment on the task of paint vessel cleaning

Case Study 1 Student Exercise

Break up into assigned groups


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p g g p

Critically review the case study video & gatheredinformation

Attempt to document a risk assessment & makeconclusions about risk

Determine actions to improve control

Case Study 1 Student Exercise

Use lecture notes for guidance and/or discuss with


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Use lecture notes for guidance and/or discuss with

lecturer if you require clarification

Time allowed is 60 minutes

Be prepared to present your assessment in the groupdiscussion period


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Hygiene Standards

Hygiene Standards

Hygiene standard:

The level of exposure via


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The level of exposure, via

inhalation, that should not cause ill health to a healthy

adult when exposed to the contaminant

Other (interchangeable) terms include:

Threshold limit values

Exposure standards

Occupational exposure limits

Workplace exposure limits

Background

Based on no observed adverse effect level


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Seems to be threshold dose

Epidemiological studies & occupational hygienemeasurements assist to identify this threshold

Threshold of intoxication accepting & detoxificationwithout injury

Background (cont)

Also based on physiological response


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Irritants Asphyxiants

Anesthetics

Carcinogens

Unbearable odour

Toxic effect

ACGIH

Threshold Limit Values TLVs - refer to airborne


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concentrations under which it is believed that nearlyalworkers may be repeatedly exposed, day after day, ove

a working lifetime, without adverse effects. TLVs are

developed to protect normal, healthy adults.

Documentation

The source publication that provides the critical


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evaluation of the pertinent scientific information anddata with reference to literature sources upon which

the TLV or BEI is based

Documentation of Threshold Limit Values for

Chemical Substances and Physical Agents and

Biological Exposure Indices

Three types of TLVs


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TLV - Time Weighted Average (TLV - TWA)

TLV Short Term Exposure Limit (TWA - STEL)

TLC Ceiling (TLC - C)

TLV TWA

TLV-TWA The TWA concentration for a conventional


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8-hour workday and a 40-hour work week, to which it isbelieved that nearly all workers may be repeatedly

exposed, day after day, for a working lifetime without

adverse effect.

TWA (8-hr) = C1T1 + C2T2 +..CnTn

8

Calculate 8-hour TWA

Working period mg/m3 Duration of sampling (h)

0800 - 1030 0.32 2.5

1045 1245 0 07 2


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1045 - 1245 0.07 2

1330 0.2 2

1545 1715 0.1 1.5

Assume exposure is zero in rest breaks 10301045, 12451330 & 15301545

8-hr TWA = (0.32 x 2.5) + (0.07 x 2) + (0.2 x 2) + (0.1 x 1.5) + (0 x 1.25)

8

= 0.8 + 0.14 + 0.4 + 0.15 + 0

8

= 0.19 mg/m3

TLV STEL

TLV-STEL is a 15 minute TWA exposure that


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TLV STEL is a 15 minute TWA exposure that

should not be exceeded at any time during a

workday, even if the TWA is within TLV- TWA

TLV STEL (cont)

Can be exposed continuously for a short period withou


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suffering from: Irritation

Chronic or irreversible toxic effects

Dose-rate dependent toxic effects or

Narcosis sufficient to increase likelihood ofaccident, impaired self rescue, or reduced workefficiency

TLV STEL (cont)

Exposures above TLV-TWA up to TWA-STEL


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< 15 minutes

4 times a day

60 minutes between successive exposures

TLV - C

TLV-C the concentration that should not be exceeded

during any part of the working exposure


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during any part of the working exposure

If instantaneous measurements are not available,sampling should be conducted for the minimum

period of time to detect exposures at or above ceilingvalue

Excursion Limits

Excursions limits are applied to TLV-TWAs that do NOT

have TLV-STELs


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have TLV STELs

Excursions up to 3 x TLV-TWA - less than 30 min/day

and NO excursions above 5 x TLV-TWA, providing

TLV-TWA not exceeded (3 x WEL in UK)

A process is not considered to be under reasonablecontrol if these levels occur

Mixtures

When two or more hazardous substances have a

similar toxicological effect on the same target system,


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similar toxicological effect on the same target system,

their combined effect rather than that of either

individually, should be considered

Where C1/TLV1 + C2/TLV2++ Cn/TLVn < 1

the TLV for the mixture should be considered as being

exceeded

Additive Effect

Agent Full shift results

(TLV-TWA)

Short term results

(TLV-STEL)


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Acetone 160 ppm

(500)

490 ppm

(750)

Sec butyl acetate 20 ppm

(200)

150 ppm

(N/A)

Methyl ethyl ketone 90 ppm

(200)

220 ppm

(320)

From the TLV basics column, the Documentation of the TLVsand BEIs all three substances indicate effects on respiratory

system and would be considered additive

Additive Effect (cont)

Full shift calculation


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C1/TLV1 + C2/TLV2++ Cn/TLVn 1

therefore 160/500 + 20/200 + 90/200

= 0.32 + 0.10 + 0.45

= 0.87

Hence full shift additive limit not exceeded

Additive Effect (cont)

Short term calculation


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= 490/750 + 150/(200 x 5)* + 220/300

= 0.65 + 0.15 + 0.73

= 1.53

This is >1 hence short term additive limitexceeded

* where no STEL exists the convention is tomultiply TWA exposure standard x 5 (x 3 in UK)

Units of Measure

Dusts

3


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mg/m

Gases and vapours

parts per million (ppm) or % (v/v)

mg/m3

Conversion of ppm to mg/m3

Conc in mg/m3 = Conc in ppm x molecular weight /24.45


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where 24.45 = molar volume of air in litres at NTPconditions (25C and 1 atm)

(NB IUPAC use 0C and 100 kPa, but ACGIH and otherbodies use 25C and 1 atmosphere)

Conversion of ppm to mg/m3 (cont)


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Where STP conditions are required (i.e. 20C not25C) the equation is:

Conc. in mg/m3 = Conc. in ppm x molecular weight24.06

Definitions & Notations

Carcinogenicity

A carcinogen is an agent capable of inducing benign


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or malignant neoplasms

A1 - Confirmed human carcinogen

A2 - Suspected human carcinogen

A3 - Confirmed animal carcinogen with unknownrelevance to humans

A4 - Not classifiable as a human carcinogen

A5 - Not suspected as a human carcinogen

Definition & Notations (cont)

Notice of Intended Change (NIC)


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Each year proposed changes are indicatedcomments are sought and suggestions for othersubstances to be added are also sought

Particulate matter / particle size

For solid and liquid matter, TLVs are expressedas total particulate matter except where terms

such as inhalable, thoracic or respirable particulatmass are used

Definition & Notations (cont)

TLV Basis/Critical Effects

Is discussed in each documentation.


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The column comments are intended to provide fieldreference for symptoms of over exposure and for whichcompounds may be considered as acting independently oradditively

Biological Exposure Indices BEIs Listed when a BEI is recommended

Two sub categories added

BEIA = see the BEI for Acetylcholinesterase inhibiting pesticide

BEIM

= see the BEI for Methemoglobin inducers

Definitions & Notations (cont)

Sen potential for agent to produce sensitisation.

Does not imply that it is the critical effect


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Respiratory

Dermal

Conjunctival

Skin where potential significant contribution to theoverall exposure by the cutaneous route by direct

contact with the vapour or direct contact with the skin

Application of Standards

Airborne concentrations are representative of workers

exposure:


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Collected in the breathing zone

Occupational or personal sampling

Note: If para-occupational or static or area samplingcarried out results should not be compared directly

with exposure standards

Extended Work Shifts

TLVs developed for conventional 8-hour workday

followed by a 16-hour break from the exposure over a

40 h k


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40-hour week

Number of models used to adjust TWA for unusual &extended shifts

Not necessary to adjust TWA-STEL or TWA-C asthese associated with acute rather than chronicexposures

Brief & Scala Model

Reduces OEL proportionally for increased

exposure & reduced recovery time


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Adjusted OEL = 8 x (24 h) x TWA

16 x h

where h = hours worked each day

Brief & Scala Model (cont)

Example: Toluene, 12 hour shift, 8 hr TWA is 50 ppm

Adj t d OEL 8 (24 12) 50


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Adjusted OEL = 8 x (24 12) x 50 ppm

16 x 12

= 25 ppm

NB Brief & Scala model developed for petroleum

industry & has not been validated for dust exposures

OSHA Model

Previously, OSHA used reduced PELs.

Example: If 10 hour shift being worked,

TWA (10H ) TWA (8 h ) (8/10)


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TWA (10Hr) = TWA (8 hour) x (8/10)

Now, OSHA official must measure the worst 8-hour

period and compare result with 8-hour TWA

Only lead has a exposure reduction

Lead PEL = 4000g/m3 / shift hours

OSHA Model - example

Toluene, 12 hour shift, 8 hr TWA is 50 ppm


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OEL = 50 x 8

12

= 33 ppm

Note difference between Brief & Scala v OSHA models

with same data

Pharmacokinetic ModelModel of Hickey & Reist considers metabolism,

biotransformation and excretion


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Modified TLV = TLV x 1-e-8k 1-e-120k

1-e-t1k 1-e-t2k

where t1 = hrs worked per day on usual schedulet2 = 24 x days worked/week on unusual schedule

k = ln2/t1/2

This model beyond scope of this course

WA Department of Minerals & Energy


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Source; DOCEP-reproduced with permission

Limitations of Hygiene Standards

Values do not exist for all substances

Apply to the workforce workers healthier than

general public


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general public Not meant to apply to general population

Not for environment or boundary emissionstandards

Not for use with a set safety factor eg divide by 100

Not a fine line between safe and dangerousconcentrations

For use by trained occupational hygienists

Standards in Other Countries

AustraliaExposure Standards

Based on ACGIH List with reference to standards from


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Based on ACGIH List with reference to standards fromGermany, Sweden & UK

www.ascc.gov.au

Data base exists for 696 current national exposure

standards TWA, STEL, peak, carcinogen, Sen, Skin

Standards in Other Countries (cont)

United Kingdom Workplace Exposure Limits

WELs replaced previous Occupational Exposure Limits


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WELs replaced previous Occupational Exposure Limits(OELs) and Maximum Exposure Limits (MELs)

HSE EH40/2005 (Workplace Exposure Limits) list ofassigned substances

8-hr TWA & STEL Comments Column containing Safety & Risk Phrases plus

the Carcinogenicity, Skin, Sensitivity and BiologicalMonitoring Guidance Value notations


European Limits

Indicative Occupational Exposure Limit Values IOELV

Chemical Agents Directive


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Chemical Agents Directive

Health based

63 substances

8-hr TWA, STEL, skin

Binding Limit Values BLVs

Carcinogen Directive

Also reflect socio-economic & tech feasibility factors

Benzene, hardwood dust, vinyl chloride monomer, lead


USA OSHA Permitted Exposure Levels (PELs)

Based on 1968 TLVs - approx 400


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Based on 1968 TLVs - approx 400 Listed updated in 1989

Number of detailed regulatory requirements

eg asbestos, lead, benzene, methylene chloride, vinylchloride etc

Contained in Title 29 of US Code of Federal Regulations


USA NIOSH Recommended Exposure Limits REL

NIOSH recommends Standards to OSHA / MSHA (Mine


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NIOSH recommends Standards to OSHA / MSHA (MineSafety & Health Administration) & some are lower thanPELs, TLVs etc

TWA up to 10-hr day, 40 hour week

Also STEL, C and Ca, skin Available on CD-ROM or website www.cdc.niosh.gov

Pocket Guide to Chemical Hazards

NIOSH Recommendations

Criteria documents etc


USA AIHA Workplace Environmental ExposureLevels (WEELs)


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Intended to provide guidance where NO legal orauthoritative limit exists

eg benzyl alcohol, butylene oxide

In current Guide > 100 WEELs 8-hr TWA, Ceiling, Short Term TWA plus Skin, Dermal &

Respiratory sensitiser notations


Germany MAK Commission

MAK values for volatile chemicals & dusts

BAT values (biological tolerance values)


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BAT values (biological tolerance values)

Analytical procedures (air & biological materials)

Notations for carcinogens, germ cell mutagenic,

sensitizing, percutaneously absorbed & embryoniceffects

Published & reviewed annually

Review of Todays Learning Outcomes

Physiology & toxicology


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Understand and be aware of the features of theinteracting systems of the human body

Understand the routes of contaminant entry into

the human body and their target organs andsystems

Understand the concept of dose response

Review of Todays Learning Outcomes (cont

Risk Assessment

Understand principles & processes of risk


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Understand principles & processes of riskassessment

Be able to apply these principles & processes in aworkplace situation

Review of Todays Learning Outcomes (cont

Hygiene standards


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Understand the principles of setting hygienestandards

Understand the application and limitations ofhygiene standards

ja36 v1-0 13apr10 w501 final slides day 1

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