Slides from a presentation at Health and Wellbeing at Work. 6-7 March 2012, Birmingham. Improving the health and wellbeing of work-aged people. www.healthatwork2012.co.uk

1. WORKING FOR A HEALTHY FUTURE
Benzene – Monitoring, Managing
and Reducing the Risk
John Cherrie
INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org

2. Summary…
• Benzene and the diseases it causes
• Sources in the workplace
• Monitoring exposure
• Air monitoring
• Biological monitoring
• Modelling exposure
• Skin exposure
• Risk assessment
• The Occupational Exposure Limit for benzene
• Risk management

3. Benzene is…
• Benzene is an aromatic hydrocarbon
• It is colorless, flammable with a
sweet smell
• It was first isolated and identified in
1825 by Michael Faraday
• It has had many varied industrial and
consumer uses
• In the past it was even used as an after-
shave lotion because of its pleasant
smell.

4. Mr Jones has leukaemia…
• He was diagnosed in 2010
• Mr Jones worked offshore
for an oil company between
1990 to 2000
• He came into contact with
natural gas and natural gas
condensate
• These streams contain
some benzene, e.g. 0.1 to
5% for condensate

5. Benzene is hazardous to health…
• It affects the blood forming system
• Main adverse effects are various cancers from
long-term exposure
• According to the International Agency for
Research on Cancer…
• acute non-lymphocytic leukaemia
• Plus limited evidence it may also cause…
• acute lymphocytic leukaemia
• chronic lymphocytic leukaemia
• multiple myeloma
• non-Hodgkin lymphoma

6. Sources in the workplace…
• Benzene was frequently used as an industrial
solvent in the past
• Now it can be found in small quantities in…
• gasoline
• petrochemical streams – onshore and offshore
• emissions from coke ovens and other similar
processes
• It may also be found in the wider environment at
very low levels

7. Monitoring exposure…
• Air monitoring
• Colorimetric detector tubes
• Active pump-based systems
• Diffusive samplers
• Direct-reading instruments
• There are standard methods available from HSE
• Biological monitoring
• Estimating exposure using simple models
• Is there any risk from skin contact?
http://www.hse.gov.uk/pubns/mdhs/

8. Active samplers…
• A glass or metal tube
containing an adsorbent
material
• Air is drawn through the
adsorbent by a pump
• Tube located close to
workers nose/mouth
http://www.skcltd.com/

9. Diffusive sampling…
• Sometimes called “passive”
samplers
• Simple container with an
adsorbent material and a
small air gap between inlet
opening and the surface of the
adsorbent
• Most commonly the adsorbent
is activated charcoal
• Sampler worn on the lapel

10. Mr Jones…
• In 2000, HSE made about 250 measurements
of occupational exposure to benzene during
routine offshore oil and gas production
operations
• 91% of measurements were less than 0.05 ppm
99% were less than 0.5 ppm, as 8-hr average
• Higher levels are measured during specific
tasks, e.g. up to 10 ppm in opening
valves, changing of filters, pipeline clean-out

11. Direct-reading monitors…
• For example, Photo-ionisation
detector (PID)
• Results can show minute-by-minute
fluctuations
• Data can be stored for later analysis
• Generally respond to a range of
compounds, although some types can
be relatively specific for benzene
• Care needed to get data relevant to
exposure
http://www.raesystems.com/products/ultrarae-3000

13. Mr Jones…
• Measurements using a direct reading instrument
ranged from zero to 200 ppm
• No information about where measurements made
• No details of the duration of measurements
• Many measurements may have been made very
close to leaks
• The limited information about the samples makes
the data useless

14. Biological monitoring…
• Analysis of blood, urine or exhaled
breath for benzene or its metabolites
• e.g. urinary S-phenylmercapturic acid
• Samples should be collected before
and after work
• Samples reflect difference between
individuals, both in their exposure and
the way they metabolise benzene
• Benzene is mostly eliminated from the
body within about 24-hr

15. Quality assurance for measurements…
• Workplace Analysis Scheme for Proficiency
(WASP)
• http://www.hsl.gov.uk/centres-of-excellence/proficiency-
testing-schemes/wasp.aspx
• Use an qualified and experienced person
• http://www.bohs.org/education/professional/
• UK Accreditation Service
• for sampling and analysis

16. Quality assurance for measurements…
http://www.ukas.com/TestingSearch.asp?qt=search+our+website

17. Exposure modelling tools…
• There are a number of model tools available to
estimate workplace exposure
• COSHH Essentials
www.hse.gov.uk/coshh/essentials
• Stofenmanager
www.stoffenmanager.nl
• Advanced REACH Tool (ART)
www.advancedREACHtool.com

18. Exposure modelling tools…

19. Skin exposure to benzene…
• Benzene may pass through the
unbroken skin and contribute to
systemic exposure
• Benzene is very volatile so splashes
and spills onto the skin may evapourate
• Probably only a problem if
the skin is occluded,
e.g. spills inside gloves
• Solvents also damage the skin
barrier and may cause dermatitis

20. Workplace Exposure Limits…
• Limits in the UK are published by the HSE, but
mostly are now derived from European Indicative
Occupational Exposure Limits
• Specified over 8-hr and/or 15-min
• Units of concentration parts per million
(ppm) or mg/m3
• Benzene limit unchanged since 2003
• No biological monitoring guidance
value for benzene

21. EH40 entry for benzene…

22. Mr Jones…
• Overall his exposure was probably less than
1 ppm
• Background level <0.05 ppm
• Average of the peak exposure levels…
5 x 1/8 = 0.625 ppm
• Risk was probably adequately controlled
under COSHH Regulations

23. Principles of Good Control Practice…
…
• Minimise emission, release and spread of substances
• Take into account all relevant routes of exposure
• Control exposure by measures that are proportionate to
the health risk
• Choose the most effective and reliable control options
• Where needed provide suitable personal protective
equipment
• Review regularly all elements of controls
• Inform and train all employees
• Ensure control measures does not increase overall risk
http://www.hse.gov.uk/coshh/detail/goodpractice.htm

24. Specific risk management for benzene
• Always use a fuel retriever when draining
petrol tanks or pipelines
• Don’t blow out fuel lines with compressed air
• Use protective gloves such as disposable
nitrile where there is a risk of short-term skin
contact

25. Is there an important health problem?
• We have estimated the number of leukaemia
deaths occurring in Britain from past exposure
• Risk estimates for acute non-lymphocytic
leukaemia
• RR = 2.17 for workers in industrial chemicals
• RR = 1.32 for land transport
• RR = 1.11 for low benzene exposure
• Using these data and estimates of the number of
people exposed gives…
• 7 leukaemia cases per year due to benzene
Rushton L, Brown TP, Cherrie JW, et al. How much does benzene contribute to the
overall burden of cancer due to occupation? ChemBiol Interact 2010;184:290–292.

26. Conclusions…
• Benzene is a known human carcinogen
• There are about 20k people exposed to higher
levels and 700k to low levels
• Monitoring exposure is relatively simple and and
methods are adequately standardised
• Few people are likely to be exposed above the
current Workplace Exposure Limit
• Very few people in Britain now get leukaemia
because of benzene exposure