Exposure Regimes and Historical Perspective

A measure of the intensity and/or extent to which the human body
experiences a particular hazard in the work place.
• For a given hazard, the greater the exposure the greater the risk of
an adverse effect on health
– exposure-response relationship.
• Determined by factors such as:
– concentration
– time duration
– severity of hazard.
• Employers have a duty under the Control of Substances Hazardous
to Health (COSHH) Regulations 2002 to control workplace
exposures to hazardous substances.
• The Health and Safety Commission (HSC) sets Work Place
Exposure Limits (WELs) for list of prescribed substances and bans
others.
Routes to occupational exposure

• There is a huge list of prescribed substances.
• Work place exposure limits for longer term (8 hour) and
short term (15 minute) exposures are set out within
COSHH and presented by the Health and Safety
Executive (EH40).
– http://www.hse.gov.uk/coshh/table1.pdf
• Not for discussion here except to note that the
standards, are lower than those set for environmental
exposure.
• E.g. Carbon Monoxide:
– WEL (8 hour): 30ppm
– Air Quality Limit: 10ppm.
• Monitoring must be undertaken to ensure standards
are not exceeded.
Dose – Response and Thresholds

Concentrations below limit does not necessarily imply total safety.
• A threshold is assumed but in some cases response may be linear.
• Principle of acceptable risk.
• Same principles apply to environmental pollution (see later).