Natural mineral particles: risks and their control

Anthony Seaton

Hazard and risk

• Hazard = potential to do harm (from the Arabic for gaming dice)

• Risk = the likelihood of harm occurring (but needs qualification by the perceived type/seriousness of the anticipated injury)

General rules for reduction of risk from inhaled substances.

• Good information for exposed public

• Total avoidance (eg substitution, migration)

• Exposure reduction– Limit duration of exposure– Reduce/modify activities likely to increase exposure– Personal protection (eg respirators, filtered vehicle

cabs)

• Audit or surveillance of effectiveness.

Assessment of hazardFolk law – not to be despised!

– Often the first indication of hazards

– Always worth talking to local people

• Toxicology – not always to be swallowed whole!– What is the target?– Problems with dose and

extrapolations– Problems with animal and cell

models.

Considering risk

• Likelihood of exposure• Intensity of exposure• Duration of exposure• Toxic potential of dust

Assessment of risk• How toxic to the lungs/other organs?• Ergonomics

– Personal behaviour (eg children, risk takers)– Activity levels (eg workers moving ash)

• Personal susceptibility– Nutritional– Genetic

• Epidemiology– Direct study of populations– Analogy from other, earlier studies

Risk reduction

• How toxic is the dust?– Mineralogy and analogy– Toxicology

• Understand the population and geography– Can they be moved?– How long will exposure last?– How will exposures be distributed?

• Reduce exposures– Concentration– Duration

Oil crisis looming -

where are the US energy reserves?In the Rocky Mountain shale deposits.

Joseph Bell(Sherlock Holmes)

described skin cancer in shale oil workers in 1876

Mineralogy of miner’s lung and of the W Lothian shale seam (from Hunterian museum)

What are the health effects of oil shale

exploitation?• Mortality study of 1960 cohort of

Scottish oil-shale workers

• Follow-up study of survivors, for skin and lung disease

• case control study of lung cancer in W Lothian– (Am J Indust Med 1986; 9: 409 et

seq)

An analogy for NMD – silicosis in metal miners

An analogy for NMD – COPD in coal miners

An analogy for NMD – simple pneumoconiosis in coal miners

Montserrat:some practical

measures

• Evacuation and rehousing• Exclusion zone• Assessment of mineralogy/toxicity of dust• Assessment of risks from dust inhalation• Information on risk reduction measures• Provision of masks• Population studies to refine risk estimates

Air quality standards or guidelines?

• Problems – – with different dusts– with regulation, monitoring and compliance– with lack of epidemiology

• But could be part of a published management strategy, based on analogous mineralogical, epidemiological and toxicological evidence.

Thank you

An interesting emergency!

68-year old ex-miner, one week post RU lobectomy

Increasingly wheezy - put on respirator

Diagnosis - acute asthma

Treatment - steroids and bronchodilators

Outcome - off respirator, and………!

(Thorax 1981;36:412)

….Pathology report: PMF:“Which coal mine did you work in?”“I was a shale miner”

An analogy for NMD – complicated pneumoconiosis in coal miners