Considering Exposure Risk to Libby Amphibole Asbestos (LAA)

Risk is a measure of probability. Risk is not a matter of something being either 100% or 0% , rather, risk is a range between 100% and 0%. Risk is a matter of probability on a continuum between absolute certainty and impossibility. Different exposure pathways may increase or decrease a person’s level of risk along that continuum. At this time, there are no scientifically supported methods of measuring what an individual’s actual “risk” of developing asbestos related disease is. While there is no “safe” level of exposure to asbestos fibers, there are factors to consider when considering risk of disease development.

Factors to Consider

  • Dose – What was the amount of asbestos fibers you were exposed to?
  • Duration – What amount of time were you exposed?
  • Frequency – How often?

Being exposed to asbestos in multiple settings, repeatedly over time, increases risk. Consider the ways you may have been exposed:

Incidental Exposures – Recreating in Rainy Creek drainage where dust from the mine was present in high concentrations. Playing or watching baseball at the downtown ballfields near the vermiculite processing plants. Gardening with vermiculite. Playing in piles of vermiculite.

Residential Exposures – Was your residence near asbestos “hot spots”? Was there vermiculite stored on your property?
Household Contact Exposures – Did someone you lived with or visited often bring asbestos fibers home in dust on their clothing or vehicles?

Occupational Exposures – Working for WR Grace, working as a contractor for WR Grace or working in the Rainy Creek Basin area, such as in logging or for the USFS.

There Are Many “Unknowns” When Considering Risk

There is not yet a set threshold of toxicity for Libby Amphibole Asbestos. We do not know what levels of exposures cause which health effects. The EPA is currently working on developing this data. At this time, we are unable to rule out the possibility of health effects even with ‘low risk’ exposure.

There may be familial or genetic predispositions that would make some individuals more susceptible to developing different severities of asbestos related disease. The age of an individual at the time of exposure may impact the development of disease. Our alveoli (air sacs in our lungs) continue to develop until 18-20 years of age.

Having other respiratory conditions can complicate asbestos related disease detection and management. Obstructive airway disease, asthma, chronic bronchitis, and emphysema can imitate signs of asbestos related disease and can cause asbestos related disease symptoms to worsen.

Smoking has a synergistic effect on the risk of developing lung cancer.

  • A cigarette smoker is 10 times more likely than the general public to develop lung cancer.
  • A person exposed to asbestos is 5 times more likely than the general public.
  • A person exposed to asbestos and smoking cigarettes is 50-90 times more likely to develop lung cancer than the general public.
  • There is evidence that asbestos exposed workers who QUIT smoking can reduce their risk of developing lung cancer by as much as 50% after 5 years of quitting smoking.
  • Cigarette smoking weakens the lungs and reduces their ability to remove asbestos fibers.
  • Cigarette smoking also irritates respiratory passages, causing them to produce more mucus. These effects block the passage of air and further decrease the removal of asbestos fibers from the lungs.

Keeping Risk in Perspective

There are many activities that we participate in on a daily basis that involve risk. Life-time odds of dying from selected activities of everyday life per 1000 individuals:

  • Natural fatal cancer = 212
  • Motor vehicle crash = 11.9
  • Second hand smoke = 4
  • Radon in home = 3
  • Pedestrian accident = 1.6
  • Arsenic in water = 1
  • Drowning = 0.9
  • Bicycling = 0.2
  • Lightning strike = 0.013

There is no current estimate of risk for development of asbestos related disease. However, just as we use safety precautions in driving such as safety belts and airbags, there are ways to decrease our risk from asbestos exposure. We can prevent further exposure by recognizing vermiculite and notifying appropriate agencies for clean-up of existing hazards, keeping potentially hazardous areas wet to reduce dust, and educating ourselves about common vermiculite uses in order to avoid potential exposure.