Asbestos Risk Assessment
Asbestos has been widely used in the UK in many different products that benefited from asbestos's durability, strength, chemical stability, and insulating properties. The quantities used were very substantial, with importation of asbestos into the UK starting at the end of the 19th century and continuing until near the end of the 20th century and reaching peak usage of about 200,000 tons annually during the 1960 and 1970s. Large quantities of asbestos containing materials remain in place in buildings and in many other applications. Given this widespread use of asbestos, it is not surprising that occasionally asbestos is inadvertently disturbed. Such incidents, once discovered, can give rise to great concern among those inadvertently exposed.
There is a very strong public awareness that asbestos is dangerous, and it is not surprising that incidents of exposure give rise to alarm because the circumstances contain many factors that tend to make risks unacceptable. The health hazards caused by asbestos are unfamiliar, the risk has been imposed (rather than freely chosen, as with smoking), and the level of risk is difficult for the lay person to assess and the adverse effects are long term. In addition, much of the publicity about asbestos is aimed at dissuading workers from taking risks with materials containing asbestos.
There is very substantial evidence on the relationship between exposure to asbestos and the risks to health. It is clear that the risks depend on the amount of exposure: the higher the exposure the higher the risk, and the lower the exposure the lower the risk. However, it has not been possible to identify any safe threshold below which there is absolutely no risk.
The IOM helps many clients manage asbestos. The IOM also helps in those occasions when an incident of asbestos exposure occurs. The IOM uses its unique experience to assess the exposures that have occurred and then uses the known relationships between exposure and future risk to health to estimate the risks of cancer in the specific incidents.
Our investigations normally have four stages. First, we gather information about the specific incident. We then estimate concentrations of asbestos in air using the scientific literature, our own extensive practical experience, any existing air concentration measurements and our own measurements of asbestos in air. Then the individuals' exposures are estimated from the time the exposure lasted and the estimated concentration in air. Lastly, the risks of lung cancer and mesothelioma are derived from the estimated exposure using widely accepted exposure-response models, taking into account age, gender and smoking habit.
Our reports are tailored to the individual situation under investigation. The report will carefully describe the methods used, the information sources and the estimated risks of cancer. The estimated risks are always put into context by comparing the asbestos-related risks with risks from common hazards (such as smoking, road accidents, or being struck by lightning) and with benchmark levels of risk used by some authorities to define "acceptable" levels of risk.
We have applied this approach to risks from asbestos in schools, fragmented asbestos cement on rights of way, damage to asbestos ceiling tiles in offices, inadvertent disturbance of asbestos-containing materials, and asbestos contamination of soils.
Our carefully constructed, authoritative reports provide the best possible estimates of risk. If the risks are low, as they often are, our reports provide reassurance to staff or public. Our reports can be used to assess the need and priority for remediation work and they are sometimes used in civil litigation cases. Although we may find that the risk from an individual incident is low, our reports will also affirm the importance of preventing repetition of such incidents.
We have also used the same approach in contaminated land risk assessments concerning asbestos. This work has been undertaken to help assess risks from past exposure, to help assess how best to deal safely with soil contaminated with asbestos, and to determine whether "significant possibility of significant harm" (SPOSH) exists under Part 2A of the Environment Act. Our reports provide the rational technical basis for the responsible authority to take the political decision as to whether a level of risk is unacceptable.