What is an Asbestos Retrospective Risk Assessment (RRA)?

An Asbestos Retrospective Risk Assessment can determine the probable exposure and potential contribution to lifetime risk if a person is exposed to asbestos fibres. There are occasions when unintended occupational exposures to asbestos can occur within the workplace, which understandably can give rise to concern and anxiety for those involved. Incidents and accidents that result in the exposure of employees to asbestos fibres could increase the risk of developing an asbestos-related disease. The extent of that risk is unlikely to be understood by either the individuals who have received the exposure or the persons informing them of the incident. 

By undertaking an Asbestos Retrospective Risk Assessment, the IOM can assess, the exposures that may have occurred and provide an estimate of dose in conjunction with a quantitative calculation of future risk of developing an asbestos-related disease or risk to health-giving consideration. 

By providing a quantitative estimate of risk an RRA can provide re-assurance in single incidents but should not divert attention from legal duties.

When would you need Asbestos Retrospective Risk Assessment?

The accidental release or escape of asbestos fibres into the air in a quantity sufficient to cause damage to the health of any person is reportable under RIDDOR (Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013). Such situations are likely to occur when work is carried out without suitable controls, or where those controls fail.

An Asbestos Retrospective Risk Assessment will also be useful if you are the focus of an intervention by a regulator, or if an employee, (past or present) has made a complaint. They can be used to assess the requirement for remediation work and are sometimes utilised 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 a repetition of such incidents.

How to decide if a case needs to be reported under RIDDOR?

Changes to the sentencing guidelines introduced in 2010 have seen penalties for asbestos prosecutions increase. In 2016-17, the HSE prosecuted over 200 asbestos cases from the construction sector alone, with a 93% success rate, that led to over £15 million in penalties. This worked out at an average fine of £77,000, which was an increase of over 100% compared to 2015-16.

IOM's incident reports can help an employer decide if a case needs to be reported under RIDDOR. Our incident reports provide evidence of any future risks of developing disease or risk to health based on individual exposures and could prevent an unnecessary prosecution.  Our carefully constructed, authoritative reports provide the best possible estimates of risk and are tailored to each individual situation. They describe the methods used, the sources of information and the estimated risks of cancer. The estimated risks are always put into context by comparing the asbestos-related risks with common hazards such as smoking or road accidents, as well as benchmark levels of risk used by some authorities to define "acceptable" levels of risk.

We have applied this approach to determine the levels of exposure and risks:

  • to personnel unknowingly disturbing asbestos in commercial and public buildings;
  • from the disturbance of fragmented asbestos materials on rights of way;
  • from the inadvertent disturbance of asbestos-containing materials during maintenance, refurbishments and demolition works; and
  • from the disturbance of asbestos-contaminated soils.

If the risks are low, our reports provide reassurance to staff or the public. They can also help employers focus on preventative measures and management controls.

What type of work activities create a significant concentration of asbestos fibres in the air?

Some work activities are more likely to create a significant concentration of asbestos fibres in the air, and therefore, add to the risk if suitable precautions are not in place; for example:

  • use of power tools (to drill, cut etc.) on most ACMs (asbestos-containing materials);
  • work that leads to physical disturbance (knocking, breaking, smashing) of an ACM that should only be handled by a licensed contractor e.g. sprayed coating, lagging, asbestos insulating board (AIB)
  • manually cutting or drilling of AIB
  • work involving aggressive physical disturbance of high-density asbestos products e.g. breaking or smashing asbestos cement building materials


How do we evaluate asbestos exposure?

Our investigations normally consist of four stages:

  • Stage one: First, we gather information about the specific incident.
  • Stage two: We estimate concentrations of asbestos in the air using the scientific literature, our own extensive practical experience, any existing air concentration measurements and/or our own measurements.
  • Stage three: The exposure of each individual is estimated from the duration of exposure and the estimated concentration in the air.
  • Stage four: The risks of contracting lung cancer and mesothelioma are derived from the estimated exposures using widely accepted exposure-response models, which take age, gender and smoking habits in to account.


How do I understand the risks from contaminated land? Assessment of risk from asbestos in soils

We have used a similar approach to contaminated land risk assessments concerning asbestos. This work has been undertaken to help assess risks from potential past exposures through use of contaminated sites, as well as to help assess how best to deal safely with soil that is contaminated with asbestos, and to determine whether "significant possibility of significant harm" (SPOSH) exists under Part IIA of the Environmental Protection Act 1990.

Our reports provide the rational technical basis for either the developer to assess and demonstrate whether a site is "safe and suitable for use", or the Local Authority to inform their decision as to the condition of land under Part IIA.

One of the difficulties in determining the risks associated with asbestos-contaminated soils is that the contamination is typically very variable within distances of only a few metres. Asbestos is only dispersed in the soil through mechanical mixing and there is an element of chance as to whether samples collected from soils containing discrete fragments of ACMs do or do not contain asbestos. It is therefore important that sufficient samples are collected and analysed in order to develop an understanding of the distribution of asbestos contamination and to properly determine the quantity present as this will have a significant impact on the determination of potential risks to health and future management. It is also important that if there are large fragments of ACMs present that their inclusion in the determination of soil asbestos content, is as part of an appropriately large sample.

Part of the risk assessment would include advice on how to manage the exposure risks when undertaking the proposed remediation/redevelopment works.

If you have any questions you can contact the team on: ExpertWitness@iom-world.org

10 June

Exploring interventions for reducing SARS-CoV-2 in hospital environments

  • 10 June 2021
  • 10:00-13:00

IOM is proud to announce that Miranda Loh has been invited to speak at the 8th UK & Ireland Occupational and Environmental Exposure Science Meeting 2021 talk about exploring interventions for reducing SARS-CoV-2 in hospital environments. This is particularly relevant to public health researchers as we’ll be sharing a new tool that we have developed.

To attend the event, please register by sending your name, position, institution, email address, Zoom name and, optionally, your professional twitter or other social media account names to ruohan.wu@student.manchester.ac.uk before 8th June 2021.

Event info
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