Employees in a significant number of workplaces are exposed to a diversity of agents, such as chemicals, biological agents and radiation, that have been shown to cause cancer. Gordon Tranter discusses some recent developments in identifying and managing occupational cancer.

The extent of the problem

In industry, there are many potential exposures to carcinogens. Generally, workplace exposures are considered to be at higher levels than for public exposures. Estimating the proportion of cancer attributable to occupational exposures is both complicated and difficult. A 2010 report, The Burden of Occupational Cancer in Great Britain: Overview Report, commissioned by the Health and Safety Executive (HSE) estimated that, in the UK in 2005, the numbers of deaths attributable to exposure to occupational carcinogens were 8010 overall (6355 for men, 1655 for women), and the numbers of cancer cases attributable to occupational carcinogens were 13,599 overall (9988 for men, 3611 for women).

An underestimate?

The Trades Union Congress (TUC) has pointed out that the estimates in the HSE’s report only includes cases where there is a proven or probable link, and that there are many links between work and cancer that are still only suspected, but not yet proven. As a consequence, it believes these figures are likely to be an underestimate, and the true level is well over 20,000 cases a year, with 15,000–18,000 deaths.

However, the TUC points out that giving a figure for what causes any kind of cancer can be very difficult. For example, the exposure can be occupational or take place outside work (for instance, exposure to solar radiation or environmental tobacco smoke), and will vary from employee to employee. For many substances, the evidence for whether they are carcinogenic, or the level at which there is a risk, is inconclusive.

Diesel engine exhaust

Recent studies of workers whose jobs bring them into regular contact with high levels of diesel engine exhaust (DEE) have conclusively linked exposure to DEE to lung cancer. The Burden of Occupational Cancer in Great Britain estimates that, in 2005, exposure to DEE caused 652 occupational deaths. In 2012, the International Agency for Research on Cancer (IARC) announced that it had reclassified DEE from “probably carcinogenic” to a “definite carcinogen” — a Category 1 carcinogen. IARC stated that there is now sufficient evidence that exposure to DEE causes lung cancer. However, IARC’s Category 1 classification is a “hazard identification” and it does not specify the level of risk posed by the carcinogen. Just because DEE has been classified as a Category 1 carcinogen does not mean it presents the same risk to health as asbestos or wood dust.

The studies on IARC’s decision were based on workers who had been heavily exposed to DEE. While the scientific evidence was “compelling” for workers exposed to high levels of DEE over long periods of time, the risk of cancer for workers who are exposed to DEE at lower levels and for shorter periods of time is unknown.

Control of exposure to DEE

DEE is harmful to health and can cause short- and long-term health effects other than cancer. As a consequence, the general provisions of the Control of Substances Hazardous to Health Regulations 2002 (COSHH) apply. However, despite the IARC classification, DEE does not meet the criteria in COSHH for classification as a carcinogen and, therefore, regulation 7(5) concerning control of carcinogens does not apply. Furthermore, DEE is not included in the COSHH list of Workplace Exposure Limits.

In 2012, the HSE published HSG187 Control of Diesel Engine Exhaust Emissions in the Workplace, which provides guidance on carrying out the assessment of risk from exposure to DEEs and controlling the risk.

Outdoor workers such as road workers, policemen, traffic wardens, and bus and taxi drivers may be exposed to DEE on roads with heavy truck or bus traffic for long periods. In these situations, while the likelihood of lung cancer is small, there are other risks including cardiovascular and respiratory diseases. Assessing the level of exposure is difficult. DEE is a complex mixture, the composition of which can vary with many factors including age of the engine and its operating conditions. Individual components such as elemental carbon and carbon monoxide can be measured, but are not unique to DEE.

Decisions as to whether controls are needed are therefore not clear cut, but the HSE recommends that controls need to be considered if there is visible haze; visible soot deposits in certain areas; complaints of irritancy; and if carbon dioxide levels are about 1000ppm for an 8-hour, time-weighted average.

Night-shift work

In 2007, IARC added night-shift work to its official list of "probable" carcinogens, and in 2009, Denmark became the first country to pay government compensation to women who developed breast cancer after long spells of working at night. In 2008, breast cancer after night-shift work was recognised as an industrial injury in 38 of 75 cases that were submitted to the Danish National Board of Industrial Injuries, Occupational Disease Committee.

However, the situation is not that clear cut. A systematic review and meta-analysis published in the Scandinavian Journal of Work, Environment & Health in 2013 concluded that, based on the low quality of exposure data and the difference in effect by study design, its findings indicate insufficient evidence for a link between night-shift work and breast cancer.

Asbestos

Asbestos is accepted as a carcinogen and its use has been prohibited. In the UK, asbestos-related cancers are the most common cause of work-related fatalities; currently around 4500 deaths a year. Although, because the long latency of asbestos-related cancers is usually 15 to 60 years, most of these deaths result from exposure before the use of asbestos was prohibited. Before the dangers of asbestos were known, it was widely used in buildings, and it is estimated that there are thousands of tonnes of asbestos remaining in buildings. If asbestos in these buildings is disturbed or damaged, people may breathe in any asbestos fibres released and subsequently develop an asbestos-related cancer. Workers who may be exposed to asbestos when carrying out maintenance and repair jobs are at particular risk. The Control of Asbestos Regulations 2012 include a duty to manage the risk from asbestos in the workplace and to set up a system for providing information on the location and condition of the material to anyone who is liable to work on or disturb it.

It is worrying that, despite efforts to publicise the importance of managing asbestos, there continues to be ignorance surrounding asbestos dangers, or the required procedures are not understood, or even ignored. There are regular reports of prosecutions for exposing people to asbestos or putting people at risk of exposure. Of these, two striking cases were that of Marks and Spencer plc, which was fined £1 million and ordered to pay costs of £600,000 for putting members of the public, staff and construction workers at risk of exposure to asbestos-containing materials during the refurbishment of its store in Reading in 2011, and a Nottinghamshire property developer who disregarded the presence of asbestos insulating board and exposed his employees to asbestos. He was given an eight-month suspended prison sentence and was ordered to pay fines and costs of £100,000.

Environmental tobacco smoke

Exposure to second-hand smoke is widely accepted as a cause of lung cancer and legislation has almost completely removed the risks from exposure to environmental tobacco smoke at work. Since July 2007, smoking has been prohibited by law in virtually all enclosed and substantially enclosed workplaces throughout the UK, with a few exemptions. However, these exemptions, which include private homes, guest bedrooms in hotels and guest houses, and certain rooms in care homes, hospices and prisons, still have the potential for exposing workers to environmental tobacco smoke. There are risks of exposure to workers in care home smoking rooms and similar situations to those whose work entails working in the homes of habitual smokers. The Royal College of Nursing has therefore issued Protecting Community Staff from Exposure to Second-hand Smoke, best practice guidance for staff and managers.

Last reviewed 6 November 2013