Night Shift Lullaby

There are relatively few good songs about work, even though it’s a major part of most people’s lives. This song, by the Magnolia Electric Company, is one of them and probably sums up the experience of many shift workers. Shift work can make it difficult to socialise, affect personal relationships and seriously disrupt family life. Shift work can also have an effect on health.

The UK Health and Safety Executive point out that

Research has shown that shifts, particularly night and early morning shifts, can have undesirable consequences for workers including disruption of the internal body clock, sleeping difficulties and fatigue. These in turn can affect performance, increase the likelihood of errors and accidents at work and might affect health and well-being.

Longer term effects, which are more difficult to confirm, may include adverse pregnancy outcomes, coronary heart disease, gastrointestinal disturbances.

Recent research has also suggested that shift workers are at higher risk of developing cancer. In particular, there is evidence from four studies of a link between breast cancer and shift work for female workers. Although there remains some doubt about this link the evidence was strong enough for the International Agency for Research on Cancer to conclude that  “shift work that involves circadian disruption is probably carcinogenic to humans” in 2007.

The reason for a link may not appear to be obvious at first but it has been suggested that altered light exposure at night on levels of melatonin or other hormones may be responsible.

Whatever the possible cause, if shift work is associated with breast cancer in women it isn’t going to be easy to eliminate or control. The top of the hierarchy of control is elimination – removing workers from the exposure that causes the disease. But banning women from night shift work would be highly controversial. More work would be needed to understand the causative factors so that other approaches to control can be developed.

A paper in the British Medical Journal (BMJ) discussing the link between shift work and cancer reviewed current approaches to control

increase sleep duration, promote quick adaptation to night work, or improve subjective wellbeing at work. One possibility is to use our increasing understanding of the physiological control of the sleep-wake cycle to time our exposure to light and darkness for maximum adaptation. Using phototherapy lamps (especially those producing blue light, which is most efficient in resetting melatonin release time), wearing goggles, wearing sunglasses when driving home, and darkening bedrooms or wearing sleeping masks are being tried. Medications that are stimulants, hypnotics, or chronobiotics (substances that control the body clock) are also being

The association between shift work and cancer hasn’t been proven conclusively yet. More work is needed. But, in any case further work is needed to develop appropriate control strategies to mitigate the known  and probable effects of shift work on health.

Further Reading

HSE guidance on shiftwork

HSE Research Report on shiftwork and breast cancer

IARC Monographs Volume 98

Shift work and cancer (BMJ 2009;339:b2653)

Long-term night shifts can “double” breast cancer risk

Reducing the occupational cancer burden

On Tuesday I was at the Safety and Health Expo at the ExCeL exhibition centre in London Docklands where I was contributing to the BOHS Worker Health Protection Arena.

During the afternoon I spoke with Leslie Rushton of Imperial College London on Occupational cancer – what you need to know. Lesley is is a medical statistician and epidemiologist and led the team that undertook research on behalf of the Health and Safety Executive to produce an updated and detailed estimate of the burden of occupational cancer in Great Britain.  Lesley spoke about the current picture based on the findings of the research while I concentrated on what we can do to prevent and control exposures to those agents responsible for occupational cancer.

The research indicated that about 8,000 cancer deaths and some 13,500 newly diagnosed cancer cases each year could be due to occupational exposures. The main causes that were identified are shown in the following chart.


Occupational cancer deaths by cause in Great Britain, 2005

The research suggests that by 2060 the number of deaths from occupational cancer will have risen by 5,000 to 13,000 a year if we do nothing. So what do we need to do. That was the question that I addressed

The main cause of occupational cancer is asbestos, accounting for almost half of the deaths. The use of asbestos has now been prohibited in Europe, but there remains large amounts within the fabric of buildings constructed before the 1980’s. Providing asbestos containing materials are in good condition the risk to health should be minimal. The potential for exposure arises when they deteriorate or are being removed. Provided the requirements of the Control of Asbestos Regulations and the associated guidance are followed the risk to health should be controlled. But there are still situations where asbestos exposure can occur accidentally or in an uncontrolled manner.

With other carcinogens, the legal position is less specific. Nevertheless, exposure to the carcinogens, and the associated risk, can be controlled by application of good occupational hygiene practices. Central to this is the idea of the “hierarchy of control”.

During my talk I used examples of real life situations to show how adopting good occupational hygiene practices can be effective at minimising the risk.

In many cases, for common industrial processes, solutions are available from Regulators such as the Health and Safety Executive in the UK, OSHA and NIOSH in the USA, and from industry sources. Unfortunately employers, especially small and medium sized countries, don’t know the information is available or how to find it. Trained, experienced, occupational hygienists are well placed to help employers locate the appropriate information to help them control the risks.

However, there are also situations when a ready made solution isn’t available – either because it’s a new process, or new substances are being handled where the hazards are not fully understood (e.g. nanoparticles) or a combination of both of these. In such cases, occupational hygienists have the underlying knowledge and skills to help employers assess the risks and develop solutions.