Women in Denmark who developed breast cancer after working night shifts and many years of disturbed working patterns are to receive government compensation.

A special report broadcast yesterday, Monday 16 March by BBC Scotland told how following a ruling by a research agency of the United Nations that working night shifts probably increases people’s risk of developing cancer, the Danish government has started to pay compensation to women whose breast cancer was probably caused that way.

The BBC also reported that experts and union bosses in Scotland are of the view that the UK government should do more to prevent such risks.

About 40 women in Denmark have already won compensation from the government.

Dr Vincent Cogliano of the International Agency for Research on Cancer (IARC), an organization under the umbrella of the United Nations World Health Organisation, told BBC Scotland that the evidence available puts the risks presented by working night shifts at the same level as those presented by industrial chemicals.

Cogliano is part of a working group that published a series of monographs in December 2007. Among these was one where they described their review of scientific evidence and concluded that “shiftwork that involves circadian disruption is probably carcinogenic to humans”.

As a result, shiftwork ranks among what the IARC calls category 2A exposures (“probably carcinogenic to humans”), a long list of chemical agents that includes lead compounds and anabolic steroids; mixtures such as creosotes and diesel exhaust; and circumstances such as sun lamps and sun beds, and some occupations. To the latter they have now added “shiftwork that involves circadian disruption”.

Cogliano and colleagues wrote that epidemiological studies show that long term night workers have a higher risk of breast cancer than women who do not work such patterns. The studies, which have been done mostly on nurses and flight attendants, are consistent with animal studies that show constant light, dim light at night, or simulated chronic jet lag substantially raises the risk of tumors.

Other studies have shown that depressing melatonin levels at night also raises the risk of developing tumors. Melatonin is a hormone that is important for regulating our body clock and is also a powerful antioxidant, and some animal studies have shown it stops damage to DNA.

The IARC monograph said the evidence shows that exposure to light at night probably disrupts the circadian rhythm of the body, which alters sleep activity patterns, suppresses melatonin production and this probably disrupts the timing of when genes switch on and off, one of the things that can trigger tumors.

Cogliano said that nearly one fifth of workers in Europe and North America work shifts across all industries in both public and private sectors. While so far most studies have concentrated on nurses and flight attendants, he suggested that:

“More studies are needed to examine this potential risk in other professions and for other cancers.”

Professor Andrew Watterson, who is an occupational health specialist at Stirling University, told BBC Scotland that Scandinavia was much further ahead than the UK in recognizing the big public health dangers of shift work.

“The evidence has been good over a long period of time about cardiovascular disease and night work, gastro-intestinal problems and nights,” said Watterson.

He said there was also evidence to suggest there were other risks such as lower weight babies and longer pregnancies.

A representative from the UK’s Health and Safety Executive told the BBC that they had commissioned their own report on the link between shift work and breast cancer matter and were expecting it to be finished in 2011.

Click here for International Agency for Research on Cancer (IARC).

Sources: BBC Scotland (15 March), IARC Monographs (Dec 2007).

Written by: Catharine Paddock, PhD