Night Shift Work Probably Carcinogenic To Humans Finds IARC

Night time shift work has now been linked with increasing levels of cancers and other health problems according to research completed by the International Agency for Research on Cancer (IARC). The following article reported in the Spring-summer 2012 edition of Hesa Mag; discusses:

The Main Health Problems From Night Work

Sleep disorders: the quality of daytime sleep is poorer than nocturnal sleep (because of noise, light, higher temperature), and shorter - generally two hours less per 24 hours compared to a day worker.
The lack of sleep leads to drowsiness and an increased risk of accidents at
or away from the workplace (road accidents, for example).

Digestive disorders: gastric acid production is known to follow a circadian rhythm (approximately
24 hours) which can be disrupted in night workers. Also, night work does nothing to promote healthy diets (eating ready meals, excess coffee consumption, imbibing alcohol in some cases, etc.).

Cardiovascular problems: recent studies have shown a relationship between night work or shift work and the risk of coronary heart disease resulting from disruption of the nervous system or hormone secretions, which increase the risk of arrhythmias and cardiac conduction disorders, and damage to artery walls.

Psychiatric disorders: night work is a source of stress and chronic fatigue, and may also be linked to an increased risk of depression.

Cancer risk: in 2008, the International Agency for Research on Cancer (IARC) classified night shift work (irregular, alternating periods of day and night work) as probably carcinogenic to humans.

The IARC experts’ conclusion was based on experimental animal tests and epidemiological studies among nurses working night shifts and airline stewardesses subject to frequent phase shifts.

The studies point to a higher risk of breast cancer among these employees than those with more standard schedules. Night work is thought to disrupt the internal biological clock that regulates the alternating periods of wakefulness and sleep. Long-term exposure to artificial light at night inhibits melatonin or "sleep hormone" production, which impairs the immune system.

It also resets clock-controlled genes that can result in the formation of cancer cells. Melatonin’s role on oestrogen secretion may explain the excess risk of breast cancer.

How many people work nights in the EU?

The European Working Time Directive defines a night worker as "any worker, who, during night time, works at least three hours of his daily working time as a normal course", and "any worker who is likely during night time to work a certain proportion of his annual working time".

Official EU statistics estimate that 7.4% of employees in the European Union (EU) worked at night in 2010 (see Table 2). That figure was 7% for the EU-15 in 2001.

The European Foundation for the Improvement of Living and Working Conditions’ survey on perceived
working conditions done in 2010 among 44 000 workers reports that:

19% of EU workers work between 10 pm and 5 am for at least two hours a month: 23% of male and 14% of female respondents;

— 25% of the men working these night time hours are aged between 25 and 39;
— 16% of the women are under 25;
— 10% of the workers work nights more than 5 times per month.

The survey's authors note in their analysis report that night work is strongly correlated with non-standard work contracts, as well as with shift work, and to a lesser extent with long working hours.

Source: Spring-summer 2012/HesaMag #05 / Unionsafety

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