Shift work and health effects

There have been number of recent studies which have added to the knowledge of the effects of shift work on our health. Here are two which subscribers may find interesting - I did!

1 - Night shift work and melatonin and sex hormone levels 
There is some evidence that disruption to the circadian rhythms and subsequent hormone-related changes may increase the risk of hormone-dependent cancers among night shift workers.

In 2007 and again in 2019, the World Health Organization’s International Agency for Research on Cancer (IARC) determined that shift work is “probably carcinogenic to humans,” (Group 2A) based on sufficient evidence from experimental animal models but limited human, epidemiological and mechanistic evidence. IARC also concluded that there were too few studies and inconsistent results to comment on the evidence of sex steroid hormone alterations, especially among men.

In this study, researchers from the Barcelona Institute for Global Health examined the melatonin and sex steroid hormone levels among night shift workers to evaluate hormone-related changes in melatonin and sex steroids in a population of male rotating shift workers working both day and night shifts in a slow backward rotation. 

After collecting data, measuring light exposure and analysing urine samples, the researchers concluded that night shift work was indeed associated with melatonin and sex hormone-related changes in timing and total production, providing insight into the mechanistic path for its association with hormone-dependent cancer. 
Read more: Harding, BN, et al, Changes in melatonin and sex steroid hormone production among men as a result of rotating night shift work – the HORMONIT study 
[AbstractFull textScand J Work Environ Health 2022;48(1):41-51 

2 - Shift work and increased risk of preterm birth 
Previous studies of preterm birth (PTB) concerning night work have been inconclusive and partly limited by imprecise data on working schedules. This Swedish study investigated the risk of PTB in relation to detailed, registry-based data on working hours.

In this cohort of Swedish health care employees with registry-based data on working hours, night work, especially working frequent consecutive nights, and quick returns from night shifts during the first trimester was associated with increased risk of PTB among pregnant women. Read more: Kader, Manzur et al. Shift and night work during pregnancy and preterm birth-a cohort study of Swedish health care employees. [Full articleInternational journal of epidemiology vol. 50,6 (2022): 1864-1874. doi:10.1093/ije/dyab135

Precarious workers under-report occupational injuries

In a first, researchers have proven that precariously employed workers in Sweden under-report occupational injuries. The researchers from Sweden and the USA noted that under-reporting of occupational injuries (OIs) among precariously employed workers in challenges effective surveillance of OIs and targeted preventive measures.

Examining the national OIs register and records from a labour market insurance company, they found that:

  • under-reporting of OIs followed a dose–response pattern according to the levels of precariousness (the higher the precarious level, the higher the under-reporting); 
  • under-reporting of OIs, decreased as the injury severity increased and was higher with highest level of precariousness in all groups of severity;
  •  there were higher under-reporting estimates among all occupations in the precarious and borderline precarious groups compared with the non-precarious ones.

The study empirically demonstrated that under-reporting of OIs in Sweden is 50 per cent higher among precariously employed workers. This may represent unrecognised injuries that especially burden precariously employed workers as financial, health and social consequences shift from the employer to the employee.
Read more: 
Kreshpaj B, Bodin T, Wegman DH, et al, Under-reporting of non-fatal occupational injuries among precarious and non-precarious workers in Sweden [Full article

Share Tweet


In a NSW District Court judgment, Edstein Creative has been fined $375,000 for failing to protect workers from exposure to dangerous silica dust, leading to one employee developing silicosis.
Read More
Florida has passed a law that removes any mention of ‘climate change’ from state laws and policies.
Read More
Aras Holdings, a specialist building company, was hired to construct ten factories in Footscray and employed a sole trader for the concreting work. On April 7, 2022, an employee of the sole...
Read More