Research Plus: June/July 2008

Night work breast cancer risk

A systematic review of 13 relevant papers published up to May 2007 found ‘limited evidence’ of a causal relationship between prolonged night work and elevated risk of breast cancer, but no evidence of an elevated risk of colon cancer, prostate cancer or all cancers. Evidence was of variable quality and none of the studies analysed cancer risk against cumulative number of night shifts; most based their risk assessments on years of nightshift work. Breast cancer risk was raised in nightshift work of at least 20 to 30 years duration, but no effects were identified in shorter exposures.

Scandinavian Journal of Work, Environment & Health 2008; 34(1): 5–22.

Depression interventions

A Cochrane review of interventions aimed at reducing work disability in depressed workers found no evidence of reduced sickness absence due to medication alone, or due to enhanced primary care (treatment plus education delivered by specially trained healthcare team) or psychological interventions, either alone or in combination with medication. There was limited evidence for the effectiveness of a combination of antidepressant medication and psychodynamic therapy, but it was insufficient to recommend its use. There were no studies on work-directed interventions and future studies should focus on work issues and outcomes.

Cochrane Database of Systematic Reviews 2008; 2: no. CD006237.

Occupational voice loss

A systematic literature review of the treatment and prevention of occupational voice disorders notes that 40,000 people with dysphonia are referred for voice therapy each year in the UK. Between 20% and 80% of teachers report suffering from a voice disorder. It identified six randomised controlled trials on treatment and two on prevention – though only one was of high quality. A combination of direct and indirect voice therapy is effective in improving vocal functioning, with evidence from two trials that the benefits remain in the medium and long term. No high-quality evidence was found to support the use of voice training in at-risk populations.

Otolaryngology–Head and Neck Surgery 2008; 138, 557–565.

Benzene link to NHL

A meta-analysis of 22 cohort and case–control studies produced a summary relative risk (RR) of non-Hodgkin’s lymphoma due to benzene exposure of 1.22 (95% confidence interval 1.02–1.47). However, after excluding studies that were likely to have included unexposed subjects in the ‘exposed’ group, it increased to 1.49 (CL 1.12–1.97). Further exclusion of papers that relied solely on self-reported work history increased the RR to 2.12 (95% CI 1.11–4.02). Misclassifications of exposure inherent in some studies may have masked the association.

Occupational & Environmental Medicine 2008; 65; 371–378.

Reactive airways dysfunction syndrome

A systematic literature review to identify agents associated with reactive airways dysfunction syndrome (RADS) – asthma-like symptoms occurring within 24 hours of a single, high concentration exposure to a gas, fume, smoke or vapour – found a lack of adequate information on exposure, investigation and, in particular, outcome of reported cases. From 69 papers, 63 cases met the definition of RADS. The most common agents were chlorine, toluene diisocyanate, oxides of nitrogen, acetic acid, sulphur dioxide and paint. Symptoms occurred within one hour in 29 patients and within 24 hours in 34 patients. The establishment of a web-based RADS database is suggested to improve information flow.

Occupational Medicine 2008; 58: 205–211.

Return to work after CTS surgery

In a study of 107 cases meeting inclusion criteria, return-to-work (RTW) rates of working-age patients undergoing surgery for carpal tunnel syndrome were significantly influenced by job classification (heavy manual, light manual, non-manual), gender (woman took less time off), exposure to repetitive work and lifting heavy objects. Surgical technique (open versus endoscopic decompression) and various personal factors – including whether self-employed or employed – were not significant in determining RTW times.

Occupational Medicine 2008; 58: 187–90.

EMF meta-analysis

A meta-analysis of 19 studies investigating the potential impact of mobile-phone electromagnetic fields on cognitive functioning was unable to find any important adverse effects. The only moderately significant effects were that reaction time was mildly reduced and that working memory was slightly impaired. However, say the authors: ‘The effects seem to be so small that implications for human performance in everyday life can be practically ruled out.’

Occupational & Environmental Medicine 2008; 65; 342–346.

Cochrane review on manual handling

The latest Cochrane OH review found six randomised controlled trials and five cohort studies on the use of training and assistive devices in the prevention of low back pain and disability. However, the evidence (graded as limited to moderate) indicates that neither intervention is effective, by itself, in preventing back pain. There was some evidence that workers expressed satisfaction with the training they received, and it improved their knowledge on manual handling, but no evidence that this led to consistent improvement in their manual handling behaviour.

Cochrane Database of Systematic Reviews 2007; 3: no. CD005958.

Whole body vibration

Employers are required to protect employees from whole body vibration (WBV) under the Control of Vibration at Work Regulations 2005; however, to date there has been little consensus on the health risks of exposure. Research carried out on healthy young adults (mean age 23 years) used a ‘wobble chair’ to measure trunk postural control. The individuals were subjected to WBV applied from under the seat. WBV was found to increase various measures of kinetic variance of unstable seated balance as well as non-linear stability control; in other words, it impaired postural control of the trunk. The results provide a possible mechanism by which WBV could increase the risk of low back injury.

Clinical Biomechanics 2008; 23(4): 381–386.

Construction injuries

A systematic review of papers published to June 2006 was designed to assess the effectiveness of interventions to prevent injuries in the construction industry. Just five papers were of sufficient research quality for inclusion. Research methodology was of generally low quality and there was no evidence that construction regulations are effective in reducing injury rates. There was ‘limited evidence’ that a multifaceted safety campaign and a multifaceted drug-misuse prevention programme can reduce non-fatal injuries.

Cochrane Database of Systematic Reviews 2007; 4: no. CD006251.