和田 耕治 医師

国立研究開発法人 国立国際医療研究センター 国際医療協力局

この論文は、今や世界中でも認識されている日本発の「過労死(Karoshi)」という現象について科学的根拠（エビデンス)を提供する成果といえます。欧州、米国、オーストラリアのデータをもとに評価することで、週35-40時間の労働と比較した場合に、週55時間以上働くと脳卒中の発症リスクが33%、虚血性心疾患の発症リスクが13%、それぞれ高まることが示されています。

わが国の労災補償制度では、脳血管疾患と虚血性心疾患等の死亡や発症の背景に業務による明らかな過重負荷・過重業務があった場合には、「過労死」として認定されるか審査が行われるとされています。

これまでは、長時間労働が直接の脳血管疾患と虚血性心疾患等の原因になるかどうかについては十分な証拠がないとされてきました。そのため、過労死の根拠として長時間労働による睡眠不足や、生活習慣の悪化などについての研究成果が用いられています。

日本においても、長時間労働を減らすということがこれらの疾患の予防に重要ということを意味する研究です。

しかしながら、わが国の労働者には長時間労働を減らす以外にもっと重要なことがあると考えています。例えば、個人でできることとしては、家族との時間を増やす、自分やパートナーを大切にする時間を増やす、運動する機会を増やす、睡眠時間を確保するといったことです。さらには、職場において普段からストレスを低下させ、職場に今以上に笑顔が増えるような介入も重要でしょう。

ちなみに日本では昨年、過労死等防止対策推進法が成立し、過労死等の防止のための対策に関する大綱が本年7月24日に閣議決定されています。今後過労死をゼロにする取り組みがさらに活発になる予定です。

 
【参考リンク】
厚生労働省 「過労死等の防止のための対策に関する大綱」についてのプレスリリース
http://www.mhlw.go.jp/stf/houdou/0000092244.html

Professor Dino Pisaniello

The School of Public Health at the University of Adelaide

脳梗塞と虚血性心疾患のリスクの根底には運動不足があるのだと考えています。長時間労働は社会経済的地位の低い労働者によく見られるもので、彼らには他のリスク因子もあるでしょう。特に低賃金で体を動かさない仕事についている男性の職場では、注意を払うべき論文です。

原文

"This paper systematically reviews the evidence for a relationship between long working hours and heart disease and stroke. It actually indicates a lower risk of coronary heart disease for workers than previously thought. However, the figure is still a 7 per cent increased risk and would apply to about 27 per cent of Australian male workers and 10 per cent of female workers.*
 
"Using 2008/9 data, Safe Work Australia (2012)** estimated that there were 30,000 cases of heart disease attributable to work, but not compensated. So, heart disease is an issue in Australian workplaces, but under-recognised in workplace management.
 
"The data on stroke, although representing a higher excess risk of 30 per cent, would account for much fewer cases.
 
"For both stroke and coronary heart disease, an underlying risk factor is physical inactivity for extended periods. Long working hours is a proxy for other risk factors, which may be more common in workers of low socio-economic status.
 
"The Lancet paper should provide a stimulus for workplaces and regulators to re-examine long working hours, and in particular long periods of physical inactivity for men in lower paid jobs."
 
*The Australian working hours are derived from Australian Bureau of Statistics data and data generated from the University of South Australia (2014)
http://www.unisa.edu.au/Global/EASS/HRI/CWL/publications/AWALI_2014_national_report_final.pdf
The Australian data actually refer to 48+ hours per week, and my risk estimates given above are derived from the dose-response relationship in the Lancet paper.
 
**http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/660/Cost%20of%20Work-related%20injury%20and%20disease.pdf

Professor Tony LaMontagne

The School of Health & Social Development at Deakin University

ヨーロッパの労働者を中心とした研究ですが、オーストラリアにも当てはまるものです。長時間労働がメンタルヘルスにも悪影響を与えることが我々の研究でもわかっています。アスベストと肺がんの件でもわかる通り、労働環境の改善には多くのステークホルダーの行動が必要です。長時間労働にも同じことがいえるでしょう。

原文

"Although this study is based primarily on European workers, the results likely apply to Australian workers as well. This paper reinforces a growing body of research that has linked long working hours to a variety of adverse health outcomes, as well as with work-family conflict and other social outcomes.  This evidence comes from both Australia and international studies. For example, we conducted a study of working hours and mental health on a national cohort of Australian workers that was published last month.* We found that compared to when a person was working standard fulltime hours, working over 49 hours was associated with lower mental health. Decreases in mental health were greater in women compared to men, and for those working in jobs at higher occupational skill levels.
 
"It is unfortunate that the authors highlight only one implication of their findings: “that more attention should be paid to the management of vascular risk factors in individuals who work long hours.” Healthcare providers are not the only group that have an influence over the health of workers. Of at least equal, and probably greater, importance is the need to control working hours as a hazard to health just like we have controlled other workplace hazards in industrialised democracies, from traumatic fatalities on the job to asbestos-related cancers.
 
"In the case of asbestos exposures, of course we pursue improvements in the early detection and treatment of asbestos diseases, but the most important action has been to ban asbestos – to apply what we learn to both prevention and treatment.  Both are essential.  Returning to the topic at hand improving the health of workers requires action from employers, unions, OH&S regulators and other workplace stakeholders to limit working hours, in addition to the authors’ acknowledged need for action by healthcare providers.
 
"In short, the findings of this study, combined with those from others, suggest the need to consider long working hours as a hazard to employee health in Australia."
 
* Milner A, Smith P, LaMontagne AD. Working hours and mental health in Australia: evidence from an Australian population-based cohort, 2001–2012. Occup Environ Med 2015;72: 573–579.