2023 Volume 45 Issue 4 Pages 243-257
国際連合のGHS（Globally Harmonized System of Classification and Labelling of Chemicals）勧告に基づく分類の10種類のヒトへの健康有害性の面から，日本の労働災害事例を対象として，化学物質による重大災害の典型的・特異的な原因とリスク低減措置をまとめることを目的とした．厚生労働省の「職場のあんぜんサイト」で公開されている「化学物質による労働災害事例」のリストに，「製品評価技術基盤機構：NITE」の「政府によるGHS分類結果」を結び付けた．2022年の自律的化学物質管理の法令改正に対応すべく，健康有害性に対する措置の参考例を得るために健康有害性別に解析を行った．クラスター解析を利用したテキストマイニングツールのKH Coder（ver. 3）を用いて，健康有害性ごとに労働災害の原因と措置をまとめた．化学物質がもつ健康有害性が起因となり労働災害が発生することは少なかったが，全健康有害性を急性毒性，急性的な有害性および慢性的な有害性で区分けした場合には，急性毒性および急性的な有害性である腐食性や感作性などについては接触が多くの原因であった．しかし，多くの労働災害は化学物質がもつ危険性の面あるいは職場の安全性面の原因で発生していた．健康有害性による労働災害が発生する原因としては，不安全な行動および不安全な状態，あるいは物質の物理化学的特性への不理解，物質の混合や加水分解などの特異的な反応があった．健康有害性での代表的なリスク低減措置としては，健康有害性物質が人と接触することを防ぐ設備，人の不安全行動を抑制するシステム，化学反応についての理解を促すこと，試験研究や下請け作業などに関わる人すべてに対する化学物質についての情報提供であった．急性的な有害性に関する事例が多いが慢性的な有害性による事例が相対的に少ない，「死亡又は4日以上休業した」労働災害事故事例のデータを用いたこともあり，健康有害性が起因となり労働災害が発生することは少なく，多くは化学物質の危険性および職場の安全性の不備で健康有害性による労働災害が生じていた．以上のことから，自律的化学物質管理においても，まずは職場の安全性および化学物質の危険性のリスク低減措置をとったうえで，急性毒性および急性的な有害性である腐食性や感作性などについては接触を防止し，慢性的な有害性のリスク低減措置として許容濃度や管理濃度を指標としたリスク低減措置を実施する必要があるとまとめられた．
The purpose of this study was to summarize the typical and specific causes and risk reduction measures of serious accidents in Japan caused by chemical substances in terms of the 10 types of human health hazards in the UN GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification. The list of “Cases of Major Accidents Caused by Chemical Substances” published on the “Safety in the Workplace Website” of the Ministry of Health, Labor and Welfare (MHLW) was linked to the “Results of GHS Classification by the Government” of the National Institute of Technology and Evaluation (NITE). Analysis was conducted by health hazards in order to obtain reference examples of measures taken against health hazards in response to the revision of the law on autonomous chemical substance management in 2022. Using the text mining tool KH Coder ver. Three using cluster analysis, we grouped causes and measures among serious disasters by health hazard, illustrated co-occurrence networks, and extracted typical examples of each in a co-occurrence network. Representative causes of and measures against occupational accidents caused by health hazardous properties were summarized from the extracted typical cases. Although few occupational accidents were caused by the health hazards of chemicals, when all health hazards were classified into acute toxicity, acute health hazard, and chronic health hazard, contact was a clear cause for many of the acute toxicity and acute health hazards, such as corrosiveness and sensitization. However, many occupational accidents were caused by the physical hazardous aspects of the chemical substances or by the safety aspects of the workplace. Causes of occupational accidents due to health hazards included unsafe behavior and unsafe conditions, or lack of understanding of the physicochemical properties of a substance and specific reactions such as mixing or hydrolysis of the substance. Typical risk reduction measures for health hazards included equipment to prevent human contact with health hazardous substances, systems to control unsafe behavior, promoting understanding of chemical reactions, and providing information about chemicals to all persons involved in testing, research, and subcontract work. The data of occupational accident cases of “death or more than 4 days lost from work” were used. Most of the cases were related to acute health hazards, but relatively few to chronic health hazards, and few occupational accidents were caused by health hazards. Most of the occupational accidents were caused by health hazards due to the physical hazards of chemical substances and inadequate workplace safety. In light of the above, it is necessary in autonomous chemical substance management to first take risk reduction measures for workplace safety and chemical physical hazards, then to prevent contact with acute toxicity and acute health hazards such as corrosiveness and sensitization, and, lastly, to take risk reduction measures for chronic health hazards, using allowable concentrations and controlled concentrations as indices.
