世界卫生组织认定，电焊致癌

从世界卫生组织WHO属下的国际癌症研究机构IARC官网上获悉，前几天颁布的致癌物清单中，有4种化学物质或工艺被确定为肯定致癌物（即1类致癌物）。其中有一种肯定致癌因子为大家经常见到的电焊！

下面是该组织的归类理由。

In March 2017, 17 scientists from ten countries met at the International Agency for Research on Cancer (IARC; Lyon, France) to evaluate the carcinogenicity of welding. These assessments will be published in volume 118 of the IARC Monographs.

2017年3月，来自10个国家的17名科学家在国际癌症研究机构（IARC，法国里昂）开会，评估电焊的致癌性。这些评估将发表在今年的IARC专著第118卷。

Worldwide, an estimated 11 million workers have a job title of welder,and around 110 million additional workers probably incur welding-related exposures. Welding can involve exposures to fumes, gases,radiation (ultraviolet [UV] radiation and electromagnetic fields) and co-exposures to asbestos and solvents.Welding involves several processes (eg, oxyfuel [gas], arc, and resistance welding) and materials (eg, mild and stainless steel). Exposure determinants include the process,material welded, ventilation, degree of enclosure, and use of personal protection.

在世界范围内，估计有1100万名电焊工，约1亿1000万名工人可能间接接触。焊接可以涉及烟雾、气体、辐射（紫外线（UV）辐射和电磁场）、石棉和溶剂等多种因素的混合接触。焊接包含几个工艺（如氧焊（气体）、电弧和电阻焊接）和材料（例如，低碳钢和不锈钢）。接触程度取决于工艺、焊接材料、通风、封闭程度和个人防护。

The carcinogenicity of welding fumes was assessed by IARC in 1989 and classified as 'possibly carcinogenic to humans' (Group 2B),based on 'limited evidence in human beings’ and 'inadequate evidence’ in experimental animals. UV radiation was classified in Group 1 in volume 100D of the IARC Monographs.Substantial new evidence has since accumulated from observational and experimental studies. In the present evaluation, welding fumes and UV radiation from welding were classified as “carcinogenic to humans”(Group 1).

在1989，IARC评估了焊接烟雾的致癌性，并将其归类为“可能对人类致癌”（2B组），基于“有限的人类证据”和“证据不足”的实验动物。紫外辐射在IARC的编号为100D手册中被归类为第1组。从观察和实验研究中积累了大量的新证据。在当前的评估中，焊接烟雾和UV辐射被归类为“对人类致癌”（第1组）。

Arc welding generates UV radiation,a risk factor for the rare cancer ocular melanoma. Various ocular disorders (eg, cataracts or keratoconjunctivis) occur in both welders and nearby workers. Sufficient evidence for the carcinogenicity of UV radiation from welding came from eight partly overlapping case-control studies and two census-based cohort studies that reported on ocular melanoma. Most case-control studies showed positive associations, with risks of developing ocular melanoma generally increased by between two-fold and ten-fold.Two of three studies that assessed risk by duration of employment as a welder showed positive trends.These studies also showed increased ocular melanoma risk associated with eye burns-a proxy for UV exposure-and one reported a positive exposure-response association for cumulative occupational exposure to artificial UV radiation, including welding.Risks persisted after adjustment for sun exposure, sun bed use, or both.

弧焊产生的紫外线辐射是罕见的癌症-眼部黑色素瘤的危险因素。各种眼部疾病（如白内障或角膜结膜炎）都发生在焊工及其相邻工人。基于焊接UV辐射致癌性的充分证据来自8个部分重叠病例对照研究和2个以人口普查为基础的队列研究，报告了眼部黑色素瘤。大多数病例对照研究显示，眼黑色素瘤发展的风险一般在2倍至10倍增加。3项研究中有2项研究结果显示与焊工工龄呈正相关。这些研究也显示了增加的眼部黑色素瘤与眼烧伤有关（UV典型损害），有人报告了累积职业暴露人工紫外线辐射（包括焊接）的正相关关系。剔除阳光暴晒、日光浴混杂因素之后，风险仍然存在。

Welding fumes are produced when metals heated above their melting point vaporise and condense to fine particles (mostly <1 µm in size).Most studies, including more than 20 case-control studies and nearly 30 occupational or population-based cohort studies, reported increased risks of lung cancer in welders or other workers exposed to welding fumes.Exposure-response associations with indices of longer or greater cumulative exposure to welding fumes were also reported in several studies, some of which were large,high-quality studies. Exposure to fumes was assessed indirectly through welding process or material, branch of industry, job title, expert assessment,or self-report.

当金属被加热到高于其熔点时，会产生蒸汽并凝结成细颗粒（主要是小于1μm），形成焊接烟雾。大多数研究，包括20多个病例对照研究和近30个职业或基于人群的队列研究，报告了电焊工或其相邻工人接触焊接烟雾，其肺癌风险增加。其他几个研究也显示了更加紧密的接触-反应关系，其中一些研究规模比较大质量还是比较高的。接触量的评估信息来源于焊接工艺或材料、工业门类、工种、专家评估或自我报告。

Asbestos exposure and tobacco smoking, which are important potential confounders, could not explain the observed excess lung cancer risk in welders. Positive associations persisted after adjusting directly or indirectly for smoking,asbestos co-exposure, or both; restricting to non-smokers or low-level smokers; and in cohorts with low or minimal asbestos exposure.

石棉接触和吸烟，这是重要的潜在混杂因素，无法解释观察到的焊工肺癌患者增加的风险。在考虑这两个混杂因素之后，依然存在正相关。研究局限于不吸烟者或少量吸烟者；以及在低或最小石棉接触的人群。

Positive associations for occupation as a welder and kidney cancer were reported in nearly all relevant cohort and case-control studies. However, few studies adjusted for solvents used for cleaning metal in tandem with welding,such as trichloroethylene (a risk factor for kidney cancer). Increased risks were consistently reported across countries,occupational settings, and study designs. However, chance, bias, and confounding could not be reasonably ruled out because some findings were not statistically significant,several studies had few exposed cases,and there was little evidence of an exposure-response association.

几乎所有相关队列和病例对照研究表明，电焊和肾癌呈正相关。然而，几乎没考虑焊接溶剂如三氯乙烯（肾癌的危险因素）这个混杂因素的影响。尽管如此，不同的国家、专业机构和实验设计的研究报告结果都一致。然而，偶然性、偏差和混杂不能被合理排除，因为一些发现没有统计学意义，一些研究只有很少的接触个案，接触反应关系证据缺乏。

For all other cancers, the evidence for carcinogenicity was inadequate because of inconsistent findings across studies, insufficient numbers of studies, or the potential for confounding or selection bias. The Working Group concluded that there is 'sufficient evidence in humans’ that welding fumes cause lung cancer and limited evidence for kidney cancer.There is limited evidence in experimental animals for the carcinogenicity of gas metal arc-stainless steel welding fumes. In one oropharyngeal aspiration study and one inhalation study in male A/J mice, gas metal arc-stainless steel welding fumes promoted 3-methylcholanthrene-induced lung tumours.

对于所有其他癌症，致癌性的证据是不够的，因为多个研究的结果并不一致，研究数量不足，存在潜在的混淆或选择偏倚。工作组得出结论，焊接烟雾导致人类肺癌证据充足，但导致肾癌证据有限。实验动物对气体金属电弧不锈钢焊接烟雾的致癌性的证据有限。1个雄性A/J小鼠经口抽烟和1个吸烟研究，此类焊接烟雾促进3-甲基胆蒽诱导的肺部肿瘤。

Absorption and excretion of metals (chromium, nickel, and manganese) was shown in people exposed to welding fumes, but data for particle deposition and clearance in welders were scarce. Strong evidence suggests that welding fumes induce chronic inflammation and are immunosuppressive. Lung and systemic inflammation biomarkers were increased in many panel studies(of cross-sectional and cohort design)of various arc welding fumes.Risk for infection (pneumonia) was increased in epidemiological studies of different designs. In rodents, welding fumes induced chronic pulmonary inflammation and, in fewer studies,impaired resolution of pulmonary infection.

电焊烟雾接触者可观测到金属（铬、镍和锰）的吸收和排泄，但是缺少电焊工颗粒沉积和清除的数据。

强有力的证据表明，焊接烟雾引起慢性炎症和免疫抑制。

有许多不同弧焊烟雾研究（横截面和队列设计）显示，肺和全身炎症生物标志物增加。不同设计的流行病学研究显示，感染（肺炎）风险增加。

在啮齿类动物中，焊接烟雾引起慢性肺部炎症，只在较少的研究肺部感染减轻。

兄弟们，要加强对自己的防护呀！！