Comments on the Respiratory Exposure to Toxic Gases and Metal Fumes Produced by Welding Processes and Pulmonary Function Tests Reply

Abstract

I read with interest the article recently published in The IJOEM on respira-tory exposure to toxic gases and metal fumes produced by welding processes by Mehrifar, et al.1 This paper has reported respiratory symptoms among welders and supported by field measurements of weld-ing gases and fumes. However, there are certain issues that need to be addressed.This study has conducted on a small population of welders. Under such cir-cumstances, controlling all confounding variables is necessary to minimize bias. Nevertheless, several confounders were not controlled. For example, alcohol con-sumption, a variable with well-document-ed effects on the respiratory system has not been controlled at all.2 Additionally, although the authors excluded smokers, it was not clear whether the study partici-pants were past/second smokers or not. Moreover, although the authors report no significant difference (page= 0.13, pweight= 0.20) between demographic character-istics of cases and controls, the age and weight have clear direct effects on respira-tory functions,3-5 and should be controlled by statistical methods.The most important weakness of this study, however, was the way gases and fumes were measured. At first, the authors state that the concentration of magnesium has been measured (page 43, Metal Fumes and Gases section) but no comments on this issue could be found throughout the manuscript, neither in the Results nor in the Discussion. The second point is about air sampling zone, where the elements and gases were captured. The authors ex-pressed that the air samples were collected from the “respiratory tract.” However, for obvious reasons, such a measurement is neither possible nor ethical to do so. Prob-ably, this is just a misspelling and it has to be corrected to the “berating zone.” The third point, and the most important one, is that the authors do not declare how many samples and for how long were collected from welders. Generally, air-sampling time has a direct relationship to the mini-mum and maximum required air volume, but there is no statement about none of these important points.6 Recently, the Oc-cupational Safety and Health Administra-tion (OSHA) has published a guideline for air sampling, indicating in-site air moni-