摘要：زمینه و هدف: در محیطهای کاری گرم، اثر شرایط دمایی محیط و گرمای متابولیسم ایجاد شده ناشی از فعالیت فیزیکی فرد موجب ذخیره گرما و افزایش دمای عمقی بدن کارگران می‌شود. در شرایط دمایی گرم افزایش جریان خون سطحی، تعریق و تهویه ریوی بیشتر و افزایش دمای بدن می‌تواند جذب مواد شیمیایی را از طریق تنفس و پوست افزایش داده و روند سمیت آلاینده شیمیایی در بدن و متابولیت‌های آن را تحت تاثیر قرار دهد. با توجه به اهمیت بررسی چگونگی تاثیر استرس‌های حرارتی بر میزان پاسخ سمی مواد شیمیایی، مطالعه حاضر با هدف بررسی ارتباط بین سطح استرین حرارتی بدن و سطح تتراکلرواتیلن در هوای بازدم شاغلین خشکشویی انجام شد. روش بررسی: مطالعه توصیفی تحلیلی حاضر در دو مرحله در زمستان و تابستان در شهر همدان انجام شد. همراه با نمونه‌های هوای بازدم 24 نفر از شاغلین خشکشویی، نمونه‌های هوای محیطی نیز مورد بررسی قرار گرفت. نمونه برداری غلظت تتراکلرواتیلن در نمونه‌های هوا (محیطی و فردی) بر اساس روش 1003 NIOSH توسط لوله جاذب کربن فعال (ساخت شرکت (SKC متصل به پمپ نمونه برداری فردی کالیبره شده مدل 222 ساخت شرکت SKC با دبی 100 میلی لیتر بر دقیقه انجام پذیرفت. نمونه‌های هوای بازدمی نیز مطابق با توصیه روش 3704 NIOSH توسط کیسههای نمونه بردار سه لیتری از جنس تدلار ساخت شرکت SKC جمع آوری گردید. جهت علاوه بر این، استرین‌های حرارتی نیز با استفاده از شاخص دمای عمقی و ضربان قلب و تهویه ریوی مطابق با استاندارد 2004 :9886 ISO اندازه گیری شد. نتایج با استفاده از نسخه 21 نرم افزار spss مورد تحلیل قرار گرفت و سطح معنی داری 05/0 درنظر گرفته شد. یافته ها: مطالعه حاضر نشان داد بین غلظت تتراکلرواتیلن در هوای محیط خشکشویی در فصول زمستان و تابستان اختلاف معنی داری وجود ندارد(05/0<p). با این حال میزان غلظت تتراکلرواتیلن در هوای بازدمی در تابستان ppm 18/3 و در زمستان ppm 23/2 به دست آمد که به ترتیب بالاتر و پایین تر از حدود مجاز مواجهه شغلی کشور (ppm 3) بود. بین غلظت تتراکلرواتیلن در هوای بازدمی در فصول زمستان و تابستان تفاوت معنی داری مشاهده شد(05/0>p). نتایج همچنین نشان داد که علی رغم کاهش غلظت آلاینده در هوای محیطی در فصل تابستان، به دلیل افزایش دمای عمقی و ضربان قلب افراد، غلظت تتراکلرواتیلن در هوای بازدمی افزایش یافته است. علاوه بر این، اختلاف بین میزان دمای بدن ، ضربان قلب نرخ تنفس در فصول زمستان و تابستان معنی دار بود(05/0>p). نتیجه گیری: مطالعه حاضر تایید نمود علی رغم یکسان بودن غلظت تتراکلرواتیلن در هوای محیط خشکشویی در فصول زمستان و تابستان، به طور کلی سطح تتراکلرواتیلن در هوای بازدم به علت افزایش سطح استرین حرارتی و تهویه ریوی شاغلین خشکشویی افزایش یافته است. بنابراین می توان گفت مواجهه کارگران با شرایط دمایی گرم منجر به افزایش جذب تنفسی آلاینده‌ها در شاغلین می‌گردد. با توجه به امکان جذب پوستی آلاینده های شیمیایی در اثر افزایش جریان خون سطحی و همچنین تعریق ناشی از مواجهه با گرما، توجه به این موضوع در مطالعات آینده ضروری است. درنهایت پایش سلامت دوره ای و مراقبت های بهداشتی در مشاغل همراه با مواجهه همزمان با گرما و الایندهای شیمیایی توصیه می گردد.
其他摘要：Background and aim: In the hot workplaces, the increase of body core temperature is induced in result of exposure to high air temperature and metabolism heating due to worker activity. Heat exposure can affect how well chemicals are absorbed into the body. Core temperature change can alter absorption, distribution, metabolism and excretion of the toxicants. Increases in respiration can cause further toxicant exposure through inhalation, while increases in sweat and skin blood and pulmonary ventilation flow can make more efficient transcutaneous absorption of toxicants. Therefore, the amounts of xenobiotic absorbed through the lungs and the skin during heat exposure can be raised significantly in result of higher pulmonary ventilation and cutaneous blood flow. Animal studies which are investigated the effects of thermal stress on chemical toxicity showed that heat exposure plays a role on toxins absorption. However, it is difficult to interpret these findings when trying to compare differences between humans and the animal models. It is observed that workers exposure in some work environment suggests that concomitant exposure to heat stress and chemicals is likely to increase the absorption and effects of certain xenobiotics. Tetrachlorethylene is a particular chemical compound is often used for laundry. The main route for human exposure to tetrachlorethylene is via inhalation, but the compound is also adsorbed by mouth contact. As mentioned, most of what is known on the effect of heat exposure on absorption of chemicals comes from animal studies. With regard to the importance of analyzing how thermal stresses can effect on toxicity response of chemical agents and moreover, need to better understanding of its related mechanisms in humans, the present study aimed to investigate the relation of body heat strain level with Tetrachlorethylene concentration in exhaled air among laundry workers in Hamadan city. Method: This descriptive analytical study was conducted in two steps of winter and summer in 2017. Twenty-four healthy workers employed in laundry workrooms located in the city of Hamadan, Iran, were enrolled in the study. Their age, height and weight were respectively 32.1 ± 5.16 year, 173.7±11.5 cm, 70.3±16.5 kg. The participants were screened using a self-reported questionnaire in terms of their state of mental and physical health. Before initiation of the tests, a written informed consent form was signed by the subjects participating in this research. Based on ISO 9920 (2007), clothing insulations (Clo unit) of the participants were 1 Clo and 0.75 in winter and summer, respectively. Ambient air samples of laundry workroom were obtained using 150 mg coconut shell charcoal tubes (20/40 mesh) SKC and using SKC personal sampling pumps model 222 calibrated to a flow rate of 100 cc/min. The air samples were analyzed by the NIOSH method no 1003 recommended for Tetrachlorethylene. Desorption of Tetrachlorethylene from activated charcoals was done with 1ml of carbon disulfide. After 30 minutes an aliquot of the resultant solution (1 µl) was injected into Shimadzu 2010 gas chromatograph equipped with a flame ionization detector (F.I.D) and Rtx-1 column. One ml volume of the sample was injected into the gas chromatograph with a Hamilton gas—tight syringe. The instrumental temperatures were as follows: injector temperature, 250C; initial oven temperature, 70C (held for 5 min), increased to 120C at a rate of 10C min-1, held for 5 min. For exhaled air samples of the same participants, individuals were asked to exhale normally into a 3 liter Tedlar air bags (SKC) until it was filled. Measuring Tetrachlorethylene in exhaled air was conducted through integrating NIOSH 1003 and NIOSH 3704 methods through optimizing analysis parameters using analytical device GC-FID. Thermal strain of exposed workers was measured based on oral temperature, heart rate and respiratory rate in accordance standard method ISO 9886:2004. The heart rate was measured using a heart rate device (Beurer PM100). Statistical analysis of the data was performed using the SPSS software version 20. The significance level of the tests was considered 0.05. Results: The mean of dry temperature, natural wet bulb temperature and globe bulb temperature were 29.42°C, 23.96°C and 30.77°C, respectively. The mean of Tetrachlorethylene concentrations in ambient air of laundry workplace in summer and winter were 45.91 ppm, 50.64 ppm, respectively. The mean values of the thermal strain indexes included oral temperature, heart rate, and pulmonary ventilation in summer and winter were 37.3°C and 37.1°C, 99.95 and 90.95 beats per minute, 26 and 20.5 breath rate per minute, respectively. The mean values work metabolism in summer and winter were 110.86 and 108.73 kcal/h, respectively. The mean of Tetrachlorethylene concentration in exhaled air in summer and winter is 3.18 and 2.23 ppm, respectively, which were higher and lower than national occupational exposure limit (3 ppm). The significant difference was observed between the mean Tetrachlorethylene concentrations in exhaled air in summer and winter (p<0.05). Paired sample t-test was not showed a significant difference between the mean Tetrachlorethylene concentrations in ambient air samples in two steps (p>0.05). According to the results of paired sample t-test, core temperature, heart beat rate and pulmonary ventilation of workers were significantly increased in summer compared to winter (p<0.05). The results showed that correlation between Tetrachlorethylene concentration in the exhaled air and ambient air samples in winter (p= 0.003, r = 0.58) and summer (p= 0.023, r = 0.46) were statistically significant. Conclusion: Few quantitative data has been published on this subject, and hence, this study aimed to investigate the interaction of coexposure to heat and chemical agents in real work condition. The present study confirmed that the Tetrachlorethylene concentration was increased in the workers̕ exhaled air in result of thermal strain in the laundry workrooms. It can be confirmed that workers who are exposed to extreme heat may be at risk for increased absorption of chemicals into the body. The quantities of Tetrachlorethylene absorbed via the pulmonary routes during work in the studied environment could significantly increase due to the elevation in pulmonary ventilation rate. It should be note that, the increase in skin temperature and skin blood flow as well as the presence of sweat on the skin surface may also promote the cutaneous absorption of chemicals during concomitant exposure to heat. It is suggested to empirically investigate workers skin absorption of chemical agents in exposure to high air temperature compared with natural condition in future studies.
