There are several reports in the li

There are several reports in the literature of blood thiosulphate levels being detected after hydrogen sulphide fatalities (Table 1). The levels reported range between 25 (Kage et al., 1997) and 230 μmol/l (Kage et al., 2004). Rabbits that received a fatal dose of hydrogen sulphide (500–1000 ppm for up to 30 min) gave blood thiosulphate levels of 53–119 μmol/l (Kage et al., 1992), which is in good agreement with the human fatality studies. Survivors of poisoning incidents are not reported to have detectable blood thiosulphate levels, as the body rapidly clears the blood, nor are the general population.

It has therefore been demonstrated, both within the case studies presented here and in the literature, that blood and/or urinary thiosulphate measurements can be useful in determining hydrogen sulphide as a potential cause of fatality or unconsciousness. The analysis is sufficiently sensitive to discriminate exposures from control samples and has reasonable specificity, if storage conditions are controlled. However, there are certain considerations that need to be taken into account in order to get the most useful information from such analyses. First, the type of sample required will depend on the condition of the workers – if they are survivors of incidents then urine samples are most appropriate as the body will rapidly clear any thiosulphate from the blood. In the case of fatalities (to determine likely cause of death or to assist in any related investigation), blood samples are most appropriate. Urine samples may be useful as additional samples to ascertain whether death was instantaneous or delayed after a period of unconsciousness, especially if the worker was not discovered until sometime after the incident. Secondly, the timing of the sample relative to the incident is important for detecting exposures in survivors. It has been shown in volunteers (Kangas and Savolainen, 1987) and workers (Kage et al., 1997) that samples taken more than 15 h after an incident are likely to be in the general population range. It is important therefore, to obtain urine samples from victims of potential hydrogen sulphide incidents within 15 h. A human volunteer study (Kangas and Savolainen, 1987) showed that after a 30 min exposure to hydrogen sulphide, raised urinary thiosulphate levels were not detected until 2 h after the start of exposure whereas an animal study (Kage et al., 1992) demonstrated a maximal urinary thiosulphate concentration at 1 h post exposure (hydrogen sulphide exposures were very much higher in this study, 100–200 ppm). It may therefore be prudent to take multiple urine samples where a hydrogen sulphide incident is suspected – as soon as possible after the incident and further samples between 2 and 15 h post-exposure. Such samples may not capture the ‘maximal’ excretion (which might be expected at 15 h post exposure according to the volunteer reported (Kangas and Savolainen, 1987) although, no samples were taken between 5 and 15 h, being overnight) but would be likely to capture any increase in urinary thiosulphate levels, sufficient to determine hydrogen sulphide as a likely causal agent in the incident. The use of multiple, timed samples may also assist in reconstructing the exposure; a linear relationship between time post-exposure and urinary thiosulphate levels has been demonstrated (Kangas and Savolainen, 1987). Finally, storage conditions of post-mortem samples are important. As demonstrated in one of the case reports here, it is not unusual to receive post-mortem samples some months after the death has occurred. If samples have not been appropriately stored then bacterial action during storage may confound the findings of the analysis. The use of thiosulphate as a biomarker in assisting clinical diagnosis, and therefore treatment, is unlikely due to the current limited availability of this analysis in laboratories and the time taken to generate a result (although, theoretically, a screening result could be available within an hour or so if facilities were available at the relevant hospital).

There are no literature reports of using biological monitoring routinely to assess occupational exposure to hydrogen sulphide. Acute, high level exposures can generally be prevented by using real-time gas sensors with appropriate alarm levels; however, there is an argument for monitoring workers exposed to more chronic, low-level concentrations. There have been a number of papers from Bhambhani et al. looking at the physiological consequences of hydrogen sulphide exposure at the current exposure limits (Bhambhani and Singh, 1991 and Bhambhani et al., 1997). These have demonstrated uncertainty around anaerobic respiration and increased lactic acid production at such exposure levels. Although, these studies showed that the current exposure limits were acceptable for fit young adults, there is a possibility of effects in older, less fit workers or in susceptible groups in the general population (chil

ผลลัพธ์ (ไทย) 1:

มีรายงานหลายฉบับในวรรณคดีระดับ thiosulphate เลือดถูกตรวจพบหลังจากไฮโดรเจนซัลไฟด์เสียชีวิต (ตาราง 1) ระดับรายงานช่วงระหว่าง 25 (คาเงะ et al. 1997) และ 230 ไมโครโมล/ลิตร (คาเงะ et al. 2004) กระต่ายที่ได้รับยาร้ายแรงของไฮโดรเจนซัลไฟด์ (500-1000 ppm ถึง 30 นาที) ให้เลือดระดับ thiosulphate 53-119 ไมโครโมล/ลิตร (คาเงะ et al. 1992), ซึ่งอยู่ในข้อตกลงที่ดีกับการศึกษามนุษย์ตาย ผู้รอดชีวิตจากพิษกรณีไม่รายงานมีระดับเลือดตรวจ thiosulphate ตามที่ร่างกายล้างเลือดอย่างรวดเร็ว หรือเป็นประชากรทั่วไปIt has therefore been demonstrated, both within the case studies presented here and in the literature, that blood and/or urinary thiosulphate measurements can be useful in determining hydrogen sulphide as a potential cause of fatality or unconsciousness. The analysis is sufficiently sensitive to discriminate exposures from control samples and has reasonable specificity, if storage conditions are controlled. However, there are certain considerations that need to be taken into account in order to get the most useful information from such analyses. First, the type of sample required will depend on the condition of the workers – if they are survivors of incidents then urine samples are most appropriate as the body will rapidly clear any thiosulphate from the blood. In the case of fatalities (to determine likely cause of death or to assist in any related investigation), blood samples are most appropriate. Urine samples may be useful as additional samples to ascertain whether death was instantaneous or delayed after a period of unconsciousness, especially if the worker was not discovered until sometime after the incident. Secondly, the timing of the sample relative to the incident is important for detecting exposures in survivors. It has been shown in volunteers (Kangas and Savolainen, 1987) and workers (Kage et al., 1997) that samples taken more than 15 h after an incident are likely to be in the general population range. It is important therefore, to obtain urine samples from victims of potential hydrogen sulphide incidents within 15 h. A human volunteer study (Kangas and Savolainen, 1987) showed that after a 30 min exposure to hydrogen sulphide, raised urinary thiosulphate levels were not detected until 2 h after the start of exposure whereas an animal study (Kage et al., 1992) demonstrated a maximal urinary thiosulphate concentration at 1 h post exposure (hydrogen sulphide exposures were very much higher in this study, 100–200 ppm). It may therefore be prudent to take multiple urine samples where a hydrogen sulphide incident is suspected – as soon as possible after the incident and further samples between 2 and 15 h post-exposure. Such samples may not capture the ‘maximal’ excretion (which might be expected at 15 h post exposure according to the volunteer reported (Kangas and Savolainen, 1987) although, no samples were taken between 5 and 15 h, being overnight) but would be likely to capture any increase in urinary thiosulphate levels, sufficient to determine hydrogen sulphide as a likely causal agent in the incident. The use of multiple, timed samples may also assist in reconstructing the exposure; a linear relationship between time post-exposure and urinary thiosulphate levels has been demonstrated (Kangas and Savolainen, 1987). Finally, storage conditions of post-mortem samples are important. As demonstrated in one of the case reports here, it is not unusual to receive post-mortem samples some months after the death has occurred. If samples have not been appropriately stored then bacterial action during storage may confound the findings of the analysis. The use of thiosulphate as a biomarker in assisting clinical diagnosis, and therefore treatment, is unlikely due to the current limited availability of this analysis in laboratories and the time taken to generate a result (although, theoretically, a screening result could be available within an hour or so if facilities were available at the relevant hospital).มีรายงานไม่มีวรรณกรรมของการใช้การตรวจสอบทางชีวภาพเป็นประจำเพื่อประเมินอาชีวแสงไฮโดรเจนซัลไฟด์ โดยทั่วไปสามารถป้องกันแสงระดับสูง เฉียบพลัน โดยใช้เซ็นเซอร์แก๊สแบบเรียลไทม์ด้วยระดับสัญญาณเหมาะสม อย่างไรก็ตาม มีอาร์กิวเมนต์สำหรับการตรวจสอบผู้ปฏิบัติงานสัมผัสกับความเข้มข้นมากขึ้นเรื้อรัง ระดับต่ำ มีหมายเลขของเอกสารจาก Bhambhani et al.กำลังดูผลทางสรีรวิทยาของไฮโดรเจนซัลไฟด์ปริมาณแสงที่จำกัดของแสงปัจจุบัน (Bhambhani และ สิงห์ 1991 และ Bhambhani et al. 1997) เหล่านี้ได้แสดงให้เห็นถึงความไม่แน่นอนรอบไม่ใช้ออกซิเจนในการหายใจ และเพิ่มการผลิตกรดแลคติกในระดับแสงดังกล่าว แม้ว่า การศึกษาเหล่านี้แสดงให้เห็นว่า ขีดจำกัดปัจจุบันยอมรับได้สำหรับคนหนุ่มสาวที่พอดี มีความเป็นไปได้ของผล ในคนงานเก่า ไม่พอดี หรือ ในกลุ่มที่อ่อนแอในประชากรทั่วไป (chil