Die blootstelling van werkers aan vlugtige organiese oplosmiddels by pad- en spoorlaairakke van 'n petrochemiese nywerheid
Steynberg, Catharina Maria
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BACKGROUND: The liver serves as a first pass filter and is an important metabolising organ for VOC's. Thus the concentration that the liver is exposed to is higher than that of other organs. The substances have different effects on the liver. These effects vary from adaptive responses to toxic effects. This can influence the liver's capacity to function normally. If the liver's biotransformation capacity is affected, it can increase the possibility/probability of the manifestation of a toxic response. Therefore it is very important that the liver's functions are regularly tested. The purpose of this study is to: 1) Identify, quantify and evaluate the VOC's the workers at the rail and road loading racks are exposed to. 2) Investigate the possibility of additional exposure through the gloves of the workers. 3) See if there are any occupational health effects manifestations present, because of VOC exposure. 4) See how optimal protection can be provided for the workers. 5) See if meteorological conditions can affect exposure to VOC's. METHOD: The study population consist of four process controllers and a general worker at the rail loading racks, as well as five process controllers at the road loading racks at a petrochemical industry. They were monitored for a week. G.A.R.B.I.E. badges monitored exposure to VOC's. One of the process controllers at the rail loading racks was also exposed to phenol and cresol. A Xad 7-tube and personal pump were used to monitor his exposure to phenol and cresol. Permea-Tec stickers monitored skin exposure to VOC's. The liver enzymes, alanine aminotrasferase (ALT) and aspartate aminotrasferase (AST), were measured six months before and six months after the study. These values were also used. The amount and type of products that were loaded, personal information, as well as working procedures and behaviour were observed and noted. The meteorological data were gathered during the study period. RESULTS AND DISCUSSION: he workers at the rail loading racks were exposed to 14 VOC's and the workers at the road loading racks to 15 VOC's. All the exposure levels were below the OEL (occupational exposure limits) from the Hazardous Chemical Substances Regulations (1995) in the Occupational Health and Safety Act (85/1993) (OSHAct). Benzene exposure was above the OEL of the ACGIH (0.1 ppm [part per million]) almost every time. A large percentage of the exposures were below 1 ppm, while a very small percentage was above 10 ppm. This was the case at both the rail and road loading racks. The average of the rail loading rack workers' liver enzymes values six months before the study (September 2000) were AST 31 mmol/L and ALT 40 mmol/L and six months after the study (September 2001) was AST 28 mmol/L and ALT 47 mmol/L. There were five values. Both the AST and ALT values were normal. The average of the road loading rack workers' liver enzymes six months before the study (September 2000) was AST 34 mmoVL and ALT 37 mmol/L and six months after the study (September 2001) was AST 47 mmol/L and ALT 68 mmol/L. (The available data were used.) CONCLUSION: he liver enzyme values seem to be rising, although not much each year. This is not the case with all the workers. The medical surveillance programme was only implemented two years before the study. A conclusion can only be made after another year or two. Some of the VOC's that the workers were exposed to during this study can affect the liver's function ability, like chloroform. The following questions were answered in this study: 1) Although exposures comply with the Hazardous Chemical Substances Regulations (1995) in the Occupational Health and Safety Act (85/1993), low-level long-term exposure is not safe. Synergism and potensiation can turn the "safe exposure limit" that the OSHAct sets into an "unsafe exposure limit". 2) Skin exposure through the gloves might be a possibility. The stickers were not efficient enough to make a definite conclusion. 3) Exposures to these VOC's do cause health effects, for example elevated liver enzymes, as well as the gradual rising in these levels. (It's more noticeable in the older workers.) Before any definite conclusion can be made, it is necessary that more liver enzymes values be obtained. The effects of long-term low-level exposure of VOC's should be studied further. 4) Although the current personal protective equipment is efficient, it should be monitored. 5) The meteorological conditions may possibly influence the exposure of the workers. Exposure was some days higher, even though less product were being loaded. If the meteorological conditions are taken in to consideration, this can be explained to some extent. RECOMMENDATION: he workers should be re-educated about the negative effects of exposure to VOC's, the proper working procedures and storing of their personal protection equipment. This personal protection equipment should also be constantly re-evaluated to make sure the workers are receiving the best protection. Engineering changes can also be installed at the VOC's pumps on the rail racks and the resting areas on the catwalks. The workers can also be better supervised.