Occupational Exposure to Cr VI during Furnace Maintenance Activities in Colombian Cement Plants
Abstract No:
1445
Abstract Type:
Professional Poster
Authors:
G Araque1
Institutions:
1CRP Ltd., Bogota, AS
Presenter:
Mr Guillermo Araque
CRP Ltd.
CRP Ltd.
Description:
Chromium (Cr) is the 21st most common element in the earth's crust. It is a metallic element of high gloss, odorless, malleable, with a high melting point and with several valence states Cr (IV) Cr (II) Cr (VI) 2, chromate being the natural presentation of Cr. The main occupational exposures to Cr (VI) are through the inhalation of dusts, mists or fumes and skin contact. Cement producing plants are a potential source of atmospheric chromium. The chromium in the cement comes from: 1) raw materials or fuel; 2) furnace lining built with refractory bricks (magnesium-chromium); 3) deterioration of the metal in the milling process; and 4) additions of plaster, pozzolana, high slag granulated oven and cement kiln powder. This descriptive cross-sectional study determined the potential occupational exposure of hexavalent chromium during the maintenance processes of cement production furnaces, through the Similar Exposure Groups evaluation process.
Situation / Problem:
The exposure and toxicology of Cr and its compounds have been thoroughly reviewed by different international organizations: a) International Chemical Safety Program (IPCS); b) United Kingdom Health and Safety Executive (HSE); c) International Agency for Cancer Research (IARC); d) United States Agency for Toxic Substances and Disease Registry (ATSDR); and e) U.S. National Institute for Occupational Safety and Health (NIOSH). Through the methodology of the Information System on Occupational Exposure to Carcinogenic Agents (CAREX), it was estimated that in Colombia, 52,654 workers are exposed to Cr (VI) and associated compounds. Making this agent the fifteenth carcinogenic agent with the highest estimated percentage of workers exposed in Colombia. The literature review on the subject concludes that there is no study in Colombia that evaluates the potential impact of exposure to hexavalent chromium by cement use. Internationally, studies have reported the health risks of workers exposed to hexavalent chromium from cement activities and characterized the different ways to estimate, determine, reduce and/or eliminate hexavalent chromium.
Methods:
A descriptive cross-sectional study was carried out on 16 workers during maintenance processes of cement production furnaces of two cement companies. The basic characterization process involved the organization of workers into specific functional groups taking into account the common processes, tasks and exposure factors during the activities of major furnace maintenance. Two Similar Exposure Groups (SEG A & SEG B), one for each cement production company, were created. Personal sampling pumps calibrated at a constant flow rate were used according to the sampling and analysis method defined in the OSHA ID215v2 method. Hexavalent chromium levels were determined by Ionic Chromatography with Ultraviolet Detection analyzed in an AIHA accredited laboratory. The results of each similar exposure group were statistically processed using LogNorm2® Version 2.9 software for Windows. For the present investigation, the criteria established by the American Conference of Industrial Hygienists of the Government (ACGIH) were taken into account. In order to adjust to the Colombian legal framework of a 48 hour workweek, an adjustment was made by attending to the Brief & Scala model, in the understanding that the reference values recommended by the association are defined for 40 hours. A reference value of 0.00016 mg / m3 was adopted that supports associated effects of pulmonary and sinus nasal cancer, asthma, and upper respiratory tract irritation.
Results / Conclusions:
Taking into account the individual results compared to the reference value applicable to hexavalent chromium, it is possible to establish that the general trend of exposures is mostly exceeding the threshold limits defined for daily workdays. Of the total samples (16), 75% (12) were above the permissible limit threshold and 25% (4) exceeded the action level.
In SEG A, a total of 6 full-time samples were taken of workers who carried out major maintenance activities (e.g., pneumatic drill operation, brick drilling and disassembly. refractory on the oven outlet, removal and disposal of waste). According to the goodness of fit test, a LogNormal distribution was recommended over a normal distribution (0.9062> 0.7999), the unbiased variance unbiased estimator presented values of 0.0006 mg / m3, with a unilateral coverage margin associated with upper confidence limit of 0.0053 mg / m3. The geometric standard deviation of the SEG was found in a moderate dispersion equivalent to 2.85, considering the values found in comparison with the threshold limit set. It can be concluded, with a confidence level of 95%, that the exposures exceeded the threshold in at least 95.18% of the 0.0003 mg / m3 scenarios corresponding to 51.87%.
In SEG B, differentiated in fracturing and removal technologies where semi-automatic drills were used with the remote operation of the equipment, in this case due to the removal activities, the subset of data was greater corresponding to 10 personal evaluations full-time. According to the goodness of fit test, a LogNormal distribution was 0.9197> 0.9168, following the Shapiro Wilk test, the unbiased unbiased variance estimator was 0.0006 mg / m3, a value that was found between a lower confidence limit of 0.0004 mg / m3 and a higher confidence limit of 0.0018 mg / m3, associated with a standard deviation geometric 2.63. According to the values calculated with a 95% confidence level, the exposures exceed the exposure limit by at least 94.98% of the exposure scenarios contemplated, finally the excess fraction with respect to the lower confidence limit was 63.60%.
The magnitudes and statistic estimators found that kiln maintenance activities in cement plants represent a potential risk for workers to hexavalent chromium. However, it should be noted that these nonroutine work activities, may not reflect the long-term dose of workers linked to work activities, unless these are carried out continuously by workers specialized in these type of tasks.
In SEG A, a total of 6 full-time samples were taken of workers who carried out major maintenance activities (e.g., pneumatic drill operation, brick drilling and disassembly. refractory on the oven outlet, removal and disposal of waste). According to the goodness of fit test, a LogNormal distribution was recommended over a normal distribution (0.9062> 0.7999), the unbiased variance unbiased estimator presented values of 0.0006 mg / m3, with a unilateral coverage margin associated with upper confidence limit of 0.0053 mg / m3. The geometric standard deviation of the SEG was found in a moderate dispersion equivalent to 2.85, considering the values found in comparison with the threshold limit set. It can be concluded, with a confidence level of 95%, that the exposures exceeded the threshold in at least 95.18% of the 0.0003 mg / m3 scenarios corresponding to 51.87%.
In SEG B, differentiated in fracturing and removal technologies where semi-automatic drills were used with the remote operation of the equipment, in this case due to the removal activities, the subset of data was greater corresponding to 10 personal evaluations full-time. According to the goodness of fit test, a LogNormal distribution was 0.9197> 0.9168, following the Shapiro Wilk test, the unbiased unbiased variance estimator was 0.0006 mg / m3, a value that was found between a lower confidence limit of 0.0004 mg / m3 and a higher confidence limit of 0.0018 mg / m3, associated with a standard deviation geometric 2.63. According to the values calculated with a 95% confidence level, the exposures exceed the exposure limit by at least 94.98% of the exposure scenarios contemplated, finally the excess fraction with respect to the lower confidence limit was 63.60%.
The magnitudes and statistic estimators found that kiln maintenance activities in cement plants represent a potential risk for workers to hexavalent chromium. However, it should be noted that these nonroutine work activities, may not reflect the long-term dose of workers linked to work activities, unless these are carried out continuously by workers specialized in these type of tasks.
Primary Topic:
Exposure Assessment Strategies
Secondary Topics:
Construction
Occupational and Environmental Epidemiology