ENVIRONMENTAL RESEARCH 59, 265--270 (1992)
Blood Lead Levels in Incinerator Workers ROBERT MALKIN,* PAUL B R A N D T - R A U F , *
JOSEPH GRAZIANO,'~
AND MICHAEL PARIDES~:
*School of Public Health, Division of Environmental Sciences; "~College of Physicians and Surgeons, Department of Pharmacology; and 4:School of Public Health, Division of Biostatistics, Columbia University, New York, New York 10032 Received May 19, 1992 Questions have been raised concerning the safety of mass burn incineration and its role in solid waste management. In 1989, the New York City Office of Occupational Safety and Health examined air levels of metals in New York City incinerators and found that workers were exposed to air lead levels as high as 2500 ~g/m3 while cleaning the electrostatic precipitators in the plant. In order to determine the biologic significance of these exposures to the workers, blood samples were taken from 56 incinerator workers and 25 controls and analyzed for lead and erythrocyte protoporphyrin levels. Incinerator workers were found to have a mean blood lead of 11.0 p~g/dl as compared to the control group level of 7.4 p~g/dl. Risk factors for increased blood lead levels were analyzed using multiple regression analyses. Wearing a personal protective device "always" or not and the interaction of smoking and cleaning the precipitator more than seven times in the past year were found to be significant predictors for blood lead. These results indicate that lead in municipal incinerator ash from electrostatic precipitators is bioavailable and that the effects of such exposure can be minimized by wearing personal protective devices, not smoking, and rotating the work force to minimize precipitator ash contact. © 1992AcademicPress,Inc.
INTRODUCTION Mass burn incineration is gradually replacing landfilling for the disposal of solid waste. This change has aroused considerable public and scientific attention to metals found in incinerator ash, particularly lead. Accordingly, the New York City Council on Occupational Safety and Health (COSH) recently undertook an industrial hygiene survey of occupational hazards of incinerator ash to incinerator workers at each of the three New York City incinerators (COSH, 1989) and found air lead concentrations as high as 2500 ixg/m 3. However, no biological monitoring of lead exposure in incinerator workers was done. The primary purpose of this study, therefore, was to determine the blood lead (BPb) and erythrocyte protoporphyrin (EP) levels of a group of incinerator workers and of a similarly matched group of non-incinerator workers. A secondary aim was to determine the risk factors for exposure to lead in these workers.
METHODS Incinerator workers were recruited from the high pressure plant tenders (HPPTs) working in three New York City incinerators. Each incinerator was equipped with an electrostatic precipitator for air pollution control. The choice of the HPPTs as the group for study was based in part on the results of the COSH industrial hygiene study (COSH, 1989), which identified duties of the HPPTs 265 0013-9351/92 $5.00 Copyright© 1992by AcademicPress, Inc. All rightsof reproductionin any formreserved.
266
M A L K I N ET AL.
(precipitator cleaning, upper and lower chamber cleaning, and undercarriage cleaning) as those with the highest potential exposure to lead, with air lead levels as high as 2500 ~g/m 3 during precipitator cleaning. Other responsibilities of the HPPTs include maintenance of the furnaces; painting the furnaces and associated structures; and housekeeping and plant cleanliness on the furnace floor. A control group was selected predominantly of HPPTs working at heating plants, where the HPPTs maintained the boilers. Blood samples were taken and questionnaires were completed in August 1989 for the incinerator workers, and in November 1989 for the control group. A multiple regression model was developed starting with l0 variables from the questionnaire, including selected interactions in the original model. These variables included: (1) number of times the worker cleaned the precipitator in the last year (dichotomized as >7 vs T
12.012 0.007
1.823 0.038
0.0001 0.99
Protective device not always worn
2.539
0.924
0.009
Number of times cleaned precip, in last year (>7 vs 7 vs 25 ~g/dl, which has been proposed by the Public Health Service as a maximum for workers in the year 2000 (PHS, 1991). Reasons for this finding of only mild elevation of blood lead are many and relate to factors specific to the job at the incinerator. First, the amount of time the workers were exposed to the more dangerous fly ash component was generally restricted to cleaning the precipitator and that was for relatively short periods of time. Second, the number of times that workers cleaned the precipitator in a given year was small; with the exception of workers specifically placed on the " s h o p " detail involving precipitator maintenance, workers were rotated in cleaning duties and entered the precipitator less than once a month in the past year. Third, consistent use of respiratory protective devices appeared to be effective in filtering out lead from the work environment and lowering exposure. Finally, the relatively long average time between the last cleaning of the precipitator and blood sampling may have introduced a bias toward finding low BPbs because the half-life of lead in blood is approximately 30 days. The health effects from incinerator emissions of lead into the environment were not addressed in this study but, based on the findings of this study, these effects merit further examination.
ACKNOWLEDGMENT This project was conducted in cooperation with DC-37, Local 1795.
REFERENCES 29 CFR 1910.1025 (1989). "Code of Federal Regulations." U.S. Government Printing Office, Office of the Federal Register, Washington, DC. Citywide Office of Occupational Safety and Health (COSH) (April 1989). "Assessment of Occupational Exposure to Fly Ash Particulates at New York City Department of Sanitation Municipal Solid Waste Incinerators." Mayor's Office of Operations, City of New York. Hernberg, S. (1988). Lead and its compounds. In "Occupational Medicine, Principles and Practical Applications, Second Edition" (Carl Zenz, Ed.), pp. 547-581. Year Book Medical Publishers, Chicago. Mahaffey, K. R., Annest, J. L., Roberts, J., and Murphy, R. S. (1982). National estimates of blood lead levels: United States, 1976-1980. Association with selected demographic and socioeconomic factors. N. Engl. J. Med. 307, 573-579. Malkin, R. (1991). "Lead Exposure in Incinerator Workers" (dissertation). Columbia University School of Public Health, Division of Environmental Sciences, New York. McLaughlin, M., Linch, A. L., and Snee, R. D. (1973). Longitudinal studies of lead levels in a US population. Arch. Environ. Health. 27, 305-311. Morbidity and Mortality Weekly Reports (MMWR) (1986). Blood lead levels among office workers-New York City. MMWR, vol. 35, pp. 298-300. U,S. Center for Disease Control. National Institute for Occupational Safety and Health (NIOSH) (1978). "Criteria for a Recommended Standard . . . Occupational Exposure to Inorganic Lead. Revised Criteria--1978. "Publication No. 78-158. U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, DHEW (NIOSH). Public Health Service (PHS) (1991). "Healthy People 2000." Public Health Service, U.S. Department of Health and Human Services. United States Government Printing Office, Washington, DC. World Health Organization (WHO) (1980). "Recommended Health-Based Limits in Occupational Exposure to Heavy Metals." Report of a WHO Study Group. World Health Organization Technical Report Series 647.
Blood Lead Levels in Incinerator Workers ROBERT MALKIN,* PAUL B R A N D T - R A U F , *
JOSEPH GRAZIANO,'~
AND MICHAEL PARIDES~:
*School of Public Health, Division of Environmental Sciences; "~College of Physicians and Surgeons, Department of Pharmacology; and 4:School of Public Health, Division of Biostatistics, Columbia University, New York, New York 10032 Received May 19, 1992 Questions have been raised concerning the safety of mass burn incineration and its role in solid waste management. In 1989, the New York City Office of Occupational Safety and Health examined air levels of metals in New York City incinerators and found that workers were exposed to air lead levels as high as 2500 ~g/m3 while cleaning the electrostatic precipitators in the plant. In order to determine the biologic significance of these exposures to the workers, blood samples were taken from 56 incinerator workers and 25 controls and analyzed for lead and erythrocyte protoporphyrin levels. Incinerator workers were found to have a mean blood lead of 11.0 p~g/dl as compared to the control group level of 7.4 p~g/dl. Risk factors for increased blood lead levels were analyzed using multiple regression analyses. Wearing a personal protective device "always" or not and the interaction of smoking and cleaning the precipitator more than seven times in the past year were found to be significant predictors for blood lead. These results indicate that lead in municipal incinerator ash from electrostatic precipitators is bioavailable and that the effects of such exposure can be minimized by wearing personal protective devices, not smoking, and rotating the work force to minimize precipitator ash contact. © 1992AcademicPress,Inc.
INTRODUCTION Mass burn incineration is gradually replacing landfilling for the disposal of solid waste. This change has aroused considerable public and scientific attention to metals found in incinerator ash, particularly lead. Accordingly, the New York City Council on Occupational Safety and Health (COSH) recently undertook an industrial hygiene survey of occupational hazards of incinerator ash to incinerator workers at each of the three New York City incinerators (COSH, 1989) and found air lead concentrations as high as 2500 ixg/m 3. However, no biological monitoring of lead exposure in incinerator workers was done. The primary purpose of this study, therefore, was to determine the blood lead (BPb) and erythrocyte protoporphyrin (EP) levels of a group of incinerator workers and of a similarly matched group of non-incinerator workers. A secondary aim was to determine the risk factors for exposure to lead in these workers.
METHODS Incinerator workers were recruited from the high pressure plant tenders (HPPTs) working in three New York City incinerators. Each incinerator was equipped with an electrostatic precipitator for air pollution control. The choice of the HPPTs as the group for study was based in part on the results of the COSH industrial hygiene study (COSH, 1989), which identified duties of the HPPTs 265 0013-9351/92 $5.00 Copyright© 1992by AcademicPress, Inc. All rightsof reproductionin any formreserved.
266
M A L K I N ET AL.
(precipitator cleaning, upper and lower chamber cleaning, and undercarriage cleaning) as those with the highest potential exposure to lead, with air lead levels as high as 2500 ~g/m 3 during precipitator cleaning. Other responsibilities of the HPPTs include maintenance of the furnaces; painting the furnaces and associated structures; and housekeeping and plant cleanliness on the furnace floor. A control group was selected predominantly of HPPTs working at heating plants, where the HPPTs maintained the boilers. Blood samples were taken and questionnaires were completed in August 1989 for the incinerator workers, and in November 1989 for the control group. A multiple regression model was developed starting with l0 variables from the questionnaire, including selected interactions in the original model. These variables included: (1) number of times the worker cleaned the precipitator in the last year (dichotomized as >7 vs T
12.012 0.007
1.823 0.038
0.0001 0.99
Protective device not always worn
2.539
0.924
0.009
Number of times cleaned precip, in last year (>7 vs 7 vs 25 ~g/dl, which has been proposed by the Public Health Service as a maximum for workers in the year 2000 (PHS, 1991). Reasons for this finding of only mild elevation of blood lead are many and relate to factors specific to the job at the incinerator. First, the amount of time the workers were exposed to the more dangerous fly ash component was generally restricted to cleaning the precipitator and that was for relatively short periods of time. Second, the number of times that workers cleaned the precipitator in a given year was small; with the exception of workers specifically placed on the " s h o p " detail involving precipitator maintenance, workers were rotated in cleaning duties and entered the precipitator less than once a month in the past year. Third, consistent use of respiratory protective devices appeared to be effective in filtering out lead from the work environment and lowering exposure. Finally, the relatively long average time between the last cleaning of the precipitator and blood sampling may have introduced a bias toward finding low BPbs because the half-life of lead in blood is approximately 30 days. The health effects from incinerator emissions of lead into the environment were not addressed in this study but, based on the findings of this study, these effects merit further examination.
ACKNOWLEDGMENT This project was conducted in cooperation with DC-37, Local 1795.
REFERENCES 29 CFR 1910.1025 (1989). "Code of Federal Regulations." U.S. Government Printing Office, Office of the Federal Register, Washington, DC. Citywide Office of Occupational Safety and Health (COSH) (April 1989). "Assessment of Occupational Exposure to Fly Ash Particulates at New York City Department of Sanitation Municipal Solid Waste Incinerators." Mayor's Office of Operations, City of New York. Hernberg, S. (1988). Lead and its compounds. In "Occupational Medicine, Principles and Practical Applications, Second Edition" (Carl Zenz, Ed.), pp. 547-581. Year Book Medical Publishers, Chicago. Mahaffey, K. R., Annest, J. L., Roberts, J., and Murphy, R. S. (1982). National estimates of blood lead levels: United States, 1976-1980. Association with selected demographic and socioeconomic factors. N. Engl. J. Med. 307, 573-579. Malkin, R. (1991). "Lead Exposure in Incinerator Workers" (dissertation). Columbia University School of Public Health, Division of Environmental Sciences, New York. McLaughlin, M., Linch, A. L., and Snee, R. D. (1973). Longitudinal studies of lead levels in a US population. Arch. Environ. Health. 27, 305-311. Morbidity and Mortality Weekly Reports (MMWR) (1986). Blood lead levels among office workers-New York City. MMWR, vol. 35, pp. 298-300. U,S. Center for Disease Control. National Institute for Occupational Safety and Health (NIOSH) (1978). "Criteria for a Recommended Standard . . . Occupational Exposure to Inorganic Lead. Revised Criteria--1978. "Publication No. 78-158. U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, DHEW (NIOSH). Public Health Service (PHS) (1991). "Healthy People 2000." Public Health Service, U.S. Department of Health and Human Services. United States Government Printing Office, Washington, DC. World Health Organization (WHO) (1980). "Recommended Health-Based Limits in Occupational Exposure to Heavy Metals." Report of a WHO Study Group. World Health Organization Technical Report Series 647.
