Discussion As would be expected, the percentage of parasitic infections was greater in specimens from patients with clinical symptoms related to parasitosis. However, infections with pathogenic parasites were also detected among patients not suspected of harboring parasites, e.g., six examinations positive for Giardia lamblia, 64 for Trichuris trichiura, three for Entamoeba histolytica, and 17 for hookworm infection. Symptoms such as anemia in hookworm-infected patients may have been ascribed to other causes of intestinal bleeding. It is noteworthy that some pathogenic parasites were found more frequently in the patients on whom no examination for parasites was requested, e.g., Schistosoma mansoni and Enterobius vermicularis. The infection patterns varied for the parasites which are considered to be nonpathogenic. Entamoeba coli was distributed equally among both groups. The high rate of infection with this parasite has an epidemiological implication. In fact, the presence of even nonpathogenic amebae in the stools indicates a reservoir of infection and a low standard of hygiene among the population.
TABLE 1-Infection with Various Species of Parasites in Two Groups of Examinations Positive Stool Examinations
Parasite
Requested by physicians
Not requested by physicians
No. (%) Ascaris lumbricoides , Hookworm Trichuris trichiura Strongyloides stercoralis Enterobius vermicularis Schistosoma mansoni Hymenolepis nana Entamoeba histolytica Entamoeba coli lodamoeba bOtschlii Endolimax nana Giardia lamblia Chilomastix mesnili Total positive examinations Total examinations
36 (3.9) 1 (0.1) 40 (4.3) 30 (2.2) 1 (0.1)
5 (0.6) 17 (1.9) 64 (7.2) 8 (0.9) 3 (0.3) 4 (0.5) 0 (0.0) 3 (0.3) 35 (4.0) 1 (0. 1) 25 (2.8) 6 (0.6) 1 (0.1)
310 (33.7) 919
172 (19.5) 882
34 (3.6)
20(2.2) 120 (13.1) 16 (1.7) 2 (0.2) 2 (0.2) 3 (0.3) 5 (0.5)
Conclusions The most important conclusion that can be drawn from the high percentage of parasitic infections in patients not suspected of harboring parasites is that good clinical criteria for requesting stool examination for parasitic information are not always available. This study suggests the usefulness of routine stool examinations for screening unsuspected parasitosis in selected urban populations with high rate of infection and poor hygienic standards, even outside tropical endemic areas.
What Purpose? Bull. N. Y. Acad. Med. 51:39-52, 1975. 2. Sackett, D. L. The Usefulness of Laboratory Tests in Health Screening Programs. Clin. Chem. 19:366-372, 1973. 3. Mantel, C. A., and Yoeli, M. Parasitological Investigations in Gastroenterologic Practice. N. Y. State J. Med. 75:39-41, 1975. 4. Most, H. Manhattan: "A Tropic Isle?" Am. J. Trop. Med. Hyg. 17:333-354, 1968. 5. Ridley, D. S., and Hawgood, B. C. The Value of Formol-Ether Concentration of Faecal Cysts and Ova. J. Clin. Pathol. 9:74-76, 1956.
REFERENCES 1. Sackett, D. L. Screening for Early Detection of Disease: To
The authors are from the State University of New York, Kings County Hospital Center, Institute of Pathology, Brooklyn, New York 11203. This article was accepted for publication August, 1975.
Carbon Monoxide in School Buses CARL J. JOHNSON, MD, MPH JOHN MORAN, BS ROBERT PEKICH, BS Introduction On December 16, 1971, eight children became ill on a school bus carrying a group of children enrolled in a private school. Symptoms included drowsiness, headache, and nausea. Five of the children were sufficiently ill that they were taken to the emergency room of a hospital. One of the five was unconscious. The symptoms were found to be due to carbon monoxide (CO) poisoning. All of the children had
been seated in the rear of the bus, which had a rearmounted engine and was later found to have a defective exhaust system. The Seattle-King County Department of Public Health was notified of the incident and an investigation was conducted. All five buses operated by the school had significant levels of carbon monoxide in the passenger compartment, ranging from 10 to 25 parts per million (ppm) with a mean value of 15 ppm. The bus in which the children PUBLIC HEALTH BRIEFS
1327
had become ill had a level of 15 ppm of carbon monoxide, despite the fact that the exhaust system had since been repaired.
Investigation and Discussion As a result of this incident, a broader investigation was conducted to determine CO levels in school buses in the Seattle area. Many of the school districts participate in ski school programs which are conducted near Seattle in the area around Snoqualmie Pass in the Cascade Range. School buses are put in use on Saturdays and Sundays to carry school children to Snoqualmie Pass. Travel time usually varies from 1 to 2 hr, unless road conditions slow traffic. Because of the large number of school buses used in this operation (over 200), it was decided that a quick evaluation could be performed by sending a small team with CO detection instruments to the Pass. On a day selected for the survey, three staff members of the Seattle-King County Health Department stationed themselves at the Pass to meet the buses. Each had a CO detection instrument.* The passenger compartments of 33 of the buses were checked immediately as they arrived to determine in-transit levels of CO. The children were asked not to leave the buses until the determinations of CO had been made. Four of the 33 buses had CO levels in excess of the Environmental Protection Agency's (EPA) maximum allowable concentrations (mac) for an 8-hr exposure (Table 1), and one bus had greater than 33 ppm. ' Apparently these four buses had a defective exhaust system or a defect in the ventilation system which permitted exhaust gases to enter the passenger compartment. During the lunch hour the students return to the buses to have their lunches and to rest (usually 12 to 2 p.m.). The bus drivers operate the bus engines at this time to heat the passenger compartments. As the buses sat with engines idling in the parking lot during the lunch hour, 65 of them were tested (Table 2). Only 40 per cent of the buses had no measurable levels of CO. A total of 24 buses (37 per cent) exceeded the EPA standards for an 8-hr exposure (9 ppm). Seven of the buses (11 per cent) exceeded EPA standards for a 1-hr exposure (35 ppm) and at least four of the buses could have been expected to produce symptoms in the children as the result of their exposure. Two of the buses were found to have nearly 3 times the concentration of CO permitted by EPA for a 1-hr exposure. In general, the higher levels of CO were found in buses that were parked behind or near other buses which had engines operating. Apparently this parking pattern caused CO to be drawn in through the ventilation system. The number of children having symptoms was not determined, but several individuals reported that on other trips passengers had experienced illness from time to time due to "fumes." Drivers were notified when excessive levels of CO were * One Mine Safety Appliance model D CO instrument and two Drager tube-type CO detectors. 1328 AJPH DECEMBER, 1975, Vol. 65, No. 12
TABLE 1-Carbon Monoxide Levels inside Buses upon Arrival at Snoqualmie Pass after an Estimated Driving Time of 1 to 2 Hrs* No. of Buses
Carbon Monoxide
% of Total
ppm 17 12
3 Total
1 33
0
Trace-8 9-34 35
52 36 9 3 100
* Measured with a Mine Safety Appliance portable model D instrument and two Dr-ger tube-type CO detectors.
CO
TABLE 2-Carbon Monoxide Levels inside Buses Parked with Engines Idling at Snoqualmie Pass during the Lunch Hour (12 to 2 p.m.)* No. of Buses
Carbon Monoxide
% of Total
ppm
20 21 17 3
4t Total
64
0 Trace-8 9-34
35-49 50-100
31 32 26 5 6 100
* Measured with a Mine Safety Appliance portable model D CO instrument and two Dr-ger tube-type CO detectors. t Two buses with CO levels of 50 ppm, one with 90 ppm. and one with 1 00 ppm.
found, and the results of the survey were given to the school districts in the area. The sclools were encouraged to purchase their own CO detection instruments in order to conduct regular surveys on a quarterly basis. The importance of regular engine maintenance and regular checking of exhaust systems was emphasized,2 as was the importance of avoiding tight parking patterns which tend to result in exhaust fumes being drawn into the passenger compartment. It was recommended that buses should not park bumper to bumper or in close proximity if the bus engines were to be operated while the children remained on the buses. Bus drivers were alerted to stop the engines as soon as the bus had been adequately warmed. One bus driver made the observation that there would be less trouble with exhaust smoke if the buses had mufflers directed overhead, in a manner similar to that used in the design of large trucks. This suggestion appears to have particular merit. Another interesting point observed was that lower tolerance levels of CO should be recommended for higher altitudes.3' This is because the CO detection devices measure an absolute and not a relative amount of CO, and a nominal value of 35 ppm probably represents an actual concentration of CO that is greater in proportion to the density of the air at a higher altitude. In addition, persons from a low elevation going to a high altitude for skiing or
mountaineering may have a higher uptake of CO than at sea level. Problems with the prevention of contamination of the air in the passenger compartments of buses were also found in an earlier survey of 39 school buses performed by the Washington State Division of Health in several small cities. Two buses had levels in excess of the EPA's mac for a 1-hr exposure, and a total of 24 buses had levels not allowable for an 8-hr exposure. Only nine buses had no detectable CO in the passenger compartment. The readings were consistently higher in the rear of the buses, especially if the back windows were operable and were open or could not be sealed shut adequately.5 The numbers of hours that a child who is bused to school actually spends in the bus during the school year may be considerable, perhaps as much as 200 hr or more each year. More work is needed to control possible hazards in the bus such as risk of injury due to faulty bus design or unsupervised play, greater exposure to communicable diseases from crowding, and possible exposure to CO levels sufficiently high to be harmful to a child,6 or the affect performance in school.7' 8
Summary Following an incident in which eight children became ill from carbon monoxide in a school bus, an investigation was made of CO levels in school buses in the Seattle area. The procedure selected for the evaluation was to test a large number of buses at a nearby ski resort. On the day selected for the sampling,, over 200 buses arrived, bringing school children from a number of school districts in the Seattle area for skiing lessons. As they arrived, 33 buses were checked immediately to determine in-transit levels of CO. Four of the 33 buses had CO levels in excess of Environmental Protection Agency maximum allowable concentrations for an 8-hr exposure. As the buses sat idling in the parking lot, 65 of them were tested-during the lunch hour when the students returned to the buses to have their lunch and to rest. Two buses had nearly 3 times the concentration of CO
permitted by the EPA for a 1-hr exposure. A total of seven buses (10 per cent) had concentrations of CO not permitted by the EPA for more than a 1-hr period. Altogether there were 24 buses (36 per cent) that had levels of CO in excess of EPA standards for an 8-hr exposure. As a result of these determinations and other observations a number of recommendations were made to reduce the hazard of exposure to carbon monoxide in school buses. REFERENCES 1. Environmental Protection Agency. National Primary and Secondary Ambient Air Quality Standards. Fed. Reg. 36, No. 21, Part II. Washington, DC, 1971. 2. Baker, S. P., Fisher, R. S., Masemore, W. C., and Sopher, I. M. Fatal Unintentional Carbon Monoxide Poisoning in Motor Vehicles. Am. J. Public Health 62:1463-1467, 1972. 3. Goldsmith, J. R., and Landau, S. A. Carbon Monoxide and Human Health. Science 162:1352-1359, 1968. 4. Stewart, R. D., Baretta, E. D., Platte, L. R., Stewart, E. B., Kalbfleisch, J. H., Van Yserloo, B., and Rimm, A. A. Carboxyhemoglobin Levels in American Blood Donors. J. A. M. A. 229: 1187-1195, 1974. 5. Walker, T. L. Carbon Monoxide Surveys in School Buses, 1972. Unpublished report, Washington State Division of Public Health. 6. Astrop, P. Carbon Monoxide, Smoking, and Atherosclerosis. Postgrad. Med. J. 49:697-706, 1973. 7. McFarland, R. A. Low Level Exposure to Carbon Monoxide and Driving Performance. Arch. Environ. Health 27:355-359, 1973. 8. Wright, G., Randell, P., and Shephard, R. J. Carbon Monoxide and Driving Skills. Arch. Environ. Health 27:349-354, 1973. Dr. Johnson is Director, Jefferson County Health Department, Lakewood, Colorado 80226, and Assistant Clinical Professor, University of Colorado School of Medicine. He was formerly District Health Officer, Seattle-King County Health Department, and Clinical Assistant Professor of Epidemiology and International Health at the University of Washington, School of Public Health and Community Medicine. Mr. Moran and Mr. Pekich are Environmental Health Specialists, Seattle-King County Health Department, Seattle, Washington. A report of this investigation was presented to the Environment Section at the 102nd Annual Meeting of the American Public Health Association in New Orleans, Louisiana on October 23, 1974. This article was accepted for publication August, 1975.
NRC TO HOLD HEARINGS ON ENVIRONMENTAL MANPOWER The National Research Council Committee for the Study of Environmental Manpower will hold a public meeting in Washington, DC, on January 16, 1976, to hear statements on aspects of personnel supply and demand in the field of environmental pollution control. Participation is expected from representatives of local, state, and federal governments and from educational, industrial, research, scientific, engineering, conservation, and citizen groups concerned with environmental quality. Persons interested in attending or in presenting a policy statement should contact Dr. Stanton J. Ware, study director, Committee for the Study of Environmental Manpower, National Research Council, 2101 Constitution Avenue, N.W., Washington, DC 20418.
PUBLIC HEALTH BRIEFS 1329
TABLE 1-Infection with Various Species of Parasites in Two Groups of Examinations Positive Stool Examinations
Parasite
Requested by physicians
Not requested by physicians
No. (%) Ascaris lumbricoides , Hookworm Trichuris trichiura Strongyloides stercoralis Enterobius vermicularis Schistosoma mansoni Hymenolepis nana Entamoeba histolytica Entamoeba coli lodamoeba bOtschlii Endolimax nana Giardia lamblia Chilomastix mesnili Total positive examinations Total examinations
36 (3.9) 1 (0.1) 40 (4.3) 30 (2.2) 1 (0.1)
5 (0.6) 17 (1.9) 64 (7.2) 8 (0.9) 3 (0.3) 4 (0.5) 0 (0.0) 3 (0.3) 35 (4.0) 1 (0. 1) 25 (2.8) 6 (0.6) 1 (0.1)
310 (33.7) 919
172 (19.5) 882
34 (3.6)
20(2.2) 120 (13.1) 16 (1.7) 2 (0.2) 2 (0.2) 3 (0.3) 5 (0.5)
Conclusions The most important conclusion that can be drawn from the high percentage of parasitic infections in patients not suspected of harboring parasites is that good clinical criteria for requesting stool examination for parasitic information are not always available. This study suggests the usefulness of routine stool examinations for screening unsuspected parasitosis in selected urban populations with high rate of infection and poor hygienic standards, even outside tropical endemic areas.
What Purpose? Bull. N. Y. Acad. Med. 51:39-52, 1975. 2. Sackett, D. L. The Usefulness of Laboratory Tests in Health Screening Programs. Clin. Chem. 19:366-372, 1973. 3. Mantel, C. A., and Yoeli, M. Parasitological Investigations in Gastroenterologic Practice. N. Y. State J. Med. 75:39-41, 1975. 4. Most, H. Manhattan: "A Tropic Isle?" Am. J. Trop. Med. Hyg. 17:333-354, 1968. 5. Ridley, D. S., and Hawgood, B. C. The Value of Formol-Ether Concentration of Faecal Cysts and Ova. J. Clin. Pathol. 9:74-76, 1956.
REFERENCES 1. Sackett, D. L. Screening for Early Detection of Disease: To
The authors are from the State University of New York, Kings County Hospital Center, Institute of Pathology, Brooklyn, New York 11203. This article was accepted for publication August, 1975.
Carbon Monoxide in School Buses CARL J. JOHNSON, MD, MPH JOHN MORAN, BS ROBERT PEKICH, BS Introduction On December 16, 1971, eight children became ill on a school bus carrying a group of children enrolled in a private school. Symptoms included drowsiness, headache, and nausea. Five of the children were sufficiently ill that they were taken to the emergency room of a hospital. One of the five was unconscious. The symptoms were found to be due to carbon monoxide (CO) poisoning. All of the children had
been seated in the rear of the bus, which had a rearmounted engine and was later found to have a defective exhaust system. The Seattle-King County Department of Public Health was notified of the incident and an investigation was conducted. All five buses operated by the school had significant levels of carbon monoxide in the passenger compartment, ranging from 10 to 25 parts per million (ppm) with a mean value of 15 ppm. The bus in which the children PUBLIC HEALTH BRIEFS
1327
had become ill had a level of 15 ppm of carbon monoxide, despite the fact that the exhaust system had since been repaired.
Investigation and Discussion As a result of this incident, a broader investigation was conducted to determine CO levels in school buses in the Seattle area. Many of the school districts participate in ski school programs which are conducted near Seattle in the area around Snoqualmie Pass in the Cascade Range. School buses are put in use on Saturdays and Sundays to carry school children to Snoqualmie Pass. Travel time usually varies from 1 to 2 hr, unless road conditions slow traffic. Because of the large number of school buses used in this operation (over 200), it was decided that a quick evaluation could be performed by sending a small team with CO detection instruments to the Pass. On a day selected for the survey, three staff members of the Seattle-King County Health Department stationed themselves at the Pass to meet the buses. Each had a CO detection instrument.* The passenger compartments of 33 of the buses were checked immediately as they arrived to determine in-transit levels of CO. The children were asked not to leave the buses until the determinations of CO had been made. Four of the 33 buses had CO levels in excess of the Environmental Protection Agency's (EPA) maximum allowable concentrations (mac) for an 8-hr exposure (Table 1), and one bus had greater than 33 ppm. ' Apparently these four buses had a defective exhaust system or a defect in the ventilation system which permitted exhaust gases to enter the passenger compartment. During the lunch hour the students return to the buses to have their lunches and to rest (usually 12 to 2 p.m.). The bus drivers operate the bus engines at this time to heat the passenger compartments. As the buses sat with engines idling in the parking lot during the lunch hour, 65 of them were tested (Table 2). Only 40 per cent of the buses had no measurable levels of CO. A total of 24 buses (37 per cent) exceeded the EPA standards for an 8-hr exposure (9 ppm). Seven of the buses (11 per cent) exceeded EPA standards for a 1-hr exposure (35 ppm) and at least four of the buses could have been expected to produce symptoms in the children as the result of their exposure. Two of the buses were found to have nearly 3 times the concentration of CO permitted by EPA for a 1-hr exposure. In general, the higher levels of CO were found in buses that were parked behind or near other buses which had engines operating. Apparently this parking pattern caused CO to be drawn in through the ventilation system. The number of children having symptoms was not determined, but several individuals reported that on other trips passengers had experienced illness from time to time due to "fumes." Drivers were notified when excessive levels of CO were * One Mine Safety Appliance model D CO instrument and two Drager tube-type CO detectors. 1328 AJPH DECEMBER, 1975, Vol. 65, No. 12
TABLE 1-Carbon Monoxide Levels inside Buses upon Arrival at Snoqualmie Pass after an Estimated Driving Time of 1 to 2 Hrs* No. of Buses
Carbon Monoxide
% of Total
ppm 17 12
3 Total
1 33
0
Trace-8 9-34 35
52 36 9 3 100
* Measured with a Mine Safety Appliance portable model D instrument and two Dr-ger tube-type CO detectors.
CO
TABLE 2-Carbon Monoxide Levels inside Buses Parked with Engines Idling at Snoqualmie Pass during the Lunch Hour (12 to 2 p.m.)* No. of Buses
Carbon Monoxide
% of Total
ppm
20 21 17 3
4t Total
64
0 Trace-8 9-34
35-49 50-100
31 32 26 5 6 100
* Measured with a Mine Safety Appliance portable model D CO instrument and two Dr-ger tube-type CO detectors. t Two buses with CO levels of 50 ppm, one with 90 ppm. and one with 1 00 ppm.
found, and the results of the survey were given to the school districts in the area. The sclools were encouraged to purchase their own CO detection instruments in order to conduct regular surveys on a quarterly basis. The importance of regular engine maintenance and regular checking of exhaust systems was emphasized,2 as was the importance of avoiding tight parking patterns which tend to result in exhaust fumes being drawn into the passenger compartment. It was recommended that buses should not park bumper to bumper or in close proximity if the bus engines were to be operated while the children remained on the buses. Bus drivers were alerted to stop the engines as soon as the bus had been adequately warmed. One bus driver made the observation that there would be less trouble with exhaust smoke if the buses had mufflers directed overhead, in a manner similar to that used in the design of large trucks. This suggestion appears to have particular merit. Another interesting point observed was that lower tolerance levels of CO should be recommended for higher altitudes.3' This is because the CO detection devices measure an absolute and not a relative amount of CO, and a nominal value of 35 ppm probably represents an actual concentration of CO that is greater in proportion to the density of the air at a higher altitude. In addition, persons from a low elevation going to a high altitude for skiing or
mountaineering may have a higher uptake of CO than at sea level. Problems with the prevention of contamination of the air in the passenger compartments of buses were also found in an earlier survey of 39 school buses performed by the Washington State Division of Health in several small cities. Two buses had levels in excess of the EPA's mac for a 1-hr exposure, and a total of 24 buses had levels not allowable for an 8-hr exposure. Only nine buses had no detectable CO in the passenger compartment. The readings were consistently higher in the rear of the buses, especially if the back windows were operable and were open or could not be sealed shut adequately.5 The numbers of hours that a child who is bused to school actually spends in the bus during the school year may be considerable, perhaps as much as 200 hr or more each year. More work is needed to control possible hazards in the bus such as risk of injury due to faulty bus design or unsupervised play, greater exposure to communicable diseases from crowding, and possible exposure to CO levels sufficiently high to be harmful to a child,6 or the affect performance in school.7' 8
Summary Following an incident in which eight children became ill from carbon monoxide in a school bus, an investigation was made of CO levels in school buses in the Seattle area. The procedure selected for the evaluation was to test a large number of buses at a nearby ski resort. On the day selected for the sampling,, over 200 buses arrived, bringing school children from a number of school districts in the Seattle area for skiing lessons. As they arrived, 33 buses were checked immediately to determine in-transit levels of CO. Four of the 33 buses had CO levels in excess of Environmental Protection Agency maximum allowable concentrations for an 8-hr exposure. As the buses sat idling in the parking lot, 65 of them were tested-during the lunch hour when the students returned to the buses to have their lunch and to rest. Two buses had nearly 3 times the concentration of CO
permitted by the EPA for a 1-hr exposure. A total of seven buses (10 per cent) had concentrations of CO not permitted by the EPA for more than a 1-hr period. Altogether there were 24 buses (36 per cent) that had levels of CO in excess of EPA standards for an 8-hr exposure. As a result of these determinations and other observations a number of recommendations were made to reduce the hazard of exposure to carbon monoxide in school buses. REFERENCES 1. Environmental Protection Agency. National Primary and Secondary Ambient Air Quality Standards. Fed. Reg. 36, No. 21, Part II. Washington, DC, 1971. 2. Baker, S. P., Fisher, R. S., Masemore, W. C., and Sopher, I. M. Fatal Unintentional Carbon Monoxide Poisoning in Motor Vehicles. Am. J. Public Health 62:1463-1467, 1972. 3. Goldsmith, J. R., and Landau, S. A. Carbon Monoxide and Human Health. Science 162:1352-1359, 1968. 4. Stewart, R. D., Baretta, E. D., Platte, L. R., Stewart, E. B., Kalbfleisch, J. H., Van Yserloo, B., and Rimm, A. A. Carboxyhemoglobin Levels in American Blood Donors. J. A. M. A. 229: 1187-1195, 1974. 5. Walker, T. L. Carbon Monoxide Surveys in School Buses, 1972. Unpublished report, Washington State Division of Public Health. 6. Astrop, P. Carbon Monoxide, Smoking, and Atherosclerosis. Postgrad. Med. J. 49:697-706, 1973. 7. McFarland, R. A. Low Level Exposure to Carbon Monoxide and Driving Performance. Arch. Environ. Health 27:355-359, 1973. 8. Wright, G., Randell, P., and Shephard, R. J. Carbon Monoxide and Driving Skills. Arch. Environ. Health 27:349-354, 1973. Dr. Johnson is Director, Jefferson County Health Department, Lakewood, Colorado 80226, and Assistant Clinical Professor, University of Colorado School of Medicine. He was formerly District Health Officer, Seattle-King County Health Department, and Clinical Assistant Professor of Epidemiology and International Health at the University of Washington, School of Public Health and Community Medicine. Mr. Moran and Mr. Pekich are Environmental Health Specialists, Seattle-King County Health Department, Seattle, Washington. A report of this investigation was presented to the Environment Section at the 102nd Annual Meeting of the American Public Health Association in New Orleans, Louisiana on October 23, 1974. This article was accepted for publication August, 1975.
NRC TO HOLD HEARINGS ON ENVIRONMENTAL MANPOWER The National Research Council Committee for the Study of Environmental Manpower will hold a public meeting in Washington, DC, on January 16, 1976, to hear statements on aspects of personnel supply and demand in the field of environmental pollution control. Participation is expected from representatives of local, state, and federal governments and from educational, industrial, research, scientific, engineering, conservation, and citizen groups concerned with environmental quality. Persons interested in attending or in presenting a policy statement should contact Dr. Stanton J. Ware, study director, Committee for the Study of Environmental Manpower, National Research Council, 2101 Constitution Avenue, N.W., Washington, DC 20418.
PUBLIC HEALTH BRIEFS 1329
