7. National Research Council. Proceedings of the workshop on alcohol-related accidents in recreational boating. Washington, DC: Transportation Research Board, National Research Council, 1986.

8. US Consumer Product Safety Commission, National Spa and Pool Institute. National Pool and Spa Safety Conference [Report]. Washington, DC: US Consumer Product Safety Commission, National Spa and Pool Institute, 1985.

9. Karter MJ Jr. Patterns of fire deaths among the elderly and children in the home. Fire J 1986; Mar:19-22.

10. McLoughlin E, Marchone M, Hanger L, German PS, Baker SP. Smoke detector legislation: its effect on owner-occupied homes. Am J Public Health 1985;75:858-62.

11. Hall JR. A decade of detectors: measuring the effect. Fire J 1985;79:37-78.

12. Jagger J, Dietz PE. Death and injury by firearms: who cares? JAMA 1986;255:3143-4. 13. Centers for Disease Control. Youth suicide in the United States, 1970-1980. Atlanta: US Department of Health and Human Services, Public Health Service, 1986.

14. Eddy DM, Wolpert RL, Rosenberg ML. Estimating the effectiveness of interventions to prevent youth suicide. Medical Care 1987;25(12):S57-S65.

15. US Department of Health and Human Services. Report of the Secretary's Task Force on Black and Minority Health. Washington, DC: US Department of Health and Human Services, Public Health Service, 1986.

16. Centers for Disease Control. CDC surveillance summaries. MMWR 1987;37(suppl SS-1) (in press).

17. Committee on Trauma Research, Commission on Life Sciences, National Research Council, Institute of Medicine. Injury in America: a continuing public health problem. Washington, DC: National Academy Press, 1985.

18. Division of Injury Epidemiology and Control, Center for Environmental Health, Centers for Disease Control. 1986 annual report. Atlanta: US Department of Health and Human Services, Public Health Service, 1987.

Erratum: Vol. 37, No. 8

p. 122 The last sentence in the second paragraph should have read, "Approximately two-thirds of the children in three large series of HSP reported symptoms of an upper respiratory infection during the month before onset (1,2,4)."

Epidemiologic Notes and Reports

Influenza Update

United States

The following are indicators of influenza activity in the United States for the weeks ending February 13, 20, 27, and March 5. Numbers and percentages are provisional and may change as additional reports are received.

*Outbreaks in counties in which total population comprises <50% of total state population. "Outbreaks in counties in which total population comprises 50% or more of total state population.

'Members of the American Academy of Family Physicians who submit weekly influenza surveillance reports based on their patient population.

**States without confirmed influenza A (H3N2) to date: Massachusetts, Nevada, New Hampshire, and Rhode Island.

**States reporting isolates of influenza A(H1N1) to date: Arkansas, Connecticut, Georgia, Maine, Maryland, Nebraska, New York, North Carolina, South Carolina, Texas, Virginia, and Vermont. Isolates from New York and Texas resemble influenza A/Taiwan/1/86(H1N1).

States reporting isolates of influenza B to date: Alabama, Arizona, California, Connecticut, Hawaii, Illinois, Maine, Montana, Nevada, New York, Ohio, Tennessee, Virginia, Washington, and Wisconsin.

The Morbidity and Mortality Weekly Report is prepared by the Centers for Disease Control, Atlanta, Georgia, and available on a paid subscription basis from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402, (202) 783-3238.

The data in this report are provisional, based on weekly reports to CDC by state health departments. The reporting week concludes at close of business on Friday; compiled data on a national basis are officially released to the public on the succeeding Friday. The editor welcomes accounts of interesting cases, outbreaks, environmental hazards, or other public health problems of current interest to health officials. Such reports and any other matters pertaining to editorial or other textual considerations should be addressed to: Editor, Morbidity and Mortality Weekly Report, Centers for Disease Control, Atlanta, Georgia 30333.

On December 8, 1986, 22 students and a teacher in a Connecticut high school chemistry laboratory were exposed to mercury vapor. The class was conducting an oxidation reduction experiment that called for silver oxide. However, mercuric oxide had been used because silver oxide was not available.

The experiment was performed at eleven work stations; exhaust hoods in the classroom were not turned on. Each experiment used 1.75 g of mercuric oxide to obtain a theoretical yield of 1.62 g of elemental mercury. The mercuric oxide was placed in a crucible and heated over burner flame for 15 minutes to drive off the oxygen. The teacher stopped the experiment when he learned that the yields were lower than expected, and, therefore, mercury was being vaporized. He turned on the hoods and had the students clean out the crucibles. The experiment had started at approximately 8:15 a.m.; the students had left the room by 9:00 a.m. The school then called the local fire department and the Toxic Hazards Section of the Connecticut Department of Health Services for assistance in determining the extent of the possible mercury exposure.

The maximum concentration of mercury in the air was estimated at 50 mg/m3 (10.9 g total mercury lost 219 m3 air volume of room).* The mercury saturation point in air at 20 °C (68 °F) is 15 mg/m3 (1). The excess 35 mg/m3 of mercury that appears to have been lost may have condensed on surfaces in the room. The maximum dose, or body burden, to each student was estimated at 9.3 mg.*

Air measurements for mercury were taken in the laboratory after it had been ventilated for several hours. The mercury level was 0.008 mg/m3 with the windows open and hoods on. However, when the laboratory was closed and the hoods were turned off for 25 minutes, the level rose to 0.04 mg/m3 (the American Conference of Government Industrial Hygienists time-weighted average is 0.05 mg/m3). This fivefold increase may have been due to vaporization of the condensed mercury from surfaces in the room. Mercury levels were measured again the day after the incident (December 9), and school personnel were given instructions for cleanup. On *This concentration is based on an assumption that the lost mercury had completely vaporized and had thoroughly mixed with the air in the room.

*Body burden was estimated using the value of the mercury saturation point in air and assuming 100% absorption of mercury in the lungs and a breathing rate of 20 m3 per 24 her a period

of 3/4 of an hour.

APR 1 4 1988

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES / PUBLIC HEALTH SERVICE

Documents Center