Public & Occupational Health Risks From Exposure To Sewage Contamination
EUGENE C. COLE, DrPH
Department of Health Science,
Brigham Young University, Provo, Utah
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The general public is at risk for infectious disease and other adverse health effects from exposure to untreated sewage through extensive backflows and sewage-contaminated flood waters. There is also a significant health risk from improper remediation of these situations. Workers who remediate sewage damage losses, as well as sewage treatment workers, and sewage sludge processors, are at risk for chronic respiratory disease, other systemic health effects, and a host of acute and chronic bacterial, fungal, viral, and parasitic diseases.

PUBLIC HEALTH. Risk to the public's health from sewage exposure is demonstrated in a 1988-1989 epidemic of hepatitis A in Ocoee, Florida, that resulted in 39 cases and fetal death (Vonstille et al, 1993). Of the 18 index cases, each had a history of contact with sewage-contaminated stormwater. Over 120 different viruses are excreted in human feces and urine and their way into sewage (Straub et al, 1993). These can include rotavirus, causing severe and sometimes life-threatening diarrhea in children, adenoviruses, causing respiratory and eye infections, and Norwalk virus, a significant cause of gastroenteritis. parasitic agents include the highly infectious Giardia and Cryptosporidium that can result in chronic and severe intestinal disease in both adults and children.

Bacterial pathogens in sewage can include virulent strains of gram-negative organisms such as Salmonella, Campylobacter, and E. coli. In addition to the infectious disease risk, gram-negative bacteria contain endotoxins that are released at the time of cell death and destruction, and can be aerosolized into the air during improper remediation, such as attempts to clean and dry sewage contaminated carpets. Drying of such carpets will liberate airborne endotoxins that induce respiratory inflammation and airway restriction, and can potentiate the allergic and infectious disease responses. Attempts at salvaging sewage contaminated carpets and other porous materials can liberate extensive amounts of endotoxins, allergens, and infectious agents, and pose a particular risk for susceptible populations such as elderly, infants, convalescents, and those that are immunocompromised through disease therapy. Sewage contaminated porous materials must be confined in plastic bags and transported to appropriate disposal facilities. After removal of contaminated materials, mechanical and natural dehumidification, temperature control, and rapid drying are essential, as are appropriate disinfection and cleaning measures. This will prevent secondary microbial colonization by allergenic and toxigenic fungi. At a minimum, procedures to be followed for effective sewage remediation are those contained in the IICRC S500 Standard and Reference Guide for Professional Water Damage Restoration of the Institute on Inspection, Cleaning and Restoration Certification (IICRC), Vancouver, Washington

Public health risks can also be incurred through the discriminate, inappropriate, and illegal transport and dumping of extracted sewage by unscrupulous companies. It is imperative that all sewage wastes extracted from indoor environments be appropriately and safely disposed of according to all local, state, and federal regulations.

OCCUPATIONAL HEALTH. Those who professionally remediate and restore residential sewage backflows are at significant risk for adverse health effects from infectious agents, potent allergens, noxious gases, vapors, and fumes, and endotoxins and mycotoxins. The latter are toxic metabolites of a variety of environmental fungi that can quickly grow in water damaged environments and liberate airborne toxin-containing spores. Recent research has shown that workers with routine sewage exposures exhibit respiratory dysfunction (Zuskin et al, 1993; Richardson, 1995), fatigue and headache (Melbostad et al, 1994), infection (Schlosser et al, 1995, and increased incidences of cancers (Friis et al, 1993). Thus the need for adequate training, immunization, and the use of personal protective equipment that provides dermal, mucus membrane, and respiratory protection.

References

Friis, L., C. Edling, and L. Hagmar. (1996). Mortality and Incidence of Cancer Among Sewage Workers: A retrospective Cohort Study, Brit. Jour. Ind. Medicine 50: 653-657.

Melbostad, E., E. Wijnand, A. Skogstsd, P. Sandven, J. Lassen, P. Sostrand, and K Heldal. (1994). Exposure to Bacterial Aerosols and Work-Related Symptoms in Sewage Workers, American Journal of Industrial Medicine 25: 59-63.

Richardson, D.B. (1995). Respiratory Effects of Chronic Hydrogen Sulfide Exposure, American Journal of Industrial Medicine 28: 99-108.

Schlosser, O., F. Roudot-Thoraval. (1995). Viral Hepatitis A and Exposure to Sewage: A Confirmed Occupational Risk. Gastroenterol. Clin. Biol., 19 (10): 844-845.

Straub, T., I. Pepper, and C. Gerba. (1993). Hazards from Pathogenic Microorganisms in Land-Disposed Sewage Sludge. Reviews of Environmental Contamination & Toxicology, pp. 56-91.

Vonstille, W.T. (1993). Hepatitis A Epidemics from Utility Sewage in Ocoee, Florida. Archives of Environmental Health, 48: 120-124.

Zuskin, E., J Mustajbegovic, and E. Schachter. (1993). Respiratory Function in Sewage Workers. American Journal of Industrial Medicine, 23: 751-761.