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Bulletin of Occupational & Environmental Health

A Hazardous Occupation? Sewer Work

Author(s): Editor-in-Chief

Vol. 1, No. 1 (2004-01 - 2004-06)

According to a Hindi Daily between March 22, 2003, and 12 November 2003 a total of 15 workers died while entering sewer in Delhi. 1 . A public interest litigation filed by an NGO in February 2004 claimed that these deaths occurred due to gross neglect of health and safety at work. These were all contract employees who died due to asphyxiation. These accidents were entirely preventable, but since worker health and safety is such a low priority, it gets overlooked in most, if not all places. Such deaths usually occur due to entry into an oxygen deficient state triggered by the presence of methane or carbon di oxide in the sewer. Medically speaking the cause of such deaths is hypoxia. Occasionally the deaths occur following exposure to Hydrogen sulfide, which is known as ‘sewer gas\', and is frequently present, in the sewers.Byard RW and Wilson GW reported deaths of two boys (age 11 and 12 years) due to methane asphyxia who were found at the bottom of a 37-ft (11.1-m)-deep sewer shaft. Attempted resuscitation of the first patient was unsuccessful and achieved only temporary stabilization of the second, who died 48 hrs. after his discovery. 2

Dorevitch and colleagues reported that a small percentage of deaths in U. S. construction workers is attributable to poisoning. 3 According to these authors from 1990 to 1999 eighty even poisoning deaths of construction workers were attributable to toxic inhalation. Cellular and simple asphyxiants accounted for the largest numbers of fatalities. The majority of these deaths occurred in confined spaces. Water, sewer, and utility line workers are at increased risk for poisoning fatalities.

The hazards encountered and associated with entering and working in confined spaces are capable of causing bodily injury, illness, and death of the worker. Accidents occur among workers because of failure to recognize that a confined space is a potential hazard. It should therefore be considered that the most unfavorable situation exists in every case and that the danger of explosion, poisoning, and asphyxiation will be present at the onset of entry. Confined spaces such as sewers, casings, tanks, silos, vaults, and compartments of ships usually have limited access. Hazardous atmospheres encountered in confined spaces can be divided into four distinct categories: Flammable, Toxic, Irritant and/or Corrosive, and Asphyxiating. 4

Hall and colleagues reported that in 2 separate incidents, 6 patients were poisoned with hydrogen sulfide (H2S) in sewer gas. In the first incident, mixing acid- and sodium hydroxide-based drain cleaners in a confined space resulted in 4 poisonings and 2 deaths. Three would-be rescuers were seriously poisoned and 1 died. Two survivors had neurological sequelae.5

Toxic inhalation fatalities in sewer work are preventable. There is a need to educate the contractors who should make adequate arrangements before allowing workers to enter such places which can cost them lives. The ones not listening must be dealt with harshly. Compensation should be paid to those suffering injuries or to the next of kin in the event of death. Occupational health and safety legislation should cover these workers, if possible by making suitable changes in the existing law.


1. Sewer Work! A Graveyard for the workers? Amar Ujala. February 12, 2004. New Delhi .
2. Death scene gas analysis in suspected methane asphyxia. Byard RW, Wilson GW. Am J Forensic Med Pathol. 1992 Mar; 13(1): 69-71.
3. Toxic inhalation fatalities of US construction workers, 1990 to 1999. Dorevitch S, Forst L, Conroy L, Levy P. J Occup Environ Med. 2002 Jul; 44(7): 657-62.
4. Occupational Safety & Health Administration. U. S. Department of Labour.
5. Hall AH, Rumack BH. Hydrogen sulfide poisoning: an antidotal role for sodium nitrite? Vet Hum Toxicol. 1997, Jun; 39(3): 152-4).

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