The management of urban solid waste in urban centers is growing in complexity and receiving increasing attention from researchers because of the potential impact on the environment and on human health if not well managed 1,2,3,4. Workers involved in management of these wastes are exposed to biological, chemical and physical risks to their health 2,5,6,7,8.
Of the types of solid waste, health care waste are particularly likely to contain biological and chemical agents 9. Only a fraction of urban solid waste are potential sources of disease for those who have inadequate contact with them. A particular risk is that of injury or infection from sharps 10,11.
The risk to human health from health care waste, compared to that from urban solid waste in general, is a subject of debate among researchers and managers. Some have claimed that the handling of health care waste involves additional risks to health, beyond those arising from domestic waste 6,9,12,13,14. Others, however have denied that there is any difference between the two 15,16,17,18.
Two reviews of the literature were found, one of which 12 focused on studies of hepatitis A and B in workers who handled waste, but only one of the papers identified involved an epidemiological study 19; another review 20 selected five cross-sectional studies, of which four correspond with papers in Table 119,21,22,23.
|Reference||Date of study||Country||Sample size||Study groups||Outcome measure *||Findings|
|Anagaw, et al. 27||April- June 2011||Ethiopia||200||100 collectors of health care waste (hospital) & 100 cleaning staff (who collect ordinary waste)||HBV (HBsAg), HCV (Anti-HCV)||HBV (OR: 6.3; p = 0.04); HCV (OR: 7.5; p = 0.02). Prevalence of HBV & HCV significantly higher in workers collecting health care waste|
|Rachiotis et al. 21||2007-2008||Greece||210||102 collectors of urban solid waste and 108 gardeners||HBV (HBsAg, Anti-HBc and Anti-HBs)||HBV (OR: 4.05; 95%CI: 1.23-13.33) – progressive increase risk for infection with age. Accidents with sharps (RR: 2.64; 95%CI: 1.01-6.96)|
|Shiferaw et al. 26||May- July 2010||Ethiopia||252||126 collectors of health care waste (hospital) & 126 who collect normal non-clinical waste in a hospital||HBV (HbsAg and Anti-HBcAg)||HBsAg (OR: 8; 95%CI: 1.02-63.02); Anti-HBcAg (OR: 1.5; 95%CI: 1.1-2.1). High prevalence of HBV in workers collecting health care waste compared with those who do not|
|Graudenz 5||September 2007/ February 2008||Brazil||217||64 (landfill), 41 (urban solid waste collection), 35 (sweepers), 45 (drivers) & 32 controls (railway maintenance)||HBV (Anti-HBc)||No difference in prevalence of hepatitis B between study groups (percentage positive varied between groups from 6.3 to 20, with p = 0.439)|
|Franka et al. 28||January-December 2004||Libya||600||300 collectors of health care waste (medical center) and 300 who collect only ordinary waste (urban solid waste)||HIV, HBV (HBsAg), HCV (Anti-HCV)||HBV (OR: 7.14; p < 0.04); HCV (OR: not given; p < 0.005). HIV not detected. Higher prevalence of HBV & HCV in health care waste group than in urban solid waste group|
|Luksamijarulkul et al. 25||Not stated||Thailand||354||169 collectors of urban solid waste & 185 public cleansing workers (not in direct contact with waste)||HAV, HBV (HBsAg, Anti-HBs and Anti-HBc)||49.4% seropositive for HBV, 5.9% for HBsAg, 37.3% for anti-HBs, 6.2% only for anti-HBc, & 85% with anti-HAV antibodies (p = 0.0058 most exposed collectors). For HAV no significant difference was found|
|Squeri et al. 23||March- May 2005||Italy||327||All were workers who collected urban solid waste||HBV (HBsAg and Anti-HBc), HCV (Anti-HCV)||183 (55.96%) protected from HBV by the presence of HBsAb (98 by immunization and 85 by previous contact). 120 (36.7%) at risk of infection. 24 (7.34%) infected by HBV and 5 (1.52%) had contact with HBV and HCV|
|Mariolis et al. 24||Not stated||Greece||69||All were workers who collected urban solid waste||HAV, HBV (HBsAg, Anti-HBs and Anti-HBc), HCV (Anti-HCV)||37 (53.6%) were HAV positive; 15 (21.7%) had been exposed to HBV. Of the whole study group, 7 (10.1%) had been immunised against HBV. 4.3% were HBV chronically infected. One was found to be HCV positive|
|Dounias et al. 22||September 1999/ December 2001||Greece||159||71 collectors of urban solid waste & 88 office workers (not in direct contact with waste)||HBV (HBsAg, Anti-HBs and Anti-HBc)||Prevalence of HBsAg was higher in exposed (11.3%) than in non-exposed (4.5%), but difference was not significant. Prevalence of anti-HBc was 24% among exposed and 8% in non-exposed, also not significant|
|Ferreira et al. 29||May- July 1996||Brazil||186||31 collectors de health care waste (hospitals) & 155 collectors of domestic urban solid waste||HBV (Anti-HBc)||HBV (OR: 0.9; 95%CI: 0.24-3.05;). No significant difference in risk found between the groups of workers studied|
|Corrao et al. 19||Not stated||Italy||93||45 sweepers, 21 waste collectors, 19 machine operators, 5 sewer workers and 3 office workers||HAV, HBV (HBsAg, Anti-HBs and Anti-Hbc)||Positive for HBV in each group were: 9 (20.0%) sweepers, 6 (28.6%) waste collectors, 1 (5.3%) machine operator, 2 (40.0%) sewer workers and 0 (0.0%) among the office workers|
* Sensitivities of serology tests for Hepatitis B: Anti-HBc – detects acute, chronic, cure stages; HbsAg – detects incubation, acute, chronic stages; Anti-HBs – vaccinated.
The aim of this review was to identify the context of scientific discussion on hepatitis B and C infection in workers who collect solid waste, whether domestic or from health care facilities, in order to assess the balance of evidence on this subject. The subject has relevant implications for urban health, considering its links with waste production by an increasingly urbanized population, environmental determinants, and the social vulnerability of the population occupationally involved in waste management.
The search was carried out between January and December 2013, accessing the world’s major publication databases, including: Web of Science, Web of Knowledge Cross Search, SciELO, and MEDLINE/PubMed.
The following search terms were used: hepatitis, prevalence of hepatitis, health care waste, medical waste, biomedical waste, solid waste, waste, waste workers, municipal solid waste workers, medical waste handlers and health care workers. All studies in which the health outcome was infection with hepatitis B or C virus in workers who collect domestic or health care waste were reviewed. No criterion was set regarding the size or gender of the study population.
Six of the studies concluded that workers collecting urban solid waste are exposed to greater risk when compared with those who have no exposure 19,21,22,23,24,25, although one study found no such additional risk 5. With regard to health care waste, three studies indicate higher risk among those collecting than those working with urban solid waste 26,27,28, and a fourth study found none 29.
Four of the papers included consider workers who collect hospital waste 26,27,28,29, comparing with workers dealing with ordinary refuse. The study by Ferreira et al. 29 involved hospital and municipal waste collection workers, compared with others who covered residential areas.
All papers used cross-sectional study designs, limiting the possibility of assessing a cause and effect relationship by making it difficult to identify the moment at which infection occurred.
Some studies determined that immunization against HBV and being under treatment for the disease should be exclusion criteria, so as to mitigate any possible selection bias. These studies show the vulnerability of the workers who are exposed to infection without the appropriate immunization 5,21,22,26,29.
Another limitation of some studies is the small number of subjects included (Table 1). This limits the representativeness of the study population. Considering prevalence for exposed and non-exposed subjects, seven studies 5,19,21,22,24,25,29 did not have a sufficient sample size to ensure statistical significance, according to Kelsey et al. 30.
Five studies 5,19,21,22,25 included workers in activities not associated with waste collection as the control group. Other studies 26,27,28,29 included household waste collectors as the control group. Finally, two studies 23,24 had no control groups at all.
The small number of papers found in this review suggests that the theme would benefit from research in greater depth. While most studies indicate a possible association between exposure to waste and infection by HBV or HCV, further research is needed to clarify this.
The papers in this review suggest that the handling of health care waste involves a higher risk of infection with HBV and HCV, compared with urban solid waste handlers. The studies providing the main evidence for that conclusion were based in hospitals, and no information is available about the separation of different categories of waste.
It must be emphasized that vaccination against hepatitis B is mandatory to protect workers who are exposed to waste, urban solid waste or health care waste, and it must be a sine qua non part of the admission process for these workers. An immunization evidentiary test is also recommended to ensure the success of vaccination.