Exposures and health outcomes in relation to bioaerosol emissions from composting facilities: A systematic review of occupational and community studies MRC-PHE Centre for Environment and Health Philippa Douglas 1, Clare Pearson 1, Emma Littlewood 1, Sarah Robertson 2, Tim Gant 2 and Anna Hansell 1,3 1 Small Area Health Statistics Unit, MRC-PHE centre for Environment and Health, Imperial College London 2 Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Harwell Camps, Didcot, Oxfordshire 3 Public health and primary care, Imperial College Healthcare NHS trust METHODS ACKNOWLEDGEMENTS The work of the UK Small Area Health Statistics Unit is funded by Public Health England as part of the MRC-PHE Centre for Environment and Health, funded also by the UK Medical Research Council. This research also received funding from the National Institute for Health Research Health Protection Research Unit in Health Impact of Environmental Hazards at King’s College London, in partnership with Public Health England and collaboration with Imperial College London. Thanks to Tim Reeves at Imperial College library and Daniela Fecht of SAHSU for assistance. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the Department of Health or Public Health England. EU directives restricting the use of landfills are increasing the number of composting facilities in the UK. Composting yields significant concentrations of bioaerosols (1), which are airborne biological particles of fungi, bacteria, pollen, and fragments, constituents, particulate matter (PM 10 ) and by- products of cells, and have the potential to harm human health (2). CONCLUSIONS Evidence to date is insufficient to inform risk-based regulation of bioaerosols emissions from waste composting Limited number of studies Most studies were conducted over short timescales Not possible to derive quantitative dose-response estimates Recommendations for further studies include: More detailed and longer-term exposure monitoring including consideration of the various components of bioaerosols More health studies in larger study populations Use of objective measures of health outcomes than self-report (e.g. biomarkers, lung function, health records) Figure 1. Study inclusion and exclusion criteria Figure 3. Mean/median airborne total bacteria (top) and Aspergillus fumigatus (bottom) concentrations in occupational exposure studies. A literature search was conducted according to recognized guidelines (3,4) across 6 electronic databases and grey literature was identified using internet wide search engines and a university database. The inclusion and exclusion criteria are presented in Figure 1. Studies were included if: Published in English between January 1960 and July 2014 Concerned exposure or health from composting Results were presented in an extractable form Peer reviewed or published by a recognized institution Studies were excluded if: Did not concern waste composting Did not concern bioaerosols Did not include any original data Review papers (the reference list was still searched) Unavailable in English Toxicological studies in animals Full texts were unavailable Only concerned Microbial Volatile Organic Compounds (MVOCs) RESULTS There were 51 occupational exposure studies measuring nine bioaerosol components. Aspergillus fumigatus and total bacteria were most commonly measured, with concentrations ranging over 8 orders of magnitude for Aspergillus fumigatus and over 5 orders of magnitude for total bacteria (Figure 3). The highest bioaerosol concentrations were observed in indoor composting areas and during compost agitation activities (Figure 3). Four studies exceeded Germany’s Federal Institute for Occupational Safety and Health (BAuA) occupational limit of 50,000 CFU/m 3 limit for mesophilic fungus. BACKGROUND OCCUPATIONAL EXPOSURE STUDIES HEALTH STUDIES There were 18 health studies, 12 occupational and 6 community based. Study designs were: 8 cross-sectional, 3 case reports, 2 quasi experimental design (one also cross-sectional), 2 lab based, 1 experimental, 1 cohort and 1 panel. Associations were found with upper respiratory symptoms and (in experimental studies) elevations of inflammatory markers. Sample sizes were generally low. Questionnaire- based studies gave a high risk of response bias. REFERENCES 1.Wheeler PA et al Health Effects of Composting – A Study of Three Composting Sites and Review of Past Data. In RandD Technical Report. Bristol: Environment Agency. 2.Douwes J et al Work related acute and (sub-) chronic airways inflammation assessed by nasal lavage in compost workers. Ann Agric Environ Med 4: Moher D et al Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. Ann Intern Med151: Stroup DF et al Meta-analysis of observational studies in epidemiology.J Am Med Assoc 283; If provided in the study, the range of values included is denoted by the error bars COMMUNITY EXPOSURE STUDIES There were 13 community exposure studies. Measured total bacteria and Aspergillus fumigatus concentrations varied widely, but generally reduced with distance from site (Figure 2). Three of 9 studies measuring total bacteria and 2 of 8 studies measuring Aspergillus fumigatus concentrations exceeded the Environment Agency’s recommended acceptable levels of 1000 and 500 CFU/m 3 respectively beyond 250m downwind of the site. Figure 2. Mean/median airborne total bacteria concentrations in community exposure studies