Q&As relating to the SAHSU study Exposures and health outcomes in. relation to bioaerosol emissions from composting facilities: A systematic

Size: px

Start display at page:

Download "Q&As relating to the SAHSU study Exposures and health outcomes in. relation to bioaerosol emissions from composting facilities: A systematic"

Janis Carr
6 years ago
Views:

1 Q&As relating to the SAHSU study Exposures and health outcomes in relation to bioaerosol emissions from composting facilities: A systematic review of occupational and community studies, published in the Journal of What is a bioaerosol? 1 Why was the review conducted? 2 What is a systematic review and how does it differ from other reviews? 2 What did the study find? 3 How does the (English) Environment Agency protect the public from bioaerosol exposures from composting sties? 4 How many papers did this study look at? 5 Why were some studies excluded? 5 Does this study suggest I should be worried about handling compost in my garden? 7 I have asthma and live near a large composting plant, should I be concerned? 7 Who funded the study? 7 Have any other reviews been completed? 8 Are there any differences between this study and the report conducted by the Institutes of Occupational medicine (IOM) by Searl in 2008? 8 Reference list 9 Further references 9 What is a bioaerosol?

2 Bioaerosols are airborne biological particles and can consist of fungi, bacteria, pollen, and fragments, constituents, and by-products of cells, which have the potential to cause adverse health effects Most studies measure one or more of; fungal spores, the fungus Aspergillus fumigatus, total bacteria, bacterial species actinomycetes and endotoxin (bacterial cell wall components) Why was the review conducted? The number of industrial composting facilities in Europe is increasing due to efforts to reduce the fraction of waste destined for landfill Composting yields significant concentrations of bioaerosols However, it is not clear whether this might pose potential health problems to communities near large-scale composting sites We conducted a systematic review of all available studies on exposure and health effects of bioaerosols emitted from large-scale composting of waste, looking both at workers at composting sites and nearby communities What is a systematic review and how does it differ from other reviews? A systematic review is a literature review, which aims to identify, select, gather and synthesise the research evidence relating to a specific scientific question It uses a standardised way to extract information from studies, assesses studies for study design flaws (bias) and analyses all available evidence, which are identified via multiple sources Systematic reviews have the potential to end confusion, highlight where there is adequate or inadequate evidence, generate new insights by combining findings from different studies, and reduce the influence of any flaws or errors in a single study

3 Further information about systematic review written for a lay audience can be found on the sense about science website What did the study find? The study found highest exposures during turning, shredding and screening of compost and in indoor composting areas Concentrations reduced markedly with distance from the site but 3 out of 9 studies measuring total bacteria and 2 of 8 studies measuring Aspergillus fumigatus exceeded acceptable levels beyond 250m downwind of the site as set by the Environment Agency It is unclear whether this has any significance for health as bioaerosols are widely present in the environment and levels are known to vary by day and by season There was wide variability in the measured concentrations on-site: Aspergillus fumigatus concentrations on-site ranged over 8 orders of magnitude, and total bacteria concentrations ranged over 5 orders of magnitude 4 studies exceeded Germany s Federal Institute for Occupational Safety and Health (BAuA) occupational limit of 50,000 cfu/m 3 limit for mesophilic fungus in breathable air in the workplace However, respiratory protection is recommended for compost site workers There are only a limited number of studies looking at health effects of bioaerosols emitted from composting facilities and several of the studies had some design flaws Most were short-term or cross-sectional in design and involved small numbers of people We identified 12 occupational studies examining health of compost workers and 6 community-based studies Occupational studies suggested slightly elevated risks of respiratory illnesses with higher bioaerosol exposures, which were supported in some studies by objective measures

4 of lung function and blood tests Community studies relied on questionnaire data, with residents nearer to sites more likely to report respiratory symptoms and odour complaints, but this may have been affected by bias in that those less happy to live near a composting site may be more likely to participate in the study and report problems We concluded more studies are needed with better and longer-term monitoring of bioaerosols exposures and larger health studies looking at potential health effects over longer timescales How does the (English) Environment Agency protect the public from bioaerosol exposures from composting sties? The Environment Agency published a position statement in 2010 with provisional guidance for composting operators when applying for an operating permit The guidance states that acceptable levels of bioaerosols, measured using the standardized sampling protocol, above upwind background concentrations, need to be maintained within 250m of the site boundary, or the nearest sensitive receptor (such as a dwelling or place of work), whichever is closer, to protect public health as bioaerosol concentrations are considered to generally reduce to near-background levels within 250m The acceptable levels are: 1000 cfu/m 3 for total bacteria 300 cfu/m 3 for gram-negative bacteria 500 cfu/m 3 for Aspergillus fumigatus It should be noted that these levels are guidelines, and are not based on dose-response relationships or health measures

5 This systematic review provides qualitative evidence of adverse health outcomes that is sufficient to justify a precautionary approach to prevent community exposures to elevated bioaerosol levels as adopted by the Environment Agency The current evidence certainly indicates that there are lower exposures beyond 250m compared with closer to site However, results from studies to date do not provide clear guidance as to where the distance boundaries from site should be placed, nor what elevation in bioaerosol levels is harmful It is unclear whether this has any significance for health as bioaerosols are widely present in the natural environment Normal concentrations of bioaerosols in the environment (background levels) are not well defined and these were not provided in many studies, which made the results harder to interpret How many papers did this study look at? The literature search terms retrieved 536 potentially relevant papers, of which 66 met the review inclusion terms There were 8 health studies: (6 occupational and 2 community studies), 48 exposure studies (38 occupational, 3 community and 6 occupational and community), and 10 studies which contained both health and exposure data (6 occupational and 4 community) Why were some studies excluded? All studies included in the review had to meet the following criteria: The study was published in English between January 1960 and July 2014 The study concerned exposure or health effects relating to bioaerosols (organisms and their cellular constituents) emitted from composting sites The study contained results relating to exposure measurements and/or health effects relating to monitored bioaerosol components

6 The study was either peer reviewed or was published by a recognized institution Studies were excluded if: They did not concern waste composting They did not concern bioaerosols They did not include any original data They were review papers, although the reference list of these was searched to identify any other potential relevant studies They were unavailable in English They were toxicological studies in animals Full texts were unavailable If the paper only concerned Microbial Volatile Organic Compounds (MVOCs) One case report study by Russell et al in of a man who contracted aspergillosis and eventually died shortly after handling mulch and compost was excluded 1 This is a notable study, as it received some media coverage This study was not included in the systematic review as it concerned a gardener handling mulch and compost and did not concern a compost worker or composting on an industrial scale A paper by Pankhurst et al 2 on bioaerosol emissions from urban community composting in 2011 was also excluded as it concerned small-scale community composting and not composting on an industrial scale

7 Does this study suggest I should be worried about handling compost in my garden? This was not investigated in our study This study only looked at large-scale industrial composting processes likely to involve much higher concentrations of bioaerosols I have asthma and live near a large composting plant, should I be concerned? Our study does now show any clear exposure-response relationship between exposure to bioaerosols emitted from large scale composting and onset of adverse health outcomes, including asthma The current evidence certainly indicates that there are lower exposures beyond 250m compared with closer to site If there is a composting plant within 250m of a residence or place of work then the Environment Agency do require the site to carry out a site specific bioaerosol risk assessment before they consider issuing an permit allowing the site to operate Public Health England is a useful resource to find out about potential health risks from environmental agents The NHS choices website is another useful resource for learning more about particular health conditions and their risk factors We suggest that you contact your GP, if you have any specific health concerns Who funded the study? 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

8 Have any other reviews been completed? Yes the most recent literature review on bioaerosols emissions from composting facilities was published by Wéry in , which provides a broad overview of the issues in this study area A more comprehensive report was conducted by the UK Institute of Occupational Medicine (IOM), in This reviewed literature on exposure and associated health effects from bioaerosols emissions from the waste management industry, which included but was not limited to composting These reviews were not systematic reviews Are there any differences between this study and the report conducted by the Institutes of Occupational medicine (IOM) by Searl in 2008? This review has refined and updated the report completed by IOM in 2008 The review completed by IOM was extensive but not fully systematic It reviewed literature on exposure and associated health effects from bioaerosols emissions from the waste management industry; this included but was not limited to waste composting Overall, the results reported in this systematic review are consistent with those previously reported by Searl (2008)

9 Reference list 1 Russell, K, Broadbridge, C, Murray, S, Waghorn, D, and Mahoney, A 2008 Gardening can seriously damage your health The Lancet Vol 371, No 9629, P Pankhurst, LJ, Akeel, U, Hewson, C, Maduka, I, Pham, P, Saragossi, J, Taylor, J and Lai KM 2011 Understanding and mitigating the challenge of bioaerosol emission from urban community composting Atmospheric Environment Vol 45, No1, P Wéry, N (2014) Bioaerosols from composting facilities a review Front Cekk Infect Microbiol 4: Searl, A 2008 Exposure-response Relationships for Bioaerosols Emissions from Waste Treatment Processes edited by Defra Edinburgh: Institute of Occupational Medicine Defra project WR0606 Available from n=none&completed=0&projectid=15140 Accessed 8 th January 2015 Further references Paper details Pearson, C, Littlewood, E, Douglas, P, Robertson, S, Gant, TW, and AL Hansell 2015 Exposures and health outcomes in relation to bioaerosol emissions from composting facilities: A systematic review of occupational and community studies Journal of Toxicology and Environmental Health, Part B Vol 18, No1, P The UK Small Area Health Statistics Unit (SAHSU) wwwsahsuorg

10 The MRC-PHE Centre for Environment and Health at Imperial College London and King s College London The Health Protection Research Unit in Health Impact of Environmental Hazards Current UK Guidance Environment agency position statement Composting and potential health effects from bioaerosols: our interim guidance for permit applicants HSE guidance on how to comply with the Control of Substances Hazardous to Health (COSHH) regulations to control exposure and protect workers health HSE guide on respiratory protective equipment

Final Report: Defra Project WR 1121 Bioaerosols and odour emissions from composting facilities. Authors: NPL

Final Report: Defra Project WR 1121 Bioaerosols and odour emissions from composting facilities Authors: Melanie Williams Baptiste Lamarre David Butterfield Sean Tyrrel Phil Longhurst Gillian Drew Reyna