Transcript ISEE Young conference Utrecht November 2015

Exposures and health outcomes in relation to bioaerosol
emissions from composting facilities: A systematic review
of occupational and community studies
Philippa Douglas1, Clare Pearson1, Emma Littlewood1, Sarah Robertson2, Tim Gant2 and Anna Hansell1,3
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
BACKGROUND
OCCUPATIONAL EXPOSURE STUDIES
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 (PM10) and byproducts of cells, and have the potential to harm human health (2).
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/m3 limit for mesophilic fungus.
METHODS
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.
Figure 3. Mean/median airborne total bacteria (top) and Aspergillus
fumigatus (bottom) concentrations in occupational exposure studies
Figure 1. Study inclusion and exclusion criteria
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
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. Questionnairebased studies gave a high risk of response bias.
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/m3 respectively beyond 250m
downwind of the site.
Figure 2. Mean/median airborne total bacteria concentrations in
community exposure studies
If provided in the study, the range of values included is denoted by the error bars
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)
REFERENCES
1. Wheeler PA et al. 2001. 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. 1997. Work related acute and (sub-) chronic airways inflammation assessed by nasal lavage in compost workers. Ann Agric Environ
Med 4:149-152.
3. Moher D et al. 2009. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. Ann Intern Med151:264-269.
4. Stroup DF et al. 2000. Meta-analysis of observational studies in epidemiology.J Am Med Assoc 283; 2008-12.
MRC-PHE Centre for Environment and Health
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.
www.environment-health.ac.uk