Imperial College London


Faculty of MedicineSchool of Public Health

Visiting Researcher Association



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Publication Type

11 results found

Robertson S, Douglas P, Jarvis D, Marczylo Eet al., 2019, Bioaerosol exposure from composting facilities and health outcomes in workers and in the community: a systematic review update, International Journal of Hygiene and Environmental Health, Vol: 222, Pages: 364-386, ISSN: 1438-4639

BackgroundRapid population growth and urbanisation around the world has led to increasing waste generation rates. Composting of organic waste in large-scale facilities is part of a growing trend in the UK, and elsewhere, to better manage and re-use the organic waste. However, composting inevitably generates bioaerosols, which have been associated with human health effects. In 2015, we reported that there was some, albeit limited, qualitative evidence linking bioaerosol emissions from composting facilities to poor respiratory health in nearby residents. However, the limited evidence precluded any quantitative assessment. Since then, the number of operational industrial-scale composting facilities in England has increased by 9% - nearly twice the growth from 2012-2014. At the same time, rapid urbanisation has led to expansion of city borders with more people living near large composting facilities and exposed to bioaerosol pollution. It is essential that regulatory authorities have access to the most up to date and accurate information. ObjectiveIn this update of a systematic review published in 2015, we review and summarise the evidence from more recent studies that have assessed bioaerosol exposures within and near composting facilities and their associated health effects in both community and occupational health settings. Specifically, we wanted to find out if new evidence has emerged since the previous review to strengthen and confirm its conclusions. Material and methodsTwo electronic databases (Medline and Embase) and bibliographies were searched for studies reporting on health outcomes and/or exposure to bioaerosols from composting facilities published between 1 January 2014 and 15 June 2018. Identification of relevant articles and data extraction was undertaken and studies were assessed for risk of bias. Results 23 studies met the inclusion criteria (15 exposure studies, 4 health studies, 4 health and exposure studies (one of which used an exposure

Journal article

Williams B, Douglas P, Roca Barcelo A, Hansell A, Hayes Eet al., 2019, Estimating Aspergillus fumigatus exposure from outdoor composting activities in England between 2005-14, Waste Management, Vol: 84, Pages: 235-244, ISSN: 1879-2456

Bioaerosols, ubiquitous in ambient air, are released in elevated concentrations from composting facilities with open-air processing areas. However, spatial and temporal variability of bioaerosols, particularly in relation to meteorology, is not well understood. Here we model relative concentrations of Aspergillus fumigatus at each postcode-weighted centroid within 4 km of 217 composting facilities in England between 2005 and 2014. Facilities were geocoded with the aid of satellite imagery. Data from existing bioaerosol modelling literature were used to build emission profiles in ADMS. Variation in input parameters between each modelled facility was reduced to a minimum. Meteorological data for each composting facility was derived from the nearest SCAIL-Agriculture validated meteorological station. According to our results, modelled exposure risk was driven primarily by wind speed, direction and time-varying emissions factors incorporating seasonal fluctuations in compostable waste. Modelled A.fumigatus concentrations decreased rapidly from the facility boundary and plateaued beyond 1.5–2.0 km. Where multiple composting facilities were within 4 km of each other, complex exposure risk patterns were evident. More long-term bioaerosol monitoring near facilities is needed to help improve exposure estimation and therefore assessment of any health risks to local populations.

Journal article

Ghosh RE, Freni-Sterrantino A, Douglas P, Parkes B, Fecht D, de Hoogh K, Fuller G, Gulliver J, Font A, Smith RB, Blangiardo M, Elliott P, Toledano MB, Hansell ALet al., 2019, Fetal growth, stillbirth, infant mortality and other birth outcomes near UK municipal waste incinerators; retrospective population based cohort and case-control study, Environment International, Vol: 122, Pages: 151-158, ISSN: 0160-4120

Background: Some studies have reported associations between municipal waste incinerator (MWI) exposures and adverse birth outcomes but there are few studies of modern MWIs operating to current European Union (EU) Industrial Emissions Directive standards. Methods: Associations between modelled ground-level particulate matter ≤10 μm in diameter (PM10) from MWI emissions (as a proxy for MWI emissions) within 10 km of each MWI, and selected birth and infant mortality outcomes were examined for all 22 MWIs operating in Great Britain 2003–10. We also investigated associations with proximity of residence to a MWI. Outcomes used were term birth weight, small for gestational age (SGA) at term, stillbirth, neonatal, post-neonatal and infant mortality, multiple births, sex ratio and preterm delivery sourced from national registration data from the Office for National Statistics. Analyses were adjusted for relevant confounders including year of birth, sex, season of birth, maternal age, deprivation, ethnicity and area characteristics and random effect terms were included in the models to allow for differences in baseline rates between areas and in incinerator feedstock. Results: Analyses included 1,025,064 births and 18,694 infant deaths. There was no excess risk in relation to any of the outcomes investigated during pregnancy or early life of either mean modelled MWI PM10 or proximity to an MWI. Conclusions: We found no evidence that exposure to PM10 from, or living near to, an MWI operating to current EU standards was associated with harm for any of the outcomes investigated. Results should be generalisable to other MWIs operating to similar standards.

Journal article

Douglas P, Robertson S, Gay R, Hansell AL, Gant TWet al., 2017, A systematic review of the public health risks of bioaerosols from intensive farming, International Journal of Hygiene and Environmental Health, Vol: 221, Pages: 134-173, ISSN: 1438-4639

BACKGROUND: Population growth, increasing food demands, and economic efficiency have been major driving forces behind farming intensification over recent decades. However, biological emissions (bioaerosols) from intensified livestock farming may have the potential to impact human health. Bioaerosols from intensive livestock farming have been reported to cause symptoms and/or illnesses in occupational-settings and there is concern about the potential health effects on people who live near the intensive farms. As well as adverse health effects, some potential beneficial effects have been attributed to farm exposures in early life. The aim of the study was to undertake a systematic review to evaluate potential for adverse health outcomes in populations living near intensive livestock farms. MATERIAL AND METHODS: Two electronic databases (PubMed and Scopus) and bibliographies were searched for studies reporting associations between health outcomes and bioaerosol emissions related to intensive farming published between January 1960 and April 2017, including both occupational and community studies. Two authors independently assessed studies for inclusion and extracted data. Risk of bias was assessed using a customized score. RESULTS: 38 health studies met the inclusion criteria (21 occupational and 1 community study measured bioaerosol concentrations, 16 community studies using a proxy measure for exposure). The majority of occupational studies found a negative impact on respiratory health outcomes and increases in inflammatory biomarkers among farm workers exposed to bioaerosols. Studies investigating the health of communities living near intensive farms had mixed findings. All four studies of asthma in children found increased reported asthma prevalence among children living or attending schools near an intensive farm. Papers principally investigated respiratory and immune system outcomes. CONCLUSIONS: The review indicated a potential impact of intensive farming on chil

Journal article

Douglas P, Hayes ET, Williams WB, Tyrrel SF, Kinnersley RP, Walsh K, O'Driscoll M, Longhurst PJ, Pollard SJT, Drew GHet al., 2017, Use of dispersion modelling for Environmental Impact Assessment of biological air pollution from composting: Progress, problems and prospects., Waste Management, Vol: 70, Pages: 22-29, ISSN: 1879-2456

With the increase in composting asa sustainable waste management option, biological air pollution (bioaerosols) from composting facilities have become a cause of increasing concern due to their potential health impacts. Estimating community exposure to bioaerosols is problematic due to limitations in current monitoring methods. Atmospheric dispersion modelling can be used to estimate exposure concentrations, however several issues arise from the lack of appropriate bioaerosol data to use as inputs into models, and the complexity of the emission sources at composting facilities. This paper analyses current progress in using dispersion models for bioaerosols, examines the remaining problems and provides recommendations for future prospects in this area. A key finding is the urgent need for guidance for model users to ensure consistent bioaerosol modelling practices.

Journal article

Douglas P, Freni-Sterrantino A, Leal Sanchez M, Ashworth DC, Ghosh RE, Fecht D, Font A, Blangiardo M, Gulliver J, Toledano MB, Elliott P, De Hoogh K, Fuller GW, Hansell ALet al., 2017, Estimating Particulate Exposure from Modern Municipal Waste Incinerators in Great Britain, Environmental science & technology, Vol: 51, Pages: 7511-7519, ISSN: 0013-936X

Municipal Waste Incineration (MWI) is regulated through the European Union Directive on Industrial Emissions (IED), but there is ongoing public concern regarding potential hazards to health. Using dispersion modeling, we estimated spatial variability in PM10 concentrations arising from MWIs at postcodes (average 12 households) within 10 km of MWIs in Great Britain (GB) in 2003-2010. We also investigated change points in PM10 emissions in relation to introduction of EU Waste Incineration Directive (EU-WID) (subsequently transposed into IED) and correlations of PM10 with SO2, NOx, heavy metals, polychlorinated dibenzo-p-dioxins/furan (PCDD/F), polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. Yearly average modeled PM10 concentrations were 1.00 × 10-5 to 5.53 × 10-2 μg m-3, a small contribution to ambient background levels which were typically 6.59-2.68 × 101 μg m-3, 3-5 orders of magnitude higher. While low, concentration surfaces are likely to represent a spatial proxy of other relevant pollutants. There were statistically significant correlations between PM10 and heavy metal compounds (other heavy metals (r = 0.43, p = <0.001)), PAHs (r = 0.20, p = 0.050), and PCBs (r = 0.19, p = 0.022). No clear change points were detected following EU-WID implementation, possibly as incinerators were operating to EU-WID standards before the implementation date. Results will be used in an epidemiological analysis examining potential associations between MWIs and health outcomes.

Journal article

Tao F, Abdallah MA-E, Ashworth DC, Douglas P, Toledano MB, Harrad Set al., 2017, Emerging and legacy flame retardants in UK human milk and food suggest slow response to restrictions on use of PBDEs and HBCDD, Environment International, Vol: 105, Pages: 95-104, ISSN: 0160-4120

The legacy flame retardants (LFRs) polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), together with six emerging flame retardants (EFRs) were measured in United Kingdom (UK) human milk collected in 2010 (n = 25) and 2014–15 (n = 10). These data are the first report of the presence of EFRs in UK human milk. The most abundant EFR was β-tetrabromoethylcyclohexane (DBE-DBCH) (average = 2.5 ng/g lw; geometric mean = 1.5 ng/g lw), which is comparable to the concentrations of the most abundant LFRs i.e. BDE 47 and α-HBCDD at 2.8 and 2.1 ng/g lw, respectively (geometric mean = 2.1 and 1.7). The estimated median dietary intake of ΣEFRs by UK nursing infants was 18 ng/kg bw/day. EFRs were also measured in UK foodstuffs with β-DBE-DBCH again the predominant compound detected, accounting – on average – for 64.5 ± 23.4% of ΣEFRs. Average estimated dietary intakes of ∑ EFRs in the UK were 89 and 26 ng/day (1.3 and 2.6 ng/body weight/day) for adults and toddlers, respectively. Concentrations of Σtri-hexa BDEs in our UK food samples exceeded those reported in UK samples from the same food categories collected in 2003–04 and 2006. Despite this and our recent report elsewhere of significant temporal declines in concentrations of BDE 209 in UK indoor dust (p < 0.05) and HBCDDs in UK indoor dust and air (p < 0.001), no significant temporal differences (p > 0.05) were observed between concentrations of Σtri-hexa BDEs, BDE 209 and HBCDDs in human milk sampled in 2010 and those obtained in 2014–15. UK adult body burdens for EFRs were predicted via inhalation, diet and dust ingestion using a simple pharmacokinetic model. The predicted EFR body burdens compared well with observed concentrations in human milk.

Journal article

Douglas P, Tyrrel SF, Kinnersley RP, Whelan M, Longhurst PJ, Walsh K, Pollard SJT, Drew GHet al., 2016, Sensitivity of predicted bioaerosol exposure from open windrow composting facilities to ADMS dispersion model parameters, JOURNAL OF ENVIRONMENTAL MANAGEMENT, Vol: 184, Pages: 448-455, ISSN: 0301-4797

Journal article

Douglas P, Tyrrel SF, Kinnersley RP, Whelan M, Longhurst PJ, Hansell AL, Walsh K, Pollard SJ, Drew GHet al., 2016, Predicting Aspergillus fumigatus exposure from composting facilities using a dispersion model: A conditional calibration and validation., International Journal of Hygiene and Environmental Health, Vol: 220, Pages: 17-28, ISSN: 1618-131X

Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are unclear. Exposure levels are difficult to quantify as established sampling methods are costly, time-consuming and current data provide limited temporal and spatial information. Confidence in dispersion model outputs in this context would be advantageous to provide a more detailed exposure assessment. We present the calibration and validation of a recognised atmospheric dispersion model (ADMS) for bioaerosol exposure assessments. The model was calibrated by a trial and error optimisation of observed Aspergillus fumigatus concentrations at different locations around a composting site. Validation was performed using a second dataset of measured concentrations for a different site. The best fit between modelled and measured data was achieved when emissions were represented as a single area source, with a temperature of 29°C. Predicted bioaerosol concentrations were within an order of magnitude of measured values (1000-10,000CFU/m(3)) at the validation site, once minor adjustments were made to reflect local differences between the sites (r(2)>0.7 at 150, 300, 500 and 600m downwind of source). Results suggest that calibrated dispersion modelling can be applied to make reasonable predictions of bioaerosol exposures at multiple sites and may be used to inform site regulation and operational management.

Journal article

Douglas P, Bakolis I, Fecht D, Pearson C, Leal Sanchez M, Kinnersley R, de Hoogh K, Hansell Aet al., 2016, Respiratory hospital admission risk near large composting facilities, International Journal of Hygiene and Environmental Health, Vol: 219, Pages: 372-379, ISSN: 1618-131X

BackgroundLarge-scale composting can release bioaerosols in elevated quantities, but there are few studies of health effects on nearby communitiesMethodsA cross-sectional ecological small area design was used to examine risk of respiratory hospital admissions within 2500 m of all 148 English large-scale composting facilities in 2008–10. Statistical analyses used a random intercept Poisson regression model at Census Output Area (COA) level (mean population 310). Models were adjusted for age, sex, deprivation and tobacco sales.ResultsAnalysing 34,963 respiratory hospital admissions in 4656COAs within 250–2500 m of a site, there were no significant trends using pre-defined distance bands of >250m-750m, >750–1500 m and >1500-2500m. Using a continuous measure of distance, there was a small non-statistically significant (p = 0.054) association with total respiratory admissions corresponding to a 1.5% (95% CI: 0.0–2.9%) decrease in risk if moving from 251 m to 501m. There were no significant associations for subgroups of respiratory infections, asthma or chronic obstructive pulmonary disease.ConclusionThis national study does not provide evidence for increased risks of respiratory hospital admissions in those living beyond 250 m of an outdoor composting area perimeter. Further work using better measures of exposure and exploring associations with symptoms and disease prevalence, especially in vulnerable groups, is recommended to support regulatory approaches.

Journal article

Pearson C, Littlewood E, Douglas P, Robertson S, Gant TW, Hansell ALet al., 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: Critical Reviews, Vol: 18, Pages: 43-69, ISSN: 1093-7404

The number of composting sites in Europe is rapidly increasing, due to efforts to reduce the fraction of waste destined for landfill, but evidence on possible health impacts is limited. This article systematically reviews studies related to bioaerosol exposures within and near composting facilities and associated health effects in both community and occupational health settings. Six electronic databases and bibliographies from January 1960 to July 2014 were searched for studies reporting on health outcomes and/or bioaerosol emissions related to composting sites. Risk of bias was assessed using a customized score. Five hundred and thirty-six papers were identified and reviewed, and 66 articles met the inclusion criteria (48 exposure studies, 9 health studies, 9 health and exposure studies). Exposure information was limited, with most measurements taken in occupational settings and for limited time periods. Bioaerosol concentrations were highest on-site during agitation activities (turning, shredding, and screening). Six studies detected concentrations of either Aspergillus fumigatus or total bacteria above the English Environment Agency’s recommended threshold levels beyond 250 m from the site. Occupational studies of compost workers suggested elevated risks of respiratory illnesses with higher bioaerosol exposures. Elevated airway irritation was reported in residents near composting sites, but this may have been affected by reporting bias. The evidence base on health effects of bioaerosol emissions from composting facilities is still limited, although there is sufficient evidence to support a precautionary approach for regulatory purposes. While data to date are suggestive of possible respiratory effects, further study is needed to confirm this and to explore other health outcomes.Waste management policy is rapidly evolving, largely because European countries are running out of space for landfill sites. Further, poor waste management contributes to climate cha

Journal article

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