Updated systematic review: associations between proximity to animal feeding operations and health of individuals in nearby communities

Abstract

ObjectiveThe objective of this review was to update a systematic review of associations between living near an animal feeding operation (AFO) and human health.MethodsThe MEDLINE® and MEDLINE® In-Process, Centre for Agricultural Biosciences Abstracts, and Science Citation Index databases were searched. Reference lists of included articles were hand-searched. Eligible studies reported exposure to an AFO and an individual-level human health outcome. Two reviewers performed study selection and data extraction.ResultsThe search returned 3702 citations. Sixteen articles consisting of 10 study populations were included in the analysis. The health outcomes were lower and upper respiratory tracts, MRSA, other infectious disease, neurological, psychological, dermatological, otologic, ocular, gastrointestinal, stress and mood, and other non-infectious health outcomes. Most studies were observational and used prevalence measures of outcome. An association between Q fever risk and proximity to goat production was reported. Other associations were unclear. Risk of bias was serious or critical for most exposure-outcome associations. Multiplicity (i.e., a large number of potentially correlated outcomes and exposures assessed on the same study subjects) was common in the evidence base.ConclusionsFew studies reported an association between surrogate clinical outcomes and AFO proximity for respiratory tract-related outcomes. There were no consistent dose-response relationships between surrogate clinical outcome and AFO proximity. A new finding was that Q fever in goats is likely associated with an increased Q fever risk in community members. The review results for the non-respiratory health outcomes were inconclusive because only a small number of studies were available or the between-study results were inconsistent.Systematic review registrationPROSPERO CRD42014010521 Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-017-0465-z) contains supplementary material, which is available to authorized users.

O’Connor et al. systematic review regarding animal feeding operations and public health: critical flaws may compromise conclusions

“…Conversely, the use of systematic reviews that suffer from critical design flaws or lack rigorous evaluation of the evidence may hurt public health. We have concern that the recently published systematic review by O’Connor and colleagues [ 6 ] on the associations between living near an animal-feeding operation (AFO) and human health falls into the latter category. Although the review integrates some best practice guidelines for conducting systematic reviews, such as developing and registering a protocol beforehand in PROSPERO, the review appears substantially flawed in its approach and conduct; the authors utilized a bias tool that is inappropriate for environmental health research, erroneously excluded important studies, and incorrectly interpreted others.…”

On the interpretation of bioaerosol exposure measurements and impacts on health

“…The variety of possible sources associated with these conditions leads to complex mixtures of microorganisms within bioaerosols emitted from farms (Douglas et al 2018;Gilbert and Duchaine 2009;Just et al 2011;Lanier et al 2010;Létourneau et al 2010;Milner 2009;Nehme et al 2008;Tsapko et al 2011). This dynamic microbial composition puts farm workers and nearby residents at higher risk for health issues such as accelerated declines in lung function, changes in blood pressure, nasal inflammation, secretory immunity, infectious diseases, and dermatological and gastrointestinal health problems (Iversen et al 2000;O'Connor et al 2010O'Connor et al , 2017Schiffman et al 2005). The respiratory health of farmers has been the subject of controversy given the recent hygiene hypothesis that stipulates that exposure to microbes resulting from intensive farming during early life could be beneficial to health later in life.…”

“…In indoor environments, concentrations of bioaerosols depend on human occupancy levels (indoor sources), building conditions, air exchange rate, and human activities, as well as outdoor concentrations (outdoor sources) (Buttner and Stetzenbach 1993;Ghosh et al 2013;Kulmala, Asmi, and Pirjola 1999;Nasir and Colbeck 2010). Moreover, bioaerosols at high concentrations could have an impact on people living in close proximity to a concentrated source, as bioaerosols can stay suspended in the air for long periods of time and can travel long distances depending on the size of the individual particles (O'Connor et al 2010(O'Connor et al , 2017.…”

Bioaerosols Play a Major Role in the Nasopharyngeal Microbiota Content in Agricultural Environment

“…Human exposure to bioaerosols is associated with a wide variety of acute and chronic diseases ranging from allergies, asthma, rhinitis, sinusitis and bronchitis, mostly due to occupational exposure [4,16,17,18,19]. However, health risks from bioaerosols also exist just from living in close proximity to an intensive source of airborne biological particles [20,21]. Additionally, other health problems linked to bioaerosols include fatigue, headache, mucous membrane irritation syndrome, nasal congestion, sore throat, and irritation of the nose and eyes [17,22,23].…”