Previously, we mentioned about how livestock production causes air pollution, particularly through the processes of enteric fermentation and manure management. We then discussed its implications on climate change.

This time, we would like to look at the health implications of livestock-induced air pollution!

 

Before we begin, it might be helpful if we can take a moment to consider this question:

To what extent are neighboring residents exposed to livestock-induced air pollution and what health problems do they encounter?

 

Implications on Human Health

On top of greenhouse gases (GHG) released by enteric fermentation and manure management, livestock production greatly reduces the quality of air of surrounding environment by emitting particulate matter (PM), microorganisms, dust, allergens and even odorous gases such as ammonia (NH3) and hydrogen sulfide (H2S) (Health Council of the Netherlands, 2012). Coupled with increasing concentration of livestock farms located nearer to residential areas, such proximity has raised various health implications on not only the farm workers, but also on the neighboring residents (Smit and Heederik, 2017).

Some of the potential health risks and concerns raised include respiratory disorders, infections with antimicrobial resistant bacteria and possibly even zoonotic infections (Smit and Heederik, 2017). As such, we would like to look at the various components of livestock-induced emissions that may result in potential health impacts on those living in close proximity to livestock farms.

 

Particulate Matter (PM)

Firstly, particulate matter is the most prominent type of emissions induced by livestock production. Agricultural activities are a significant source of PM2.5 in Europe, China and eastern USA. In the case of Europe, agricultural PM2.5 emissions are responsible about 55% of their anthropogenic air pollution, highlighting PM’s role in air pollution (Bauer, Tsigaridis and Miller, 2016).

Particulate matter is a collective term to describe air particles of varying sizes, sources and chemical compositions. The smaller these particles are, the deeper they can penetrate through into our lungs, which is to say, they can pass through the larynx when breathed in.

In particular, studies on PM2.5 and ultrafine particles have shown a clear exposure-effect relationship for deteriorating lung function, worsening of respiratory problems and even the potential to cause early mortality in the case of respiratory tract disorders and cardiovascular disease (Health Council of the Netherlands, 2012; Smit and Heederik, 2017). With particulate matter from livestock emissions diminishing the quality of air in the vicinity, it is no doubt that close proximity to livestock farms and exposure to the emissions may entail a certain risk level of respiratory problems.

 

Endotoxins

Next, endotoxins are also of concern when it comes to livestock emissions. Endotoxins are part of the outer membrane of the cell walls of gram-negative bacteria. Gram-negative bacteria are often more harmful than the gram-positive bacteria. In fact, endotoxins often constitute in the coarser composition of particulate matter, adding on to the potential risks entailed by livestock-induced PM emissions.

Studies have shown that increased endotoxins levels have been measured up to distances of about 250m away from farms, highlighting that proximity is therefore likely to play a role heightening certain health risk levels (Health Council of the Netherlands, 2012). It is also found that increased and prolonged endotoxins exposure have acute effects on lung functions (Wallace et al., 2016). As such, in the case of endotoxins, on top of farm workers being affected, having a close proximity to livestock areas also do imply a greater potential of health risks.

With concerns raised about increased endotoxin levels, new health advisories then responded and recommended an exposure limit of 90IU/m^3 for farm workers, whereas concentrations below this measurement level is deemed to pose no risk to worker’s health.

(*IU: International Unit)

 

With that, I will end today’s post here. Stay tuned for the next post as we find out about the other aspects!

 

Defective Out,

Linying

 

References

Bauer, S. E., Tsigaridis, K. and Miller, R. (2016). Significant atmospheric aerosol pollution caused by world food cultivation. Geophysical Research Letters, 43, 5394-5400. Retrieved from: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL068354

Health Council of the Netherlands (2012). Health risks associated with livestock farms. The Netherlands: Health Council of the Netherlands. Retrieved from: https://www.healthcouncil.nl/binaries/healthcouncil/documents/advisory-reports/2012/11/30/health-risks-associated-with-livestock-farms/advisory-report-health-risks-associated-with-livestock-farms.pdf

May, S., Romberger, D. J. and Poole, J. A. (2014). Respiratory health effects of large animal farming environments. J Toxicol Environ Health B Crit Rev., 15(8), 524–541. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001716/

Smit, L. A. M. & Heederik, D. (2017, Sep 27). Impacts of intensive livestock production on human health in densely populated regions. Geohealth, 1(7), 272-277. Retrieved from: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GH000103

Wallace et al. (2016). Risks associated with endotoxins in feed additives produced by fermentation. Environ Health, 15(5). Retrieved from: https://ehjournal.biomedcentral.com/articles/10.1186/s12940-016-0087-2#citeas