Environmental Science: Processes & Impacts blog

Choosing how we get to work is often based on money, time and local infrastructure; however Kam et al. have studied how this choice may also impact commuter’s exposure to pollutants and potential health risks.

This paper looks at the concentrations of a variety of particulate matter including metals and trace elements, using inductively coupled plasma mass spectrometry, and polyaromatic hydrocarbons (PAHs), via gas chromatography.  All of the compounds studied have been linked to life threatening conditions such as cancer, cardiovascular diseases and neurodegenerative disorders.

The sampling regime takes account of a variety of commuting methods in Los Angeles such as the subway, surface ‘light’ railway and a variety vehicular routes including a freeway, a surface-level street and a route used frequently by heavy duty vehicles (HDVs).

The compound profiles identified in the study fitted well with those predicted for each transport mode.  For example iron, associated with stainless steel and mechanical wear, was highest in the subway, lead and other elements associated with fuel use and vehicular traffic were higher in the road samples and elements which are greatly influenced by the environment, e.g. sodium, did not differ between the modes.  However the results also point to a more complex picture than this suggests with the season, location of the transportation and other transport users also playing significant roles in the exposure model.

Kam et al. also compared the relative potencies and unit risk factors of each individual PAH to estimate the cancer risk for commuters.  Road users were at greater risk from this pathway, particularly users of roads which have a higher HDV use.

This highly detailed study not only provides an insight into the potential long term health risks which may be associated with commuting, but is relevant to any group who lives near, works in or is routinely using these transport modes.  It also highlights the complexity involved in carrying out studies of this kind and interpreting environmental exposures.  It’s free to access* on our site for the next four weeks, so why not download the paper here:

A comparative assessment of PM2.5 exposures in lightrail, subway, freeway, and surface street environments in Los Angeles and estimated lung cancer risk
Winnie Kam, Ralph J. Delfino, James J. Schauer and C. Sioutas
DOI: 10.1039/c2em30495c

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

Published on behalf of Sian Evans, Environmental Science: Processes and Impacts web science writer. Sian is a PhD student based in Bath, United Kingdom

Sewage contains a myriad of potentially life threatening chemical and biological matter.  This paper shows studying sewage is crucial to understanding its threat, but it can also unlock potential epidemiological information.

Disposing of sewage appropriately is one of the most important life-saving technologies that exist, however processing such waste poses health risks.  Some of the hazards associated with sewage are from adenoviruses, which can be infectious through direct contact, ingestion and aerosol exposure; a particular concern as solid material from sewage plants is often disposed of as agricultural fertiliser.  Previous studies have focussed on single adenovirus species or grouped them together; however the seven main species all possess unique symptoms when contracted.  Bibby and Peccia have therefore used PCR and primers able to distinguish between the species to amplify DNA from samples of sewage influent and effluent.

The results revealed that the adenovirus-C was most abundant, responsible for respiratory symptoms, followed by adenovirus-B, also associated with respiratory illnesses as well as urinary infections.  It should be noted though that increased virus abundance does not necessarily correlate with increased infectious risk.  Interestingly, wastewater treatment had no impact on the virus numbers, showing treated solid waste, spread on agricultural land, poses an equal risk as raw influent from adenoviruses.

Whilst providing information for risk assessments this data also lends support to the notion that sewage contains a great amount of information regarding its source population, negating the need for, and potential flaws in, medical data.  In this case, adenovirus C and B, the most abundant in the sewage, are also the most abundantly reported infections within the population. 

This work is of interest to a variety of people including those involved in human health risk assessments, gene amplification, sewage treatment and disposal and sewage epidemiology it’s free to access* on our site for the next four weeks, so why not download the paper here:

Prevalence of respiratory adenovirus species B and C in sewage sludge
Kyle Bibby and Jordan Peccia
DOI: 10.1039/c2em30831b

*Free access to individuals is provided through an RSC Publishing personal account. Registration is quick, free and simple

Published on behalf of Sian Evans, Environmental Science: Processes and Impacts web science writer. Sian is a PhD student based in Bath, United Kingdom