3.12.2014

Beach water sampling on the decline. What about the sand?

Last month, I looked at a study that identified the potential for using qPCR as a technique to identify pathogens in bathing water, and stated that it would be a lot faster than culturing samples, but there were potential cost implications. Since more and more of the water sampling is being put onto local governments (rather than the regional health authorities), the costs of undertaking new practices are not going to be undertaken lightly.

Now there's evidence that simply sampling the bathing water and enumerating pathogens (by whatever means) isn't necessarily sufficient or best for identifying potential public health concerns with recreational water. A group of experts at the "Microareias 2012" workshop in Portugal convened to discuss the potential for public health concerns within bathing beaches, and how to best monitor and remedy these concerns. Given that the vast history of public health protection around beaches has focused on injury prevention and bathing water quality, moving into a realm where public health practitioners are looking at the sand itself as a potential source of pathogens is truly groundbreaking.

The paper states a lack of legislation in the EU and USA for minimum indicator organism levels in sand, and Canada is no different. The "Guidelines for Canadian Recreational Water Quality" section on sampling location simply talks about water samples. Given that some of the aspects that can affect water quality negatively originate on the beach itself (e.g. feces from waterfowl), it makes sense that some consideration should be given to pathogens in the sand.

The expert group recommended that beach sand monitoring should be implemented alongside existing bathing water monitoring, and that consistent protocols for sampling and pathogen identification be developed to ensure adequate comparisons of public health risk between locations. This is similar to the need for protocols when changing from a culture-based sampling of beach water to a qPCR (or similar molecular) sampling regime. The group also recommended that more research be done in the potential effects of "contaminated" beach sand on public health.

The concerns I wrote about when discussing qPCR hold equally true when discussing new ways of identifying public health risks. When local governments are doing their own recreational water sampling, they likely won't have public health practitioners on-staff to make recommendations on new and unique methods of identifying risks to public health. Given the lack of research, it's also unlikely that the Federal government will make any changes to their guidelines to represent the potential risk sand may pose. The province of B.C. does not have any of its own legislation around beach water quality, but simply works from the above-mentioned Federal guidelines, so it's even more unlikely that a local or provincial initiative would start the science moving in this direction.

This study highlights one of the fundamental difficulties with public health protection: while the science marches forward at a rapid rate, the legislation and enforcement is slow to catch up. The use of culture-based sampling for E. coli and enterococcus is such a timeless method for identifying bacterial risks to public health in bathing water that convincing stakeholders (federal/provincial legislators, regional health authorities, local governments) to undertake something new and unproven is near impossible.

Source: Sabino, R., Rodrigues, R., Costa, I., Carneiro, C., Cunha, M., Duarte, A., ... Brandão, J. (2014, 12). Routine screening of harmful microorganisms in beach sands: Implications to public health. Science of The Total Environment, 472, 1062-1069.
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