Variations in setback distances from sewerage systems: one size doesn't fit all

It's often too easy to assign a "safe" setback distance from a source of contamination when considering the installation of a new drinking water source. In B.C., that setback is set forth in the Sewerage System Regulation, and states that an onsite sewerage system can't be installed closer than 30m from a drinking water supply (unless a hydrogeologist is willing to say that there's no risk to reducing it). This distance of 30m, or 100', is fairly common: it's also used by Maine, Massachusetts, California, etc. In a province as diverse and large as B.C., however, this singular measure does not take into account the soil and climate differences that might prevent wastewater from being adequately treated before it makes it to somebody's tap.

After a Norovirus outbreak in Iceland, which was traced back to contaminated drinking water, a group of researchers set out to identify whether there were some considerations for setback distances that weren't being accounted for. The outbreak in question occurred in late summer at a location frequented by tourists and those who owned summer property, with the drinking water being drawn from a well. Due to a few different factors, which will be discussed further on, the minimum setback required for a 9-log reduction in viral load was nearly 900m. That's 30x the setback in the B.C. legislation!

According to this specific study, approximately 1/3 of waterborne outbreaks in affluent nations are due to sewage contamination of groundwater. We assume that a combination of deep drilled wells and relatively slow-moving soils will allow for adequate filtration of the waste water to ensure the effluent entering the aquifer is treated. However, what this doesn't account for are the aspects of soil chemistry that can affect the filtration rate. For instance, viruses travel longer distances in cold groundwater. The groundwater in the Iceland study was around 5'C, which can lead to an inactivation rate for viruses of 1 order of magnitude lower than ground water at 25'C. The researchers point out that not many studies have focused on the relationship between groundwater temperature and viral inactivation.

To properly identify a safe distance between a sewerage system and a well, it's important to consider more than just soil grain size. It's also necessary to look at groundwater temperature, seepage velocity, and soil acidity to determine how long it will take to adequately neutralize the wastewater. The researchers suggest that looking at travel times (e.g. 50 days) may be more reasonable than simply looking at setback distances.

I mentioned above that a 9-log reduction in viral load would've required a setback of 900m in this specific case study. While B.C. legislation has no requirements for reduction of viruses, the Guidelines for Canadian Drinking Water Quality speak to a minimum 4-log reduction of viruses in treatment systems. Since most groundwater systems don't have subsequent treatment (because of their inherent safety), one could attribute a 4-log reduction in soil to being adequate as well. Given all the various parameters that must be considered to determine viral inactivation, it's nearly impossible to say "this setback distance throughout B.C. will lead to a 4-log reduction in viruses".

The summary of this study was that a) the setback distance between the well and the hotel's septic system was inadequate to provide safe drinking water, and that subsequent treatment was necessary, and b) that a lot more research needs to be done to determine how various soil chemistry factors affect wastewater treatment in vivo. Simply saying "it's 30m away, so it's safe" isn't an adequate means of protecting public health, without considering what happens in those 30m.

Source: Gunnarsdottir, M.J., Gardarsson, S.M., & Andradottir, H.O. (2013). Microbial contamination in groundwater supply in a cold climate and coarse soil: case study of Norovirus outbreak at Lake Mÿvatn, Iceland. Hydrology Research, 44(6), 1114-1128.


Food safety in developing countries

I've written a couple of recent articles about street food in developing nations (Brazil and Nigeria, specifically), and the evidence was pretty overwhelming that there's a lack of formal food safety training in these countries, which leads to mediocre food handling practices and increases food safety concerns. A study in Critical Reviews in Microbiology took a broader look at food safety practices in developing countries by performing a thorough literature search, and highlighted some of the concerns with the current system.

One of the first things they pointed out is that food safety is "well recognized" as a primary indicator of economic growth in the developing world. In other words, it's not only important to ensure a safe food supply for health reasons, but also for economic reasons. The cost of health care treatment, missed employment, and lowered production are all financial reasons for improved food safety systems. While countries like the U.S.A. and Canada closely track the economic impacts of food-related outbreaks, and can identify specific numbers of specific illnesses, the researchers found no such data for developing nations. Besides the fact that the majority of food-borne illnesses go unreported (everywhere, not just in developed countries), there's also a lack of formalized surveillance programs in developed countries that could identify these cases and outbreaks. The lack of information is actually representative of a problem unto itself: you can't manage what you can't measure. Without the surveillance systems in place, knowing where to start a food safety program in a developed country would be guess-work, at best.

The authors estimate that 1.8 million children die from diarrheal diseases in developing countries every year. The lack of potable water, adequate medications, and inappropriate hygiene all contribute to an inability to adequately prevent diarrhea from becoming deadly. The lack of post-exposure solutions highlights the importance of preventative systems to ensure diarrhea is not contracted in the first place. Unfortunately, while "improved hygiene, sanitation, and awareness" would lead to reduced illness, death, and economic burdens in developing nations, the fact remains that "poor food supply systems and microbiological contamination" are rampant. Specifically, the authors highlight that "microbiological contamination ... has been identified as a potential cause of food-borne illness in Latin American countries", and that "Argentina has the highest incidence of HUS (hemolytic uremic syndrome) in the world".  They also referenced a study in which Brazilian chickens were analyzed for Salmonella contamination, which found antibiotic resistant strains of S. enteritidis and S. infantis. So, not only does the microbial contamination exist, it exists in a form that would be nearly impossible to quickly and properly treat in developed countries.

Tying in with the street food studies that I've recently written about, Akhtar, Sarker, & Hossain point out that "street vending of foods is believed to be a potential cause of illness and thus needs to be precisely focused". This echoes what the other studies have suggested as well: street food brings about some unique challenges to safe food handling, and hazard management needs to be able to mitigate these specific dangers. When considering the economic benefits of street food that were identified in Nigeria & Brazil, this paper's commentary on the detriments of food-borne illnesses to developing nation's economies makes even more sense. In these nations where street food is considered a great way for females to make money and provide for their families, lack of controls and food safety programs could derail the entire system.

So, while it's clear what needs to be done, why hasn't it happened yet? Akhtar et al indicate an "absence of political commitment, intervention of international agencies, awareness, and strict legislation". Political commitment is clearly one of the most important first steps that needs to occur, however. Agencies like the UN and WHO are unable to provide anything more than information and basic guidance unless the leaders of these developing nations are willing and able to commit to specific food safety programs. Education, legislation, and funding for enforcement all need to be in place before change can occur. It may be a difficult sell to convince poor nations to provide funding to preventative measures, but with further research into the true economic cost of food-borne illnesses in developed countries, a strong case could be made that prevention is the best medicine.

Source: Akhtar, S., Sarker, M.R., & Hossain, A. (2014). Microbiological food safety: a dilemma of developing societies. Critical Reviews in Microbiology, 40(4), 348-359.


Food safety & socioeconomic considerations of Brazil's street food industry

Previously, I looked at food safety in the Nigerian street food market, where research indicated that there was a lack of food safety knowledge among street food vendors, and this was likely correlated with a lack of formalized food safety training in that country. A new study looks at street food in Salvador, Brazil, and focuses not only in the food safety implications of the industry, but also on its contributions to the economy.

Similar to the demography of Nigerian street food vendors, the majority of those (56%) in Salvador were found to be women. Street food plays an important role in the economy in many lower-income regions, as it allows a source of income for women (who often are the head of household in lower income families), and also provides affordable food to low-income consumers. In Salvador, because the street food is positioned near the beach, it largely caters to out-of-town visitors, allowing 95% of the vendors to earn up to $186USD per day; the average income of the vendors was between 1 and 3 times the Brazilian minimum wage. Interestingly, though the majority of vendors were female, females were found to have an income slightly lower than their male counterparts.

The average (mean) age of the vendors was 40 years old, showing that this is a group of individuals who would otherwise be in the workforce in some other way. Again, showing the importance of street food to the economy, 54% of vendors were the heads of their families, with street food being the sole source of income. 86% of vendors were their own bosses, and 34% worked every day of the week. Interestingly, 46% of vendors only worked on weekends, presumably when there would be more patrons visiting the beach.

The other aspect of the study was food safety habits among the vendors. Similarly to Nigeria, hand washing was essentially non-existent: 23% of vendors reported that they "never" washed their hands, while only 41% washed their hands "often". As there are no sanitary facilities available at the beach, those vendors who did wash their hands had to rely on water brought from home, or in certain cases, sea water. Most vendors did bring water from home for use in their food sales, with 92% using it to drink, and only 61% using it for hand washing. Less than 30% of vendors were found to be sanitizing their food preparation surfaces and equipment, and the majority of perishable food items were not stored properly. I found it somewhat humorous that 82% of vendors stored beverages in Styrofoam coolers to keep them cold, but only 38% stored potentially hazardous food items in the same way.

Since the removal of food kiosks at the Salvador beach, street food has become essentially the only place to eat. The data from this study shows that there's clearly a market for street food in the area, allowing vendors to make a relatively decent income, and provide for their families. Given the economic importance of the industry, logical next steps would implementing some food safety measures to ensure customers (and workers) don't become ill. Requirements like those in B.C. (mechanical refrigeration, hand washing stations, etc.) would be overkill, and would likely put many of these vendors out of business. However, providing formalized food safety training, similar to that recommended for Nigeria, would enable the vendors to make their own outcome-based decisions on how to best run their businesses. A simple explanation of the importance of cold-holding could move some of those beverages out of the coolers to make room for the potentially hazardous food items!

Source: Silva, S. A., Cardoso, R. D., Góes, J. Â, Santos, J. N., Ramos, F. P., Jesus, R. B., ... Silva, P. S. (2014, 12). Street food on the coast of Salvador, Bahia, Brazil: A study from the socioeconomic and food safety perspectives. Food Control, 40, 78-84.


Environmental contaminants in early learning environments

It's known that children are more susceptible to various environmental health risks due to their unique physiology, unique behaviours, and their general curiousity. While parents go out of their way to ensure their homes are safe for the newest members of their family, many children spend a large portion of their days in child care. In B.C., requirements for licensed child care facilities are generally outcome based: they speak to ensuring the health and safety of the children in care, but don't really talk about the potential environmental hazards that might be found in the facility, and how they should be mitigated.

An American study looked at the current scope of legislation around environmental hazards in "early learning environments" (i.e. child care facilities), and how these environments contributed to "environmental exposures". In the USA, "children of working parents ... spend on average 40 hours a week in child care". This isn't really a surprising number: unless there are close friends or family members in the immediate vicinity, working parents have no option but to find child care for their children. One would assume that the numbers are similar in Canada.
Table 2 from Hudson, Miller, & Seikel

Just like in Canada, the U.S.A. has no federal legislation surrounding environmental health in child care facilities. Licensing standards are set at a state level, and state officials are responsible for their application. The study pointed out that the standards varied greatly between states, with some requiring such controls as environmental testing (for asbestos, lead, etc.), and others not licensing family child care facilities at all. It also speaks to the fact that most states have a requirement for environmental health inspections of the facilities, but their frequencies vary "from zero to four inspections annually". One consistency found in the study was that nearly every state required some sort of protection for the children from environmental tobacco smoke (though again, there were differences in how severe these restrictions were).

The study goes through a long list of potential environmental hazards for children in care, and looked at which states had controls in place for each of them. While nearly all, as mentioned above, had restrictions on ETS, only 12 states required environmental health inspections for "small" family child care facilities, and only 13 states required some sort of environmental testing. Further, the authors pointed out that "even in states where environmental testing requirements are in place, compliance ... is low".

The report concluded that "current regulatory and licensing standards ... address only the most basic environmental health protections", and Table 2 above seems to graphically describe that quite well. While it's easy to see the difficulties in a federally-mandated legislative process for environmental health in care facilities, some consistency (both in the U.S.A. and in Canada) would be helpful to ensure infants and children are protected from some of the more egregious risks.

Personally, I'm a fan of the idea of testing for various environmental hazardous to provide concrete data on the need for remediation or mitigation. As an example, Interior Health has sent out radon test kits to all child care facilities (letter from Senior Medical Health Officer here). A friend of mine did some research a few years back on the efficacy of surface lead test swabs (such as these ones) and found that they did a decent job. Legislation in B.C. requires that a number of child care facilities (depending on size, etc.) test their drinking water quality to ensure compliance with provincial drinking water legislation. Once we (as a society) have the knowledge that these types of exposures are a risk, why not take advantage of testing mechanisms to determine whether further action is required?

Source: Hudson, G., Miller, G.G., & Seikel, K. (2014). Regulations, policies, and guidelines addressing environmental exposures in early learning environments: a review. Journal of Environmental Health, 76(7), 24-34.


Yet another Listeria recall

I'm late to the game on this one, but it's still worth noting: in late February, Castle Cheese (West) Inc., based in Lumby, B.C., issued a recall notice for some of its shredded cheese products due to potential Listeria contamination. The first recall notice posted on the CFIA's website on February 24 (here) listed just two products: shredded cheddar, and shredded parmesan (or, more specifically, "shredded dairy product" made with these two types of cheeses).

On March 13, the CFIA posted an expanded recall notice on its website (here), which included the nacho blend, cheddar, mozzarella, parmesan, and "all shredded cheese products" with specific UPC codes that were sold to institutions, hotels, and restaurants.

Four days later, yet another notice was posted on the CFIA website (here), adding crumbled feta, chipped parmesan, and more shredded parmesan to the recall list. The products were distributed throughout Canada, in the retail chain, to hotels, restaurants, and to institutions.

It's worth noting that the recall was initiated by the manufacturer, and they've been proactive in ensuring the products are removed from the marketplace. The CFIA is working with the company to ensure that the products are removed from the marketplace, and is conducting "food safety investigations" to identify the cause of the Listeria. It's also important to note that there have been no reported illnesses from these products, and that the recall is a precautionary measure.

Sources: Food Recall Warning - Sun Valley and Castle brand shredded cheese products recalled due to Listeria. (February 24, 2014). Retrieved March 25, 2014, from http://www.inspection.gc.ca/about-the-cfia/newsroom/food-recall-warnings/complete-listing/2014-02-24/eng/1393307606171/1393307607062

Food Recall Warning - Okanagan's Choice Cheese brand Shredded Cheese Products recalled due to Listeria. (March 13, 2014). Retrieved March 25, 2014, from http://www.inspection.gc.ca/about-the-cfia/newsroom/food-recall-warnings/complete-listing/2014-03-13/eng/1394763186626/1394763213149

Food Recall Warning - Meddo Belle and Okanagan's Choice Cheese brands shredded cheese products recalled due to Listeria. (March 17, 2014). Retrieved March 25, 2014 from http://www.inspection.gc.ca/about-the-cfia/newsroom/food-recall-warnings/complete-listing/2014-03-17/eng/1395091471822/1395091480655