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

Delicious, delicious lamb legs

Okay, to be fair this post doesn't have a LOT to do with environmental health topics. I just came across it while doing some research, and thought it was interesting. And, if I stretch it, I can say that meat processing has to ensure not only food safety aspects, but also food quality: no matter how safe a product is, if it's not delicious, people won't want to eat it. I should also clarify that I really don't know a lot about meat curing techniques, so I won't have a lot of insight or personal opinions on the topic.

The main premise of the study is that if you "tumble" your lamb leg while you're salting it, there's a natural breakdown of the connective tissues that will lead to a change in texture/taste/quality of the product. Further, you'll get a more complete coverage of the salt through tumbling, so you should have a fully cured product in less time. The researchers wanted to take this existing knowledge, and determine what changes ("physiochemical, microbial and sensory") occurred.

To get the most important aspect of the study out of the way, the researchers noted that "hardness and chewiness decreased during ripening", which is a good thing (unless you like hard, chewy lamb leg). There was no significant change in flavour between the different treatment methods, although "pastiness" did increase with tumbling (where "pastiness" is described as "the feeling of paste detected in mouth during mastication). To be fair, the researchers noted that the tumbled legs were only a BIT more pasty, so it shouldn't be seen as an impediment to deliciousness.

From a food safety perspective (see, I can bring this back to relevance), they found that there was no significant difference in aw (water activity)  between the different treatment methods, and the tumbled meat still was capable of an aw as low as 0.6, allowing for room temperature shelf stability. NaCl content was also statistically equal between the treatment methods, and there was no effect on pH noted from tumbling.

Besides the pastiness, one of the only other differences the researchers found between tumbling and "normal" curing was the presence of 3-methylbutanal, which they note "could have an impact on leg flavour". They hypothesize that the 3-methylbutanal appears because of the structural damage that occurs to the meat when it's being tumbled around, and the associated degradation of amino acid leucine. Now, since I'm not a food scientist, it was unclear to me whether the presence of 3-methylbutanal (which is a "major contributor of dry-cured ham flavour") was a good thing or a bad thing. However, when talking about cured meats, I'm going to go out on a limb and say that a "dry-cured ham flavour" isn't necessarily a bad thing. So that's a win for the tumbled meat!

So while the tumbling of the meat had no apparent effect on the shelf stability of the product vis-à-vis non-tumbled curing, it did have some quality effects: more pasty, but also more flavourful. Which means when you're curing your Mediterranean lamb leg, you might as well tumble it!

Source: Villalobos-Delgado, L.H., Caro, I., Blanco, C., Morán, L., Prieto, N., Bodas, R., Giráldez, F.J., & Mateo, J. (2014). Quality characteristics of a dry-cured lamb leg as affected by tumbling after dry-salting and processing time. Meat Science, 97, 115-122.


The link between PM 2.5 exposure and hospitalization

While there's no question that inhalation of contaminated air can have negative long-term health consequences, it's difficult to directly link ambient exposure to particulates with acute hospitalization. It's also interesting to note that not all PM2.5 (airborne particulates 2.5 micrometers or smaller) are the same, and can be made up of various different compounds with (theoretically) different health implications. 

To determine which of the heterogeneous PM2.5 sources/components were most closely related to hospitalization, a group of researchers analyzed filter samples various air quality testing stations, identified sources and major contributors of PM2.5, and then looked at whether there was any correlation between hospitalization and PM2.5, and whether specific particulate sources were more likely to contribute to hospitalization.

Unsurprisingly, they found that total PM2.5 was positively correlated with hospitalizations. Interestingly, they also found that specific PM2.5 constituents were more likely to cause specific negative health events than others: PM2.5 originating from road dust, calcium, black carbon, vanadium, and zink were positively correlated with cardiovascular hospitalizations, while PM2.5 road dust, sea salt, aluminum, calcium, chlorine, black carbon, nickel, silicon, titanium, and vanadium were all positively correlated with respiratory hospitalizations. An increase in PM2.5 concentrations of 1.73µg/m3 led to an increase in cardiovascular hospitalizations of  2.11%, and an increase of 3.47% in respiratory hospitalizations.

This is the type of research that helps move environmental health legislation forward. Rather than focusing on the well-known idea that air pollution is bad for you, and that smaller particles are more likely to cause negative health events, the researchers did some fairly extensive mathematical modeling to identify what specific compounds cause which specific types of health events. This type of data can allow legislators and health professionals to focus their efforts and (limited) resources on mitigating health events that are more likely to occur, given the knowledge of what compounds are prevalent in their specific geographic regions.

Source: Bell ML, Ebisu K, Leaderer BP, Gent JF, Lee HJ, Koutrakis P, Wang Y, Dominici F, Peng RD. 2014. Associations of PM2.5 constituents and sources with hospital admissions: analysis of four counties in Connecticut and Massachusetts (USA) for persons ≥ 65 years of age. Environmental Health Perspectives 122:138–144.

Effects of wastewater on small streams

If there's one thing that interests me, it's the intersection between ecology and human health. There's a fascinating link between our interactions with the world in which we live, and public health outcomes. In the most straightforward sense, these interactions manifest themselves in things like drinking water quality and outdoor air quality. But there can also be considerations for things like freshwater ecology and wildlife health. Environmental health often looks at how changes to the environment can affect public health, but rarely look at how public activities can affect the environment (mostly because it's out of scope). 

There's value to looking at ecology and environmental indicators without thinking directly about public health, however.  In the early part of the millennium, 80% of creeks surveyed in the USA were found to be contaminated with "environmentally relevant" concentrations of compounds that were indicative of sewage contamination; I would suspect the number to be similarly high in semi-populated areas of Canada (either those within proximity to large communities, or those within proximity to a large number of onsite wastewater systems). Our sewage treatment systems are still designed to remove (mostly) contaminants of biological concern, and are unable to adequately remove contaminants of emerging concern, such as pharmaceuticals and "hormonally active compounds". While the long-term risk of these compounds to human health is relatively unknown, there is certainly an environmental impact to them making their way into lakes and streams.

A study by the North Carolina Water Science Center looked at water quality in a number of small, freshwater streams to determine how effective on-site and centralized wastewater treatment methods are, and to identify potential new indicators for sewage contamination. They looked at a number of sites, and ensured they had representative samples from areas served by municipal wastewater systems and onsite systems, and a control with no houses nearby. Using GC/MS, they looked for a total of 33 pharmaceutical compounds (in addition to normal fecal coliform analysis) to identify sewage contamination of the freshwater streams.

In general, and somewhat surprisingly, the researchers found that "properly functioning onsite wastewater" systems really had no effect on the water quality in freshwater streams. The "properly functioning" part is important, since one of the sites they looked at (which showed "effects of wastewater") was close to a "suspected" sewer line leak. Though they found that some compounds were prevalent in higher concentrations in the sites serviced by onsite wastewater, the site with the lowest concentration was actually one serviced by an onsite system.

Given the small sample size (just 7 sites) , and the relative lack of information provided on what specific "onsite" treatment methods were being utilized, I'm not sure I'd be willing to take this data to the Ministry of Environment as proof that there's no risk to freshwater streams from nearby sewerage systems. However, it is nevertheless interesting that the onsite systems were found to be equally as effective at treating wastewater as the larger, centralized systems. From experience, I know how difficult it is to link stream contamination with a specific sewerage system or event. Unless there's only one in the area, there's always a factor of doubt in your head that any contaminants you find are actually due to some other system. True background data or control sites are exceedingly difficult to find and match to your sample sites, but the researchers here did a decent job of identifying a freshwater stream with a low chance of being impacted by sewage.

Personally, I think that one of the most interesting things that came out of this research was the identification of a potential indicator for wastewater contamination. The researchers state that "optical brighteners" were strongly correlated with the presence of wastewater, and therefore have value in identifying sources of contamination. These are the compounds that you find in your laundry detergent that make your "whites whiter" (and aren't bleach). They're relatively inexpensive to test for, since they fluoresce at a specific wavelength, and could provide a quick and dirty methodology for "yes/no" contamination data. However, it's worth pointing out that other (naturally occurring) compounds fluoresce at the same wavelength, so one wouldn't want to hinge a court case on the presence of optical brighteners identified through fluorescence, unless one first removed any source of that background organic material.

While research like this isn't going to cause a sea change in the way we identify contamination from sewerage, every study helps to change the way we view the interactions between our waste disposal and our environment. It's clear that simply looking at coliform bacteria is no longer an adequate means of assessing whether our wastewater treatment is effective; we must recognize that there are new contaminants in our wastewater, and identifying their prevalence is the first step to determining how to remove them.

Ferrell, G.M., & Grimes, B.H. (2014). Effects of centralized and onsite wastewater treatment on the occurrence of traditional and emerging contaminants in streams. Journal of Environmental Health, 76(6), 18-27.


Can meat inspection help with animal health & welfare analysis?

Meat inspection is a hot topic in this area. Since the new meat inspection legislation came into effect in B.C. in 2007, local farmers and politicians have been pressuring the government to allow the sale of meat slaughtered on-farm (which would require a class D/E licences, without getting into the finer details of the legislation). In response to the pressure, the province established a pilot project last February that allowed North Okanagan farmers to apply for a Class E licence. According to local stakeholders, since the establishment of the Meat Inspection Regulation, the number of local meat producers has decreased from 1200 to 300. Just today, a newspaper article came out lamenting the fact that one year in, no licences have been issued pursuant to this pilot project.

The local farmers and other stakeholders all focus on the need for sustainable meat (beef and poultry) production in an agricultural-based economy, allowing consumers to have access to local products. There is seldom talk about the benefits of the meat inspection program itself in ensuring food safety, and even less often, talk of the benefits of meat inspection to animal health and welfare.

In analyzing published reports associated with meat inspection programmes in Europe (which involve both ante and post mortem parts), researchers found a lack of data indicating what, and how many, diseases were found in food animals. Further, it was unclear whether the meat inspection programmes in Europe were actually successful (and to what degree) in identifying these animal health conditions. 

Given the lack of concrete data from peer-reviewed journal articles, the researchers relied on expert opinions and knowledge of the types of conditions they were studying. Using this methodology, they found that the EU meat inspection programmes were highly competent at determining "clinical and/or pathological signs in affected animals", but fairly useless at identifying "early or subclinical cases". A visual-only inspection of the meat (that is, post mortem only) did not significantly detract from the programme's ability to identify most of the conditions of concern.

The researchers also looked at whether the existing meat inspection programme in the EU would be sufficient for identifying animal welfare concerns (i.e. identifying the types of diseases and conditions that aren't necessarily associated with human health, but are associated with animal health). They found that, so long as data was collected and appropriate recorded and shared, the existing programme "could provide an efficient means of identifying producers in need of animal health advice". 

In essence, the study showed that ante mortem inspections are much needed for identifying animal health and welfare issues, but post mortem visual inspections are adequate for ensuring public health and safety, with one important caveat: the visual-only inspection was inadequate for identifying tuberculosis. 

While it was identified that the meat inspection programme could have added benefits in ensuring animal health and welfare if data was collected and kept, the researchers do point out the potential economic struggles with doing so. Meat inspection is not a cheap business to be in (see: article on the CFIA leaving the business), and so adding additional factors into the inspection focus is unlikely to take place without additional resources. In essence, it's similar to the beach sampling: there is more that could be done, but the resources just aren't there to make it happen.

Source: Stärk, K., Alonso, S., Dadios, N., Dupuy, C., Ellerbroek, L., Georgiev, M., ... Lindberg, A. (2014, 12). Strengths and weaknesses of meat inspection as a contribution to animal health and welfare surveillance.Food Control, 39, 154-162.

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.


Would those Nigerians benefit from B.C.'s FOODSAFE program?

Yesterday, I wrote about food handling practices in street food vendors in Nigeria, and how the research suggested that they food handlers would be well-served by some formal education and training, potentially provided or designed by the government for quality and consistency assurance. B.C. has such a program in place, and last year a group of researchers from one of the province's regional health authorities and the B.C. Centre for Disease Control did a study to determine the level of success of the program.

The researchers did a telephone survey, similar to that performed by the artisan cheese researchers mentioned previously, and looked at worker's knowledge and attitudes about food safety, as well as their (self-reported) hand washing practices. It's worth noting, before we get too far in, that in 2013, once you took FOODSAFE, you were certified for life. There was no expiry date on the certification, and no upgrades or re-training was required.

Unsurprisingly, the research found that workers with FOODSAFE training had scores that were "significantly higher" than untrained workers, and that they also had "significantly better hand washing practices". They also found that after 15 years of being certified, knowledge scores "significantly decreased". It's worth noting that this study interviewed nearly 700 individuals to achieve their data, as compared to the relatively low "n" value of the artisan cheese study.

Linear regression model showing years since
FOODSAFE taken (McIntyre, et al. 2013)
While the fact that trained FOODSAFE workers had a better grasp on food handling and hygiene practices, and hand washing techniques is not at all surprising, it was interesting to note the statistically significant trend in knowledge loss over time. As the regression model to the right shows, the longer it had been since FOODSAFE was taken, the worse the knowledge scores were. The provincial authorities took notice of this study: as of July, 2013 (this study was published in March, 2013), all FOODSAFE certifications have a five year expiry date (for those taken before July, 2013, the expiry date is July, 2018).

The study results mimic what other research has shown: specific, formal, food handling education increases the skills and abilities of workers to provide safe food to consumers. However, it also shows that just giving the education isn't enough to maintain the knowledge base; there is no "set it and forget it" approach that will maintain public health. When considering the quandary of the Nigerians, and their demonstrated need for food handling and hygiene training for street vendors, it's worth keeping the need for recurring training in mind. Granted, one-off training is better than nothing, but it's clearly not the best approach.

Source: McIntyre, L., Vallaster, L., Wilcott, L., Henderson, S.B., Kosatsky, T. (2013). Evaluation of food safety knowledge, attitudes and self-reported hand washing practices in FOODSAFE trained and untrained food handlers in British Columbia, Canada. Food Control, 30, 150-156.


Street food in Nigeria: how safe is it?

Street food is becoming more popular throughout the world. It's not just us first-world people who watch "The Great Food Truck Race" on the Food Network, but globally people are seeking new ways to provide inexpensive, ready-to-eat food products to consumers on the go.

Typically, reducing a food service into a "mobile" location brings with it some inherent food safety challenges: new electricity sources need to be identified, water usage has to be limited to that which can be contained in freshwater and grey water tanks, there's not a lot of storage space, etc. With a good food safety plan, all of these challenges can be reduced. However, therein lies the rub: do mobile food service operators have the food safety acumen to develop a good food safety plan?

A group of Nigerian researchers looked to answer this very question by surveying 160 street food vendors to study food safety behaviors and hygiene practices. What they found wasn't great, if I'm being honest. Nothing in the study made me want to hop aboard a flight to southwestern Nigeria for some street meat. Nearly 62% of respondents had no formal food safety training at all, which was reflected in their hygiene practiced and attitudes toward keeping consumers safe. A stunning 3.8% of respondents "always" store food in the refrigerator, while 76% don't store food at refrigerated temperatures, and 16% don't have any food storage facilities at all.

In terms of personal hygiene, only 17% of respondents "always" washed their hands after using the toilet (though 79% responded that they did so "often"). Unfortunately, 77% of respondents admitted to using a reusable household towel to dry their hands after washing, instead of single-use paper towel.

Given the hygiene behaviors identified during the survey, it's very likely that there's a correlation between worker knowledge on how to prevent food-borne illnesses and formalized food safety training. While socioeconomic factors can reduce an individual's access to this type of training, and their ability to take time away from the workforce to participate, some sort of state-funded option could go a long way toward correcting some of these behaviors. Further, inspections and legislation surrounding street food (full disclosure: I don't know what's already in place in Nigeria) could ensure that vendors have refrigerated storage where necessary, and access to soap and paper towels for hand washing.

Source: Aluko, O.O., Ojeremi, T.T., Olaleke, D.A., & Ajidagba, E.B. (2014). Evaluation of food safety and sanitary practices among food vendors at car parks in Ile Ife, southwestern Nigeria. Food Control, 40, 165-171.


How deep does the E. coli go?

The B.C. Sewerage System Regulation (B.C. Reg. 326/2004) restricts individuals from placing sewerage systems within 30m from a well supplying a domestic water system, unless a "professional" provides written confirmation that doing so would not cause a health hazard. While setting a minimum setback level gives sewage practitioners and homeowners a baseline for ensuring the safety of their water supply (and that of their neighbors), it doesn't take into account the multitude of factors that can limit or extend the transport of disease-causing bacteria from a sewage system to a water system.

While "professionals" (essentially engineers) can reduce this setback distance, it's not clear how much research and information gathering goes into doing so. In my experience, professionals will provide support for a reduced setback because of secondary or tertiary treatment methods, or because they've looked at the soils and feel that lateral transport is going to be minimal. A study in last month's issue of the Journal of Environmental Health looked at the ability of E. coli to move through sandy loam soil (specifically that from North Carolina) to a water table in situ. They looked at 30cm, 45cm, and 60cm vertical separation between ground level and the water table, and took samples daily to identify whether those individual soil separation distances were sufficient to reduce the load of E. coli prior to the effluent coming into contact with the water.

Using a 64% sand / 30% silt / 6% clay mixture of soil (that was obtained in the field by the researchers), the researchers applied 200mL of an artificial wastewater solution to each soil column daily. The artificial wastewater (which contained nutrients like potassium, sodium, and phosphate) was spiked with E. coli that was obtained from human urine. With this application, they found that 30cm and 45cm of vertical separation were inadequate to mitigate the bacterial content to acceptable levels, with 45cm reducing the levels somewhat, but not below the recommended standard of 200cfm/100mL. 60cm of vertical separation, on the other hand, was found to be most efficient at removing E. coli to levels where the water table would not be adversely affected.

While this research was done with a specific soil type, and did not include extenuating factors that could impact the amount of bacteria that was able to move through the soil, it does provide some great data on what sort of vertical separation is required when designing onsite sewerage systems. It's the type of relatively low-cost research that should be done more often by both regulators and practitioners to ensure that the best sewerage systems (and those that are most cost effective) are being installed in areas that are potentially sensitive. When "professionals" (as defined in the Regulation) are determining whether or not to reduce the minimum setback to a well, this is the type of data that should be consulted prior to making that determination. One can use mathematical models to determine rates of flow, but they might not adequately determine the actual decrease in bacterial concentrations. Having actual in situ research that shows how wastewater moves through a specific soil composition, and how effective it is at reducing bacteria, would give professionals the confidence to reduce minimum setbacks without putting themselves at any professional liability risk.

Source: Amoozegar, A., Graves, A., Lindbo, D., Rashash, D., & Stall, C. (2014). Transport of E. coli in a sandy soil as impacted by depth to water table. Journal of Environmental Health, 76(6), 92-100.


Food safety of artisan cheese in Ontario

There have been a couple notable outbreaks associated with cheese in Canada in the past: Gort's Gouda had the recent (and well-publicized) outbreak of E. coli, 2002 and 2008 both had outbreaks of Listeria associated with both raw and pasteurized cheese products, and 1998 had a nation-wide Salmonella outbreak which was traced back to cheese found in commercially-available lunch packs. For the most part, commercially-produced cheese items are quite safe. They're made with pasteurized milk products, and undergo processing that's well-studied and well-documented. In B.C., the B.C. Centre for Disease Control has dairy specialists on-staff who routinely inspect cheese plants for best practices and adherence to policies and guidelines.

There is also a growing movement for "local" and "artisan" products, which include cheeses. To determine the perceptions around food safety and attitudes about "food safety management programs" in cheese making, a group of researchers from the University of Guelph in Ontario put together an interview for artisan cheesemakers in the area. Their sample size was pretty small (of 50 cheesemakers that were identified, they were only able to get 11 to agree to participate, and of those, only 6 would let their employees speak with the researchers), but the interview questions were based on recommendations from existing research and incorporated a "Risk Assessment Framework".

Using private, anonymous telephone interviews, the researchers spent approximately 30 minutes speaking with each of the employees and managers from the cheese companies. While they found that nearly all of the respondents were aware of biological risks to food safety in cheese manufacturing, most perceived chemical and physical hazards as a low concern. Of all potentially hazardous biological agents, Listeria was named as the main one, due to its ability to multiply at fridge temperatures, its prevalence in raw milk, and because of awareness from past outbreaks. Interestingly, more than half of the respondents were proponents of using raw milk in cheese manufacturing because of the perceived increase in product quality, customer demand, and the ability of European countries to do so safely.

In terms of risk assessment and mitigation, all respondents were aware of their individual company's biosecurity policies and procedures (such as putting on clean boots before entering the facility), and typical sanitation regimes. However, more than half of those interviewed expressed concerns with the cost of these risk management programs, including the cost of having workers performing "excessive documentation" rather than being on the production floor making cheese. The respondents also spoke to the cost of formal education around best practices and food safety, but realized the value of these education programs, and felt that the cost was outweighed by the benefits they provide. When asked about risk communication, several of those interviewed stated that they didn't think the public was concerned about the safety of their cheese, and that they cared more about "cheese quality".

While the results of this study show that most of those interviewed recognize bacteriological concerns in cheese manufacturing, it also showed that there is still the need for further education around chemical and physical contaminants. Further, while the respondents valued formal food safety education, they felt that HACCP programs took too much time and weren't efficient, especially in small cheese manufacturing plants where there were fewer person-hours of work to go around. There is also a recognized lack of knowledge and commitment to risk communication, with producers thinking that their consumers care more about the quality of the product than its safety.

Since this study looked at such a small subset of the food manufacturing industry (a small number of cheese manufacturers in a geographically small part of Canada), it's hard to say how indicative these results might be of the food processing industry as a whole. However, it certainly highlights how media attention to a specific area of concern (Listeria) can ensure widespread knowledge.

Source: Le, S., Bazger, W., Hill, A.R., & Wilcock, A. (2014). Awareness and perceptions of food safety of artisan cheese makers in Southwestern Ontario: a qualitative study. Food Control, 41, 158-167.


Don't flush your drugs down the toilet, please

It's fairly common knowledge that prescription medication is becoming a concern in wastewater treatment (both municipal, and on-site). The systems that are in place to treat bacteria that is common in sewage aren't set up to deal with the other metabolites that tend to make their way into wastewater. This is increasingly leading to concerns with effluent making its way into drinking water supplies (both ground water, and surface water).

What is studied less often is the impact that illicit drugs have on the quality of wastewater effluent, and how they might affect drinking water quality. These compounds in sewage effluent and influent have the ability to not only impact on public health, but also to impact on the environment. As a biologist, I can only imagine the impact that cocaine and methamphetamine would have on fish and frogs who come into contact with the contaminated water supplies!

A group of French scientists decided to look at illicit drugs in a number of sewage treatment plants to determine how efficient the systems were at reducing the levels of the drugs and their metabolites, and also to identify patterns of illicit drug use in the country. Though the patterns of drug use are certainly of public health interest, they're not really of environmental health interest (although the data could help to identify areas where better sewage treatment would be best placed). The efficacy of "normal" sewage treatment plants at removing illicit drugs from wastewater, however, is of great interest.

The scientists looked at 17 different illicit drugs and their metabolites, including cocaine, methamphetamine, opiates, and cannabis. The indicator for cannabis (THC-COOH) was found in every single influent the researchers looked at. They found morphine, major metabolites of cocaine, and methadone and its metabolites in 75% of influents, but found methamphetamine and amphetamine, heroin and its metabolites, and minor metabolites of cocaine in less than 10% of influents. The study goes on to further discuss what compounds were found in influent/effluent, and in what amounts, and how this can be related to patterns of drug usage throughout France, but as mentioned above, the environmental health concern is more about how efficient the sewage treatment plants are in removing the drug compounds.

While THC-COOH was found in all of the influent samples, it was also noted to be the easiest of the illicit drugs to remove, regardless of sewage treatment plant technology. Methadone and its metabolite EDDP, on the other hand, appeared to be very difficult to remove from the wastewater. Falling somewhere in between were cocaine and its metabolites, and morphine. Based on the data, it appeared as though low-load activated sludge was more effective at removing the drug compounds than medium-load activated sludge or biofilters (likely due to the longer retention time associated with low-load activated sludge).

The results of the study should be of interest to public health practitioners, and to those involved with making decisions surrounding wastewater treatment. Treatment methods that are common in municipal sewage treatment plants just aren't effective for a large number of illicit drugs and their metabolites. Performing similar "sewage epidemiology" studies in specific geographic regions would allow local governments to identify the compounds of concern in their specific area, and work on identifying treatment methods that may be somewhat more successful than activated sludge. From a terrestrial biology perspective, working together with public health practitioners could lead to a mutually beneficial outcome: reduction of illicit drug metabolites in sewage effluent will lead to safer drinking water, and safer habitats for aquatic and terrestrial animals alike.

Source: Nefau, T., Karolak, S., Castillo, L., Boireau, V., & Levi, Y. (2013). Presence of illicit drugs and metabolites in influents and effluents of 25 sewage water treatment plants and map of drug consumption in France. Science of the Total Environment, 461-462, p.712-722.