Objectives: Kombucha tea is becoming an increasingly popular food item within the Vancouver area. The tea is prepared through fermentation at room temperature during which acidic by-products are produced lowering the overall pH of the tea. Though the pH eventually reaches levels below 4.6, many health authorities prevent the sale of kombucha in farmers markets due to potential food safety issues. The initial pH before fermentation is around 5.5 and is then left at room temperature to ferment. As a result, this process potentially could allow for food borne illness causing organisms to survive and proliferate within the sugared tea. This research project will investigate the relationship of pH and time during fermentation at both room and refrigeration temperatures. Fermentation within a refrigerator could provide a safer alternative fermentation method
Methods: The pH was measured using a pH meter for 30 samples at both room and refrigeration temperatures providing a total of 60 samples. The pH was measured periodically every twelve hours for a total of 120 hours. The data was analyzed using a linear regression model to determine if the pH change over time was statistically significant. The time at which the pH dropped below 4.6 was also noted for food safety purposes
Results: At room temperature the pH steadily decreased in a linear fashion throughout the entire sampling period, dropping below 4.6 within 12 hours. The pH decreased in a nearly identical fashion when fermented in a refrigerator for the first 72 hours of sampling. After the 72 hour mark the pH stabilized at approximately 3.75, whereas the pH at room temperature continued to decrease down to 3.10 after the full sampling period
Conclusion: The results indicate that kombucha tea becomes a non-potentially hazardous food within the first 12 hours of fermentation. The pH dropped below 4.6 after 12 hours at which point no food borne illness causing bacteria are able to survive and proliferate within the tea. The observed decrease in pH during the first 72 hours within a refrigerator is unlikely to have resulted from the fermentation process and therefore is not a feasible practice. Fermentation at room temperature appears to be a relatively safe process if home brewers are able to measure the pH change and carry out the process in a sanitary manner, Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2017., Peer reviewed, Kombucha, Fermentation, pH, Temperature, Refrigeration, Tea
Background and Purpose: Most Canadians have lead in their blood and it has been shown that even low levels of lead can cause harm. Children are the most susceptible population to the harmful effects of lead due to their increased absorption and earlier stages of brain development. Lead exposure in children has been shown to have negative and irreversible effects, including delayed development and reduced neurological function. As parents and daycare staff have the most interaction with young children, their health knowledge is important for minimizing day-to-day exposures. This research project assessed the level of knowledge of daycare staff and parents of young children on lead sources and health risks.
Methods: An in-person, self-administered knowledge survey was given to parents and Early Childhood Educators (ECEs) at daycare centres located in Surrey, BC and Burnaby, BC. The data was then analyzed using SAS statistical software to compare the two groups using a chi square test.
Results: Daycare staff and parents showed no significant differences in knowledge levels. The mean score on the knowledge test for daycare workers was 39.98 +14.77% and for parents was 30.73 +16.53%. Both groups had significant gaps in knowledge on lead, its sources, its risks for children, and preventive measures.
Conclusion: Daycare staff and parents have an important role in minimizing children’s exposure to lead. Identifying knowledge gaps in these groups can lead to more targeted health promotion projects as well as changes to education and training., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Lead, Children, Daycare, Parents, Exposure, Public health, Knowledge
Background: Bisphenol A (BPA) is a proven endocrine disruptor and has been found in the urine of 95%
of Canadians. Though the chemical has been banned for use in certain applications, it is still common in
items such as thermal paper used for receipts because the compound is heat stable. This study aims to
determine if the levels found in thermal receipt paper are high enough to pose a public health concern.
Methods: Samples of thermal paper used for receipts were tested for BP A by soaking and incubating
lOOmg of the paper in lOmL of methanol for 3 hours at room temperature, and then overnight at 4°C. The
resulting methanol solution was then analyzed by using an HPLC (high performance liquid
chromatography) system with fluorescence detection.
Results: A total of 30 receipts were tested from various stores around the Lower Mainland, including
retail stores and restaurants. Of the 30 samples, 13 tested positive for bisphenol A, and of those 13, the
amount ranged from 0.124 to 871.17 mg BPA per kg paper. Using the provisional total daily intake
(0.025mg/kg body weight/day) set by Health Canada in 1996, results indicate that there can be enough
BPA present in a minimum of 2 grams of the paper to exceed the daily limit for a person weighing 70kg.
However, the human body does not absorb all of the BPA it may come into contact with, nor does a
person touch the entire surface of the paper; thus, more than 2 grams of thermal paper would be required
to actually exceed the pTDI.
Conclusion: Although the human body does not absorb all of the BPA it may come into contact with,
thermal receipt paper can still be a significant source of BP A, especially for those who handle them
frequently, such as cashiers. Public education on common sources of BP A, such as thermal receipts,
would reduce exposure., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Bisphenol A, BPA, Thermal paper, Retail receipts
Background and Purpose: Adverse effects of lead and mercury on human health due to environmental and occupational exposures require a public health attention. These metals can cause severe harm to vulnerable populations such as children and pregnant women. The probability of chronic and harmful exposure is higher in occupational settings. Monitoring the levels of these two metals in blood is an important tool to identify and quantify exposure to these metals in the environment. Monitoring data provides vital information required for management of health risk posed by these metals. The purpose of this study was to perform a comparative analysis of blood lead levels and blood mercury levels within the province of British Columbia on the health services data obtained from BC Centre of Disease Control. The primary objective was to compare the levels of lead and mercury in blood among different health authorities of British Columbia. The secondary objective was to compare the levels of lead and mercury among different age groups and gender.
Methods: The blood lead and mercury concentrations used for the analysis were provided by Environmental Health Services at the British Columbia Centre for Disease Control (BCCDC). The data comprised of blood analyses that were ordered by physicians during the period of 2009-2010 for reasons not disclosed. Access to this data was provided by Dr. Reza Afshari with the permission of Dr. Tom Kosastsky for the completion of this project only. Statistical analysis of data was performed using Microsoft Excel 2013 and SAS University Edition Analytic Software. Various descriptive and inferential statistical tests were performed on the data to determine the differences of blood mercury and lead levels among different genders, Health Authorities and age groups.
Results: The levels of blood mercury and lead concentrations were not significantly different in males and females in province (p-value 0.5543 for mercury; p-value 0.5336 lead). However, it was found that blood levels of lead were higher in Interior Health and “Unknown” category (p<0.02), while blood mercury levels were significantly higher in coastal health authorities (highest in Vancouver Coastal Health Authority, followed by Fraser Health Authority and Vancouver Island Health Authority) (p<0.001). For both toxic metals, levels were highest in age group of 50 and above. (p<0.0001 for mercury, p<0.02 for lead).
Conclusion: The statistical analysis of lead and mercury data was useful in characterizing the exposure among Health Authorities, age and sex of the people tested in province of British Columbia. Analysis of mercury data has generated clear patterns inferring association between coastal Health Authorities and elevated mercury levels. Vancouver Coastal Health had highest median mercury levels 4.02 μg/L higher than other health authorities (p<0.0001). Analysis of lead data established a pattern among physicians suggesting that they are more likely to order a test if the patient is under 18 years of age. Median levels were found to be highest in Interior Health Authority and “Unknown”, Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Lead, Mercury, Pregnancy, Children, British Columbia, Blood lead levels, Blood mercury levels, Vancouver Coastal Health, Fraser Health, Interior Health, Northern Health, Vancouver Island Health Authority, Occupational exposure
Background: Hand sanitizers are commonly used as an alternative to washing hands with warm water and soap. There are a variety of different hand sanitizers including gel and foam and they are known to kill several bacteria. Many factors play a role in the effectiveness of hand sanitizers such as the alcohol concentration and the techniques used to apply hand sanitizers. Alcohol based hand sanitizers must have an alcohol concentration of 60 - 70% to be effective. There is currently no legislation regulating hand sanitizers and there is a lack of research focusing on differences between foam and gel hand sanitizers. This research study investigates effectiveness of gel compared to foam hand sanitizers by evaluating the prevalence of Escherichia coli (E.coli) on pigskins.
Methods: To compare the hand sanitizers, microbiological sampling was completed. E.coli was introduced onto 65 pigskins. Five pigskins were used as a baseline to determine the average amount of Colony Forming Units (CFUs) of E.coli present prior to the application of hand sanitizers. One set of the 30 pigskins was applied with gel hand sanitizer, whereas the other 30 was applied with foam hand sanitizer. The pigskins were swabbed with QuickSnap swabs and plated onto 3M Petrifilms. The 65 petrifilms were incubated at 35oC for 48 hours. After incubation, the CFUs of E.coli present on the petrifilm were enumerated. The difference in CFUs was calculated to determine the reduction in E.coli and the overall effectiveness of hand sanitizers.
Results: The data was analyzed by using the statistical software, NCSS. Statistical analysis showed that the findings were statistically significant and the null hypothesis (Ho: no difference in CFUs of E.coli between foam versus gel alcohol-based hand sanitizers) was rejected with a power of 0.9997 at p-value of 0.00000. This indicates that there is a difference in the ability to reduce E.coli between gel and foam hand sanitizers and gel sanitizers appeared to be more effective.
Conclusion: These results indicate that there was a difference in the effectiveness between foam and gel hand sanitizers in reducing E.coli that was inoculated onto pigskins. However, consumers should be aware that hand sanitizers do not completely eliminate all pathogens. Though gel hand sanitizers are more effective, they should only be used when there are no other methods of keeping hands clean., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, E.coli, Escherichia coli, Foam, Gel, Hand Sanitizer, Pigskin, Public health
Background: Water quality in live retail shellfish holding tanks are vital in increasing shellfish quality and reducing risk of shellfish-associated outbreaks. Poor holding tank water conditions may not only cause mortality of shellfish, but also allow for harmful pathogens to contaminate the shellfish, proliferate in the holding tanks, and ultimately potentially affect consumer health. Shellfish are processed and handled at a variety of levels at the retail stage. Therefore, the purpose of this research project is to compare water quality in live retail shellfish holding systems between processing plants and retail food markets. Differences may indicate a need for attention at a particular level in order to effectively and efficiently reduce mortality and disease among shellfish, and thus potentially humans as well. Methods: 30 water samples were taken from the two types of locations with the help of the Department of Fisheries and Oceans (DFO), Ministry of Agriculture, and the BCCDC. These samples were tested for parameters including temperature, pH, nitrites, turbidity, and dissolved oxygen using a LaMotte Fresh Water Aquaculture Kit and a HACH 2100P turbidimeter. A two-tailed t-test was used to compare the means of each of the parameters among the two types of locations with live shellfish holding tanks. Results: The mean values for all parameters in both retail and processing met the requirements set by the BCCDC. However, temperature and dissolved oxygen showed statistically significant differences between retail markets and processing facilities. Nitrites, pH, and turbidity showed no statistically significant differences between the two types of locations. Conclusion: Differences in dissolved oxygen may have been due to salt levels, failing recirculation systems, or high levels of organic matter from sanitation issues. Differences in temperature may have been due to differences in holding tank size, or inconsistencies from using two different thermal measuring devices. High levels of nitrites were a concern as well due to overcrowding of holding tanks. More attention may be needed for these issues, especially during certain seasons such as Chinese New Years, in order to lower the risk to public health., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Shellfish, Holding tanks, Water quality, Processing facility, Retail food market, Food safety, Public health
Phthalates are a class of plasticizing chemicals used to improve the flexibility of soft plastics (1, 6, 12, 15). As such, they have drawn increased attention as food contact substances (1, 10, 14), mostly entering food items from packaging materials (1, 8, 10, 14). Even though they had been approved as indirect food additives in Europe and the U.S. (1), the discovery of high concentrations of di(2-ethyl-hexyl) phthalate (DEHP), also known as bis 2-ethylhexyl phthalate (BEHP) (12, 15), in a probiotic food product by a scientist from Taiwan in April 2011 initiated the world’s greatest health safety efforts (7). Investigators found that DEHP, along with other phthalates, were deliberately added to food products in replacement of the approved food additives, which would normally be added to emulsify the components in the drinks to achieve a natural and appealing appearance (7, 12, 15). This contamination event has been known as the 2011 Taiwan Food Scandal, where processed food items such as sports drinks, concentrated juice beverages, tea drinks, jam or jelly and food supplements were adulterated with phthalates, a harmful class of chemical compounds. Consequently, ingestion of these harmful compounds may result in adverse health affects such as endocrine disruption, malformation of reproductive organs, infertility and abnormal neurodevelopment (12). Many products made it across the border to 22 different countries (15, 17) including Canada and U.S. (17). Since then, the Taiwanese government made improvements to the food industry regulations (15, 17). This study was aimed to determine if DEHP was present, and compared to the European Food Safety Authority (EFSA) DEHP tolerable daily intake (TDI) of 0.05 mg/kg body weight (bw)/day (12, 17), in 30 different drinks of imported and domestic brands sold in Canada. For comparison purposes, the author completed calculations based on the average adult (over 18 years old) body weight of 70 kg, according to EFSA (41). Using liquid/liquid extraction followed by Gas Chromatography-Mass Spectrometry (GC-MS), 30 beverages were tested and analyzed for the presence of DEHP. Low concentrations of DEHP was detected in 3 of the beverages and none in the other 27 beverages tested on a calibrated instrument. The concentrations detected for the 3 beverages were lower than the TDI for a 70 kg body weight. Control samples were used to ensure method validity., Peer-reviewed article, Published., Peer reviewed, DEHP, di(2-ethyl-hexyl) phthalate, bis 2-ethylhexyl phthalate (BEHP), Imported drinks, Imported beverages, Canadian beverages, US beverages, Bubble tea, 2011 Taiwan Scandal, Phthalates
Background and Purpose: Seafood makes up a significant portion of the diets of people around the world. Especially fatty fish such as salmon and herring, seafood items contain numerous nutritional benefits including omega-3 fatty acids which studies have shown aid in cognition and memory. However, due to natural and anthropogenic sources of pollution, contaminants such as mercury which studies suggest decreases cognitive functioning if consumed in excess bioaccumulate in marine life including various fish and shellfish species. The purpose of this study was to categorize participants into either the “fish” group (more fish than shellfish consumed) or the “same” group (either more shellfish than fish consumed or equal amounts of fish and shellfish consumed) via a seafood frequency questionnaire, and to administer a memory test to the participants to determine whether there is a significant difference in mean memory test scores between the groups.
Methods: 31 participants were randomly selected at BCIT to participate in the study. Participation was voluntary and participants were given written and oral instructions on how to complete both the seafood frequency questionnaire and memory test. Memory test scores were based on the length of the longest digit sequence that the participant was able to recite upon hearing the examiner list the sequence. The highest possible score was a 10, while the lowest possible score was a 1.
Results: The mean memory test scores of the groups, “fish” (more fish than shellfish consumed) and “same” (either more shellfish than fish consumed or equal amounts of fish and shellfish consumed), were 5.83 and 5.92, respectively. The median memory test scores of the groups, “fish” and ”same”, were both equal to 6. The standard deviations of the groups, “fish” and “same”, were 1.2004901 and 0.9540736, respectively. The ranges of the groups, “fish” and “same”, were 4 (minimum) to 8 (maximum) and 5 (minimum) to 8 (maximum). From the non-parametric Wilcoxon Rank sum test, the P-value was found to be >0.05 at α = 0.05.
Conclusion: The results of this study suggest that diets relatively high in fish are neither positively nor negatively correlated with memory. However, the limitations of this study in combination with the various studies that contradict this study’s findings illustrate the need for further research., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Memory, Seafood, Shellfish, Fish, PCBs, Mercury, Brain, Neurodevelopment, DHA, EPA, Omega-3 fatty acids
Background and Purpose: Electronic cigarettes are gaining vast popularity because the perceived impression about electronic cigarettes is they are a safer alternative to conventional smoking (Belluz, 2015). As a result, more teenagers are switching to electronic cigarettes either as a smoking cessation tool, or for recreational use. However, it is supported by the evidence review that there is nicotine mislabeling between what the manufacturer has labeled and the actual nicotine content in the liquids (Goniewicz et al., 2012). This is a critical health concern for teenagers and recreational users because they are exposed to nicotine, which is a neurotoxin that creates the addiction for smoking. As a result, over a period of time, recreational electronic cigarette users have a higher chance of switching to conventional smoking (Bach, 2015). Hence, the purpose of this research is to determine whether nicotine can be found in nicotine free electronic cigarette liquids
Methods: The nicotine content in the electronic cigarette liquids will be determined using Gas Chromatography - Mass Spectrometry. Inferential statistics such as a one tailed t-test will be done using Microsoft Excel and SAS to see if nicotine can be detected in nicotine-free electronic cigarette liquids and if there is a statistically significant difference.
Results: The two p-values from the parametric test were 0.2811 and 0.2953. The p-value to reject the null hypothesis was set at 0.05. Because the p-values from the inferential statistics were greater than 0.05, the null hypothesis was not rejected and the actual nicotine content is equal to what the manufacturer had labeled as nicotine free.
Discussion: Although the inferential statistics indicated that there was no statistical significance in nicotine concentration, two out of the ten nicotine free electronic cigarette liquids measured nicotine levels above 0 ppm.
Conclusion: There was not a significant difference in nicotine concentration found in the electronic cigarette liquids and the actual nicotine concentration is equal to the labeled concentration. However, because the sample size of only ten is too small, there is a potential for type 2 error. Also, the samples came from only two manufacturers. Therefore, the results from this research are not representative for all the electronic cigarette liquids. More research should be conducted to provide scientific evidence to stop recreational electronic cigarette users from the exposure of electronic cigarettes as these could act as a stepping-stone towards smoking conventional cigarettes. Teenagers who start smoking at an early age will be more, Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Electronic cigarettes, Conventional smoking, Nicotine, Gas Chromatography Mass Spectrometry, Nicotine-Free electronic cigarette liquids
Background and Purpose: Personal service establishments are abundant such as piercing shops, tattoo parlours, spas and now float spas. Sensory deprivation tanks were popular in the 1980s and have come back as a new way to relax, reduce pain and relieve stress and to provide a complete deprivation of the senses. The sanitation of these tanks have caused concern in the public health field as bacteria and parasites can easily live and proliferate in the tank water. Environmental Health Officers (EHOs) have to keep up to date with new or returning technology in order to provide information to the public and to ensure their safety. This research project investigated EHOs with differing years of employment in the field, geographic working location and age and their knowledge of sensory deprivation tanks.
Methods: A survey created in Google Forms and Survey Monkey was disseminated through e-mail who then forwarded an e-mail to all EHOs in BC. The survey asked demographic questions, health and safety, sanitation and disinfection and general knowledge of floatation tanks. A t-test and ANOVA was used to analyze the data.
Results: Three comparisons were tested: first was the number of years an EHO has worked in the field and their test score; second was their age and test score; and last was their geographic location and test score. The null hypotheses were not rejected as the p-value was found to be greater than 0.05 for all of the variables analyzed.
Discussion: Overall, there was weak knowledge in EHOs and due to the small sample size there was weak statistical significance between the associations found regarding the number of years an EHO has worked in the field, their age and geographic location where they work compared to their test scores.
Conclusion: More information needs to be provided to all EHOs to keep them updated on new personal service establishments., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Floatation tanks, Sensory deprivation tanks, Environmental health officer, Knowledge, BC, Public health, Personal service establishments, PSE, Float tank, REST tank, Isolation tank
Background and Purpose: Hand washing is one of the most important critical control points in public
premises in preventing the spread of bacteria and viruses. There is vast research on the effectiveness of
alcohol-based hand sanitizers in killing germs. However, the efficacy of alcohol-free hand sanitizers lacks
real-world evidence. With little to no guidelines in which one type of hand sanitizers may be more
appropriate depending on the types of public premise such as food establishments, hospitals, work place, or
schools, Environmental Health Officers(EHOs)/ Public Health Inspectors(PHIs) will need to educate the
public and operators on the effectiveness of these hand sanitizers and their advantages and disadvantages.
The purpose of the study was to compare the effectiveness of alcohol-based hand sanitizers and alcoholfree
hand sanitizers by conducting statistical analyses of the reduction in mean E.coli counts.
Methods: 60 pigskins were prepared (30 for alcohol-based hand sanitizers, 30 for alcohol-free hand
sanitizers), which were inoculated with E. coli, then applied either alcohol-based hand sanitizers or alcoholfree
hand sanitizers. After 48 hours of incubation for E.coli growth, E.coli was counted. The difference in
mean E.coli counts before applying hand sanitizers and after hand sanitizers was calculated, then compared
between the two hand sanitizers.
The mean E.coli reduction count (CFU) from alcohol-based hand sanitizers (30 samples) was 10.200; the
median was 11; the standard deviation was 1.7889; the range was 5.0000.
The mean E.coli reduction count (CFU) from alcohol-free hand sanitizers (30 samples) was 10.233; the
median was 10.5; the standard deviation was 0.8976; the range was 3.0000.
The statistical t-test resulted in p-value of 0.1034.
Conclusion: There was no significant difference between the two types of hand sanitizers. Both the
alcohol-based hand sanitizers and alcohol-free hand sanitizers effectively reduced the number of E.coli
counts (CFU) by averages of 10.2000 (92.7% reduction) and 10.2333 (93.03% reduction) respectively.
While the BC Centre for Disease Control recommends 60 percent alcohol hand sanitizers to prevent the
spread of germs, this research showed that alcohol-free hand sanitizers with sulfactants, allantoin, and
benzalkonium chloride (SAB) formula is just as effective in killing germs. Therefore, EHOs/PHIs can
educate the public and operators on the advantages and disadvantages on the two types of hand sanitizers in
preventing the spread germs during the flu season and give practical advice or guidance on which type of
hand sanitizers would be most appropriate in restaurants for example., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Alcohol-based hand sanitizers, Benzalkonium chloride, E. coli, Alcohol-free hand sanitizers
Objectives: Pathogens are introduced into foods, surfaces, and hands by our surrounding environment which includes soil, air, and fecal contamination. It can be due to improper handling, cleaning, washing or sanitizing. Sanitizers are applied to surfaces in order to kill all the vegetative cells of microbes. Health Canada regulates the types, uses and concentration of the sanitizers. These sanitizers are chemically formulated to kill microbes and hence there is a rising concern about toxicity associated with their use. People are moving away from regulated sanitizers to natural alternatives. This research project examined the efficacy of vinegar, one of the natural alternatives, as a sanitizer.
Methods: 3M Quick Swabs were used to collect coliform samples from a plastic cutting board before and after inoculating it with coliform culture and subsequently cleaning it with vinegar. A one tail paired t-test was conducted to assess whether the coliform counts were reduced after cleaning with vinegar.
Results: For all 30 samples there was a reduction in the number of coliforms when comparing before and after cleaning with vinegar. Results show that there is a significant difference in the mean numbers of coliforms before and after cleaning with vinegar; p <0.0001.
Conclusion: These results indicate that undiluted vinegar when used for cleaning food contact surface significantly reduces the coliform counts but not to the safer levels for human exposure., Peer-reviewed article, Published., Project submitted in partial fulfillment of the requirement for the degree of Bachelor of Technology in Environmental Health, British Columbia Institute of Technology, 2016., Peer reviewed, Sanitizer, Vinegar, Food contact surfaces, Alternatives, Efficacy