Tap Water: public perception of its quality
Incidents such as the one that took place in the city of Flint, Michigan are one of the reasons that lead the public to distrust the quality of municipal drinking water. (Masten 2016) ( 2 ).
Many consumers opt for drinking bottled water to avoid the health risks perceived in supposedly polluted tap water as stated by Hu (2011) ( 3 ): "U.S. consumers are more likely to [drink] bottled water as their primary drinking water source when they perceive that drinking water is not safe."
Flint Water Crisis
A switch in the source of the municipal water supply and incorrect treatment (chlorination) of raw water led to lead contamination of the water supplied to over 100,000 city residents. The lead leached from the water pipes into the drinking water. It is also possible that an outbreak of Legionnaries' disease (caused by the Legionella bacteria) was due to the same cause. This outbreak caused 91 cases and 12 deaths.
Poor Quality: taste
Doria (2009) ( 4 ) pointed out that the organoleptic properties of water are one of the factors that influence how consumers estimate water quality.
These are the properties of food and water that are experienced via the senses: taste, sight, smell, and touch.
Other factors are external information, trust in water suppliers and perceived water chemicals (lead, chlorine, hardness).
Levêque and Burns (2017) ( 5 ) found that the people in a mid-sized West Virginia city consumed bottled water did so because they "were most likely to perceive health risks from tap water consumption" while those who used a household filter when drinking from the tap had higher organoleptic perceptions.
Facts: how safe is tap water?
Water quality: tap vs. bottled
The CDC - Centers for Disease Control and Prevention ( 6 ) confirms that "The United States has one of the safest public drinking water supplies in the world. Over 286 million Americans get their tap water from a community water system".
However Allaire (2018) ( 7 ) reports that in 2015 "9% of Community Water Systems in our study sample violated health-based water quality standards, affecting nearly 21 million people. During each of the past 34 y[ears], 9-45 million people were affected, representing 4-28% of US population."
This is supported by the CDC (6) data which reports the outbreaks of illness associated to tap water: 42 outbreaks in 2013-2014 involving 1,006 cases which lead to 124 hospitalizations and, believe it or not, 13 deaths.
Bottled water on the other hand only had 1 outbreak with 2 cases, nobody went to hospital and there were no fatalities.
Nevertheless, there have been recalls of bottled water ( 8 ), for instance: 40 million bottles by Niagara in 2015 (tested positive for E. coli) or 8 million bottles by Dasani (Coca Cola) due to mold and plastic pieces in the water.
Inflammatory Bowel Disease and Drinking water?
The causes that trigger inflammatory bowel disease or IBD are unknown. Forbes (2016) ( 9 ) studied if the microbes in drinking water may be one of the causes of this disease. The study found that areas with high incidence of IBD had lower frequencies of Proteobacteria such as Gammaproteobacteria. They also had higher presence of Bradyrhizobium and Pseudomonas than areas with lower incidence of IBD. So tap water supply may be an environmental source of IBD triggers.
Get your EPA Water Quality Report
The EPA (Environmental Protection Agency requires that community water systems provide an annual drinking water quality report (Consumer Confidence Report). Request your report and get full details about your local drinking water quality. They are sent out by July 1, each year. Find your Consumer Confidence Report.
Bottled Water Bacteria
Raj (2005) ( 10 ) studied what happened to microorganisms after drinking once from a water bottle and compared it to tap water: "The bacterial count in bottled water increased dramatically, from less than 1 colony per milliliter (col/mL) to 38,000 col/mL over 48 hours of storage at 37 degrees C... Interestingly, tap water resulted in only minimal growth"
Raj recommends storing opened bottles in the refrigerator which reduces bacterial colonies by up to 84%.
What is Bottled Water anyway?
Bottled water is drinking water that is packaged in plastic or glass water bottles.
It is now the "No.1 beverage product by volume in the US", overtaking soft drinks in 2017. (1)
A total of 13.7 billion gallons of bottled water were consumed in 2017: that is 42 gallons per capita year. (1)
It may be carbonated or still.
It may be mineral water, but most of the bottled water sold in the US, is treated tap water.
Most Bottled Water is bottled tap water
According to Food & Water Watch (8), the share of bottled water using municipal tap water as a source rose from 51.8% in 2009 to almost two thirds of the supply in 2014: 64%. So only 1 out of 3 bottles of water is actually mineral water from a natural spring.
The U.S. Food and Drug Administration (FDA) ( 11 ) defines mineral water as "water containing not less than 250 parts per million (ppm) total dissolved solids (TDS), coming from a source tapped at one or more bore holes or springs, originating from a geologically and physically protected underground water source... No minerals may be added to this water".
Tap water health risks
The use of chlorine as a biocide to kill the germs present in water was first proposed in 1894. It was tested and Great Britain became the first country to implement in the early 1900s. Its application dramatically reduced the incidence of typhoid deaths. The US followed the British example and wiped out all waterborne diseases (cholera, hepatitis, dysenteria and typhoid).
Chlorine has the disadvantage of having a particular taste and odor which can be detected by most individuals at concentrations as low as 0.3 parts per million. And this organoleptic perception is the leading cause of complaint related to drinking water taste and smell.
Chlorine reacts with organic matter in raw water producing "Disinfection by-products" or DBPs. This led to concerns abouth their effects, however the International Agency for Research on Cancer (1990) ( 12 ) studied the existing research and concluded that: " There is inadequate evidence for the carcinogenicity of chlorinated drinking-water in humans... Chlorinated drinking-water is not classifiable as to its carcinogenicity to humans."
More recently, Villanueva (2003) ( 13 ), performed a meta-analysis (a statistical procedure that combines data from multiple studies to find a common effect) which concluded that "long term consumption of chlorinated drinking water is associated with bladder cancer, particularly in men", however the relative risk is "only moderately high".
Fluoride is present in many natural water sources and in some mineral waters and its effect of rendering tooth enamel resistant to decay was reported in the early 1900s by McKay's and Black's studies on fluorosis in Colorado.
The U.S. has artificially fluoridated water since 1945 and its effects were very clear: children who drank fluoridated water had less cavities than those who drank non-fluoridated water.
The latest figures (2014) show that 75% of Americans drink fluoridated water, and the fluoride level in drinking water has been set at 0.7 mg per liter. ( 14 )
The impact is enormous: this water reduces tooth decay by 25% in both children and adults.
As expected, consumers also have risk perceptions associated with fluoridation, Knox (2017) ( 15 ) lists the five of the major themes for opposition to fluoridation: scepticism, health effects, ethics, environmental impacts and economics. They also voiced concerns about 'fraudulent research' and the influence of industry on government bodies.
Bucher (1991) ( 16 ) studied the effect of sodium fluoride in rats and mice at concentrations which were between 16 and 113 times higher than the recomended level mentioned further up. They found that some developed dental fluorosis (mottling of the teeth) and some female rats had had increased osteosclerosis (abnormal hardening of bone). There were no Increases in neoplasms (tumors) in female rats or in male rats. There was equivocal (ambiguous or questionable) evidence of carcinogenic activity of sodium fluoride in male rats based on the occurrence of a small number of osteosarcomas (the most common type of bone cancer) in treated animals.
Bottled water health risks
Bottled water's most common packaging is a Polyethlyene Terephthalate (or PET) plastic bottle. PET is much safer than the PVC bottles used in the past (whose free vinyl chloride monomer (VCM) content, a well known carcinogenic, could migrate from the plastic into the bottle's content.
However there are some concerns regarding migration of PET production residues:
Acetaldehyde (AA for short) is generated during the polymerization reaction in the manufacture of PET and in the melt process that makes the PET bottles.
AA has a distinct smell and taste, often described as sweet plastic-like. It remains inside the plastic matrix, but under certain conditions can leach out of it:
Bach (2012) ( 17 ) reports that carbonated bottled water promotes the release of acetaldehyde from the PET into the water. However this effect wasn't detected with still bottled water. Bach also noticed that acetaldehyde exceeded the water organoleptic threshold (between 20-40g/L) so that the odor of water stored in PET bottles compared to that of soft drinks, could be detected at very low levels, due to the absence of masking flavor compounds.
Seitz and Stickel (2009) ( 36 ) mention acetaldehyde as a risk factor that can provoke cancer, but their study is focused on the AA generated during the metabolization of alcohol in alcoholics.
In the manufacture of plastics building blocks known as monomer molecules link together to form the "polymer" or final product.
PET polymer is manufactured by catalizing its monomers (a catalyst accelerates chemical reactions) using compounds based on a metalloid called antimony (Sb). These catalysts are antimony trioxide or antimony acetate. Almost all of the catalyst is recovered but very small trace amounts of it remain inside the PET.
This residual Antimony can migrate or leach out of the plastic bottle and into the bottle's contents a process which can accelerate if the bottle is heated or microwaved.
Although antimony is regarding as having low toxicity it is limited to 6 parts per billion (6 ppb) in drinking water by the US regulations and 5 ppb in the EU.
Shotyk and Krachler (2007) ( 18 ) determined the concentration of antimony in 132 brands of bottled water from 28 countries. Two brands surpassed the Japanese maximum limit of 2 ppb. They also found that antimony concentrations increased with time even if stored at room temperature: by +19% in 14 Canadian brands after 6 months and by +90% in 48 European brands from 11 countries.
Antimony concentration varied from 0.28 to >2 ppb in comparison to tap water which contained 0.07 ng⁄liter or a well, with 0.026 ng⁄liter. Nevertheless, these values are well below the limits mentioned furhter up (6 ppb in the US or 5 ppb in the EU).
Westerhoff (2008) ( 19 ) tested bottled water in Arizona, southwestern US finding antimony levels that ranged from 0.095 to 0.521 ppb well below the maximum allowed value of 6 ppb. However they pointed out that "Summertime temperatures inside of cars, garages, and enclosed storage areas can exceed 65 degrees C in Arizona, and thus could promote antimony leaching from PET bottled waters... and, for exposure temperature of 65 degrees C the exposure duration necessary to exceed the 6 ppb level is only 38 days".
Sax (2010) ( 20 ) studied the possibility that antimony is an Endocrine disruptor (a chemical that interferes with the endocrine (hormonal) systems causing cancer, birth defects and other health issues) and concluded that "Some evidence suggests that antimony may be at least partially responsible for these estrogenic effects".
This agrees with Choe (2003) ( 21 ) whose studies were the first to suggest that antimony may be estrogenic.
Chemicals having estrogenic activity (EA)
Chun (2011) ( 22 ) studied some chemicals that mimic or interfere with the natural occurring estrogens. These chemicals are defined as "having estrogenic activity (EA)". And they are endocrine disruptors.
One of the most known endocrine disruptors is BPA (Bisphenol-A), a plasticiser -compounds used to soften rigid plastics. It has been banned in several countries and US states for use in children's bottles and containers. PET does not contain BPA, but it may contain other EAs.
According to Chun, as the polymerization of monomers is often incomplete and certain additives don't bond to the plastic's polymer structure, chemicals with an EA can leach from the plastic. Leaching which is accelerated by exposure to ultraviolet ratiation (sunlight's UV), heat, microwave radiation, boiling or dishwashing.
Chun cites a monomer used in the manufacture of PET (dimethyl terephthalate monomer) as exhibiting EA effect, adding that "breakdown products of dimethyl terephthalate, PET, and PETG resins probably contain and release phenolic moieties that have EA".
Plastics and toxicity
Some toxic chemicals are employed as the building blocks used to make the monomers used to manufacture PET. DMT is based on aromatic compounds known as xylenes and it is reacted with ethyleneglycol (the main component of your car's antifreeze) to produce PET. Another route is to combine ethyleneglycol and terephthalic acid (which is made from xylenes).
According to a report by the Berkeley Plastics Task Force (1996) ( 23 ), making a 16-ounce bottle out of PET creates more than 100 times as much air and water pollution as making the bottle out of glass. Yet glass has the advantage of not leaching them into the water inside the bottle.
Microplastic contamination in Bottled Water
Mason (2018) ( 24 ) studied the presence of "microplastics" (tiny microscopic pieces of plastic) in bottled water. They found that:
- 93% of bottled water showed some sign of microplastic contamination
- This is twice as much as the content detected in tap water
- On average there were 335 particles per liter of water (size range from 6.5 to >100 um)
- Most comon plastic is polypropylene -which is used in bottle caps
- 4% of the particles also contained industrial lubricants
- "Contamination is at least partially coming from the packaging and / or the bottling process itself"
Sustainability and Environmental Costs
As mentioned above, plastics do have an impact on the environment through the generation of toxic pollutants during their manufacture. But there is the additional issue of the disposal of plastics and their final environmental fate.
Environmentally conscious consumers worry that bottled water has a serious impact on the environment in comparison to regular tap water, and their concerns are well founded: bottled water is not eco-friendly. Consider these "costs":
Bottled water requires a bottle, which involves its manufacture (bottle and cap) from plastics and the final fate of the empty discarded bottle.
The Association of Plastic Recyclers and the American Chemistry Council inform (2016) ( 25 ) that the total plastic bottle recycling collection rate was 29.7%.
This means that 7 out of ten bottles go into landfills, litter or incineration.
The USA per capita consumption of plastic bottles is slightly above 30 lbs. per year. So each American only recycles 9 lbs. of plastic bottles a year, discarding the other 21 lbs.
The tab for plastic waste is picked up by the Municipalities, who pay over $100 million per year for disposal of plastic water bottles (8).
Each liter of bottled water requires an input of 1.32 liters: so end users only get two thirds of the water input into the process, one third is wasted.
Gleick and Cooley (2009) ( 26 ) compared the energy required to manufacture, bottle, transport, distribute and chill mineral water (recycling and reuse was not considered in the study) with the energy reequired to treat and distribute tap water and they found that bottled water requires 2000 times more enregy than tap water: between 5.6 and 10.2 MJ ⁄ liter for bottled water while tap water only needs 0,005 MJ ⁄ liter.
To put it into perspective, they give a clear example: "the annual consumption of bottled water in the US in 2007 required an energy input equivalent to between 32 and 54 million barrels of oil or a third of a per cent of total US primary energy consumption.".
Cost comparison of Tap and Bottled waters
Mineral Water costs 2000 times the price of tap water
Food & Water Watch (8) found that one gallon of single-serve bottled water costs on average almost $9.50, which is 2.000 times the cost of a gallon of tap water ($0.005) and four times the cost of a gallon of regular-grade gasoline or three times the price of a gallon of milk.
Common Benefits of bottled and tap water
Health benefits of the Minerals dissolved in both bottled and tap water
Mineral water contains dissolved elements and compounds that it picked up as it percolated through the bedrock and sediments to its sources. These are found in small (trace) amounts, but they can and do have an effect on your health. Further down we list some of these compounds and their effects.
So this is a good reason to drink bottled mineral water. Remember though that not all bottled water is "mineral water".
Minerals in tap water
Tap water also contains minerals. Azoulay (1991) ( 27 ) sampled tap water from 21 major American cities and found that it "may contain high levels of Ca2+, Mg2+, and Na+ and may provide clinically important portions of the recommended dietary intake of these minerals." however they found that bottled mineral waters sampled content of those minerals was "appreciably higher than from most tap water sources".
Quattrini (2017) ( 28 ) concludes that the diluted bicarbonate in mineral water improves the values of several markers: reducing total-cholesterol, LDL-cholesterol and fasting glucose values; and increasing HDL-cholesterol.
Present as magnesium or sodium sulphates is efficient as a treatment for constipation (28).
Calcium and Magnesium ions are dissolved in water, and the higher the content, the harder the water is said to be ("hardness" due to an increased alcalinity which impedes soaps from producing suds, which was a problem in the days before synthetic detergents).
Water hardness has a negative association with cardiovascular and cerebrovascular disease: in other words the harder the water you drink, the lower the risk of dying of either disease). This was confirmed by:
- Jiang (2016) ( 29 ) in Europeans (especially in the Scandinavian population) found that a high content of magnesium in drinking water reduces the risk of Coronary Heart Disease mortality.
- Chun-Yuh (2018) ( 30 ) contrasted 34,266 deaths with the levels of calcium and magnesium in the drinking water of the subjects, finding that calcium levels had no impact on the death rate but that there was "a significant protective effect of magnesium intake from drinking water on the risk of cerebrovascular disease"
Most of us get a large share of magnesium through our food and a smaller share through our drinking water. The recommended daily amount is 6 mg/kg per day, but the magnesium in water appears as hydrated ions which are more easily absorbed by the body than the magnesium in food. ( 31 )
High-calcium waters in certain regions is an important dietary source of calcium, and this is a great calcium supplementation impacting on bone health as proven by Costi (1999) ( 32 ): it improved the average spine bone density in women. Aptel (1999) ( 33 ) found that in 4,434 women over 75 years of age an extra 100 mg/day of calcium in their drinking water increased femoral bone density by 0.5%.
Sparkling Bottled Water
There is some concern that natural or artificial carbonated water (sparkling) may erode teeth enamel (for complete details visit our webpage - Sparkling or Still Water?, which is better?).
But the acid range of mineral water is too low to erode enamel (its pH value is around 5). So unlike carbonated soft drinks which have added acids and are very acidic (pH closer to 2) and do erode the surface of teeth, carbonated water is safe.
In support of this we cite two studies:
- Parry (2001) ( 34 ) who found that "mineral waters appear to offer a safe alternative to more erosive acidic beverages and their complex mineral ion compositions may positively influence any dissolution processes at the tooth surface", in other words mineral waters may remineralize the enamel.
- Avanija (2016) ( 35 ) considered as "minimally erosive (pH above 4.0)" the following bottled waters: S. Pellegrino Sparkling Natural Mineral Water pH 4.96 and Perrier carbonated mineral water pH 5.25
Some bottled seltzers are flavored with citric acid (an acid which is found in lemons, limes or oranges) and this extra touch of acid may lower the pH below the threshold and cause damage to tooth enamel.
Adding a slice of lemon to your glass of carbonated water will not increase acid levels so it is a safe way to add flavor to your drinks.
Cite this article:
A. Whittall. ©2018. Dehydration. Patagonia Wellness, 11 Oct. 2018. http://www.patagoniawellness.com/health/tap-or-bottled-water.html
Subject: Tap or Bottled Water?. The benefits and risks of drinking tap or bottled water
References and Further Reading
(1) Rachel Arthur, (2018). ’Bottled water is America’s favorite drink!’ Bottled water takes top spot in US. 01-Jun-2018
(2) Susan J. Masten, Simon H. Davies, and Shawn P. Mcelmurry, (2017). Flint Water Crisis: What Happened and Why?. J Am Water Works Assoc. 2016 Dec; 108(12): 22-34.doi: 10.5942/jawwa.2016.108.019
(3) Hu Z, Morton LW, Mahler RL, (2011). Bottled water: United States consumers and their perceptions of water quality. Int J Environ Res Public Health. 2011 Feb;8(2):565-78. doi: 10.3390/ijerph8020565
(4) Doria, M. F., Pidgeon, N. and Hunter, P. R., (2009). Perceptions of drinking water quality and risk and its effect on behaviour: a cross-national study. Science of the Total Environment 407 (21), 5455-5464
(5) Levêque, J. G. & Burns, R. C., (2017). Predicting water filter and bottled water use in Appalachia: a community-scale case study. Journal of Water and Health 15 (3), 451-461
(6) CDC, (2014). Commercially Bottled Water, last updated: April 7, 2014
(7) Maura Allaire, Haowei Wu, and Upmanu Lall, (2018). National trends in drinking water quality violations. National Academy of Sciences, February 7, 2018, https://doi.org/10.1073/pnas.1719805115
(8) Food & Water Watch, Take Back the Tap The Big Business Hustle of Bottled Water.
(9) Jessica D. Forbes et al., (2016). Microbiome profiling of drinking water in relation to incidence of inflammatory bowel disease. Canadian Journal of Microbiology, 2016, 62:781-793, https://doi.org/10.1139/cjm-2016-0219
(10) Raj SD, (2005). Bottled water: how safe is it?. Water Environ Res. 2005 Nov-Dec;77(7):3013-8
(11) Code of Federal Regulations, Title 21 retrieved 06.09.18
(12) International Agency for Research on Cancer (IARC), (1991). Chlorinated Drinking-Water. Summaries & Evaluations (Group 3) VOL.: 52 (1991) (p. 45)
(13) C M Villanueva, F Fernandez, N Malats, J O Grimalt and M Kogevina, (2003). Meta-analysis of studies on individual consumption of chlorinated drinking water and bladder cancer FREE. Journal of Epidemiology & Community Health 2003; 57 166-173 Published 01 Mar 2003. doi: 10.1136/jech.57.3.166
(14) CDC, (2017). Over 70 Years of Community Water Fluoridation. last updated: May 4, 2017
(15) Knox MC, Garner A, Dyason A, Pearson T, Pit SW, (2017). Qualitative investigation of the reasons behind opposition to water fluoridation in regional NSW, Australia. Public Health Res Pract. 2017 Feb 15;27(1). pii: 2711705. doi: 10.17061/phrp2711705
(16) Bucher J. et al., (1991). Results and conclusions of the national toxicology program's rodent carcinogenicity studies with sodium fluoride. Vol 48:5 International Journal of Cancer, 733-737. 9 July 1991
(17) Cristina Bach, Xavier Dauchy, Marie-Christine Chagnon, and Serge Etienne, (2012). Chemical migration in drinking water stored in polyethylene terephthalate (PET) bottles: a source of controversy. Water Research, IWA Publishing, 2012, 46 (3), 571-583. 10.1016/j.watres.2011.11.062
(18) William Shotyk and Michael Krachler, (2007). Contamination of Bottled Waters with Antimony Leaching from Polyethylene Terephthalate (PET) Increases upon Storage. Environ. Sci. Technol., 2007, 41 (5), 1560-1563 doi: 10.1021/es061511+
(19) Westerhoff P, Prapaipong P, Shock E, Hillaireau A., (2008). Antimony leaching from polyethylene terephthalate (PET) plastic used for bottled drinking water. Water Res. 2008 Feb;42(3):551-6. Epub 2007 Aug 6
(20) Leonard Sax, (2010). Polyethylene Terephthalate May Yield Endocrine Disruptors. Environ Health Perspect. 2010 Apr; 118(4): 445-448. doi: 10.1289/ehp.0901253
(21) Suck-Young Choe et al., (2003). Evaluation of estrogenicity of major heavy metals. Science of The Total Environment Vol 312:1-3, 1 August 2003, 15-21
(22) Chun Z. Yang et al, (2011). Most Plastic Products Release Estrogenic Chemicals: A Potential Health Problem That Can Be Solved. Environ Health Perspect. 2011 Jul 1; 119(7): 989-996. 2011 Mar 2. doi: 10.1289/ehp.1003220
(23) Report of the Berkeley Plastics Task Force. 1996
(24) Sherri A. Mason, Victoria Welch, Joseph Neratko, (2017). Synthetic polymer contamination in bottled water. State University of New York at Fredonia, Department of Geology & Environmental Sciences
(25) 2016 United States National Postconsumer Plastic Bottle Recycling Report. The Association of Plastic Recyclers and American Chemistry Council
(26) Gleick, P.H. and Cooley, H.S., (2009). Energy implications of bottled water. Environmental Research Letters 4 (2009) 014009 (6pp)
(27) Arik Azoulay, Philippe Garzon and Mark J Eisenberg, (2001). Comparison of the Mineral Content of Tap Water and Bottled Waters. J Gen Intern Med. 2001 Mar; 16(3): 168-175. doi: 10.1111/j.1525-1497.2001.04189.x
(28) Sara Quattrini, Barbara Pampaloni, and Maria Luisa Brandi, (2016). Natural mineral waters: chemical characteristics and health effects. Clin Cases Miner Bone Metab. 2016 Sep-Dec; 13(3): 173-180. 2017 Feb 10. doi: 10.11138/ccmbm/2016.13.3.173
(29) Jiang L et al., (20). Magnesium Levels in Drinking Water and Coronary Heart Disease Mortality Risk: A Meta-Analysis. Nutrients. 2016 Jan 2;8(1)
(30) Chun-Yuh Yang, (2018). Calcium and Magnesium in Drinking Water and Risk of Death From Cerebrovascular Disease. Stroke. 2018; 29:411-414 https://doi.org/10.1161/str.29.2.411
(31) Durlach J., (1989). Recommended dietary amounts of magnesium: Mg RDA. Magnes Res.1989;2:3:195-203
(32) Costi D. et al., (1999). Importance of bioavailable calcium drinking water for the maintenance of bone mass in post-menopausal women. J Endocrinol Invest. 1999 Dec;22(11):852-6
(33) Aptel I, Cance-Rouzaud A, Grandjean H, (1999). Association between calcium ingested from drinking water and femoral bone density in elderly women: evidence from the EPIDOS cohort. J Bone Miner Res. 1999 May;14(5):829-33
(34) Parry J, Shaw L, Arnaud MJ, Smith AJ, (2001). Investigation of mineral waters and soft drinks in relation to dental erosion. J Oral Rehabil. 2001 Aug;28(8):766-72
(35) Avanija Reddy et al., (2016). The pH of beverages in the United States. April 2016 Vol 147:4, 255-263 JADA
(36) Helmut K. Seitz and Felix Sticke, (2009). Acetaldehyde as an underestimated risk factor for cancer development: role of genetics in ethanol metabolism. Genes Nutr. 2010 Jun; 5(2): 121-128. Published online 2009 Oct 22. doi: 10.1007/s12263-009-0154-1