Science

New toxic byproducts found in chlorinated water

New toxic byproducts found in ...
Researchers have found that treating drinking water with chlorine could produce previously-unknown byproducts
Researchers have found that treating drinking water with chlorine could produce previously-unknown byproducts
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A diagram showing that chlorine in water treatment may react with natural compounds called phenols, creating toxic byproducts in drinking water
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A diagram showing that chlorine in water treatment may react with natural compounds called phenols, creating toxic byproducts in drinking water
Researchers have found that treating drinking water with chlorine could produce previously-unknown byproducts
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Researchers have found that treating drinking water with chlorine could produce previously-unknown byproducts

Adding chlorine is one of the most common methods of disinfecting drinking water, but just how safe is it? Researchers from Johns Hopkins have now found evidence that reactions between chlorine and natural compounds in water may produce previously-unknown toxic byproducts.

It’s well known that chlorine is a powerful disinfectant, killing bacteria, viruses and other microbes effectively. As such, it’s credited with drastically stemming the tide of waterborne disease such as cholera and typhoid, after it became widely used to treat drinking water in the early 20th century.

But adding chlorine isn’t without its own problems. The chemical reacts with compounds called phenols that are naturally found in water, creating potentially-harmful byproducts. But as the World Health Organization (WHO) says in a report (PDF, page 6), “the risks to health from these byproducts are extremely small in comparison with the risks associated with inadequate disinfection.”

But now, the Johns Hopkins researchers have found signs of new byproducts that have until now gone undetected. The team suspected that current methods of analyzing the chemistry of drinking water may miss some of these byproducts, so they tested another technique.

The researchers used N-α-acetyl-lysine, an amino acid that’s often used in toxicology to detect harmful molecules known as reactive electrophiles. The team added this amino acid to water that had first been treated with chlorine the same way that drinking water usually is at large scales. They then left it to sit for a full day before analyzing it using mass spectrometry.

And sure enough, the researchers detected two related compounds: 2-butene-1,4-dial (BDA), and chloro-2-butene-1,4-dial (BDA with chlorine). These are known to be toxic and carcinogenic, and have never been detected in drinking water before.

A diagram showing that chlorine in water treatment may react with natural compounds called phenols, creating toxic byproducts in drinking water
A diagram showing that chlorine in water treatment may react with natural compounds called phenols, creating toxic byproducts in drinking water

That said, the team points out that they still haven’t been found in actual drinking water yet – the lab tests just show that they could be produced under those conditions. There’s also the question of whether these compounds are present in high enough concentrations to pose any actual threat to health. And even then, there’s still the tradeoff that preventing waterborne illnesses is likely a much greater good.

"There's no doubt that chlorine is beneficial; chlorination has saved millions of lives worldwide from diseases such as typhoid and cholera since its arrival in the early 20th century," says Carsten Prasse, lead author of the study. "But that process of killing potentially fatal bacteria and viruses comes with unintended consequences. The discovery of these previously unknown, highly toxic byproducts, raises the question how much chlorination is really necessary."

Alternate methods of disinfecting water, such as ozone, UV light or filtration, keep waterborne disease at bay in many countries around the world without producing toxic byproducts. The team says that it may be better to put these into even wider use.

"Our study also clearly emphasizes the need for the development of new analytical techniques that allow us to evaluate the formation of toxic disinfection by-products when chlorine or other disinfectants are being used,” says Prasse. “One reason regulators and utilities are not monitoring these compounds is that they don't have the tools to find them.”

The research was published in the journal Environmental Science & Technology.

Source: Johns Hopkins University via Phys.org

7 comments
paul314
Do the other methods of killing bacteria definitively produce no toxic byproducts? I'd think that both UV light and ozone would promote a bunch of interesting chemical reactions. (Perhaps fewer or less-toxic byproducts, since chlorine is a nasty in many cases.)
Aross
I have always been worried about the chlorine levels in our drinking water. Where I live you can actually smell the chlorine when taking a shower or filling containers. I now let the water stand for 24 hours before watering plants and don't drink the tap water at all It seems to me that in everything we do to "keep ourselves healthy and safe from disease" we just create other problems. So many of the health studies done only last a few years, when in fact, they should cover generations.
Signguy
Reverse Osmosis is the only way to get clean water.
buzzclick
The air you breathe, the water you drink and the food you eat, in order of importance. You can live for a few minutes without air, a couple of weeks without water and just over a month or two without food. Aross has it right, let the chlorine dissipate before using. Ozone, UV light and filtration (reverse osmosis being the best but most expensive) is the way to go if you want that insurance.
Infiinityandbeyond
I have a theory that the historic increase in diabetes has a direct correlation with the increased use of chlorinated water - affecting those with a predisposition to the condition.
dls
The alternate methods of disinfecting water, does not include an environmentally-friendly compound that is used in more and more waste-water treatment plants (and many other commercial disinfectant purposes) as a replacement for chlorine. It's name is peracetic acid or PAA. It is an equilibrium mixture of acetic acid and hydrogen peroxide and is very potent. It degrades rapidly to water and vinegar (the vinegar degrades and only leaves a small carbon source).
Pay attention, you'll be hearing more about this compound!
Venetian
Chlorine itself is toxic and among its many harmful effects is water retention and inflammation in the body. It also does nothing for particulates and heavy metals which are often far more harmful than the bacteria the chlorine is supposedly killing. There is also the reaction between chlorine and lead found in most water pipes and many homes. Only multi stage filtration with carbon, followed by disinfection with ultraviolet light and reverse osmosis is an effective way to create clean water. The irony is that unless you get your water directly from a deep underground spring it will be already loaded with harmful chemicals thanks to the acid rain effect which now affects open water sources around the entire planet. Not to mention the microplastics present in the rain and main water supplies which for the most part are either rivers, or reservoirs natural or man made. Additionally, there are no set world standards for the universal levels of chlorine in water which is why so many places in the world have tap water that smells and tastes like a hot tub. Do not drink tap water that has been chlorinated. It is responsible for a lot of health problems including dementia etc.
If you can, but spring water bottled as recently as possibly to minimize the contact between the water and the plastic containers used for transport.
Some studies below to show the harms of drinking chlorinated water:
Siritapetawee J, et al. Trace element analysis of hairs in patients with dementia. J Synchrotron Radiat. 2010 Mar;17(2):268-72. doi: 10.1107/S0909049509055319. Epub 2010 Jan 16.
Fisk MZ, et al. Asthma in swimmers: a review of the current literature. Phys Sportsmed. 2010 Dec;38(4):28-34. doi: 10.3810/psm.2010.12.1822. Review.
Carlsen KH. The breathless adolescent asthmatic athlete. Eur Respir J. 2011 Sep;38(3):713-20. doi: 10.1183/09031936.00068510. Epub 2011 Mar 24. Review.
Anderson PD. Emergency management of chemical weapons injuries. J Pharm Pract. 2012 Feb;25(1):61-8. doi: 10.1177/0897190011420677. Epub 2011 Nov 11. Review.
Mohan A, et al. Acute accidental exposure to chlorine gas: clinical presentation, pulmonary functions and outcomes. Indian J Chest Dis Allied Sci. 2010 Jul-Sep;52(3):149-52.
Ginsberg JP, et al. Posttraumatic stress and tendency to panic in the aftermath of the chlorine gas disaster in Graniteville, South Carolina. Soc Psychiatry Psychiatr Epidemiol. 2012 Sep;47(9):1441-8. doi: 10.1007/s00127-011-0449-6. Epub 2011 Nov 10.
Florentin A, et al. Health effects of disinfection by-products in chlorinated swimming pools. Int J Hyg Environ Health. 2011 Nov;214(6):461-9. doi: 10.1016/j.ijheh.2011.07.012. Epub 2011 Sep 1. Review.
Jahangiri L, et al. Severe and rapid erosion of dental enamel from swimming: a clinical report. J Prosthet Dent. 2011 Oct;106(4):219-23. doi: 10.1016/S0022-3913(11)60126-1.