Chlorinated Pools May Increase Cancer Risk

Chlorinated Pools May Increase Cancer Risk. Learn more about Chlorinated Pools May Increase Cancer Risk in this article.


- Chemicals in chlorinated swimming pools may cause asthma, respiratory problems and even cancer.

- There are alternatives to chlorine and methods for using less of it.

- You can do your part to help by taking a shower before you swim.

Swimming in a chlorinated pool may increase your risk of developing cancer, suggest a new suite of studies, which identified more than 100 chemical byproducts in pools that use chlorine as a disinfectant.

The work is too preliminary to suggest that people should stop swimming, said Manolis Kogevinas, an epidemiologist at the Center for Research in Environmental Epidemiology in Barcelona. The studies were small, and they found a rise in blood markers that have been associated with cancer -- not a rise in cancer itself.

Still, Kogevinas said, the findings suggest that people need to work harder to reduce everyone's exposure to chlorine.

"People should not be afraid of swimming, but we should get more research on whether there are better practices for disinfecting pools," Kogevinas said. "It's all a matter of costs and benefits."

Chlorine is really good at killing microbes in swimming pools. Over the years, though, scientists have become concerned about its possible health effects. In water, chlorine reacts with sweat, urine, skin cells and other organic materials to produce all sorts of chemical byproducts. In animal studies, some of those chemicals have been linked with asthma and bladder cancer.

In a new study -- one of three just published in Environmental Health Perspectives -- chemists for the first time analyzed exactly what was in chlorinated water from a public swimming pool in Barcelona. They identified more than 100 chemical byproducts in the water. Many were toxic. Some had never been found in swimming pools or in chlorine-treated drinking water.

For the other two studies, 50 healthy adults swam laps for 40 minutes. The researchers measured levels of a number of substances in the blood, urine and breaths of the swimmers, both before they got in the pool and after they emerged. Each measurement looked at a marker, or sign of what was happening in the body.

The scientists expected to find some sign of respiratory distress. Previous studies have shown higher rates of asthma in lifeguards and competitive swimmers, as well as higher rates of eye, nose and throat irritation in pool workers.

Among a variety of markers for respiratory problems, though, the new work found that swimming led to a rise in just one. This marker showed an increase in how easy it is to penetrate the lining of the lungs. That's a sign, scientists think, of inflammation and a higher risk for asthma allergic diseases.

The most striking results came from the part of the research that looked at markers for cancer. After 40 minutes of swimming, the study found, people showed a large rise in markers of DNA damage that can lead to cancer. Concentrations of four of the most common byproducts were seven times higher after people swam.

Chlorine's chemical byproducts can get into our bodies through the skin. Exposure also comes from breathing air at the surface of the water, where chemicals become volatile. When exercisers swim hard, they breathe faster and end up with even more exposure.

It's far too soon to conclude that these short-term changes lead to long-term health problems, said Alfred Bernard, a toxicologist at the Catholic University of Louvain in Brussels, Belgium.

But he thinks there's already enough reason to swim with caution. His own work suggest that chlorine byproducts are a major risk factor for rising rates of asthma, airway irritation and allergic diseases, especially during windows of sensitivity in babies and young children.

"We have good evidence that you have to be careful with these chemicals," Bernard said. "Maybe chlorine is not the best choice for disinfecting swimming pools."

Alternatives do exist. Some pools use ozone, copper and silver ions, or even moss to kill bacteria.

Even if pools continue to use chlorine, there are ways to reduce how much of it they use, Kogevinas said. Regular emptying and cleaning of the pool helps. So does introducing freshwater.

Swimmers can make a difference, too. By simply showering before they get in the pool, they wash off much of the organic material that reacts with chlorine to produce toxic byproducts. Swimming, Kogevinas added, is still healthier than not exercising.

Just choose your pools wisely, Bernard advised. If you go to a pool with a strong chlorine smell, and you see children with skin rashes or breathing problems, find somewhere else to go.

"Parents send their children to pools because they want to do something good for them," Bernard said. "But we actually don't know the long-term effects. It's an irony if there is something bad in there."

After 40 minutes of swimming, people in a study showed a rise in markers of DNA damage that can lead to cancer.

Michael Marin Self-Poisons in Courtroom

July 3, 2012 --

Shortly after hearing a guilty verdict while on trial for setting fire to his Phoenix mansion in an effort to get out of his mortgage, former Wall Street trader Michael Marin shocked the courtroom by collapsing and dying in a suspected suicide. Video of Marin suggests he swallowed what media reports are speculating to be a poison pill. Within minutes of swallowing the pill, Marin goes into convulsions and later he's pronounced dead. Whatever Marin succumbed to needed little time to take full effect if the video of the courtroom drama does in fact detail the 53-year-old swallowing the poison that killed him. In this slideshow, take a look at some of the most dangerous poisons known to man.

Amatoxins The mushroom in this photo may not seem as terrifying as its nickname would imply. But a single ounce of this "death cap," which unfortunately can resemble its more edible cousins, is enough to kill a human being. Amatoxins, the poison found in this fungus, is what's behind this mushroom's deadly kick. They can severely damage liver and kidneys, and lead to coma, organ failure and more.

PHOTOS: Magic Mushrooms in My Yard

Anthrax Anthrax was a bacteria that was all but off the radar thanks to decades of vaccination and sterilization programs aimed at containing infection rates. Then in 2001, anthrax became headline news when a series of attacks through the United States Postal Service killed five and sickened 17, according to the Federal Bureau of Investigation. Anthrax spores can spread through the air and can infect a person or animal by coming into contact with a wound on the skin, by being inhaled by the host, or by being ingested in the form of tainted meat. Symptoms of anthrax infection depend on the method of exposure, but typically resemble the common flu. Inhaling anthrax is the most dangerous means of exposure and can be fatal up to 90 percent of the time.

WATCH VIDEO: Killing Anthrax Faster and Greener

Botulinum Given that there are many poisons that can be lethal in small doses, pinning down the most dangerous can be considered a somewhat objective exercise. But toxicology experts all seem to agree that botulinum toxin, the same stuff that's used in Botox injections to clear up wrinkles, takes the cake. Botulinum, which causes botulism as the name implies, can cause respiratory failure, neurological damage and more at its worst. The bacteria can enter the body through open wounds or by being ingested in food.

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Cyanide If there's one toxin that has almost become a synonym for poison, it's cyanide. Cyanide can come in the form of a crystal or colorless gas that's been described as having a "bitter almond" smell, according to the Centers for Disease Control and prevention. Cyanide also happens to be everywhere: It's naturally occurring in some foods and plants. It's in cigarettes. Cyanide is used to manufacture plastics, develop photographs, remove gold from ore, and of course kill unwanted insects, among other applications. Cyanide exposure can come from inhalation, ingestion or even touch. Poisoning from cyanide can lead to convulsions, respiratory failure and death in extreme cases.

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Mercury As described by the National Institutes of Health, there are three forms of mercury that can be potentially deadly: elemental mercury, inorganic mercury and organic mercury. Elemental mercury, which is what you find in glass thermometers, older dental fillings and florescent light bulbs, is harmless to the touch, but can be fatal if inhaled. Even if the person exposed survives, poisoning can still lead to long-term or even permanent lung and brain damage. Inorganic mercury, which is used to make batteries, can be deadly when ingested, and lead to kidney damage and worse. Organic mercury, found in fish, can be inhaled or ingested, and usually only affects those exposed over the long term, except in rare cases. Symptoms can range from memory loss to blindness to seizures and more.

Ricin Derived from castor beans, ricin is a naturally occurring poison, and humans can be exposed to it in the air, food or water, according to the CDC. Although the symptoms can vary depending on the method of exposure, ricin works by preventing cells from creating proteins they need to survive. Eventually, these cells die off, which can lead to organ failure.

Sarin Unlike all of the other entries on this list so far, Sarin is a synthetic toxin manufactured as a nerve agent. As explained by the CDC, sarin was originally developed as a pesticide, but this odorless, clear gas quickly became a tool for chemical warfare. Sarin can be inhaled or exposure can come through contact with the eyes or skin. The most recent use of sarin gas was in a series of terrorist attacks in 1994 and 1995 in Matsumoto and Tokyo, Japan, respectively, causing 20 deaths and injuring some 1,600 others. Symptoms from sarin gas exposure include blurred vision, convulsions, respiratory failure and more.

Strychnine Derived from the Strychnos nux-vomica tree native to India and southeast Asia, pure strychnine comes in the form of a white, bitter powder that can be deadly when inhaled, injected or ingested. Although commonly used as a pesticide, it has also surfaced in illegal drugs such as heroin and cocaine, according to the CDC. Strychnine poisoning can lead to muscle spasms, respiratory failure and even brain death within 30 minutes of exposure.

Tetrodotoxin Pufferfish may not seem like particularly dastardly animals based on their appearance alone, but they harbor one of the most deadly poisons known to man. Found in the skin, liver, intestines and other organs of the pufferfish, tetrodotoxin can cause paralysis, convulsions, mental impairment and more to anyone who eats this fish, at least when it's been served improperly. Although only a handful of cases are ever reported in the United States, there are as many as 200 cases annually of tetrodotoxin poisoning in Japan, with a 50 percent mortality rate, according to the Food and Drug Administration (FDA).

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