To Your Health

A. There are many unsafe substances in shower water, but chlorine is the most worrisome. One estimate is that two-thirds of our harmful exposure to chlorine is due to inhalation and skin absorption while showering. A hot shower opens up the pores of the skin and allows increased absorption of chlorine, plus the steam we inhale while showering has yet more vaporized chlorine. The chlorine that we inhale or absorb through the skin goes directly into our bloodstream, while the chlorine we swallow from drinking water is carried to the liver where at least some is removed before it can circulate throughout the body.

Chlorides, the salts of chlorine, are not necessarily toxic, but chlorine, which is used to kill infectious bacteria in our water, is poisonous enough to be a chemical warfare agent.

About 80% of Americans drink chlorinated water. The addition of chlorine to our drinking water began around 1890 and has been the standard in water treatment for more than a century. Chlorine is not the safest or most effective means of water treatment, but, in spite of all our technological advances, it is still the cheapest.

Perhaps even more harmful than chlorine are the chlorinated compounds that result when chlorine in water reacts with the harmless organic substances that are always present in our water. Chlorination of drinking water generates low levels of numerous "chlorinated hydrocarbons," many of which are carcinogenic to animals if there is long-term exposure.

No one disputes that chlorine water treatment has freed civilization from the constant dangers of waterborne disease epidemics, and that the hazards of doing away with chlorine are greater than the health risks of low exposure to chlorine. The simple truth is that it is just not realistic to suppose we will do away with chlorine water treatment in the near future.

It is also clear that once chlorine has served its purpose in keeping our water free from harmful bacteria, it should be removed. As a bonus, some people notice that skin and hair feel better when chlorine is removed, and for others dispensing with the objectionable odor of chlorine is a sufficient reason to take out the chlorine.

Although not a proven cause of asthma, chlorinated hydrocarbons can trigger asthma attacks in asthmatics and provoke other "allergic" reactions.

Chlorine is relatively easy to remove from water. Showerhead filters (known as KDF filters) are available for less than $50. They use copper and zinc granules that will take out chlorine for about six months. Low-flow filtering showerheads also save money by reducing the amount of hot water you would use. Charcoal showerhead filters are available also, but are much less efficient at removing chlorine because of the high water volumes and hot water temperatures we like for showering.

N-acetylcysteine reduces the toxicity of chlorine compounds and can be supplemented when exposure to chlorine is unavoidable. This versatile antidote to a number of toxins also has a reputation for helping breathing, which could be helpful if exposed to chlorine.