The Negative Health Effects of Chlorine

Do you know what’s in the water you’re drinking? Now, you probably think that I’m talking about some dangerous chemicals. I bet that you wouldn’t think about chlorine at all.

Chlorine is used to purify water, you might say. Nevertheless, chlorine can have negative effects on your health. Let’s see what chlorine is and what effects it can have on you.

What’s chlorine and why do we use it?

Chlorine is a chemical element with numerous applications. You know one of its compounds, and you probably use it every day. I’m talking about sodium chlorine, also known as salt. On the other hand, chlorine gas has been used as a weapon since 1915.

But why do we use chlorine for water purification? Well, there are several reasons:

  • it kills bacteria
  • it impedes the growth of bacteria
  • it prevents the spreading of waterborne diseases
  • it’s cheap

Chlorine might lead to cancer

The danger with chlorine is that it might react with compounds naturally occurring in the water. If that happens, it can produce disinfectant by-products called trihalomethanes (THMs) and haloacetic acids.

Chlorine in the water usually produces two types of THMs -bromoform and dibromochloromethane. Both are potentially dangerous for a person’s health because they produce free radicals in the body and damage cells.

Depending on the dose and the duration of exposure, these disinfection by-products cause:

  • heart diseases
  • liver and kidney cancer
  • unconsciousness
  • death

Haloacetic acids, on the other hand, can cause:

  • severe skin irritation
  • cancer
  • birth defects

Since these by-products are potentially carcinogenic, their concentration in the drinking water is carefully monitored, and according to the World Health Organization, the risk is minimal. But according to the Council of Environmental Quality, people who drink chlorinated water regularly have a higher chance of developing cancer.

Chlorine can cause asthma

If you think that you’re safe because you don’t drink chlorinated water, think again. Chlorine is frequently used in pools for disinfection. So if you go for a swim in your local pool together with your kids, you’re still exposed to chlorine.

And scientists speculate that swimming or bathing in chlorinated water increases the risk of respiratory problems such as asthma. Just breathing the fumes from an overchlorinated pool might be enough to make you feel ill.

Swimming in chlorinated water can also cause skin irritations, eczema in people with sensitive skin, and dry hair.

As usually, young children with developing immune system are the one to be affected. One study even concluded that children who swim in pools regularly are more likely to develop asthma than non-swimming children.

Chlorinated water increase heart disease risk

Way back in the 1960s, Dr. Joseph M. Price published a book called “Coronaries Cholesterol Chlorine.” In his book, he proposes the theory that heart attacks, strokes, and atherosclerosis are not caused by high cholesterol levels, but chlorine instead.

Since chlorine produces free radicals in the body, these radicals damaged the cells. The cell damage leads to high level of serum cholesterol and the building of plaques on the artery’s walls.

To support his claims he experiments on chickens. The result showed that 95% of the chicken, which drank chlorinated water, developed atherosclerosis. Another scientist Richard Bull did the same experiment with pigeons and obtained the same results.


Chlorine has played a significant part in purifying water and keeping dangerous diseases at bay in the past. But in light of the recent discoveries, it might be time to find new ways to purify water. Don’t you agree?