Chlorine is widely used to disinfect water. You find it not just in swimming pool water, but also in the water that comes from your tap. Since chlorine evaporates out of water at relatively low temperatures, a steamy morning shower can expose you to up to 100 times the amount of chlorine than is contained in the water itself. This means that when you take a nice hot morning shower, you are exposed to chlorine on your skin and in your lungs. In fact, you get more chlorine in your body from one hot shower than you do drinking chlorinated water the rest of the day.

The problem with this scenario is that chlorine is poison.

Chlorine makes a great disinfectant because it kills germs, bacteria, and other living organisms by invading the cell walls, attaching to the fatty acids within the cell, and causing cell death. Chlorine does this to germs and it does it to cells in people. A big manufacturing plant that produces chlorine knows that, by law, it must take strict precautions in the manufacture and handling of chlorine because chlorine is toxic. Exposure to a large amount of chlorine is fatal. All of us ingest minute amounts of chlorine every single day, but the biggest share of chlorine we get every day is not in the form of tap water—it’s from the shower. We actually can get more than half of our daily chlorine exposure from the shower. So what can you do? Switching to a bath or a cool shower may reduce exposure but it does not prevent it. Some good, non-alarmist steps to reduce your chlorine intake:

1. Drink bottled or filtered water.
2. Use bottled or filtered water for your coffee and tea and in your cooking.
3. Get a filter for your shower to eliminate the chlorine. There are several types on the market.
4. If you can’t filter your shower water, swap out baths for showers whenever you can and take cooler, shorter showers.

Source:

http://www.bidness.com/esd/showering.html