Shampoo 
Beauty, Your Health, and the Environment

The major environmental risk involving shampoo is the release of chemicals into the water supply through the drain.  Most chemicals in shampoo are harmful to the environment in one way or another.  Most shampoos contain a chemical called Sodium Laureth Sulfate, which is mutagenic to animals.  When animals in the wild drink water with this chemical, it can be harmful to them.  Shampoo also contains Ammonium Chloride and Methylchloroisothiazolinone, both of which are proven to be harmful to the environment.  When you think about how many people use shampoo and hair products each day, the amount of chemicals being dumped into our water supply is monstrous!  
The Environmental Dangers
Although shampoo seems harmless, it, unfortunately like many other commonly used products, has the potential of causing serious health problems. For example, many shampoos contain the chemical Sodium Laureth Sulfate which is a known skin irritant and in studies has caused mutagenic effects on animals. Another chemical found in shampoo is Ammonium Chloride which is a respiratory and eye irritant and harmful if swallowed, while Formaldehyde, a carcinogen, can cause eye and throat irritation, nausea, difficulty breathing, fatigue, and allergic reactions. 
The Health Risks
However, there are some alternative shampoos that are safe for the environment.  These are usually created from plant oils, are free of petroleum products, and do not use synthetic fragrances.  Not only do these products contain fewer chemicals, but they will also help to keep the environment safe and you healthy.
Methylchloroisothiazolinone, a antibacterial and antifungal preservative, is toxic to the immune system, a skin irritant, allergen, and can cause chemical burns. Even the fragrance of many shampoos can be harmful to people, often containing cancer-causing chemicals. While the majority of shampoos contain these toxic chemicals, there are certain shampoos that are toxic free. Although they are not chemical-free, many of the toxic chemicals found in common shampoos are not present in these shampoos. These shampoos also provide those who are sensitive to harsh chemicals an alternative because they cause less skin irritation. 
Source: news-medical.net, agreenliving.net