The twentieth century brought us many industrial wonders. Things like the automobile (and along with it the assembly line), microwave ovens and even the Internet. In the process we have super sized, super valued and super built just about everything. Furthermore, when you have super stuff you need super cleaners and super lubricants.
Industrial machinery and our mechanized society require (?) chemicals of an industrial nature like Sodium Lauryl Sulfate (SLS), Propylene Glycol (PG), and Diethanolamine (DEA). So let us take a brief moment to look at these various chemicals and don't worry, I am going somewhere with this.
Sodium Lauryl Sulfate was initially developed as a detergent gaining in popularity as a garage floor cleaner. It is characterized as a harsh detergent which is entirely believable since garage floors can get a tad bit dirty. Its ability to break down oils made it ideal for this type of clean up duty. Sodium Lauryl Sulfate can incarnate in different products as Sodium Laureth Sulphate as well which in some ways could be a lot worse considering the process to turn a Lauryl into a Laureth may produce 1,4 Dioxane, a known cancer causing substance and an ingredient in Vietnam era Agent Orange. In other words it's bad stuff!
Propylene Glycol started out as one of the ingredients that could be found in anti-freeze, brake fluid, paint, and airplane de-iceing fluids. To this very day it is still used as such. Propylene Glycol is an alcohol primarily used for its solvent properties.
Diethanolamine (DEA) is used as an industrial solvent, emulsifier, and detergent. It is used as wall and floor cleaners among other things.
Now here's the rub (literally): Everyone of the aforementioned chemicals can be found in most shampoos. It's a curious matter when you consider that each one of these chemicals is known to cause health issues in humans and animals as well.
Sodium Lauryl Sulfate has been shown to hinder proper eye development in children, cause cataracts in adults and impedes healing in all beings (See summary report of Research to Prevent Blindness, Inc.). SLS is easily absorbed and stored in the body making it a cumulative toxin. Do you remember how SLS breaks down oil on garage floors? It interferes with the biology of the skin primarily through breaking down the oil in skin leading to stripping and over-drying. What is even more incredible is that SLS is commonly used as a skin irritant in clinical testing to see if other products can alleviate the irritation!
The American Academy of Dermatologist published a report back in 1991 establishing Propylene Glycol as a primary skin irritant even at low levels (5% concentration). Unfortunately, PG is usually a top three ingredient in most products it is used in which means it is at least 20% of the product making it at 20% concentration. Judy Vance, author of "Beauty To Die For" stated that in order to sell PG you would have to furnish the buyer with a material data safety sheet (MSDS). Ironically a warning clearly listed on the MSDS states "If on skin: Thoroughly wash with soap and water".
The US DOT regulates the transport of every version of Diethanolamine (DEA). Why, do you ask? Well, the US DOT lists DEA as an environmentally hazardous substance and an immediate health hazard as described as being the only hazardous ingredient in a product called Monamine (CD -100-CAS 68814-92-6). When combined with nitrates it is known to chemically form nitrosamines - a carcinogen (that which causes cancer). Even without nitrates newer studies are showing a carcinogenic effect in addition to mucous membrane and skin irritation.
Yes we undoubtedly live in an industrial age but we do not have industrial bodies. If a chemical was designed to strip a floor please know and understand that it will strip your skin and disrupt your inner and outer biology. I got curious the day I typed this blog and took a look at the ingredients in Wish Bone Ranch Dressing and was amazed that among some of the other questionable ingredients was listed Propylene Glycol! Would you like a little antifreeze with your salad or wings? So the question remains: What's in YOUR shampoo (or deodorant, toothpaste, or any number of personal care/hygiene products and even food)?
Post Script: Most sources were directly referenced within the post. In addition to those another source with great information is a book called Health Wars by Phillip Day.