Petroleum is for your Gas Tank, Not Your Skin
Most of us have used petroleum jelly on our skin as a lubricant, moisturizer or otherwise. Since it is such a common ingredient in many products, we often forget where it comes from and the potential dangers within.
The key is something known as PAH's, polyaromatic hydrocarbons. PAH's are contained in most petroleum jellies. Many however are not aware that PAH's are know neurotoxins and carginogens.
3rd Rock doesn't use petroleum based ingredients, because when petroleum is refined - we never know how much of the toxins have been removed or added during the extraction process. In addition, petroleum (oil) from one part of the planet to another varies in degree of toxicity - some is extremely high in sulfur content, for instance, while from other regions it is sulfur-free.