Simple answer: because they’re cheap, readily available, and easy to dilute.
Are they in the products you currently use? It’s time to check. Go grab your containers of skin care products and check them against the following …
Heavily used preservatives in the cosmetic industry; used in an estimated 13,200 cosmetic and skin care products. Studies implicate their connection with cancer because their hormone-disrupting qualities mimic estrogen and could disrupt your body’s endocrine system.
These petroleum products coat the skin like plastic – clogging pores and creating a build-up of toxins. They can slow cellular development, creating earlier signs of aging. They’re implicated as a suspected cause of cancer. Plus, they can disrupt hormonal activity. When you think about black oil pumped from deep underground, ask yourself why you’d want to put that kind of stuff on your skin…
Found in over 90% of personal care products! They break down your skin’s moisture barrier, potentially leading to dry skin with premature aging. And because they easily penetrate your skin, they can allow other chemicals easy access. SLS combined with other chemicals may become a "nitrosamine" – a potent carcinogen.
Found in many facial creams. Linked to mammary tumors.
Common cosmetic moisturizer and carrier for fragrance oils. May cause dermatitis and skin irritation. May inhibit skin cell growth. Linked to kidney and liver problems.
Phenol carbolic acid
Found in many lotions and skin creams. Can cause circulatory collapse, paralysis, convulsions, coma, and even death from respiratory failure.
Hidden in ingredients such as PEG, polysorbates, laureth, ethoxylated alcohols. Very common in personal care products. These chemicals are often contaminated with high concentrations of highly volatile 1,4-dioxane that’s easily absorbed through the skin. Its carcinogenicity was first reported in 1965, and later confirmed in studies including one from the National Cancer Institute in 1978. Nasal passages are considered extremely vulnerable, making it, in my opinion, a really bad idea to use these things on your face.
May be very poisonous! Made from petroleum and coal tar… found in most synthetic fragrances. Chronic exposure linked to anemia, lowered blood cell count, liver or kidney damage…May affect a developing fetus."
(The following was taken from Mercola.com.)