Parabens 
Also known as: methyl-, ethyl-, butyl-, propyl-
A preservative known for disrupting hormones and causing skin irritation. 

Phthalates
Also known as: DBP (dibutyl phthalate), DEP (diethyl phthalate), BPA (Bisphenol)
These disrupt the endocrine system, and may cause infertility and birth defects. 

Formaldehyde
Also known as: Formaldehyde, Quanternium-15, DMDM hydantoin, Imidazolidinyl Urea, Diazolidinyl Urea, Sodium Hydroxymethylglycinate
A known carcinogen, this preservative is linked to asthma. It is thought to contribute to liver toxicity, among other side effects with long-term exposure. 

Triclosan
This antibacterial ingredient is harmful to aquatic environments, and is linked to reproductive issues and thyroid disruption.

Siloxanes 
Also known as: Cyclomethicone, Cyclotetrasiloxane, Cyclopentasiloxane, and Cyclohexasiloxane
A product-smoother found in everything from deodorant to moisturizers, this ingredient is thought to harm the reproductive system and cause uterine tumors. 

SLES, SLS, ALS
Also known as: BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene)
These synthetic antioxidants are known to cause liver and stomach damage, and are proven to cause skin depigmentation. 

PEGs
Also known as: PEG, Polyethylene, Polyethylene Glycol, Polyoxyethylene, Ceteareth
The “cream” base in most cosmetics. PEG’s are often contaminated by the carcinogen 1,4-Dioxane, they’re known to penetrate the skin and harm the nervous system. 

Petrolatum
Also known as: Petroleum Jelly, Mineral Oil
These are found in a large proportion of beauty products, and are believed to contaminate the human body. 

Phenoxyethanol
Also known as: Phenoxyethanol
A preservative shown to cause skin and lung irritation.