Which ingredients in skin care products should I avoid?

Here are a few. I would avoid parabens (preservatives that are widely used and have been found in low levels in breast cancer), xenoestrogens (foreign Estrogens that have estrogenic effects on living organisms) or carcinogens (such as sodium lauryl sulfate that is often found in cleansers and toothpaste).
Fragrance. Fragrance is a frequent sensitized. There is also controversy re parabens if they increase the risk of cancer formation. Parabens are found in high levels in some women in breast tissue . It is thought these chemicals are absorbed through deodorant.