Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its name is a portmanteau of the words wiki (a technology for creating collaborative websites, from the Hawaiian word wiki, meaning "quick") and encyclopedia. It is an excellent source for information about ingredients and chemicals used in the cosmetic, skin care and hair care industries...

PubMed Central is a free digital archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).

With PubMed Central, NLM has taken the lead in preserving and maintaining access to electronic literature, printed biomedical literature, scientific studies and their findings and especially many studies on the effects of various ingredients on the human body...

Oeko-Test Magazine was started by a few journalists in 1985. It evaluates and ranks various consumer products for its effect on health & environment, helping stores and manufacturers to improve their products. It is similar to Consumer Reports in the US, but with a much stronger emphasis on consumer safety and health...

TheGreenGuide.com is a great educational resource from the National Geographic focused on green living. It has a section on Personal Care, with Beauty Tips, a Buying Guide, and a great Dirty Dozen section on ingredients to avoid. Also, check out their ingredient glossary.

The Environmental Working Group is a popular site for research into ingredients and skin care products. They maintain a database called Skin Deep that ranks products and ingredients with a health score. 0 is safest...

The Stiftung zur Förderung der Hautgesundheit (Institute for the Advancement of Skin Health) has given itself the task to advance through different means and measures skin health to the broadest public. For this, we have called on cooperation with official offices of administrations, associations, communities and experts. Depending on the type of project, the measures will be carried out in German-speaking and also international contexts...