Page 224 - Cosmetology

There is concern that hydroquinone is a potentially carcinogenic substance. In vitro, hydroquinone has a
toxic effect on cells containing melanin. Aside from the in vitro studies (done in test tubes), the only harmful
effects are reported in animal studies where hydroquinone is fed to animals. In these studies tumor creation
or DNA damage is noted. However, this is not the case in epidemiological studies in which production
workers (meaning those workers involved in the manufacture of hydroquinone) have been shown to have
lower death rates and reduced cancer rates when compared with the population as a whole. Adverse effects
associated with skin-lightening products that contain hydroquinone in FDA-regulated products have been
limited to a small number of cases of hyperpigmentation. A review of the safety evidence for hydroquinone
as it is used in over-the-counter drug products revealed that in its 50-year history, there has not been a
single reported case of an internal or external (meaning skin)malignancy.

hydroxyethylcellulose. Plant-derived thickening agent typically used as a binding agent or emulsifier. Also
used (most often in styling products) as a film-forming agent.

hydroxylated lecithin. See lecithin.

hydroxypalmitoyl sphinganine. Sphinganine is a sphingoid base, found concentrated in mammalian
epidermis, that may serve as a natural antifungal barrier preventing infection by pathogenic fungi. However,
it may also inhibit ceramide production.

hydroxyproline. Derived from the amino acid proline, it is a fundamental component of collagen and other
structural proteins. Skin's ability to heal is partly determined by the presence of hydroxyproline within it.
Whether topical application of hydroxyproline to the skin can help with wound healing has not been
substantiated. However, it does have water-binding properties similar to those of collagen.

hydroxypropyl guar. See guar gum.

hypericum extract. See St. John's wort.

Hypnea musciformis extract. See algae.

hypoallergenic. Term used by the cosmetics industry to lead consumers to believe they are using a product
that will not cause them to have an allergic or sensitizing skin reaction to a product. However, the word
"hypoallergenic" is not regulated in any manner by the FDA and it is therefore used indiscriminately by
cosmetics companies without any substantiation or need to show proof of the claim.
I

Ilex paraguariensis. See yerba mate extract.

Illicium vernum. See anise.

imidazolidinyl urea. Formaldehyde-releasing preservative.

Imperata cylindrica root extract. There is no research to support the claims that this extract has any
benefit for skin.

in vitro. Literally means "in glass." It refers to a biochemical process or reaction tested in a Petri dish or test
tube, rather than one taking place in a living cell, organism, animal, or person.

in vivo. Refers to a biological or chemical process or reaction taking place in a living cell, organism, animal,
or person.

inactive ingredient. The inactive ingredients list is the part of an ingredient label that is not regulated by the
FDA, although the FDA does require the complete listing of contents. These are given in descending order
of concentration; that is, the largest concentration is listed first, then the next largest, and so forth.
Thousands and thousands of inactive ingredients are used in cosmetics, and there is controversy as to how
truly inactive these substances are in regard to safety as well as about their long-term or short-term effects
on skin or the human body.

Indian gooseberry. Can have anti-inflammatory, antioxidant, and anti-mutagenic properties.

inositol. Major component of lecithin and may have water-binding properties for skin. It is not a vitamin,