Glossary

INCI, identifiers & label basics

INCI (International Nomenclature of Cosmetic Ingredients)

Standardised ingredient names used on cosmetic labels worldwide. An INCI name helps you find the same ingredient across brands (for example Sodium Laureth Sulfate is the INCI for a common surfactant). See the Ingredient Library for INCI-based entries.

CAS number

Chemical Abstracts Service registry number, a numeric identifier for a specific chemical. Useful for researchers to avoid synonym confusion (example: CAS 9004-82-4 for a polymer or surfactant). We include CAS when available on ingredient pages.

DOI / PMID

Persistent identifiers for academic papers (DOI) and PubMed entries (PMID). When we cite studies we include these so readers can retrieve the original research.

INCI vs common/trade names

Trade names vary; INCI keeps things consistent, which also explains why many ingredients sound chemical even when they are familiar substances. If a label shows a trade name, look for the INCI next to it or check our Ingredient Library for synonyms.

Surfactants (what they do and simple types)

Surfactant

A substance that reduces surface tension, allowing water to remove oil and dirt. In soaps and cleansers , surfactants create foam and cleansing action.

Anionic Surfactant

Negatively charged in solution (e.g., Sodium Lauryl Sulfate, SLS). Often effective cleaners, sometimes more drying or irritating at higher concentrations.

Non-ionic surfactant

No charge; generally milder and used to reduce irritation or as co-surfactants (e.g., decyl glucoside).

Amphoteric (zwitterionic) surfactant

Can carry positive or negative charges depending on pH (e.g., Cocamidopropyl Betaine). Often used to soften formulas and reduce irritation.

Syndet

Short for synthetic detergent, bars and cleansers made from manufactured surfactants instead of true soap (saponified fats). Syndets often have milder pH and can be gentler on sensitive skin.

Soap (true soap)

Made by saponification, reacting fats/oils with an alkali (lye), as explained in our Soap Ingredients Guide. Classic bar soap is alkaline; pH and formulation affect gentleness and skin feel.

Preservatives, antimicrobials & controversy

Preservative

Ingredient added to products (especially water-containing ones) to prevent microbial growth. Examples: phenoxyethanol, parabens, formaldehyde releasers. Preservative choice affects safety and regulatory limits.

Paraben

A class of esters used as preservatives (e.g., methylparaben). They are effective, inexpensive and widely studied; regulatory bodies set concentration guidance where needed.

Formaldehyde releaser

Compounds that slowly release formaldehyde to act as a preservative. They can cause allergic reactions in some people and are flagged on ingredient pages when relevant.

Antimicrobial vs preservative

Antimicrobials (like triclosan historically) were sometimes used for marketing 'antibacterial' claims. Most consumer soap products rely on preservatives, not triclosan-style antimicrobials.

Skin & clinical terms

Patch test

A clinical procedure where a small amount of ingredient or product is applied to the skin under occlusion to check for allergic or irritant reactions. Where available, patch-test evidence is referenced in ingredient documentation.

Contact dermatitis

Skin inflammation caused by direct contact with an irritant or allergen. Distinguish allergic contact dermatitis (immune-mediated) from irritant contact dermatitis (direct damage).

Atopic dermatitis (eczema)

A chronic inflammatory skin condition; people with eczema are often more sensitive to irritants and allergens and may need more cautious ingredient choices.

Hypoallergenic

Not a regulated term in many jurisdictions, it suggests lower allergy risk but is not a guarantee. Always check ingredient lists and clinical evidence.

Non-comedogenic

Means a product is less likely to block pores. Also not strictly regulated, check ingredient types (heavy oils can be comedogenic for some).

pH

Acidity/basicity of a product. Skin's natural pH is slightly acidic (around 4.5–5.5). Many syndet cleansers are formulated to be closer to skin pH; traditional soap is often more alkaline.

Environmental & ingredient impact terms

Biodegradability

How readily an ingredient breaks down in the environment. 'Ready biodegradability' is a specific OECD testing classification we reference when available.

Aquatic toxicity (LC50 / EC50)

Concentration of a substance that causes harm to aquatic life (LC50 = lethal concentration for 50% of organisms). Lower LC50 = higher acute toxicity. We list such endpoints when available.

Microplastic

Tiny plastic particles that persist in the environment. Look for polyethylene, polypropylene, or 'microbeads' on labels; we flag these in the Ingredient Library.

Bioaccumulation & BCF

Bioaccumulation is the tendency of substances to concentrate in organisms over time. BCF (bioconcentration factor) is a metric used to describe this tendency.

Research, evidence & metadata terms

Evidence tier

Our internal system (Tier A–D) that ranks source reliability (regulatory opinions and systematic reviews are Tier A; supplier data or preprints are lower tiers). See Review & Verification Policy.

Reproducibility pack

A package we provide on request to researchers containing search strings, extraction sheets, code and dataset extracts so others can reproduce our analyses.

Changelog / Last reviewed

Every page shows a "Last reviewed" date and a changelog entry for substantive updates. Cite that date when you refer to a page in research or media to preserve provenance.

Margin of safety

A toxicology concept comparing estimated exposure with doses used in experimental studies. Not always available for cosmetics; when present, we note it.

How to use this glossary (tips & quick actions)

Tip: If you arrived with a product label, copy an exact INCI name into the site search or into the Ingredient Library. If you see multiple synonyms, use the CAS number (if listed) or the DOI on the evidence list to find the precise study.

Want to suggest a new term or correction? Use Feedback & Suggestions and choose "Missing term / correction." Include a short definition or source if you can, we acknowledge requests within 7 business days.