About

People meet chemicals in almost everything they do. Food, makeup, cleaning products, medicines, plastics, and the air and water around a house all carry named substances. Chemical Century exists to say what the evidence supports about the harms, in language a person holding a label can follow.

Each chemical article is one substance: what it is, where it turns up, and which harms the cited sources actually support. A topic is broader than one chemical. Added sugar and the glycemic index are the first two. They can point at chemical articles, and those articles can point back.

What “harm” means here

Harm is whatever a cited source has evidence for: tooth decay from free sugars, a bleeding risk from a medicine, a regulator withdrawing a use. The page names the source, the date, and the limit of the finding. A study in one country, at one dose, by one route, is not quietly stretched to every product on a shelf.

There is no harm score and no colour code. Those flatten different evidence into a ranking the sources did not make. Categories are a map of products, so a pigment used in food and in paint can sit in both groups. The group is not a verdict.

A residue or a manufacturing input is not described as an ingredient that was added on purpose, and it is not treated as proof that a finished product exposes you to it.

What a page cannot do

Medicine and diet pages are general information. They are not a diagnosis, a dose, or a reason to start or stop a treatment. A pharmacist or clinician is the right person to ask about a specific product or a specific body.

Articles stay marked as editorial drafts until a qualified reviewer has signed off on the medical and regulatory claims. Each page shows that status and the date it was last reviewed. A fetched government page is a source, not a clinical review. An older page is not silently treated as today’s consolidated law.

Images

Photographs and diagrams keep their credits. The caption, the photographer or illustrator, the license, and any change made to the file are taken from the article’s record and shown under the image. A Creative Commons license on a photograph does not relicense the article text.

The library

The site is one Markdown file per chemical, and one Markdown file per topic. Search runs in the browser over titles, aliases, CAS numbers, and the text. A candidate spreadsheet of names sits in the project as research material. Those names are not articles, and they are not published here.

The mark in the header is /assets/logo.svg. Replacing that file changes the logo. The words “Chemical Century” stay beside it if the file is missing.