Methodology
How the CC INDEX works
The CC INDEX (Chemical Century Index) is a score from 1 to 100 on each chemical article. A higher number means the evidence the article cites points to more serious, better-established harm at the exposure people typically get.
The four parts
Each score is the sum of four parts. Each part is judged only from what the article and its numbered sources say. Nothing comes from outside those sources.
| Part | Points | What it asks |
|---|---|---|
| Severity | 0–35 | How serious is the worst documented human harm? Irritation or mild intolerance scores low. Allergy and sensitization are in the middle. Cancer, serious bleeding, organ damage and harm to a fetus score high. |
| Strength of evidence | 0–30 | How firm is the evidence for the serious harms, using the article’s own labels? Established human harm scores high. Probable is next, then Possible. Disputed claims and animal-only findings score low. |
| Everyday exposure | 0–20 | How common and how large is ordinary exposure from everyday products, as the sources describe it? Trace or occasional exposure scores low. Frequent dietary or daily-use exposure scores high. |
| Regulatory signal | 0–15 | What have regulators and assessors done? Bans, withdrawals, legal limits, required warnings and IARC classifications all raise this part. “No concern at current use” lowers it. |
Bands
- 1–20 Low
- 21–40 Mild
- 41–60 Moderate
- 61–80 High
- 81–100 Very high
The colours run from teal to deep red, so each band is easy to tell apart. Every badge also shows the number and the band name in text, so the score doesn’t rely on colour alone.
Current scores
| Article | Severity | Evidence | Exposure | Regulatory | CC INDEX |
|---|---|---|---|---|---|
| Lead | 33 | 28 | 8 | 11 | CC INDEX 80 out of 100, High |
| Carbon monoxide | 32 | 26 | 10 | 6 | CC INDEX 74 out of 100, High |
| Formaldehyde and releasers | 28 | 24 | 6 | 10 | CC INDEX 68 out of 100, High |
| Inorganic arsenic | 26 | 20 | 10 | 12 | CC INDEX 68 out of 100, High |
| Ibuprofen | 28 | 26 | 7 | 5 | CC INDEX 66 out of 100, High |
| PFAS | 26 | 16 | 10 | 12 | CC INDEX 64 out of 100, High |
| Acetaminophen | 30 | 22 | 5 | 5 | CC INDEX 62 out of 100, High |
| Chlorpyrifos | 24 | 18 | 4 | 14 | CC INDEX 60 out of 100, Moderate |
| Ethylene glycol | 32 | 22 | 4 | 2 | CC INDEX 60 out of 100, Moderate |
| Nitrite and nitrate in processed meat | 26 | 16 | 11 | 6 | CC INDEX 59 out of 100, Moderate |
| Benzo[a]pyrene | 22 | 16 | 10 | 10 | CC INDEX 58 out of 100, Moderate |
| Iron supplements | 30 | 22 | 3 | 3 | CC INDEX 58 out of 100, Moderate |
| Phthalates | 22 | 13 | 10 | 12 | CC INDEX 57 out of 100, Moderate |
| Hydroquinone | 22 | 16 | 6 | 12 | CC INDEX 56 out of 100, Moderate |
| p-Phenylenediamine | 18 | 20 | 8 | 10 | CC INDEX 56 out of 100, Moderate |
| Bisphenol A | 20 | 12 | 10 | 13 | CC INDEX 55 out of 100, Moderate |
| Diphenhydramine | 22 | 20 | 7 | 6 | CC INDEX 55 out of 100, Moderate |
| Acrylamide | 22 | 10 | 12 | 8 | CC INDEX 52 out of 100, Moderate |
| High-fructose corn syrup | 16 | 20 | 14 | 2 | CC INDEX 52 out of 100, Moderate |
| Camphor | 26 | 16 | 4 | 4 | CC INDEX 50 out of 100, Moderate |
| Talc | 18 | 12 | 8 | 10 | CC INDEX 48 out of 100, Moderate |
| Ammonia | 20 | 16 | 8 | 3 | CC INDEX 47 out of 100, Moderate |
| Deoxynivalenol | 12 | 14 | 10 | 10 | CC INDEX 46 out of 100, Moderate |
| Sodium hypochlorite (household bleach) | 22 | 16 | 6 | 2 | CC INDEX 46 out of 100, Moderate |
| Styrene | 18 | 12 | 8 | 8 | CC INDEX 46 out of 100, Moderate |
| Heterocyclic amines | 18 | 12 | 12 | 3 | CC INDEX 45 out of 100, Moderate |
| Vitamin A (retinol) | 22 | 14 | 4 | 5 | CC INDEX 45 out of 100, Moderate |
| Furan | 18 | 12 | 10 | 4 | CC INDEX 44 out of 100, Moderate |
| Toluene | 22 | 12 | 5 | 5 | CC INDEX 44 out of 100, Moderate |
| Titanium dioxide | 14 | 8 | 9 | 12 | CC INDEX 43 out of 100, Moderate |
| Melatonin | 12 | 12 | 8 | 8 | CC INDEX 40 out of 100, Mild |
| Quaternary ammonium compounds | 12 | 12 | 10 | 6 | CC INDEX 40 out of 100, Mild |
| Sulfites | 12 | 14 | 6 | 7 | CC INDEX 39 out of 100, Mild |
| Aspartame | 12 | 10 | 12 | 4 | CC INDEX 38 out of 100, Mild |
| Caffeine | 13 | 13 | 10 | 2 | CC INDEX 38 out of 100, Mild |
| Melamine | 16 | 12 | 4 | 4 | CC INDEX 36 out of 100, Mild |
| Oxybenzone | 10 | 6 | 10 | 10 | CC INDEX 36 out of 100, Mild |
| Triclosan | 10 | 8 | 5 | 12 | CC INDEX 35 out of 100, Mild |
| Allura Red AC | 10 | 8 | 12 | 4 | CC INDEX 34 out of 100, Mild |
| Glyphosate | 14 | 6 | 8 | 6 | CC INDEX 34 out of 100, Mild |
| SLS and SLES | 6 | 14 | 12 | 2 | CC INDEX 34 out of 100, Mild |
| Coumarin | 12 | 10 | 6 | 5 | CC INDEX 33 out of 100, Mild |
| Patulin | 10 | 10 | 4 | 9 | CC INDEX 33 out of 100, Mild |
| Linalool | 8 | 12 | 8 | 4 | CC INDEX 32 out of 100, Mild |
| Microplastics | 8 | 4 | 14 | 6 | CC INDEX 32 out of 100, Mild |
| Benzoyl peroxide | 10 | 12 | 4 | 4 | CC INDEX 30 out of 100, Mild |
| Parabens | 8 | 7 | 10 | 5 | CC INDEX 30 out of 100, Mild |
| Vitamin D | 14 | 12 | 2 | 2 | CC INDEX 30 out of 100, Mild |
| Sodium benzoate | 10 | 6 | 9 | 3 | CC INDEX 28 out of 100, Mild |
| Chlormequat | 8 | 8 | 6 | 4 | CC INDEX 26 out of 100, Mild |
| Limonene | 8 | 9 | 6 | 3 | CC INDEX 26 out of 100, Mild |
| Folic acid | 8 | 10 | 4 | 2 | CC INDEX 24 out of 100, Mild |
| Monosodium glutamate (MSG) | 4 | 4 | 9 | 1 | CC INDEX 18 out of 100, Low |
Limits
- Class articles, like PFAS or parabens, cover substances with different evidence. Their score reflects the article as a whole, including its most concerning members.
- Harm that depends on dose, route or a susceptible group, like aspartame and PKU or ibuprofen in pregnancy, is weighed by how the sources frame it. It isn’t applied to everyone.
- Environmental harm is described in the articles but isn’t part of this health score.
- Topics, like added sugar, aren’t single chemicals and don’t get a score.
The age index
Each chemical article also has an age index near the top. It shows which age groups are more affected by the chemical’s possible health issues: pregnancy (unborn babies), infants (0 to 1), young children (1 to 5), children (6 to 12), teens (13 to 19), adults (20 to 64) and older adults (65 and over).
- ▲ Higher concern: the article’s sources single out this group, for example because of a developing brain, eating more food for their body weight, hand-to-mouth behaviour, workplace exposure or a specific warning.
- ● Moderate: the group is exposed or affected in the ordinary way the article describes, without being singled out.
- ▼ Lower concern: the sources indicate this group is less exposed or less affected.
- ? Not well studied: the sources don’t address this group, so we don’t guess.
Ratings come only from each article’s cited sources. A reason marked “general principle” reflects well-established toxicology rather than a finding about that chemical. Like the CC INDEX, the age index is an editorial summary, not a personal risk estimate.
Review
Scores are set by the editors and stored with each article, next to a short reason for the score. When an article’s sources or evidence labels change, the score is reviewed with them. The date the article was last reviewed is shown on every page. Corrections and better sources are welcome.