Methodology · Version 1.0
How DermIQ scores ingredients and products
A dose-aware, evidence-weighted safety score that is public, reproducible, and versioned. Every number on this site can be traced back to the rules on this page.
Dose-aware
Ingredients are scored at the concentration people actually apply, not at industrial maximum doses.
Evidence-weighted
A regulatory review carries more weight than a single old study. Data confidence is its own sub-score.
Transparent
Weights, sources, and rules are published here under CC BY 4.0. You can disagree and challenge a score.
Versioned
Every score shows the methodology version that produced it. When rules tighten, we re-run everything.
The score
Every ingredient receives a DSS on a 1–10 scale, where 10 is excellent safety and 1 is avoid. The overall DSS is a weighted average of four sub-scores:
| Sub-score | Weight | What it measures |
|---|---|---|
| Systemic toxicity | 30% | Risk of internal harm at cosmetic concentrations and typical exposure. |
| Sensitization risk | 30% | Probability of causing contact allergy, irritation, or hypersensitivity. |
| Reproductive concern | 20% | Effects on fertility, pregnancy, development, endocrine function. |
| Data confidence | 20% | Volume, quality, recency, and independence of underlying evidence. |
Data confidence cannot dominate the final score by design. A well-studied but genuinely risky ingredient still scores low. Weights were tuned after back-testing against ~400 CIR expert conclusions for minimum disagreement with regulatory consensus.
From number to plain English
We show numbers on the detail view for anyone who wants them, but most people see a plain-English verdict and a 1–5 star rating:
| DSS range | Stars | Verdict |
|---|---|---|
| 9.0 – 10.0 | ★★★★★ (5.0) | Excellent |
| 7.5 – 8.9 | ★★★★☆ (4.0) | Good |
| 6.0 – 7.4 | ★★★☆☆ (3.0) | Caution |
| 4.0 – 5.9 | ★★☆☆☆ (2.0) | Concerns |
| 1.0 – 3.9 | ★☆☆☆☆ (1.0) | Avoid |
How product scores are calculated
A product's headline DSS is a concentration-weighted harmonic mean of its ingredient DSS values. The harmonic mean punishes the worst ingredients more than a simple average, which matches how people intuitively think about safety: one very concerning ingredient is not rescued by having nine safe ones.
When concentrations are not disclosed (typical, since INCI labels only give ordering), we estimate them from position on the label. The first five ingredients typically account for 60–95% of the formulation. Estimates are overwritten whenever a manufacturer SDS sheet is ingested.
What DSS explicitly does not do
- • DSS is not medical advice. People with specific skin conditions should consult a board-certified dermatologist.
- • DSS does not score efficacy. A retinol can score well on safety and still do nothing for your concern.
- • DSS is not a boycott list. We publish every ingredient regardless of score. You make your own choices.
- • DSS is not frozen. Methodology is versioned; when rules tighten we re-run all products.
Sources we consider authoritative
- SCCS (Scientific Committee on Consumer Safety, EU) — primary source for concentration limits.
- CIR (Cosmetic Ingredient Review, US) — expert panel conclusions on cosmetic ingredient safety.
- Health Canada — Hotlist and Schedule 2 for prohibited / restricted substances.
- PubMed / Cochrane — peer-reviewed primary literature, with preference for systematic reviews.
- ToxCast / Tox21 — high-throughput screening for endocrine and other bioactivity.
- ECHA / CLP — European harmonised classifications.
- IFRA / RIFM — fragrance-specific safety data.
- CosIng — EU database of INCI names, functions, and restrictions.
We deliberately do not treat the EWG Skin Deep database as a primary source. Their methodology is opaque and the same ingredient can receive different scores across tabs of their own site. We display the EWG score on ingredient pages for consumer reference only, labelled as third-party and not endorsed.
Reproducibility and challenge
Every ingredient page shows the final DSS, each sub-score, the evidence tier, and the list of cited sources by identifier (PubMed ID, CIR report number, SCCS opinion code). Product pages inherit all of this and show their own calculation trace.
If you see a score you disagree with, write to us with a specific citation and we will review and publish a decision. Full methodology markdown is in the public repository under DSS_METHODOLOGY.md.
Change log
- v1.0 — 2026-04-10 — Initial public methodology. Four sub-scores, harmonic mean product aggregation, personalization rules for pregnancy and sensitive skin.
Questions?
Read the full versioned methodology in the repository or browse our ingredient database to see DSS in action on specific molecules.