Thiomersal (Thimerosal) and Phenylmercuric salts (phHg) - as preservatives in cosmetic eye products: What the SCCS Concluded About Safety in Cosmetics
Thiomersal (Thimerosal) and Phenylmercuric salts (phHg) - as preservatives in cosmetic eye products safety summary from SCCS/1686/25: SCCS conclusion, NOA.
is covered by SCCS/1686/25, an SCCS-family cosmetic safety opinion dated 2026-02-02. The opinion conclusion for this opinion is direct enough for a substance-specific summary: In light of technical and scientific progress and SCCS' expert judgement and taking under consideration in particular the various health concerns, the SCCS is requested: (1) to identify and justify whether there are specific concerns regarding the current use of Thiomersal and Phenylmercuric salts as preservatives in cosmetic eye products; Considering that the Margin of Safety based on renal toxicity as the most.
Core Opinion Facts
- Opinion: SCCS/1686/25
- Opinion date: 2026-02-02
- Primary substance:
NOAEL Values Cited in the Opinion
The no-observed-adverse-effect data below is shown only from the SCCS source fields for this opinion. It is not a calculated margin-of-safety output.
| Endpoint | Value | Unit | Study context |
|---|---|---|---|
| Kidney damage - enlargement of kidneys, moderate tubular dilation, atrophy, granularity, fibrosis in females at 0.5 ppm and above | 0.1 ppm (0.0084 mg PMA/kg bw/day; equivalent to 5.0 ug Hg/kg bw/d) | mg PMA/kg bw/d | Rat (female more susceptible than male), oral (diet), Chronic oral toxicity (2-year diet feeding) |
| Cardiovascular - elevated systolic blood pressure and pulse pressure (meHg); inorganic Hg no effect | 3.25 ug Hg/kg bw/d | Male Wistar rat, oral (drinking water), 4-week drinking water cardiovascular BMD |
Maximum Concentration or Conditions
| Use condition | Value | Unit |
|---|---|---|
| Concentration phrase in conclusion | 0.007% | |
| Concentration phrase in conclusion | 0.014% | |
| Concentration phrase in conclusion | 0.012% | |
| Concentration phrase in conclusion | 50% |
Conditions from the Opinion
Current use: only in cosmetic eye products per Annex V entries 16 (Thiomersal) and 17 (Phenylmercuric salts including borate); Current max concentration: 0.007% as Hg (alone or in combination); Mandatory labelling: 'Contains Thiomersal' or 'Contains Phenylmercuric compounds'
How to Read This Safety Conclusion
The key point for formulators is the match between the named ingredient, the cited NOAEL, and the SCCS conclusion. A NOAEL is a study point of departure, not a standalone permission to use at any level. The SCCS conclusion and any concentration or product-type conditions remain the controlling context for cosmetic use.
The source also matters because SCCS opinions can be ingredient-specific. The internal ingredient page for Thiomersal (Thimerosal) and Phenylmercuric salts (phHg) - as preservatives in cosmetic eye products should be treated as the substance hub, while SCCS/1686/25 is the opinion-level page for the committee record.
Practical Formulation Takeaway
For a formula review, start with the identity check: confirm the INCI name, CAS number, and opinion reference align with the material in the formula. Then compare the intended product type against the SCCS concentration or condition language above. If the formulation uses a different exposure route, product category, or concentration basis, the SCCS conclusion should not be stretched beyond what SCCS/1686/25 actually assessed.
Source
- SCCS opinion: SCCS/1686/25
- Source file: sccs_o_308.pdf
- Extraction JSON: SCCS Scientific Opinions