What is a Margin of Safety calculation for cosmetics?

Margin of Safety (MoS) is the ratio between the No Observed Adverse Effect Level (NOAEL) and the Systemic Exposure Dose (SED). A MoS above 100 is generally considered safe by the EU SCCS. The formula is: MoS = NOAEL / SED, where SED depends on ingredient concentration, product amount applied, dermal absorption rate, and body weight.

How do I calculate MoS without a toxicologist?

Our MoS Calculator automates the SCCS methodology. Select your product category (15 types available with default exposure values), enter ingredient concentration and NOAEL value, and the tool calculates SED and MoS automatically. It uses standard SCCS default values for body weight (60kg), body surface area, and daily application amounts per product category.

What NOAEL value should I use for cosmetic safety assessment?

NOAEL values come from toxicological studies — typically repeated dose oral toxicity studies (90-day or chronic). Sources include SCCS opinions, CIR safety assessments, ECHA REACH dossiers, and published literature. Our Ingredient Database provides source-traced NOAEL values for thousands of cosmetic ingredients. When multiple studies exist, use the lowest relevant NOAEL for the most conservative assessment.

Margin of Safety Calculator

Calculate MoS and SED for cosmetic ingredients using SCCS methodology. 15 product categories with default exposure values.

SCCS/1647/22 Compliant

The World's First Free MoS Calculator

No login. No paywall. No subscription. Calculate your Margin of Safety instantly using the official SCCS methodology (SCCS/1647/22). Every cosmetic safety assessor, formulator, and regulatory consultant needs MoS calculations for their Cosmetic Product Safety Reports — now you can do it in seconds, for free.

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Search Ingredient for Auto-Fill

Type an ingredient name to auto-populate NOAEL, dermal absorption, and safety data from our database.

Ingredient Name (optional)

NOAEL (mg/kg bw/day) *

Alternative NOAEL studies:

Concentration in Product (%) *

Product Category *

Dermal Absorption (%)

SCCS default: 50% if no in vitro data available

Body Weight (kg)

SCCS default: 60 kg

Example: Salicylic Acid in Face Cream

Here's how a typical MoS calculation works for a cosmetic safety assessment:

Ingredient:Salicylic Acid (2%)

Product:Face Cream (24.5 mg/day)

NOAEL:50 mg/kg bw/day

Dermal Absorption:50% (SCCS default)

Body Weight:60 kg

SED:0.00408 mg/kg bw/day

MoS:12,245

Threshold:≥ 100 required

PASS — Safe for use

This example uses SCCS/1647/22 methodology. Try the calculator above with your own ingredient data.

What is the Margin of Safety (MoS)?

The Margin of Safety (MoS) is a fundamental safety metric required in every EU Cosmetic Product Safety Report (CPSR) under Regulation EC 1223/2009. It quantifies how far below the toxic dose an ingredient's actual exposure is.

MoS = NOAEL / SED

Where:

NOAEL = No Observable Adverse Effect Level (mg/kg bw/day) — the highest dose in animal studies showing no adverse effects
SED = Systemic Exposure Dosage (mg/kg bw/day) — how much of the ingredient enters the body through normal cosmetic use

Safety threshold: MoS must be ≥ 100 to be considered safe. This 100x factor accounts for 10x interspecies variability (animal → human) and 10x intraspecies variability (between humans).

How SED is Calculated

SED = (C/100) × (DA/100) × (Amount × Retention) / BW

Variable	Description
C	Concentration of ingredient in product (%)
DA	Dermal absorption (%). Default 50% per SCCS; 100% for oral products
Amount	Daily amount of product applied (mg/day, from SCCS Table 3)
Retention	1.0 for leave-on; 0.01 for rinse-off products
BW	Body weight (default 60 kg)

SCCS Default Product Category Values

Source: SCCS Notes of Guidance (SCCS/1647/22), Table 3

Category	Amount (mg/day)	Retention	Type
Body Lotion	7,820	1.0	Leave-on
Face Cream	800	1.0	Leave-on
Hand Cream	1,700	1.0	Leave-on
Lipstick	57	1.0	Oral
Toothpaste	138	1.0	Oral
Mouthwash	1,000	1.0	Oral
Deodorant	500	1.0	Leave-on
Eye Cream	160	1.0	Leave-on
Shampoo	10,460	0.01	Rinse-off
Shower Gel	16,350	0.01	Rinse-off
Conditioner	14,000	0.01	Rinse-off
Hand Soap	800	0.01	Rinse-off
Hair Styling	3,920	1.0	Leave-on
Sunscreen	18,000	1.0	Leave-on
Foundation / Makeup	510	1.0	Leave-on

How to Find NOAEL Values

The NOAEL is typically derived from 90-day repeated-dose oral toxicity studies. Key sources:

SCCS Opinions

Scientific Committee on Consumer Safety publishes ingredient-specific opinions with NOAEL values. Search at ec.europa.eu/health/scientific_committees

CIR (Cosmetic Ingredient Review)

US-based expert panel reviews. Available at cir-safety.org. Often includes NOAEL data from toxicological studies.

ECHA REACH Dossiers

European Chemicals Agency REACH registration dossiers contain repeated-dose toxicity data. Search at echa.europa.eu

EFSA Scientific Opinions

European Food Safety Authority for ingredients also used in food. Available at efsa.europa.eu

Dermal Absorption Guidelines

Default 50%: When no in vitro or in vivo dermal absorption data is available, the SCCS recommends using 50% as a conservative default.

100% (oral route): For products with oral exposure (lipstick, toothpaste, mouthwash), 100% absorption is assumed since the ingredient is ingested.

In vitro studies: If validated in vitro percutaneous absorption data is available (OECD TG 428), the mean + 2 standard deviations of the absorbed amount should be used.

100% for small molecules: For substances with molecular weight below 100 Da, 100% absorption may be warranted.

References

SCCS (Scientific Committee on Consumer Safety). Notes of Guidance for the Testing of Cosmetic Ingredients and Their Safety Evaluation, 12th Revision. SCCS/1647/22. European Commission, 2023.
Regulation (EC) No 1223/2009 of the European Parliament and of the Council on cosmetic products. Official Journal of the European Union, 2009.
OECD Test Guideline 428: Skin Absorption: In Vitro Method. OECD Guidelines for the Testing of Chemicals, 2004.