HumanSafe™ Methodology — Transparent, Context-Aware Scoring

Foundation

How HumanSafe™ Scoring Works

HumanSafe™ evaluates products across four independent dimensions. Each score uses different data sources, methodologies, and weightings. This page documents our complete approach—what we measure, how we calculate it, and where we get our data.

Methodology vs. Process: This page covers the scientific methodology (how we calculate scores). For the operational verification process (how brands apply), see our Verification Process page.

The Four Independent Scores

🛡️ HSS - Human Safety

Letter Grade (A+ to F)

Health risk assessment

🌍 ESS - Environmental

Numerical (1.0–10.0)

Environmental impact

📖 CTS - Transparency

Numerical (1.0–10.0)

Information disclosure

⭐ CES - Experience

Numerical (1.0–10.0)

Real-world performance

Score 1 of 4

HSS - Human Safety Score

Letter Grade: A+ (9.0–10.0) to F (<4.0)
Context-aware health risk assessment considering toxicology, concentration, exposure route, duration, and target population.

Important: Letter grades represent relative risk bands, not absolute safety guarantees. Individual responses vary.

Multi-Layer Assessment Framework

HumanSafe™ uses a sophisticated multi-layer system that evaluates ingredients through multiple gates before arriving at a final score. Each layer refines the assessment based on scientific principles:

Layer 1: Base Toxicity

Intrinsic hazard profile from peer-reviewed toxicology data. Evaluates acute toxicity, chronic toxicity, skin safety, organ toxicity, carcinogenicity, and regulatory status.

Layer 2: Molecular Penetration

The 500 Dalton Rule: Molecules above ~500 Da generally cannot penetrate intact skin. Large molecules receive modified assessment focused on surface interactions only.

Layer 3: Product Type

Rinse-off, leave-on, spray, mucous membrane, and oral products have different risk profiles. Factor weightings adjust based on exposure duration and absorption pathway.

Layer 4: Population & Context

Adults, children, babies, pregnancy each have different safety thresholds. Compromised skin, medical conditions, and concurrent exposures further refine assessment.

The Seven Core Risk Factors

Each ingredient is evaluated across seven independent risk dimensions. The relative importance (weighting) of each factor varies based on molecular size and application type:

Factor	What We Evaluate	Weighting Approach
F1: Acute Toxicity	Immediate harm potential based on LD50/LC50 data from animal and in-vitro studies	Higher weight for rinse-off products where accidental ingestion is possible
F2: Chronic Toxicity	Long-term repeated exposure effects, cumulative organ damage, systemic impacts	Higher weight for leave-on products with daily use patterns
F3: Skin Safety	Irritation potential, sensitization (allergic) reactions, dermal absorption, barrier damage	Highest weight for all dermal products; primary concern for large molecules
F4: Organ/System Toxicity	Effects on liver, kidneys, nervous system, endocrine disruption, reproductive health	Higher weight for penetrating molecules (<500 Da); reduced for non-penetrating molecules
F5: Carcinogenicity	Cancer risk based on IARC, NTP, and EPA classifications; mutagenicity data	Weight adjusted based on exposure frequency and cumulative dose potential
F6: Regulatory Approval	FDA, EU Cosmetics Regulation, Health Canada, REACH, and international clearances	Consistent baseline weight; serves as safety net for data-limited ingredients
F7: Data Quality	Strength, reliability, and completeness of available safety data (peer-reviewed studies preferred)	Acts as confidence modifier; incomplete data lowers final score

Molecular Weight Penetration Logic

Before applying factor weights, we determine if the ingredient can penetrate the skin barrier:

<500 Daltons

Skin Permeable
Can penetrate intact skin barrier and reach systemic circulation. Full 7-factor assessment with systemic toxicity factors at standard weights.

500–1000 Daltons

Limited Penetration
Borderline permeability, especially with penetration enhancers or compromised skin. Modified assessment with reduced systemic weights.

>1000 Daltons

Non-Penetrating
Cannot penetrate intact skin; surface interaction only. Assessment focuses primarily on F3 (skin safety) with systemic factors de-emphasized.

Example: Why Molecular Size Matters

Ingredient A (Ethanol, 46 Da): Small molecule, full skin penetration. Evaluated across all 7 factors because it can reach bloodstream and affect internal organs.

Ingredient B (High MW Hyaluronic Acid, >1000 Da): Large molecule, cannot penetrate intact skin. Assessment emphasizes surface irritation and allergic potential only—systemic factors receive minimal weight because ingredient stays on skin surface.

Product Type Application Modifiers

Factor weights adjust based on how the product is used. The same ingredient at the same concentration will have different risk profiles depending on application type:

Rinse-Off Products: Brief contact time reduces exposure. Acute toxicity weighted higher due to ingestion risk.
Leave-On Products: Extended contact increases cumulative exposure. Chronic toxicity and sensitization weighted higher.
Spray/Aerosol Products: Inhalation pathway introduces respiratory concerns. Lung toxicity considerations added.
Mucous Membrane Products: Higher absorption rates require stricter thresholds across all factors.
Oral/Ingestion Products: Direct systemic absorption. Organ toxicity and carcinogenicity weighted most heavily.

Proprietary Weighting System: The exact percentage weights applied to each factor for each product type and molecular size category constitute HumanSafe™'s proprietary methodology. This intellectual property is documented internally but not publicly disclosed to maintain competitive advantage while ensuring transparent conceptual understanding.

Confidence Score Integration

Every assessment includes a confidence score that reflects data quality and completeness:

High Confidence (Score: 8.5–10.0)

Multiple peer-reviewed studies
Long history of safe use
Complete toxicity profile
Regulatory approval in major markets

Low Confidence (Score: 1.0–5.0)

Limited safety data
New ingredient with short market history
Data gaps in critical endpoints
Conflicting research findings

When confidence is low, final scores are adjusted downward. This precautionary approach protects consumers when scientific certainty is insufficient.

Letter Grade Ranges

Grade	Range	Classification	Typical Meaning
A+	9.0–10.0	Elite Biocompatibility	Exceptionally safe, minimal concerns
A	8.0–8.9	High Safety Integrity	Very safe, reliable profile
A-	7.0–7.9	Functional Safety	Generally safe for intended use
B	6.0–6.9	Exposure-Conditional	Safe under specific limits
C	5.0–5.9	Toxicological Alert (L1)	Notable data gaps or sensitivities
D	4.0–4.9	High Toxicological Risk	Elevated risk potential
F	< 4.0	Biocompatibility Breach	Severe safety failure

Why letter grades for HSS? Human safety is the most critical score for consumers. Letter grades provide instant recognition (like school grades) while numerical ranges allow for precision.

Score 2 of 4

ESS - Environmental Score

Numerical: 1.0–10.0 (10 = best for environment)
Lifecycle environmental impact from raw material sourcing through disposal. Evaluates biodegradability, aquatic toxicity, bioaccumulation, and manufacturing footprint.

The Five Environmental Factors (Weighted)

Factor	Weight	What We Evaluate
Biodegradability	30%	How quickly and completely the ingredient breaks down in the environment (OECD tests)
Aquatic Toxicity	30%	Harm to aquatic organisms: algae, daphnia (water fleas), and fish (LC50/EC50 data)
Bioaccumulation	20%	Tendency to accumulate in organisms and food chains (BCF/log Kow values)
Manufacturing Impact	15%	Energy, water usage, emissions, and waste in production
End-of-Life	5%	Packaging recyclability, disposal impacts, circular economy potential

Score Ranges

9.0–10.0: Readily biodegradable, minimal aquatic toxicity, sustainable sourcing
7.0–8.9: Good environmental profile with minor concerns
5.0–6.9: Moderate impact, some persistence or toxicity
3.0–4.9: Significant environmental concerns, poor biodegradability
1.0–2.9: High environmental risk, persistent, bioaccumulative

Score 3 of 4

CTS - Company Transparency Score

Numerical: 1.0–10.0 (10 = complete transparency)
How openly the company shares ingredient data, concentrations, sourcing information, and testing data beyond regulatory minimums.

The Five Transparency Criteria

Criterion	Weight	What We Evaluate
Ingredient Disclosure	35%	Complete INCI names + concentration ranges or exact percentages
Sourcing Information	25%	Supply chain transparency, origin of raw materials, supplier ethics
Manufacturing Process	15%	Production methods, quality control, facility information
Testing & Studies	15%	Clinical studies, safety testing data, third-party verification
Responsiveness	10%	How quickly and completely the company answers questions

What Lowers CTS

Hiding behind "proprietary formula" claims
Refusing to disclose concentrations
Vague ingredient listings ("fragrance," "natural flavors")
No response to information requests
Inconsistent labeling across markets

Why transparency matters: Full disclosure allows for accurate safety assessment and builds consumer trust. Companies with nothing to hide shouldn't hide anything.

Score 4 of 4

CES - Customer Experience Score

Numerical: 1.0–10.0 (10 = excellent experience)
Real-world performance and user satisfaction based on verified customer feedback. Does the product actually work as claimed?

The Five Experience Factors

Factor	Weight	What We Evaluate
Verified Reviews	40%	Aggregate rating from verified purchaser reviews across platforms
Claim Validation	25%	Does the product deliver on its marketing promises?
Sensory Experience	15%	Texture, scent, feel, ease of use (subjective but aggregated)
Value for Cost	10%	Performance relative to price point
Customer Service	10%	Company responsiveness, returns policy, support quality

Why include experience? Safety without efficacy is pointless. If a product doesn't work, people won't use it consistently—undermining even the safest formula.

Real-World Application

Context Adjustments

The same ingredient at the same concentration can have vastly different risk profiles depending on how it's used. We adjust base scores for real-world context.

Four Context Factors

1. Product Type

Rinse-off products: Lower exposure (shampoo, cleanser)
Leave-on products: Higher exposure (lotion, serum)
Spray products: Inhalation risk (aerosols, mists)
Mucous membrane products: Higher absorption (lip balm, eye cream)

2. Concentration

0.001%: Trace/incidental (minimal risk)
0.1%: Low concentration
1%: Moderate concentration
10%+: High concentration (active ingredient level)

3. Exposure Route

Dermal: Skin application (most common)
Inhalation: Breathing (sprays, powders)
Ingestion: Oral products (toothpaste, lip products)
Ocular: Eye area (mascara, eye cream)

4. Target Population

Adults: Standard safety thresholds
Children: Lower tolerance, higher standards
Babies: Much stricter limits
Pregnancy: Additional reproductive/developmental considerations

Example: Preservative in Different Contexts

Ingredient: Phenoxyethanol at 0.5%

Rinse-off shampoo (Adult): Score A — Brief contact, washes away quickly, low systemic exposure.

Leave-on face cream (Adult): Score A- — Extended contact on facial skin, moderate absorption potential.

Baby lotion (Infant): Score B — Higher safety standards for infants, extended exposure, larger surface area relative to body weight.

Where We Get Information

Data Sources

We rely on peer-reviewed science, regulatory databases, and established toxicology resources. Our assessments are only as good as the data available.

Primary Data Sources

🔬 Scientific Literature

PubMed / MEDLINE
Peer-reviewed toxicology journals
Clinical studies
OECD test guidelines

🏛️ Regulatory Databases

FDA GRAS list
EU Cosmetics Regulation (CosIng)
Health Canada Cosmetic Ingredient Hotlist
EPA TSCA Chemical Substance Inventory

🧪 Toxicology Resources

IARC Monographs (carcinogenicity)
NTP (National Toxicology Program)
ATSDR ToxProfiles
SCCS opinions (EU Scientific Committee)

🌍 Environmental Data

ECHA (European Chemicals Agency)
OECD biodegradation studies
EPA ECOTOX database
ISO 14040 lifecycle assessments

Data quality varies: Not all ingredients have complete safety profiles. When data is limited, we disclose this limitation and adjust our confidence level accordingly.

Honest Disclosure

What Our Scores Don't Cover

No scoring system is perfect. Here are the explicit limitations of our methodology:

✗ Individual Variation

Scores reflect population-level safety. Your personal response may differ due to genetics, allergies, skin conditions, or medication interactions.

✗ Long-Term Effects

Many ingredients lack 20+ year longitudinal studies. We can't predict effects that might appear decades from now.

✗ Synergistic Interactions

We assess ingredients individually and in formulation context, but complex multi-ingredient interactions are difficult to predict.

✗ Emerging Research

Science evolves. What's considered safe today may be questioned tomorrow as new research emerges.

✗ Proprietary Formulas

When companies hide concentrations, we must estimate—reducing accuracy. Transparency enables better assessment.

✗ Subjective Experience

CES (experience) scores rely on aggregated reviews, which can be manipulated or biased despite verification efforts.

Use Scores as One Input Among Many

HumanSafe™ scores should inform your decisions—not replace your judgment, your doctor's advice, or your personal experience. Discontinue use if you experience adverse reactions, regardless of scores.

Methodology Updates

Version History

We update our methodology as science evolves. All changes are documented transparently.

Version	Date	Changes
v2.0	January 2026	Major methodology update: Added multi-layer assessment framework (4 layers), molecular penetration logic (500 Dalton Rule), confidence scoring system, and product type modifiers. Changed HSS from numerical to letter grades. Expanded conceptual explanations while protecting proprietary weighting formulas.
v1.5	September 2025	Added context adjustments for target population (adults, children, babies, pregnancy). Refined weighting of chronic toxicity factor. Enhanced data quality assessment criteria.
v1.0	March 2021	Initial methodology release. Established four-score system (HSS, ESS, CTS, CES) with documented weighting and data sources. Foundation for risk-based assessment.

Backward compatibility: When we update the methodology, we don't automatically re-score all products. Brands can request re-assessment at 50% of original verification cost.

Related Pages

Learn more about how we apply this methodology in practice.

🏷️ Understanding Your Score

Consumer-friendly guide to reading and interpreting HumanSafe™ scores and badges.

Learn to Read Scores

✓ Verification Process

How brands get verified—the operational steps from application to publication.

See the Process

📖 About HumanSafe™

Our mission, approach, and why we built HumanSafe™ differently from existing systems.

About Us