How to Calculate ATE for Chemical Mixtures (GHS Formula)

When formulating a chemical mixture, you need to determine its acute toxicity classification to label it correctly under GHS/CLP. This is done using the ATE (Acute Toxicity Estimate) additivity formula.

The GHS ATE Formula

100 / ATE_mix = Σ (Ci / ATE_i)

Where:

• ATE_mix — the calculated ATE for the mixture (mg/kg or mg/L)
• Ci — concentration of component i in % by weight
• ATE_i — ATE value of component i

This formula is applied separately for each route of exposure: oral, dermal, and inhalation.

Which Components to Include

Only components with concentration ≥ 1% are included in the calculation.

However, components present at < 1% must still be included if their individual ATE would affect the mixture classification (e.g., highly toxic substances at 0.5%).

ATE Default Values

When an exact LD50 is not available, GHS provides default ATE values by toxicity category:

Category	Oral (mg/kg)	Dermal (mg/kg)	Inhalation vapour (mg/L/4h)
1	0.5	50	0.05
2	5	200	0.5
3	100	1000	3
4	500	2000	11

Worked Example

Mixture: Industrial Degreaser

Component	Concentration	Oral ATE (mg/kg)
n-Hexane	60%	25,000
Acetone	30%	5,800
Toluene	10%	636

Calculation:

100 / ATE_mix = (60/25000) + (30/5800) + (10/636)
100 / ATE_mix = 0.0024 + 0.00517 + 0.01572
100 / ATE_mix = 0.02329
ATE_mix = 100 / 0.02329 = 4,294 mg/kg

Result: ATE_mix = 4,294 mg/kg → Category 5 / Not classified (threshold for Cat 4 is < 2,000 mg/kg)

Classification Thresholds

ATE Range (oral, mg/kg)	Category	Signal Word	Pictogram
≤ 5	1	DANGER	GHS06
> 5 – ≤ 50	2	DANGER	GHS06
> 50 – ≤ 300	3	DANGER	GHS06
> 300 – ≤ 2,000	4	WARNING	GHS07
> 2,000 – ≤ 5,000	5	WARNING	—

Use the Calculator

Instead of doing this by hand, use our ATE Mixture Calculator:

1. Search for each component by name or CAS number
2. Set the concentration percentage
3. Click Calculate to get the mixture ATE and classification
4. Download a PDF report for your SDS documentation

The calculator uses ATE values from the ECHA CLP Annex VI database and applies the GHS additivity formula automatically.

Related Resources

• Chemical Storage Segregation Guide — storage rules for classified mixtures
• GHS H-Statements Complete Guide — H-codes assigned after ATE classification
• GHS Signal Words: Danger vs Warning — signal word determined by ATE category
• ATE Mixture Calculator →

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Reference: UN GHS Rev.9, Chapter 3.1 — Acute Toxicity. CLP Regulation (EC) No 1272/2008, Annex I.