Your supplier updates the formulation by 0.1%. The product looks the same, performs the same and is sold for the same use. What do you do?

A.       Nothing – the change is negligible

B.       Update the SDS only

C.     Reassess the classification and wider regulatory impact

D.     Only reassess if the change involves a hazardous substance

The answer is C.

The outcome of the reassessment is dependent on exactly what has changed.

A 0.1 percentage-point change (w/w) might seem small from a formulation perspective, but from a regulatory perspective, it could be the difference between sitting just below a threshold and crossing it.  The finished mixture could now meet the criteria for a new or more severe hazard classification.

How Small Formulation Changes Can Affect CLP Classification

This does not just affect compounds at very low concentrations. Specific Concentration Limits (SCLs) are substance-specific thresholds and can apply at much higher concentrations.

Perchloric acid illustrates this point. A change in concentration from just below 50% to just above 50% can affect both its oxidising-liquid and skin-corrosion classifications.

In that example, the hazard was already there, the 0.1% change altered its severity. However, what if that small change introduces an entirely new classification?

When a 0.1% Change Creates a New Hazard Classification

This is where a seemingly minor change can have a significant consequence. Dichloromethane (DCM) currently has an EU harmonised classification of Carcinogenicity Category 2. At 0.95%, DCM is still identified and relevant to the assessment, but it would not by itself cause the whole mixture to be classified as Carcinogenicity Category 2. Increase it to 1.05% however, and that changes. The 0.1 percentage-point increase takes it across the applicable 1% generic concentration limit. The formulation has barely changed, but the whole mixture now has a Carcinogenicity 2 classification, and the label may now need to communicate “Suspected of causing cancer.”

The 0.1% REACH SVHC Threshold for Articles

Sometimes, 0.1% is just enough to cross a threshold, but sometimes 0.1% is the threshold.

For Candidate List SVHCs in articles, exceeding 0.1% w/w can trigger additional REACH information duties and, where applicable, SCIP notification requirements.

Imagine, the candidate list, SVHC, di(2-ethylhexyl) phthalate (DEHP) increases from 0.05% to 0.15% w/w in an article. On paper, that is still only a 0.1 percentage-point change, however, from a regulatory perspective, the position is very different. The article has moved from below the 0.1% threshold to above it, potentially creating information and SCIP obligations (EU only) that did not previously apply.

What Should You Do When a Formulation Changes?

So, what should you do when a formulation changes by 0.1 percentage point?

Reassess it.

The reassessment may ultimately show that nothing changes. However, it may also identify: a new classification, a new hazard statement, a different label or SDS requirement, or additional REACH obligations.

The right response is not to assume a small change is insignificant. It is to understand what has changed, which regulatory thresholds apply, and whether any of them have been crossed.

Ultimately the size of the change does not tell you the size of the regulatory consequence.

All classifications, thresholds and regulatory examples in this article are correct at the time of writing. Regulatory requirements and harmonised classifications can change, so the current position should always be checked before relying on them.

About the author

Dr Milly Stoneley, Regulatory Consultant: Milly supports clients with chemical regulatory compliance, with a particular focus on REACH submissions and the analysis of chemical and analytical data to support regulatory dossiers.