Does the titanium dioxide classification show chemicals legislation has a problem with solids?


Chemical Watch science editor, Andrew Turley, examines the reasons for the longevity of the dispute over the classification – and asks whether the concept of ‘a substance’ is in need of overhaul

After a decade of dispute, the classification of titanium dioxide as a category 2 carcinogen under EU CLP is now the subject of three court cases. The outcome of those cases may eventually bring some closure to an issue that has been the subject of contention for far too long. But why exactly has the classification generated so much strife?

This is an important question, given the European Commission’s ambition to make the legislative process for the regulation of chemicals faster and more efficient – a goal described in its chemicals strategy for sustainability (CSS).

Much is at stake commercially. Titanium dioxide is widely used across a range of downstream sectors and manufacturers have warned of significant negative economic impacts as a result of the classification. Furthermore, there are many other compounds that have the potential to exhibit the same toxicological profile that underpins the titanium dioxide classification, prompting fears it could be just the first in a series of regulatory measures spanning a broad range of compounds. As a consequence, industry, which stands to take a significant financial hit, lobbied hard. But there is more than just commercial interest behind the controversy.

A broad scope

First, the original classification proposal applied to titanium dioxide in all its forms – but the toxicity did not. To many, classifying the substance generally on the basis of a subset of particle forms, seemed wrong. The hazard was carcinogenicity from inhalation. Therefore, what sense was there in classifying forms that could never be inhaled?

The classification we have today is more targeted, applying only to powder forms containing 1% or more of particles with an aerodynamic diameter of ten micrometres or more, but this narrower scope was introduced only relatively recently. It seems reasonable to assume that, particularly in the early phases of the dispute, a lot of time and energy might have been saved had it been more focused from the start.

The proposal’s broad initial scope was partly a result of uncertainty over what substance identity information the registrants were obliged to provide under REACH. In 2014, Echa told them that they had supplied insufficient information and requested the following for each form:

· the crystal phase;

· the impurity profile;

· whether there is a surface treatment and if so what it is; and

· whether the form is ‘pigmentary’ or ‘sub-pigmentary’.

The agency also asked registrants to:

· specify whether the substance manufactured or imported by them only related to some of the forms and phases covered by the joint registration; and

· provide an explanation of how the phase-specific properties were addressed and how all test data accounted for that phase in relation to hazard and risk management measures.

The request was challenged by the lead registrant, plus eight co-registrants, arguing that, among other things, REACH did not compel them to provide such information. The appeal effectively stalled substance and dossier evaluation, leaving Echa and member state regulatory authorities in an awkward position. Evidence suggested to them that certain forms of titanium dioxide were carcinogenic. However, they could not target those specific forms with regulatory risk management measures because they did not have the information they needed to differentiate one form from another. They might yet get that information, but not for years, if at all.

France decided that it was not prepared to wait. It reasoned that if industry would not provide the information needed to differentiate the forms and target the ones of concern, it would have to consider the substance as a whole for the purposes of hazard assessment.

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Chemical Watch, 9 September 2021