Lack of data makes TTC method inappropriate for cosmetics

The model is currently used within the food and pharmaceutical industries but recent publications have suggested it may be useful in other areas, including cosmetics.

Late November saw the publication of a preliminary report, authored by the Scientific Committees on Consumer Products (SCCP), Health and Environment (SCHER) and Emerging and Newly Identified Health Risks (SCENIHR), which concluded a lack of data made the approach currently inappropriate for cosmetics ingredients.

Threshold under which there is low risk​

The TTC approach aims to establish threshold values for various chemicals, under which there is a very low probability of appreciable risk.

It is designed to provide threshold values for chemicals for which little data is available, based on the known behaviour of structurally related chemicals.

For the approach to be successful, databases must be extensive, up to date, and cover a range of structural chemical classes, which is currently not the case for cosmetics ingredients, according to the report.

Insufficient data​

Only 19 of the 250 cosmetics ingredients that have been looked at by the SCCP are included in the Munro database, one of the two major databases used to establish threshold values.

Interestingly, 4 of these substances have acceptable doses derived from conventional risk assessments that are lower than those calculated by the TTC.

This suggests the TTC may not be the most applicable system as, in this case, it may produce values higher than those already calculated to be the safest maximum dose.

In addition, Cramer classes (a classification system developed in the late 1970s that attempts to establish toxicity levels) and NOELs (No Observed Effect Levels) are known for only 155 cosmetics ingredients, and for 96 of the ingredients banned from cosmetics products. The report concludes this is a very small percentage of the estimated 15,000 ingredients in the cosmetics inventory.

Furthermore, the TTC approach was developed with oral administration in mind. Before it can be applied to cosmetics, methods to extrapolate the data allowing for differences between the administration routes must be designed.

Although the report agreed that the TTC approach is scientifically valid, it concluded it should not be adopted at present by the cosmetics industry.

The SCCP, SCHER and SCENIHR invite comments on this preliminary report until the January 2, 2009.