Data Waivers and Weight of Evidence

The standard set of toxicological studies can be very extensive and use many experimental animals, so it is important to make maximum use of data waivers . Clearly any studies that are impossible for technical reasons have to be omitted, but there may be a justification for data waivers on the grounds of low exposure or because the study is not scientifically necessary. 

There is provision within REACH for data waivers on the grounds of low exposure for the additional Annex 

A case can often be made to omit studies as scientifically unnecessary, because it is possible to conduct an adequate risk assessment without them. This is most often the case if the substance decomposes to degradants of known hazardous properties. For example the substance may hydrolyse rapidly to non-toxic products, so the key issue is to establish that this happens rapidly in the stomach before the parent substance can be absorbed. There may then be a case for omitting the expensive long-term animal studies, providing it is also established that there is no dermal or inhalation absorption from these exposure routes. In a similar way, it may be justified to omit ecotoxicity studies on a substance which hydrolyses or otherwise decomposes in the aquatic environment to stable products that have already been tested. 

Potentially it may be useful to have an expert report to collect, summarise and evaluate all the available literature data and in-house studies to get an overall view of the toxicity, environmental fate or ecotoxicity of a substance. A simple expert report would be on a single hazardous property, such as toxicokinetics or long-term general toxicity, and in effect would be a review article. 

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