Development of a guideline for the estimation of surface contamination

Status:

completed 03/2021

Aims:

The contamination of surfaces with hazardous chemicals is measured – for example by wipe tests – for the conducting of exploratory measurements or the monitoring of hygiene measures. As yet however, a limit value similar to that used for monitoring indoor air is not applied. At the same time, discussion of binding limit values for surfaces, the benefit of such values and the setting of them, raises many questions to which answers must first be sought. The distribution of contaminants on surfaces is in most cases not homogeneous, in contrast to their distribution in indoor atmospheres. In addition, according to the substance and the nature of the surface, mutual influences occur between the two, making standardization of sampling difficult. The objective is to summarize the current state of research into the measurement of surface contamination and the interpretation and evaluation of the results, in order for a sound basis to be created for the evaluation of surface contamination.

Activities/Methods:

A literature review was first conducted for published methods for measuring surface contamination, both for organic hazardous substances and for the analysis of metals. The review was intended to evaluate, systematically, the influence of the surface properties, the influences of a number of analytes and the sampling technology, and the reciprocal influences of these parameters. Experiments were to be performed involving example substances on a range of surface types under controlled laboratory conditions, in order for sampling parameters to be evaluated. For the purpose of setting limit values for the monitoring of surface contamination, it was to be determined, with reference to published methods and in cooperation with the Toxicology of industrial chemicals Expert committee and the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance – Institute of the Ruhr-Universität Bochum (IPA), what suitable form should be taken by a sampling strategy by which valid interpretations of surface contamination may be obtained.

Results:

The literature review and practical tests conducted at the IFA for sampling on surfaces showed that in order for methods for the quantitative determination of surface contamination to be standardized, numerous factors must be considered. These include the nature of the surface, the material, and its distribution on the surface, and are difficult to standardize. In the field, a quantitative assessment of the contamination of a surface with hazardous substances is therefore possible only with limitations, particularly given that the routes of transmission from the surface into/onto the human body cannot as yet be quantified. In view of this situation, the setting of limit values for surface contamination is difficult to justify.

Surface measurements have a different objective and provide qualitative information for example on the carry-over of hazardous substances to and from surfaces. Such methods can be used for example to detect inadequate cleaning processes and can be taken into account during the optimization of procedures. This methods may be regarded as a useful supplement to established methods for measuring hazardous substances sampled in atmospheres.

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