In some cases it may be possible to establish guidance values based on the acceptable levels of exposure control. One example of this type of value is the ‘benchmark’ approach used in the UK based on the 90th percentile of data from workplaces where it has been judged that there is good Ibrutinib in vivo control of exposure. Although not health-based this type of guidance value is useful for assessing lapses in control and the need for remedial action. Examples include biological monitoring guidance

values for sensitisers (isocyanates) and carcinogens (hexavalent chromium, 4,4′methylene bis(2-chloroaniline) methylenedianiline and polyaromatic hydrocarbons) (HSE, 2005). This type of control-based guidance value requires fewer data and can be revised as technology

and controls improve (Cocker et al., 2009 and Keen et al., 2011). This 90th percentile approach may be suitable for the derivation of in-house guidance values and an aid to improving control by targeting action at the highest exposures. One of the potential problems of using occupational biological monitoring guidance values after chemical incidents comes from the data used to propose the guidance values which is usually based on a defined exposure period (usually 8 h) and a defined sample collection selleck screening library time related to the half-life of elimination of the substance or its metabolites Substance with short half-lives are usually sampled at the end of exposure or end of shift and samples collected at other times should not be compared to occupational guidance values. Sampling for substances with longer half-lives is less critical but variance caused by diurnal variation may be reduced if sampling is done at the same time each day (Akerstrom et al., 2014). If exposure to long half-life substances is repeated over the work week, there may

be a gradual increase in biomarker levels with time. In these cases the guidance values should only apply after several weeks or months of exposure. In addition, occupational biological monitoring guidance values are derived from studies of people of working age who may have different physiological and metabolic responses to the general population. The possibility of saturation of metabolic pathways with high exposures and multiple sources of exposure C59 price in incidents should also be considered. In all cases the documents supporting the guidance value should be consulted to establish its basis and relevance for use interpreting results after an incident. An example of the use of occupational BMGVs was given by Scheepers et al. (2011) who showed by means of a fictitious case of a benzene spill based on a documented chemical incident, how occupational biological monitoring data can be used in a chemical incident scenario. In this case, the aim was to determine the longest time after the incident that urine samples should be collected in order to assure detectable levels of the biomarker. In addition, Scheepers et al.