“A harmonised and consistent approach to performing mixture assessments, across different regulations, is still lacking, according to a Joint Research Centre (JRC) report.
In 2014, the JRC surveyed experts to ascertain if and how they use “novel” tools to assess chemical mixtures. It gained responses from 58 people from academe, regulatory authorities and industry, in 16 EU countries, as well as in Canada, Japan, Norway, Serbia, Switzerland and the US.
The report shows a good uptake of some techniques. For example, almost half of respondents use in vitro tools, valuing the information that they can provide on mechanisms.
However, time and again in the survey, those not using particular tools, from Qsars to physiologically-based pharmacokinetic (PBTK) modelling and ‘omics techniques, partly lay the blame at a lack of guidance.
“The greatest hurdles that experts identified in the survey were a lack of guidance, lack of standardisation, lack of legal drivers and lack of expertise,” said co-author Stephanie Bopp. In some cases, a “lack of relevant input data” might also hamper the application of tools, she added.
According to the survey, this is particularly true for PBTK models, used to correlate in vitro concentrations with in vivo scenarios, and to link internal to external dose.
Overall, the JRC report identifies a “high potential” for applying novel tools to assess chemical mixtures, particularly in an integrated manner. However, it concludes that “in order to benefit from these tools in the hazard assessment of mixtures, more guidance on their use is needed”.
In 2009, a state-of-the-art report on mixture toxicity by scientists, including Andreas Kortenkamp from Brunel University, also highlighted a need for new guidelines.
In some cases, existing guidance on analytical tools can simply be updated to include mixtures, suggested Dr Bopp. However, in the “long term”, specific guidance still needs to be developed, she said.
She highlighted the efforts of an OECD working group on combined exposure to multiple chemicals, as a step towards specific mixtures guidance.”
Article of Emma Davies
JRC report : http://publications.jrc.ec.europa.eu/repository/bitstream/JRC97522/jrc_tech_rep_sci%20meth%20for%20mix_final.pdf
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