Sample Processing and QA
For the laboratories analysing the DEMOCOPHES samples, effective capacity-building along with a strict quality assurance and control process took more than one year before obtaining comparable HBM measurements.
Environmental pollutants values might be very low in the general population and laboratory introduced variation and limits of detection are to be considered carefully.
This was achieved through the Interlaboratory Comparison Investigations (ICI’s) and External Quality Assessment Scheme (EQUAS) organised by COPHES.
The ICI were seen as a first test for newcomers to HBM, to improve laboratory skills in measuring relatively low levels. Experienced labs could receive confirmation of their measuring skills. Labs received two control samples per round with different concentrations of the target biomarkers and prepared from native biological samples. During the different rounds the range of expected concentrations was covered. A consensus value among participating labs was calculated. The aim was to obtain comparability across the labs.
In the EQUAS, the control samples were analysed again in experienced reference laboratories. Their results were used to define an assigned value and tolerance ranges for each of the concentrations of biomarker in the samples. The aim was to attain accuracy, i.e. the ‘true’ assigned values.
Selection of laboratories
Only those laboratories that successfully passed the quality assurance process, according to the criteria defined under COPHES/DEMOCOPHES, were allowed to analyse the DEMOCOPHES samples. Thus, in early 2012, 16 labs carried out the mercury analysis in hair, 14 labs did cadmium, 9 did cotinine, 7 did phthalate metabolites (countries agreed to analyse at least 5 phthalate metabolites from a list of 20, taking into account their policy relevance), 5 did Bisphenol-A and 14 did creatinine (creatinine levels in urine need to be measured to adjust urinary concentration of the biomarkers).
Achievements during sample processing and QA
- Capacity-building in HBM analytics advanced significantly through the ICI’s and EQUAS exercises . Nevertheless, although started early in the project, the time for capacity-building was too short for labs in many countries to set up new analytical methodologies and to succeed in the selection process. With the consequence that a lot of samples had to be analysed in other labs than in the country labs.
- Results of the chemical analyses, were cleaned and entered into national and EU databases, along with questionnaire data.
- Storage for a minimum of 10 years has been organised for remaining samples in DEMOCOPHES countries when authorized by their ethical committee. Human samples are precious and their collection is a labour-intensive and costly effort. These remaining biological material will be available for use in relevant further steps or in complementary analysis after this project in agreement with national and European regulation for data protection and ethics and following a procedure which will be defined.