Identification of collection materials free from BPA contamination. A) Eight vacutainer butterflies (VB) and one straight needle (SN) were tested for BPA contamination. Double-stripped serum was run through these materials and tested by one participating laboratory. Vacutainer butterfly #3 (VB3) was tested twice. B) Samples collected with BPA-contaminated vacutainer butterflies were easily distinguished from samples collected with a straight needle. Very high uBPA concentrations were reported for all samples collected via contaminated collection materials by all laboratories whereas multiple samples collected with the straight needle had uBPA concentrations reported as undetectable (UD) from several laboratories. C) uBPA and BPA-G concentrations measured in blank water samples. Three laboratories reported no uBPA or BPA-G in any sample. Laboratory 4 reported a low concentration (0.17 ng/ml) of uBPA. D) uBPA and BPA-G were not reported at quantifiable levels in stripped human serum by any participating laboratory. In all panels, UD indicates undetected levels; <LOQ indicates detectable levels that were below the limit of quantification.