Use of salivary biomarkers in biobehavioral research: cotton-based sample collection methods can interfere with salivary immunoassay results

In a series of studies, we evaluated the susceptibility of immunoassays for saliva biomarkers to interference effects caused by cotton materials used to absorb saliva during sample collection. Salivary assay results for testo sterone, DHEA, progesterone, and estradiol are artificially high, and for s IgA artificially low, when samples are collected using cotton absorbent mat erials. In contrast, results for salivary cortisol, DHEA-S, and cotinine ar e not affected by the use of cotton collection methods. The order of indivi dual results from samples collected using cotton versus no-cotton methods f or certain markers is not conserved, suggesting that for some biomarkers th is collection method can be a significant source of unsystematic error. It was shown, using DHEA as an example, that the cotton interference effect is of sufficient magnitude to attenuate the association between serum and sal iva levels. Awareness of this issue is critical to ensure measurement valid ity in future studies and analyses of archived samples collected using cott on materials. (C) 2001 Elsevier Science Ltd. All rights reserved.