The use of saliva as a diagnostic fluid is a relatively recent trend. This is not surprising when one considers its many advantages and the fact that saliva contains a wide array of constituents.¹ Saliva collection is non-invasive compared with phlebotomy, and, as a result, more acceptable to patients. As obtaining saliva is easy, self-collection after instruction is possible and there is no need for trained staff. Moreover, it does not carry the risk of needle-stick injuries. Saliva collection is also less likely to cause stress compared with other invasive procedures such as phlebotomy, an important consideration when researching biomarkers of stress. Lastly, saliva samples can reflect real-time levels of biomarkers, unlike other biological fluids, such as urine, which is stored in the bladder for a few hours before sampling.

BIOMARKERS IN SALIVA

A wide range of biomarkers is measurable in saliva, including heavy metals (eg, lead), hormones (eg, cortisol, dehydroxyepiandrosterone (DHEA)), toxins and their metabolites (eg, cotinine), enzymes (eg, lysozyme, α-amylase), immunoglobulins (eg, IgA), other proteins (eg, eosinophil cationic protein) and DNA. Researchers are also studying the proteomic components of saliva in the hope of identifying novel biomarkers of disease.^2,3

A search of PubMed using the medical subject heading terms “saliva” and “biological markers” showed an increase in the number of studies using salivary biomarkers in the past decade (fig 1). However, when a search using the terms “saliva”, “markers” and “occupation” was performed, the numbers of occupational health papers using salivary markers lagged far behind. Of the 20 papers obtained from the second search, a review of abstracts showed that only 11 had actually used saliva biomarkers in occupational health research. These 11 papers were classified according to areas of occupational health research and the biomarker studied (table 1). The subsequent part of this paper will discuss these …