Human biomonitoring of emerging pollutants through non-invasive matrices: state of the art and future potential

Abstract

Human biomonitoring (HBM) is a scientific technique that allows us to assess whether and to what extent environmental pollutants enter humans. We review here the current HBM efforts for organophosphate esters, emerging flame retardants, perfluoroalkyl substances, and phthalate esters. Use of some of these chemicals has already been banned or restricted; they are regularly detected in the environment, wildlife, and human matrices. Traditionally, blood and urine collection have been widely used as sampling methods. New non-invasive approaches (e.g., saliva, hair, nails) are emerging as valid alternatives since they offer advantages with respect to sampling, handling, and ethical aspects, while ensuring similar reliability and sensitivity. Nevertheless, the identification of biomarkers of exposure is often difficult because chemicals may be metabolized in the human body. For many of the above-mentioned compounds, the mechanisms of the favorable metabolization pathways have not been unraveled, but research on important metabolites that could be used as biomarkers of exposure is growing. This review summarizes the state of the art regarding human exposure to, (non-invasive) HBM of, and metabolism of major organophosphate esters, emerging flame retardants, perfluoroalkyl substances, and phthalate esters currently detected in the environment.

Review of OPFRs in animals and humans: Absorption, bioaccumulation, metabolism, and internal exposure research

“…For exposure assessments of wild animals, only residual OPFRs were analyzed in the plasma or in different tissues. The major OPFR metabolites formed in in vitro studies are valuable candidate markers for monitoring wild animal exposure (Alves et al, 2014). Future research focusing on the quantification of more OPFRs and their metabolites in other metabolically inactive tissues may provide a comprehensive picture of the internal exposure of OPFRs in animals and humans.…”

“…The migration of OPFRs in the environment leads to their exposure to organisms (Abdallah and Covaci, 2014;Alves et al, 2014). There are diverse pathways for organisms to uptake or absorb OPFRs through ingestion, gill absorption, skin absorption and inhalation.…”

“…In contrast to external exposure, which concerns the source or pathway to the body, studies of internal exposure have focused on the total concentration of circulatory OPFRs and their metabolites within the body, which indicates the total burden of exposure (Alves et al, 2014).…”

“…In human biomonitoring, non-invasive matrices are required. Aside from plasma, urine, saliva and hand wipes are the most frequently used matrices in human biomonitoring (Alves et al, 2014;Hoffman et al, 2015;Meeker et al, 2013b). Hair and nails are less metabolically active tissues that may also be promising samples for internal exposure studies (Alves et al, 2014).…”

“…In this article, we organized recent studies on the absorption, bioaccumulation, biomagnification and the metabolic processes of OPFRs in animals and humans (Fig. 1), rather than simply listing the occurrences of OPFRs in biota, which has often been conducted in previous reviews (Alves et al, 2014;Reemtsma et al, 2008;Van der Veen and de Boer, 2012;Wei et al, 2015). In addition, we also propose a perspective on research into the internal exposure of OPFRs to animals and humans.…”