Human Biomonitoring: Parts per Quintillion— A New Frontier for Toxicologists and Risk Assessors

Biomonitoring has become an indispensable tool for studying occupational and environmental exposure to chemicals, including persistent organic pollutants (POPs). POPs are lipophilic compounds and tend to accumulate in the lipid stores of the body.

Adipose tissue is mostly constituted by lipids (generally about 95% of the tissue) and therefore the POPs are generally found at the highest levels in this tissue. Because of the invasive nature of the surgical procedure required to obtain the adipose tissue sample, the analytical community then turned their attention to developing methods in blood. This was a less invasive matrix, but the levels were much lower in the blood matrix due to the small amount of lipids (~0.6%) compared to adipose tissue (~95%). The methods required high resolution mass spectrometry (HRMS) in order to have the sensitivity required to measure normal background POPs levels in the picogram to femtogram range.

It is important to continue to try and develop more sensitive analytical methods for environmental chemicals: 1) to determine the normal human background levels of chemicals that we cannot detect with current methods; 2) to continue monitoring chemical levels that are decreasing in populations around the world (eg. dioxins, furans, PCBs, pesticides); 3) to provide better analytical CVs of chemicals that we can measure which will translate into lower measurement uncertainties; and 4) a lower analytical CV translates directly into higher statistical power in epidemiological studies.

Newer, more sensitive analytical techniques are currently being developed using cryogenic zone compression and loop modulation coupled with HRMS to measure POPs. A modification of this technique, called timed controlled cryogenic zone compression, is being developed by Thermo Scientific. This technique allows targeted cryofocusing of certain peaks that might need enhanced sensitivity, while allowing the remainder of the chromatographic separation to proceed unaltered.

The potential for these techniques to generate parts-per-quintillion detection are presented in a plenary lecture entitled ‘Human Biomonitoring: Parts per Quintillion— A New Frontier for Toxicologists and Risk Assessors’, by Donald G. Patterson Jr, Exponent, Inc.

View the plenary lecture.