ISES meetings are fascinating events, as the society’s membership consists of a melting pot of scientists from industry, academic researchers, and regulatory bodies (i.e. the policy makers). The 2011 meeting was no exception, with the diversity of the ISES members reflected in the dizzying array of talks, workshops, and symposia taking place over the week of the conference.
The conference began on a Sunday with a number of workshops, including two on pharmacokinetic modelling in exposure science. Pharmacokinetics is a branch of pharmacology that seeks to quantify the fate of substances introduced into a living organism. This is an element that is often lacking in most studies of human chemical exposure. For example, in studies involving dietary intakes of pesticides, the study often concludes once the distribution of dose of pesticide in a population is known. But what then? What is the fate of the compound once it enters the body? How long does it remain in the bloodstream? What tissues and organs does it distribute in to, and which ones does it affect? And how is excreted from the body? How does this very from person to person? These are all pertinent questions that are not often addressed. Pharmacokinetics is also an important consideration when examining biomonitoring data. In large scale studies like the National Health and Nutrition Examination Survey (NHANES) in the United States, the blood levels of contaminants from packaging like Bisphenol A (BPA) are often measured, in an effort to determine what the consumer exposure to the substance might be. Typically, one measurement per subject is taken. BPA however, has a very short half-life, meaning that it is eliminated quite quickly from the body. If a consumer is consistently consuming BPA due to their diet, their blood levels will oscillate considerably due to this quick elimination. Thus, inferring dose from a single measurement must be done quite carefully in order to avoid drawing false conclusions.
There were so many interesting symposia and talks taking place over the course week that it would take more than one short blog post to account for them all. The hot topic over the week was undoubtedly environmental sources of exposure like air pollution. Amongst the other highlights was the Risk 21 initiative, which seeks to bring risk assessment into the 21st century by combining four complimentary disciplines; exposure science, dose-response, in vitro in vivo extrapolation, and cumulative risk assessment. The initiative consists of 11 participating companies like Coca Cola and Exxon Mobil, and over 100 scientific partners from industry, academia, and government. As usual, the US EPA had a very strong presence at ISES and announced the launch of the next version of their Exposure Factors Handbook. Professor Stephan Rappaport from the University of California, Berkeley, presented a wonderful overview of the “Exposome” concept, which seeks to quantify a complete profile of the external chemical substances the internal human environment is exposed to, in effort to undercover previously unknown causes of chronic disease. Other interesting talks were on the discourse between science and the media, and a discussion on the future of exposure science as a whole. It was also very comforting to see that probabilistic methods were being applied across all areas of exposure science, in an effort to more accurately reflect reality in each case (which, let’s not forget, is the reason we use them). Indeed, Bayesian analysis was a buzzword that was ringing in my ears by the week's end.
Being one of the most important scientific gatherings our annual, Creme Global were of course at hand to participate. I presented a poster entitled “Software tools for probabilistic modelling of consumer exposure to chemicals in foods to assess susceptible human subpopulations”, and was very pleased with the interest it garnered.
On the whole, it must be said that exposure science is in a very healthy state. It is truly an interdisciplinary study, involving (in no particular order) statistics, mathematical modelling, biology, environmental science, engineering, toxicology, nutrition, computing, epidemiology, and much more besides. Despite this diversity, it is increasingly being recognised as a discipline meriting recognition in and of itself. ISES now even have their own journal, the Journal of Exposure Science and Environmental Epidemiology (JESEE). All of these efforts ultimately go towards the protection of human health, which we can all agree on, is a worthwhile outcome. So here’s to the future of exposure science!