Heating Up the Environmental Context of Chemical Pollution: Ecotoxicology in a Changing Global Climate

Humans and wildlife are exposed to an ever-increasing array of man-made chemicals that are now measured in every habitat on our planet from the Earth’s highest mountain peaks to sediments in the deep ocean (e.g., Farrington and Takada, 2014; Quiroz et al., 2009; Veron et al., 1987; Villa et al., 2006). In addition to the expanding variety of synthetic chemistries in use, there are many substances that are components of the Earth that may through human activities concentrate at highlevels or be released into the environment in forms that enhance their bioavailability, exposure, and toxicity potential. Thus, environmental chemical pollution is widespread with a diversity of chemicals and sources including, but not limited to: metals (e.g., mercury, arsenic, cadmium, lead) that are natural but can be released, transformed (e.g., methylated), and concentrated above background levels with mining and other activities; petroleum hydrocarbons like polycyclic aromatic hydrocarbons (PAHs) that are formed from petrogenic and pyrogenic processes both natural and anthropogenic; dioxins and furans that are toxic byproducts of a variety of industrial operations; synthetic organohalogens such as polychlorinated biphenyls (PCBs), brominated and fluorinated flame retardants, and organochlorine pesticides (e.g., dichlorodiphenyltrichloroethane [DDT]); polymers and their additives(e.g., bisphenol A [BPA], phthalates); and numerous other chemicals that, among other uses, function as industrial feedstocks, pesticides, pharmaceuticals, and nanoparticles. Depending on their structural features, biological disposition, and bioactivity potential, these chemicals may be highly persistent in the environment, bioaccumulate or biomagnify in species and food webs, and elicit toxicity and maladaptive behaviors in some cases at low exposure levels depending on the target (e.g., endocrine system) and chemical (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin). Research efforts by scientists working in the field of toxicology have provided abundant evidence that many chemicals classified as environmental pollutants have the potential to disrupt the developmental, reproductive, cognitive, chemical signaling (e.g., hormones), or metabolic processes of wildlife and humans. Researchers from around the world are continually adding new information to characterize the biological targets, mechanism of action, and adverse effects of chemical contaminant exposures, and there are now over eighty academic journals listed under the category of ‘toxicology’ in the Journal Citation Reports database of the ISI Web of KnowledgeTM (Thompson Reuters, New York, NY, USA). And yet, there are tens of thousands of chemical compounds being used today in human activities around the world, and it remains the case that little is known about the toxicity potential of most environmental chemicals for most species and life stages (Dix et al., 2007, Grandjean and Landrigan, 2006). Even as scientists continue working to address knowledge gaps in the environmental behavior and biological effects of chemical contaminants, it is likely that future research in the toxicological sciences will require greater integration across biological and computational disciplines to incorporate foundational principles and methodologies from environmental physiology, ecology, evolutionary biology, and bioinformatics as the dynamics of chemical pollution transport, degradation, bioaccumulation, pharmacokinetics, and toxicity are reshaped under the shifting environmental conditions associated with a changing global climate. There is now scientific consensus that the anthropogenic production of non-water vapor greenhouse gases including CO2 and CH4 is altering the Earth’s global climate system. Globally averaged land and ocean sur-