Table 1.

Potential effects of global climate change (GCC) on human exposures from major chemical contaminant sources

Contaminant of concern	Relative importance of environmental exposure pathways compared to other pathways (e.g., direct use, occupational)	Major sources	Direct and indirect effects of GCC on contaminant source	Direct and indirect effects of GCC on fate and transport	Overall effect of GCC on human environmental exposure	Evidence base for climate impact
Criteria air pollutants SO2, NOx, PMx	High	Automobiles, chemical production sites, power stations, incinerators, residences	Emissions of many air pollutants harmful to human health may be lower if society mitigates against greenhouse gas emissions by moving toward biofuels 72. Emissions may increase at biofuel production sites 20.	Limited	Adverse/positive	High
Ground-level O3	High	Precursor gases NOx, VOCs, and CO	If global carbon emission controls are implemented, a reduction in ozone is predicted in developed areas, but an increase is expected in developing countries. If controls are not implemented, exposure will increase globally. An increase expected in number of pollution days is also expected 81.	Limited	Adverse/positive	High
Arsenic	High	Natural contamination	Altered climates that impact the microbial communities and water chemistry of freshwater systems can affect the distribution of arsenic species in surface water 82.	Increased irrigation results in greater contamination of food crops 83.	Adverse	High
Mercury	High	Contaminated soils and sediments	Altered climates may affect microbial biotransformation of mercury from the divalent to the more biologically available organic species 33.	Increases in temperature may increase Hg mobility as a result of increased conversion of Hg species to vapor Hg and to methyl mercury 80. Uptake into fish expected to increase 33.	Adverse	High
Dioxins, PCBs, DDT	High	Waste sites, combustion, electrical equipment, forest fires	Increasing temperatures will increase the release of POPs from sources such as buildings and electrical equipment 27. Use of DDT may increase due to increased need for malaria control 27.	Thawing of ice caps will release persistent organic compounds. Increases in flooding events will remobilize soil- and sediment-associated POPs and transport them to uncontaminated areas 18. Uptake into fish may increase or decrease 84. Degradation of some POPs will increase in some areas 85	Adverse	High
Pesticides	Medium	Agriculture	Outbreaks of a wider variety of insects and pathogens is expected, resulting in increased pesticide use and changes in application timings 58. Geographical shifts in agriculture will mean that cropping patterns change and types of pesticide use change 86.	Increased volatilization of pesticides expected following application 1. Degradation in soils may increase due to increased temperatures and changes in soil moisture 25.	Adverse—bystander exposure anticipated to increase	Medium
Pharmaceuticals	Low	Health care	Increases in human diseases (e.g., malaria, depression) may result in increasing pharmaceutical use.	Increased recycling of water and use of treated wastewater for irrigation may result in entry into food items.	Adverse	Low
Veterinary drugs	Low	Agriculture	The proliferation of animal diseases due to climate-related changes may result in an increased use of veterinary drugs that could lead to increased releases to the environment 18.	Degradation in soils may increase due to increased temperatures and changes in soil moisture 25.	Adverse	Medium
Industrial process chemicals	Low	Industrial facilities	Increased catastrophic weather events (floods, wildfires) may result in increased catastrophic accidental releases.	Limited	Adverse	Low
Algal toxins	High	Algal blooms	Warmer conditions are generally linked to increased frequency, duration, and geographic scope of HABs, due to changes in water temperatures and stratification and increased nutrient inputs, so GCC is predicted to increase the incidence of HABs in the future 18, 23, 86, 87	Limited	Adverse	High
Mycotoxins	High	Fungi-infected crops	Mycotoxin contamination of crops is anticipated to increase due to drought stress, temperature stress, stress induced by pest attack, increases in arthropod vectors, poor nutrient status 54, 86. Changes in the geographical range of crops produced could provide opportunity for new fungus–plant associations to arise, so mycotoxins currently not considered a threat to public health (e.g., sterigmatocystin, cyclopiazonic acid, moniliformin) may become important 18.	Limited	Adverse	High
Pollen	High	Plants	GCC is predicted to lengthen the pollen season as well as increase pollen and spore rupture; increase in pollen allergenicity 22, 88	Increase in long-distance transport	Adverse	High

SO₂ = sulfur dioxide; NO_x = nitrogen oxide; PM_x= particulate matter; O₃ = ozone; VOC = volatile organic compound; CO = carbon monoxide; Hg = mercury; POP = persistent organic pollutant; PCB = polychlorinated biphenyl; DDT = dichlorodiphenyltrichloroethane; HAB = harmful algal blooms