Impacts of climate change on indirect human exposure to pathogens and chemicals from agriculture

Abstract

Objective: Climate change is likely to affect the nature of pathogens and chemicals in the environment and their fate and transport. Future risks of pathogens and chemicals could therefore be very different from those of today. In this review, we assess the implications of climate change for changes in human exposures to pathogens and chemicals in agricultural systems in the United Kingdom and discuss the subsequent effects on health impacts.

Data sources: In this review, we used expert input and considered literature on climate change; health effects resulting from exposure to pathogens and chemicals arising from agriculture; inputs of chemicals and pathogens to agricultural systems; and human exposure pathways for pathogens and chemicals in agricultural systems.

Data synthesis: We established the current evidence base for health effects of chemicals and pathogens in the agricultural environment; determined the potential implications of climate change on chemical and pathogen inputs in agricultural systems; and explored the effects of climate change on environmental transport and fate of different contaminant types. We combined these data to assess the implications of climate change in terms of indirect human exposure to pathogens and chemicals in agricultural systems. We then developed recommendations on future research and policy changes to manage any adverse increases in risks.

Conclusions: Overall, climate change is likely to increase human exposures to agricultural contaminants. The magnitude of the increases will be highly dependent on the contaminant type. Risks from many pathogens and particulate and particle-associated contaminants could increase significantly. These increases in exposure can, however, be managed for the most part through targeted research and policy changes.

Keywords: agriculture; climate change; environmental fate; health risks; nutrients; pathogens; pesticides.

Figure 1

Predicted impacts of climate change on major environmental pathways for human exposure to pathogens and chemicals from agriculture. Letters indicate which contaminant classes are likely to be transported via an individual pathway: P, particulate (e.g., bacteria, viruses, spores, engineered nano-particles); PA, particle-associated (e.g., hydrophobic organics, ammonium, heavy metals); S, soluble contaminant (nitrates, group 1 and 2 elements, reactive phosphorus, hydrophilic pesticides); V, volatile contaminant. Larger and smaller letters indicate the greater and lesser extent, respectively, to which each contaminant type will be transported by the pathway (e.g., methane, nitrous oxide, ammonia, sulfides).

Figure 2

Possible time lines and strategy for research, surveillance, and risk mitigation for the predicted increases in human exposure to biological and chemical contaminants from agriculture.