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[edit] Impact of Climate Change on the Risk to Humans of Agricultural Contaminants
[edit] Introduction
- Hi this is me keith, editing the page !!!! <-- just logged in as Nancy and changed it again!
Within the next century it is predicted that winters will be wetter, summers drier and intense rain events will be more frequent, with average temperatures in the UK increasing by up to 5oC by the 2080s. This will bring changes in agricultural practices, in possible routes and vectors for exposure to pathogens that may be associated with agriculture, and thus potential effects on human health too. When the public consume food and drinking water they may be exposed to chemical (e.g. pesticides and veterinary medicines) and biological (e.g. bacteria and viruses) contaminants originating from agriculture. In future, climatic changes may influence the type, identity and extent of exposure of these contaminants. Consumers can be exposed to these through a number of routes, which include the: · Consumption of crops that accumulate contaminants from soils; · Consumption of livestock that accumulate contaminants through food; · Consumption of fish exposed to contaminants in water; · Consumption of natural waters abstracted for drinking; · Inhalation of gases or particles from agriculture; · Contact with carriers of disease or pathogens; and · Contact through recreational use of contaminated water bodies.
[edit] Potential change in contaminant type
With a requirement for agricultural intensification if more land is passed over to bio-energy crops, pesticide usage may increase and new more potent pesticides may be developed and applied. Warmer climates could lead to new pathogens, diseases and vectors previously only seen in other countries, whilst thermal stress in summer and pasture water-logging in winter could lead to increased indoor housing requirements for livestock. Veterinary medicine, biocide and dietary supplements use could increase, which in turn would increase worker contact with animals and thereby increase exposure to diseases that maybe transferred to humans. Flooding of contaminated areas such as land-fills, sewage-works and brownfield sites could move non-agricultural contaminants, such as heavy metals, dioxins or faecal born diseases in floodwater and/or contaminated sediment to agricultural land with a potential for then to accumulate in crops and grazing livestock.
[edit] Potential change in contaminant behaviour
Pests and diseases associated with agriculture may increase since changes in climate may allow for an expansion of their range and mild winters could increase their survival, whilst raised temperatures may reduce the time it takes for the organisms to reproduce, thereby leading to increases in population size. Pesticide effectiveness may be reduced due to extreme weather, provoking more intensive usage; warmer weather could increase the chemical degradation and hence reduce their risk to humans, whilst wetter weather may wash away the compounds (into soil and water courses) before they have chance to be active on the designated crop. Reduced rainfall in warm dry summers will decrease the levels in rivers and lakes; with less water available to dilute contaminants, resultant concentrations may be higher.
[edit] Potential change in contaminant transport
Warmer and drier weather may increase the dispersal of contaminants through the air, either as volatiles or bound to soil particles. Pesticides volatilisation may increase, and there could be increased quantities of soil particles and pathogens picked up by the wind. Pesticide usage may increase as crop diseases become more prevalent, but efficacy could increase resulting in an overall reduction in pesticide environmental load. The movement of agricultural contaminants may become more prevalent with pesticides, veterinary medicines and pathogens moving from agricultural land when it floods to water bodies subsequently used as a source of drinking water. Contaminant movement through the environment, such as across the surface of soil and vertically through soil, may be amplified by increased intensity of rainfall and water-logged soils in winter and increased cracking allowing rapid vertical movement, crusting of soil surface and increased irrigation requirements in summer.
[edit] Conclusions
As a result of climate change, it is apparent that there will be changes in the amount and identity of chemical contaminants and pathogens from agriculture to which humans will be exposed. Chemical usage could increase through agricultural intensification and pathogen prevalence may also increase. There may be a requirement to consider new contaminants in food and water due to flooding events. Contaminant and pathogen transport processes will also be affected. It is anticipated that the risks to human health will be greater but currently the significance of these are unknown. Risks from chemicals may be managed through regulation and monitoring but it is difficult to predict changes in pathogen behaviour and thus devise control methodologies.
