A Human Health Perspective On Climate Change - The Oceans and ...

Waterborne DiseasesA Human Health Perspective ON CLIMATE CHANGEOur understanding of weather and climate impacts on specificpathogens is incomplete. Climate also indirectly impacts waterbornedisease through changes in ocean and coastal ecosystemsincluding changes in pH, nutrient and contaminant runoff, salinity,and water security. These indirect impacts are likely to result indegradation of fresh water available for drinking, washing food,cooking, and irrigation, particularly in developing and emergingeconomies where much of the population still uses untreatedsurface water from rivers, streams, and other open sources for theseneeds. Even in countries that treat water, climate-induced changesin the frequency and intensity of extreme weather events could leadto damage or flooding of water and sewage treatment facilities,increasing the risk of waterborne diseases. Severe outbreaks ofcholera, in particular, have been directly associated with flooding inAfrica and India. 290 A rise in sea level, combined with increasinglysevere weather events, is likely to make flooding events commonplaceworldwide. A 40 cm rise in sea level is expected to increasethe average annual numbers of people affected by coastal stormsurges from less than 50 million at present to nearly 250 million by2080. 291Several secondary impacts are also a concern. Ecosystem degradationfrom climate change will likely result in pressure on agriculturalproductivity, crop failure, malnutrition, starvation, increasingpopulation displacement, and resource conflict, all of which arepredisposing factors for increased human susceptibility andincreased risk of waterborne disease transmission due to surfacewater contamination with human waste and increased contact withsuch waters through washing and consumption. 292,293Climate change may also affect the distribution and concentrationsof chemical contaminants in coastal and ocean waters, for examplethrough release of chemical contaminants previously bound upin polar ice sheets or sediments, through changes in volume andcomposition of runoff from coastal and watershed development,or through changes in coastal and ocean goods and services. Bothnaturally occurring and pollution-related ocean health threats willlikely be exacerbated by climate change. 294 Other climate-relatedenvironmental changes may impact marine food webs as well, suchas pesticide runoff, leaching of arsenic, fluoride, and nitrates fromfertilizers, and lead contamination of drinking and recreationalwaters through excess rainfall and flooding.Mitigation and AdaptationAlternative energy production, carbon sequestration, and water reuseand recycling are some of the mitigation and adaptation options thatcould have the greatest implications for human health. As with alltechnologies, the costs and benefits of each will need to be carefullyconsidered and the most beneficial implemented.The potential impacts of different mitigation strategies forwaterborne illness depend on the strategy. For instance, increasedhydroelectric power generation will have significant impacts onlocal ecologies where dams are built, often resulting in increasedor decreased incidence of waterborne disease, as was the case withschistosomiasis (increase) and haematobium infection (decrease)after construction of the Aswan Dam in Egypt. 295 Other modes ofelectric power generation, including nuclear, consume large quantitiesof water and have great potential environmental impacts rangingfrom increased water scarcity to discharge of warmed effluent intolocal surface water bodies. Shifting to wind and solar power, however,will reduce demand on surface waters and, therefore, limit impactson local water ecosystems and potentially reduce risks of waterbornediseases. The impacts on waterborne pathogen ecology of othergeoengineering mitigation strategies, such as carbon sequestration,have the potential to be substantial but are currently largelyunknown. 296 Thorough health impact and environmental impactassessments are necessary prior to implementation and widespreadadoption of any novel mitigation technology.There is also significant potential for adaptation activities to impactthe ecology of waterborne infectious disease. Certain adaptationstrategies are likely to have a beneficial impact on water quality; forinstance, protecting wetlands to reduce damage from severe storms.290 Sidley, P, BMJ, 2008. 336(7642): p. 471, Sur, D, et al., Indian J Med Res, 2000. 112: p. 178-82.291 Ford, TE, et al., Emerging Infectious Diseases, 2009. 15(9): p. 1341-1346.292 Shultz, A, et al., American Journal of Tropical Medicine and Hygiene, 2009. 80(4): p. 640-645.293 Diaz, JH, Am J Disaster Med, 2007. 2(1): p. 33-42.294 Sandifer, P, et al., Interagency oceans and human health research implementation plan: a prescription for the future.2007, Interagency Working Group on Harmful Algal Blooms, Hypoxia and Human Health of the Joint Subcommitteeon Ocean Science and Technology: Washington, DC, USA.295 Abdel-Wahab, MF, et al., Lancet, 1979. 2(8136): p. 242-4.296 White, CM, et al., Energy & Fuels, 2005. 19(3): p. 659-724.www.niehs.nih.gov/climatereport 53