“The significant problems we face cannot be solved at the same level of thinking we were at when we created them.”
Albert Einstein (1879–1955) Environmental pollution may be defined as“irresponsible discharge or disposal of toxic waste by humans based on the anticipation that Mother Nature will take care of it”. Whether intentional or unintentional, environmental pollution by humans is a fact (see Figure 1.2.2). However, in the last decades, some remediation emerged following scientific community warning and political awareness. Besides the environment, pollution is a multi-edged sword that may affect also humans, animals, pathogens and their vectors (Chuet al., 2008). Briefly, pollution sources can be chemical (from various industrial activities), biological (from waste and agricultural activity) and radioactive (from domestic and military industries).
The chemical pollution emitted by different industries is huge (most of chemical pollution originates from developed countries) affecting human and animal health in the short- and long-term based on production processes and practices (Figures 1.6.1 and 1.6.2).
There are three environments affected significantly by human activity and pollution: soil, water and air. It can be stated that soil pollution is more pervasive than water and air (due to its relative volume and also its structure). Figure 1.6.3 represents different human activities (industrial and municipal waste) in some European countries (developed and developing). Plants are the primary organisms that accumulate contaminants that are further consumed by animals and humans. Ingestion, inhalation and direct contact with such polluted soil may also impact their health.
Contaminated soil does contribute substantially to groundwater pollution depending on the local geology affecting many areas: potable and bathing waters, different household uses, agriculture and industry (Figure 1.6.4).
It is clear that water contamination with a large variety of chemicals and biological components has a direct impact on our health. However, some long-term effects are also noticeable, such as alteration of global nutrient cycles. Johnson et al. (2010) evaluated the impact of nitrogen and phosphorus eutrophication on human and wildlife health. According to these authors there are several postulated mechanisms that link eutrophication to several pathogen transmission modes (direct horizontal and
indirect vector-borne or complex life cycle): 1) host abundance and distribution; 2) pathogen virulence alteration and 3) changes in host susceptibility. These links seem to occur more frequently in tropical and subtropical regions that are the most vulnerable ones. Indeed, oligotrophic limestone-based wetlands that were “polluted”by phosphorous-enriched runoff caused replacement of rush vegetation with dense cattail. This vegetation shift had important consequences on the larval mosquito community: from Anopheles albimanustoAnopheles vestitipennis(each preferring a typical habitat, respectively) which is a superior vector of the parasitePlasmodiumto humans (Griecoet al., 2006). Another excellent example is nutrient input in mesocosms containing snails, larval amphibians and parasites (Johnsonet al., 2007).
Via eutrophication of such mesocosms, enhanced growth of algae occurred that affected positively the growth and reproduction of snail intermediary hosts (susceptible to parasitic miracidia). In addition, infected host snails from the high nutrient condition did produce, on average, twice as many parasites as did snails from a low nutrient environment.
A nice example of environmental pollution in urban areas that affected animals and potentially humans was described by Scialfaet al.(2010). These authors reported on the presence ofLeptospira interrogansin a highly dense rat’population (Rattus norvegicus) in a suburban area of Buenos Aires. The high density of the rat’reservoir is directly connected to environmental pollution (refuse, waste, etc.) and poverty.
Finally, Fayeret al.(2004) linked land to sea environment through wastewater discharge into estuaries and coastal waters. Encysted zoonotic protozoan parasites present in raw sewage (e.g., Giardia, Cryptosporidium andToxoplasma) contaminate bathing beaches, infect a wide range of marine animal
Source: World Bank, 2004
Figure 1.6.1. Emissions of organic water pollutants. (2004). InUNEP/GRID-Arendal Maps and Graphics Library. Retrieved 21:53, May 4, 2011 from http://maps.grida.no/go/graphic/emissions_of_organic_water_
pollutan, credit to Philippe Rekacewicz, UNEP/GRID-Arendal (World Bank, 2004) Environmental Aspects of Zoonotic Diseases 24
Figure 1.6.3. Soil polluting activities from selected sources. (2004). InUNEP/GRID-Arendal Maps and Graphics Library. Retrieved 21:47, May 4, 2011 from http://maps.grida.no/go/graphic/soil_polluting_
activities_from_selected_sources, credit to Philippe Rekacewicz, UNEP/GRID-Arendal (EEA, 2002) Figure 1.6.2. Hazardous waste generation in 2001 as reported by the Parties to the Basel Convention.
(2004). InUNEP/GRID-Arendal Maps and Graphics Library. Retrieved 21:56, May 4, 2011 from http://maps.
grida.no/go/graphic/hazardous_waste_generation_in_2001, credit to Philippe Rekacewicz, UNEP/ GRID-Arendal (Basel Convention)
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Figure1.6.4.Differentsourcesofdangerandtheirimpactstotheenvironment.(2004).InUNEP/GRID-ArendalMapsand GraphicsLibrary.Retrieved21:50,May4,2011fromhttp://maps.grida.no/go/graphic/different_sources_of_danger_ and_their__impacts_to_the_environment,credittoPhilippeRekacewicz,UNEP/GRID-Arendal(GeologicalSurveyof Canada,theGeologicalSociety) Environmental Aspects of Zoonotic Diseases 26
1.6.1 REFERENCES
Chu, I., Bowers, W.J., Caldwell, D., Nakai, J., Wade, M.G. (2008) Toxicological effects of in utero and lactational exposure of rats to a mixture of environmental contaminants detected in Canadian Arctic human populations.
J Toxicol Environ Health A71, 93–108.
Fayer, R., Dubey, J.P. & Lindsay, D.S. (2004) Zoonotic protozoa: from land to sea.Trends Parasitol.20, 531–536.
Grieco, J.P., Johnson, S., Achee, N.L., Masuoka, P., Pope, K. et al. (2006) Distribution ofAnopheles albimanus, Anopheles vestitipennis, andAnopheles cruciansassociated with land use in northern Belize.J. Med. Entomol.
43, 614–622.
Johnson, P.T.J., Chase, J.M., Dosch, K.L., Hartson, R.B., Gross, J.A. et al. (2007) Aquatic eutrophication promotes pathogenic infection in amphibians.Proc. Natl. Acad. Sci. U.S.A.104, 15781–15786.
Johnson, P.T.J., Townsend, A.R., Cleveland, C.C., Glibert, P.M., Howarth, R.W. et al. (2010) Linking environmental nutrient enrichment and disease emergence in humans and wildlife.Ecol Appl20, 16–29.
Scialfa, E., Bolpe, J., Bardon, J.C., Ridao, G., Gentile, J. & Gallicchio, O. (2010) Isolation ofLeptospira interrogans from suburban rats in Tandil, Buenos Aires, Argentina.Rev. Argent. Microbiol.42, 126–128.
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