Human Health and Environment - Assignment Example

1. a) Yellow fever and malaria have at least three similarities. The first commonality is they are both caused by mosquitoes. Yellow fever is caused by mosquitoes infected by the yellow fever virus. According to the Division of Vector Borne Infectious Diseases (2007) these mosquitoes may get the virus from infected monkeys in the jungle or by infected humans in the urban areas. Malaria, on the other hand, is caused by a parasite that infects only a certain kind of mosquito feeding on humans. (Raun, E. S.,1992) The second common factor between the two is they are both deadly diseases. In 1793, more than 5000 Americans died as a result of the yellow fever epidemic which started in Philadelphia. (Murphy, J., 2003) There are an estimated 200,000 cases of yellow fever, causing 30,000 deaths, worldwide each year. (Yellow Fever, 2009) On the other hand, The World Health Organization’s Guidelines for the treatment of malaria (2010) has reported an estimated 863,000 deaths in 2008 due to malaria. Still another similar factor yellow fever and malaria share is that they almost have the same symptoms. Both diseases make the victim feel feverish and body ache. Conversely, yellow fever can be different from malaria, too. Firstly, where malaria has a cure thanks to the medicine quinine (Agosta, W., 1997), there is only a vaccine for yellow fever and a cure dependent on the resulting illness manifested by the patient. (Hayes, J.J., 1858) The said vaccine was discovered by Max Theiler in 1937. (Monath, T., 2010) Secondly, the incubation fever for yellow fever is only for 3-4 days, malaria victims only show signs of the symptoms after 7 to 30 days. (WHO, 2010) Last but not the least, while yellow fever has mostly affected people in Africa and Latin America, deaths and cases of malaria are in sub-Saharan Africa. (WHO, 2010) 1.b) A mosquito’s bite causes malaria and yellow fever. Since North America goes through the winter season, egg production stops and there is no drive for the female mosquito to take blood meals. (Humphreys, M., 2001) Because there is no need to bite humans for blood, these diseases are not threats in North America. 1.c.) No single country in sub-Saharan African has shown a substantial decline in malaria, according to WHO’s Africa Malaria Report 2004 (Crowe, S., 2003) This can be attributed to two things: Africa is a tropical country and a poor one at that. Tropical countries only have two seasons: sunny and rainy. Inasmuch, the climate in tropical countries can be warm, humid or cool. As the mosquito breeds only in water (Cornish, A., 1923), these insects are a common site in tropical countries. “Simply put, rainfall increases mosquito habitats while temperature increases mosquito and parasite development: the result is increased malaria transmission.” (Githeko, A.,2007) Poverty in Africa leads to poor sanitation services for the country. This problem eventually leads to vector-borne diseases such as malaria. “Vector-borne diseases are affected by a range of environmental conditions and factors… and open sewers and certain types of sanitation. In Africa alone, malaria is responsible for about 800,000 deaths annually.” (The World Bank, (2001) 1.d) Mosquitoes, the carrier of the West Nile virus, breed more often during warm weather. According to Dr. Vicki Kramer, chief California Department of Public Health’s vector-borne disease section, “warmer weather helps spread West Nile Virus because it extends the length of the mosquito season.” (Gammon, C., 2009) 2.a.) Toxicology is the science that studies poison and its effects. “In the absence of human data, research with experimental animals is the most reliable means of detecting important toxic properties of chemical substances and for estimating risks to human and environmental health.” (Science of Toxicology, 2006) Toxicological databases indicate that the more animal species used, the better predictive value of the human situation. (Hau, J., 2003) 2.b) The dose-response curve can be used to plot the results of many kinds of experiments. (What are dose-response curves?, 2007) In toxicology, the dose-response curve is used in relation to the concept of dose-response, which is in turn “used as a basis for determining the relative safety of a chemical compound in the living organism.” (Moss, P., 1991) The X-axis represents the doses while the Y-axis is where the response is plotted. From the dose-response graph, one can determine at what dose a substance can be lethal. The concept of the dose-response came from Swiss experimentalist, Paracelsus, who said “Everything is a poison and nothing is a poison, it is only the dose that counts.” (Hacker, M., 2009, p.4) 2.c.) “LD50 is a statistically calculated dose of a chemical that causes death in 50% of the animals tested, based on the objective observation of lethality.” (Barile, F., 2004, p. 71) Put more simply, a chemical’s LD50 would kill a person. A lower LD50 of a chemical is more dangerous because death would result in just a small dose of the said chemical. (Richardson, J. and Miller, G., 2010) The substance is potent at that small of a dose. Conversely, a higher LD50 is safer as it would take much of the substance to cause death. For example, alcohol has a high LD50 which is why just a few number die from severe alcohol consumption. (Gilbert, S., 2004) 3. a) Despite the results of recent research attributing risks to human health brought about by the use of sunscreen, the greatest risk can still be ascribed to non-application of sunscreen. According to the graph presented, high dosage of sunscreen results only to a 10% relative risk from the chemicals in the sunscreen. Despite its negative effects, sunscreen stops the UV photons before they can reach the skin and damage it. (Vazquez, M and Hanslmeier, A., 2006) On the other hand, the same graph shows that non-application of sunscreen can result to more than 40% of relative risk due to UV exposure. This is dangerous as UV exposure is one of the major causes of skin cancer. Thorough application of sunscreen since childhood can prevent severe sunburn and lessen the risk of cancer due to ultraviolet (UVL) exposure. (Bennett, W., Goldfinger, S., and Johnson, T., 1987) 3.b.) Zero dosage of applied sunscreen will result to the least risk (at 0%) due to chemical in the sunscreen. However, a high dosage of applied sunscreen corresponds to the least risk from UV exposure with the graph reflecting only 2%. Given this data, zero application of applied sunscreen is still associated with the greatest risk as although there is no chemical from the sunscreen to cause harm, there is also no protection at all from the danger due to UV exposure. Once exposed, UV radiation can be dangerous to any living creature. (Hill, M., 2004) Aside from skin problems, it can also accelerate cataract formation, cause “snow blindness” and cancer of the eye and interfere with the immune system making the body more susceptible to illnesses. (Ropeik, D., Gray, G. and Gray, G.M., 2002) Research on sunscreen applied on mice has shown that sunscreen may possibly reduce the risk of skin cancer. (Kodali, S., Beissert, S. and Granstein, R., 2005) 3.c.) Since the total risk is the sum of the individual risks, non-application of sunscreen is the point that poses the greatest risk since the combined risk from UV exposure and sunscreen totals to 40%. On the contrary, a moderate dosage of applied sunscreen would result to the least total risk seeing the combined relative risk to health due to UV exposure and sunscreen only comes up to 10%. From the graph, it appears that the risk from increased dosage of applied sunscreen is inversely proportional to the risk from UV exposure. 3.d.) Based on the data presented, I would apply a moderate amount of sunscreen next time I’m at the beach since this dosage results to only a combined 5% risk due to UV exposure & the chemicals in the sunscreen. Although there has been much new information that chemicals in sunscreen may destabilize rendering them ineffective as protection against UV rays and also making them a threat to the individual, even more data has been gathered attesting to the fact that sunscreen can indeed help in decreasing the harmful effects of sun exposure. It would be helpful to remember that before purchasing one, the sunscreen should be natural and hypoallergenic with no harmful chemicals. (Graci, S., Rao, L., and DeMarco, C., 2006) References: Agosta, W., (1997). Medicines and Drugs from Plants. Journal of Chemical Education. 74 (7). p. 857.doi: 10.1021/ed074p857. Barile, F. (2004). Clinical toxicology: principles and mechanisms. Boca Raton: CRC Press LLC. Bennett, W., Goldfinger, S. and Johnson, T. (1987). Your good health: how to stay well, and what to do when you’re not. Cambridge: Harvard University Press Cornish, A. (1923). Have You A Mosquito Farm at Home? How to Stamp Out Summer Joy Killers. Popular Science. August. pp. 31-32. Crowe, S. (2003). Health and Medical Issues in Sub-Saharan Africa 2004. In Europa Publications, Europa Publications Limited’s Africa South of the Sahara. (pp. 22-31). London: Europa Publications. Division of Vector Borne Infectious Diseases. (2007). Yellow Fever. Retrieved on March 27, 2010 from http://www.cdc.gov/ncidod/dvbid/yellowfever/ Gammon, C., (2009). Changing climate increases West Nile threat in U.S. Daily Climate. Retrieved on March 25, 2010 from http://wwwp.dailyclimate.org/tdc-newsroom/west-nile/Changing-climate-increases-West-Nile-threat-in-U.S Gilbert, S. (2004). A small dose of toxicology: the health effects of common chemicals. Boca Raton: CRC Press LLC. Githeko, A. (2007). Malaria, climate change and possible impacts on populations in Africa. In Caraël, M. and Glynn, J.’s (Eds.) HIV, resurgent infections and population change in Africa. (pp. 66-99). The Netherlands: Springer. Graci, S., Rao, L., and DeMarco, C. (2006) The Bone-building Solution. Ontario: John Wiley & Sons Canada, Ltd. Hacker, M. (2009). History of Pharmacology- From Antiquity to the Twentieth Century. In M. Hacker, W. Messer and K. Bachmann’s (Eds.) Pharmacology: Principles and Practice. (pp. 1-7). Oxford: Elsevier Inc. Hau, J. (2003). Choice of Animal Species. In J. Hau and G.L. Van Hoosier’s (Eds.) Handbook of Laboratory Animal Science: Animal Models.(pp.20-21). Boca Raton: CRC Press LLC. Hayes, J.J. (1858). Yellow fever: its nature , cause and cure. New Orleans: John James Hayes. Hill, M. (2004). Understanding environmental pollution: a primer. Cambridge: Cambridge University Press. Humphreys, M. (2001). Malaria: poverty, race, and public health in the United. States. Baltimore: The John Hopkins University Press. Kodali, S., Beissert, S. and Granstein, R. (2005). Physiology and Pathology of Skin Photoimmunology. In Bos, J.’s (Ed.) Skin immune system: cutaneuos immunology and clinical immunodermatology.. (pp. 457-474) Boca Raton: CRC Press LLC. Monath, T. (2010). Yellow Fever. In A. Artenstein’s (Ed.) Vaccines: A Biography. (pp. 159-190). New York: Springer Science+Business Media, LLC. Moss, P. (1991). The Dose-Response Concept. In Hansen, D.J.’s (Ed.) The Work Environment: Occupational health fundamentals. (pp.23-27). Boca Raton: CRC Press, Inc. Murphy, J. (2003) An American plague: the true and terrifying story of the yellow fever epidemic of 1793. New York: Houghton Mifflin Company.. Raun, E.S. (1992). Malaria and mosquitoes in a Mexican town. In J.R. Adams’ (Ed.) Insect potpourri: adventures entomology. (pp. 73-74). Gainesville: The Sandhill Crane Press, Inc. Richardson, J. and Miller, G. (2010) Toxicology. In H. Frumkin’s (Ed.) Environmental Health: From Global to Local. Second Edition. (pp. 49-78). San Francisco: John Wiley & Sons, Inc. Ropeik, D., Gray, G. and Gray, G.M. (2004). Risk: A practical guide for Deciding What’s Really Safe and What’s Really Dangerous in the World Around You. New York: Houghton Mifflin Company. The Society of Toxicology. (2006). Animals in Research. Reston: the Society of Toxicology. The World Bank.(2001). Making sustainable commitments: an environment strategy for the World Bank. Washington: World Bank Publications. Vazquez, M. and Hanslmeier, A. (2006). Ultraviolet radiation in the solar system. The Netherlands: Springer. WHO. (2010). Guidelines for the treatment of malaria. Geneva: World Health Organization. What are dose-response curves? (2007). Retrieved on March 25, 2010 from http://www.graphpad.com/help/prism5/prism5help.html?dose_response___special.htm Yellow fever. (2009). Key Facts. Retrieved on March 25, 2010 from http://www.who.int/mediacentre/factsheets/fs100/en/ Read More