Asteroid Affirmative



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UV-B Radiation  Disease



UV radiation weakens the immune system to invaders.

Environmental Protection Agency 2010 (Sunwise Program, Health effects of overexposure to the sun , July 01, 2010, http://www.epa.gov/sunwise/uvandhealth.html, znf)

Scientists have found that overexposure to UV radiation may suppress proper functioning of the body’s immune system and the skin’s natural defenses. For example, the skin normally mounts a defense against foreign invaders such as cancers and infections. But overexposure to UV radiation can weaken the immune system, reducing the skin’s ability to protect against these invaders.
UV radiation suppresses the immune system and severely increases risk of disease

CIESIN No Date (Center for International Earth Science Information Network @ Columbia University “Suppression of the Immune System from Increased Ultraviolet-B Exposure due to Ozone Depletion” http://www.ciesin.org/TG/HH/ozimmun.html) JM

Excessive ultraviolet-B radiation (UV-B) exposure interferes with the normal functioning of immune systems in animals and human beings. Relatively low doses of UV-B compromise the immunological defenses of the skin, thus limiting the skin's allergic response to local attacks. Higher doses of UV-B can lower an individual's overall immunological response. Damage to the immune system has several implications for an individual's health: increased risk of the incidence and severity of infectious disease, increased risk of malignant melanoma, and diminished efficacy of vaccinations. Longstreth et al. (1991) present evidence indicating skin pigmentation does not serve a protective role for the immune system, as it does in the prevention of skin cancer. Vermeer et al. (1991) also reach this conclusion. Ilyas (1986) and Jeevan and Kripke (1993) emphasize that damage to the immune system due to UV-B could have far-reaching effects for the health of populations.



Disease !  Extinction


Disease will kill off all humans

Yu 09 (Victoria, Dartmouth Undergraduate Journal of Science, writer, “Human Extinction: The Uncertainty of Our Fate”, May 22nd, 2009, Accessed 7-10-11, AH)

RIP Homo sapiens A pandemic will kill off all humans. In the past, humans have indeed fallen victim to viruses. Perhaps the best-known case was the bubonic plague that killed up to one third of the European population in the mid-14th century (7). While vaccines have been developed for the plague and some other infectious diseases, new viral strains are constantly emerging — a process that maintains the possibility of a pandemic-facilitated human extinction. Some surveyed students mentioned AIDS as a potential pandemic-causing virus.  It is true that scientists have been unable thus far to find a sustainable cure for AIDS, mainly due to HIV’s rapid and constant evolution. Specifically, two factors account for the virus’s abnormally high mutation rate: 1. HIV’s use of reverse transcriptase, which does not have a proof-reading mechanism, and 2. the lack of an error-correction mechanism in HIV DNA polymerase (8). Luckily, though, there are certain characteristics of HIV that make it a poor candidate for a large-scale global infection: HIV can lie dormant in the human body for years without manifesting itself, and AIDS itself does not kill directly, but rather through the weakening of the immune system.  However, for more easily transmitted viruses such as influenza, the evolution of new strains could prove far more consequential. The simultaneous occurrence of antigenic drift (point mutations that lead to new strains) and antigenic shift (the inter-species transfer of disease) in the influenza virus could produce a new version of influenza for which scientists may not immediately find a cure. Since influenza can spread quickly, this lag time could potentially lead to a “global influenza pandemic,” according to the Centers for Disease Control and Prevention (9). The most recent scare of this variety came in 1918 when bird flu managed to kill over 50 million people around the world in what is sometimes referred to as the Spanish flu pandemic. Perhaps even more frightening is the fact that only 25 mutations were required to convert the original viral strain — which could only infect birds — into a human-viable strain (10).



Disease can result in the extinction of mammal species – Empirically proven

Keim 08 (Brandon, writer, Wired Science, “Disease can cause the extinction of mammals”, November 5th, 2008, Accessed 7-10-11, AH)

Disease can drive a mammal species to extinction: this doesn’t seem surprising, but until today it hadn’t been proven. And now that it has, members of our own mammalian species might understandably feel uneasy. The extinction in question took place a century ago on Christmas Island, an uninhabited Indian Ocean atoll to which a merchant ship inadvertently carried flea-ridden black rats. Within a decade, both of the island’s native rat species were extinct. Scientists have argued whether the native rats were outcompeted by the newcomers, or fell victim to diseases carried by the fleas. According to DNA analysis of remaining native rat specimens, infection was widespread within the population after contact, and nonexistent before — suggesting that disease caused the die-off. Resolving this argument has implications for another debate, over the hypothesis that disease can be so lethal and contagious as to drive a mammal species extinct. This had been observed in snails and amphibians, but not in mammals. The authors of the study, published today in Public Library of Science ONE, hope conservationists will take heed: accidentally-introduced pathogens could wipe out endangered species. But to me, the findings also have human implications. Some would say that the rats were vulnerable because they lived on an island; but the Earth is an island, too.


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