Good Bacteria and Bad Bacteria

Environmental Hazards

What are toxicants and how do they affect living organisms?

According to Dr. Celine Godard, toxicants and toxins both reference substances that are toxic; however, toxins are made in nature (like in poisonous mushrooms or in the poisonous venom that snakes use to kill their prey) and toxicants are human made (Godard, et al., 2001). Examples of toxicants would be "industrial waste products and pesticides" -- along with pollutants that get into the oceans. In fact pesticide residues (toxicants) are found in the ocean, and Godard's article in the Public Broadcast Service (PBS) is about how the Ocean Alliance is researching the impacts that toxicants have on sperm whales.

Sperm whales are exposed to the pollution (toxicants) that humans allow to flow into the oceans, and the whales have a "layer of fat called blubber" beneath their skins; Godard explains that toxicants accumulate in fatty tissue and so the longer the whale lives, the more toxicants accumulate in its blubber (body). This accumulation of toxicants in a whale's body is called "bioaccumulation" -- and sperm whales are also subject to "biomagnification" (Godard, p. 2). Biomagnification is the magnifying effect that toxicants have on species as it moves up the food chain (a good answer to how toxicants impact living organisms). A fish that eats ten shrimp (and each shrimp has 1 unit of a toxicant), and in turn if a bigger fish eats ten of the smaller fish, the bigger fish now has "100 units of toxicants" in its body (Godard, p. 2).

What are disease-causing agents? Select two agents -- describe their effects and how they are transmitted:

Disease-causing agents are actually "biological pathogens" that spread disease, and those pathogens can find their way into the human body through a number of ways (Education Portal). The two agents to be discussed are viruses and bacteria. Viruses are the most common kind of disease-causing agent -- or at least the agent that most people come into contact with and are familiar with. Viruses can cause the flu, and chicken pox, West Nile disease HIV, and other diseases once they get into your blood stream (Education Portal). Hepatitis A is also a virus, and it causes liver failure; echoviruses can cause meningitis.

There is good and bad bacteria; the Education Portal reports that most bacteria that humans come into contact with are not necessarily harmful -- in fact, many bacteria "actually provide some health benefits." The human body is "literally covered with good bacteria, both inside and outside the body"; and bacteria is the main reason that humans' digestive system works, because "numerous types of bacteria help break down and absorb" the nutrients that are in the goods humans eat (Education Portal). Pneumonia is caused by bacteria, as is strep throat, Lyme disease and many troublesome intestinal conditions result from bacteria.

When it comes to bacteria that cause strep throat, for example, that is clearly an environmental hazard because it is so contagious. As to viruses, they can be a horrific environmental hazard; for example Ebola is a virus, which at this time has become an epidemic in Western Africa.

How do changes in the environment contribute to human diseases? Is there a link between human activities on the environment and disease-causing agents?