Scenario Endotoxins Are Commonly Found in the Air, Both Inside and and Outside

question 25

Multiple Choice

Scenario
Endotoxins are commonly found in the air, both inside and outside our homes. These "air endotoxins" can come from sources that include house dust mites, agricultural and industrial dust, and dust from indoor pets. Air endotoxins are typically found in low amounts, but production of them can increase dramatically under specific environmental conditions such as dampness, mold, and sewage. Many scientific studies have been conducted investigating possible links between indoor endotoxin levels and asthma, chronic bronchitis, and other upper respiratory diseases. Interestingly, some studies have found positive correlations between indoor endotoxin exposure and severity of some of these diseases while other studies have suggested that some air endotoxin exposure can actually decrease the risk of developing asthma in children. Additionally, data suggest that industrial workers who are exposed to endotoxins in the air can develop irreversible lung damage.

In 2005, Hurricane Katrina devastated the eastern coastline of the United States. The state of Louisiana, and in particular the city of New Orleans, experienced tragic loss of human life and homes due to the failure of the levee system. Intense flooding destroyed homes and created severe exposure to wet, moldy surfaces. At that time there were no regulations in existence on the amount of exposure that individuals should have to air endotoxins. Scientists from the Natural Resources Defense Council who wanted to determine if endotoxin levels had risen in New Orleans conducted tests across 12 outdoor areas, 9 of which had been significantly flooded while the other 3 were less affected. Two indoor areas were also sampled for endotoxin levels. No significant differences were found in endotoxin levels between the flooded and non-flooded areas or between the indoor and outdoor areas. However, a limited number of samples were collected, and they were taken after a recent dry spell. Endotoxin levels at all sites were found to be higher than national average levels but were lower than levels typically associated with long-term changes in lung function.
-What is an implication of the fact that tests were conducted after a period of dry weather?

• A)Dry weather creates harsher sampling conditions for scientists.
• B)If more periods of rainfall occur after the testing, bacteria that secrete endotoxins may increase, thereby increasing endotoxin levels.
• C)Dry weather increases the amount of carbon available for the endotoxin bacteria to use for organic compound production.
• D)Endotoxin bacteria provide greater bioremediation effects in dry weather than in wet weather.

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