© George Frey/Getty ImagesA hazardous material clean-up crew lift up an oil soaked boom and move it to another location in a pond in Liberty Park on June 12, 2010 in Salt Lake City, Utah. The oil pipe owned by Chevron Oil Company broke several miles upstream and spewed out a significant amount of oil into Red Butte Stream before they were able to shut it off. At one point 50 gallons a minute was coming from the eight inch pipe.
Since 2010, at least three ruptured pipelines have spilled oil into U.S. neighborhoods, forcing officials to decide quickly whether local residents would be harmed if they breathed the foul air. But because there are no clear federal guidelines saying if or when the public should be evacuated during an oil spill, health officials had to use a patchwork of scientific and regulatory data designed for other situations.
As a result, residents of the three communities received different levels of protection.
No houses were evacuated in Salt Lake City, Utah, where a ruptured pipeline leaked 33,000 gallons of medium grade crude oil before it was discovered on the morning of June 12, 2010. The oil ran down Red Butte Creek, past neighborhoods where windows were left open in the summer heat. The fumes, which are known to cause drowsiness, left some people so lethargic that they didn't wake up until after noon.
In Marshall, Mich. officials called for a voluntary evacuation after more than a million gallons of heavy Canadian crude spilled into the Kalamazoo River on July 25, 2010. But they agonized over the decision for four days before making that recommendation.
In Mayflower, Ark. authorities quickly evacuated 22 families after a broken pipeline leaked about 200,000 gallons of heavy crude on March 29, 2013. But people living in the same subdivision, just a few blocks away, were not asked to leave. Neither were the residents of the lakeside community where the oil eventually pooled and where the cleanup continues today.
After each of these spills, people complained of headaches, nausea and respiratory problems - short-term symptoms that health experts say are common after any chemical spill and usually disappear as the air clears.
Comment: Learn more about the gut-brain connection and how this important relationship affects our mood, well being and behavior:
The Neuroscience of the Gut
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Are Gut Bacteria In Charge?
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'Knowing it in your gut' is real": The state of your immune system and your gut bacteria influences your personality
The Real Butterfly in Your Stomach: Scientists Explore the Possibility of a "Second Brain" in Our Gut
Mind-Gut Connection: Why Intestinal Bacteria May Have Important Effects on Your Brain
Link between gut bacteria and behavior: That anxiety may be in your gut, not in your head