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Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
Dogs have been used in studies to detect various cancers in human subjects. They have been trained to sniff breath samples from humans that were collected by having them breathe into special tubes. These people included 55 lung cancer patients, 31 breast cancer patients, and 83 cancer-free patients. The dogs detected 54 of the 55 lung cancer patients as having cancer, detected 28 of the 31 breast cancer patients, and gave only three false-positive results (detecting cancer in people who didn't have it).
According to research, pregnant women tend to eat more if carrying a baby boy. Male fetuses may secrete a chemical that stimulates their mothers to step up her energy intake.
The average adult has about 21 square feet of skin.
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
![The phosphorus cycle. Numbers are 1012 g P or fluxes as 1012 g P per year (data from Schlesinger 199](https://biology-forums.com/gallery/47/medium_33_17_02_12_7_02_17_2037874.jpeg)
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