North American beaver large, webbed hind feet. The unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane which allows the beaver to see under water. The nostrils and ears are sealed while submerged. A thick layer of fat under its skin insulates the beaver from its coldwater environment. The beaver's fur consists of long, coarse outer hairs and short, fine inner hairs (see Double coat). The fur has a range of colors, but usually is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur.
Regulation of food and dietary supplements by the U.S. Food and Drug Administration concerns about the safety of new food additives. The amendment established the designation of "generally recognized as safe", which refers to chemicals or substances which can be used as food additives without further evaluation or testing just because they have been long used and there is broad acceptance of their use. New food additives would be subject to testing including by the "Delaney clause". The Delaney clause was a provision in the amendment which said that if a substance were found to cause cancer in man or animal, then it could not be used as a food additive. The Dietary