Read the passage about the fluoridation of drinking water.
Since the early 1960s, fluoride has been added to many sources of drinking water to prevent cavities in teeth. This is called fluoridation. There are some who say that this is unnecessary and increases the risk of cancer.
In 1993, the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council, part of the National Academy of Sciences, conducted an extensive study about the link between fluoridated drinking water and increased cancer risk. The study included data from more than 50 human disease studies and six animal studies. The Subcommittee concluded that none of the data showed a link between fluoridated drinking water and cancer. A 1999 report by the CDC supported these findings. The CDC report concluded that studies so far have produced "no credible evidence” of a link between fluoridated drinking water and an increased risk for cancer.
Which information makes this article reliable?
Fluoride has been added to drinking water since the 1960s.
Some people doubt the necessity of fluoridation.
More than 50 studies were conducted.
Fluoride has been found to prevent cavities in teeth
Answers
Answer:
it's very simple
Explanation:
Many decades after fluoride was first added to drinking water in some parts of the United States, there is still controversy about the possible health effects of drinking water fluoridation. Many people have strong views either for or against water fluoridation. Their concerns are based on everything from legitimate scientific research, to freedom of choice issues, to government conspiracy theories.
This is a review of the possible link between water fluoridation and cancer. Other possible health effects of fluoridation (positive or negative) are not addressed here. This is not a position statement of the American Cancer Society.
What is fluoride?
Fluorides are compounds that combine the element fluorine with another substance, usually a metal. Examples include sodium fluoride, stannous fluoride, and fluoride monofluorophosphate (MFP fluoride).
Some fluorides occur naturally in soil, air, or water, although the levels of fluoride can vary widely. Just about all water has some fluoride. Fluoride is also found in plant and animal food sources.
Once inside the body, fluorides are absorbed into the blood through the digestive tract. They travel through blood and tend to collect in areas high in calcium, such as the bones and teeth.
How are people exposed to fluoride?
The major sources of fluoride for most people are water and other beverages, food, and fluoride-containing dental products (toothpastes, mouth rinses, etc.). Because dental products are generally not swallowed (except, perhaps, by younger children), they cause less concern for possible health issues.
Fluoride in drinking water
Water fluoridation began in some parts of the United States in 1945, after scientists noted that people living in areas with higher water fluoride levels had fewer cavities. Starting in 1962, the United States Public Health Service (PHS) recommended that public water supplies contain fluoride to help prevent tooth decay.
Fluoride is now used in the public drinking water supplied to about 3 out of 4 Americans. The decision to add fluoride to drinking water is made at the state or local level. The types of fluoride added to different water systems include fluorosilicic acid, sodium fluorosilicate, and sodium fluoride.
Natural drinking water sources in the US also have some fluoride in them, although the levels are much higher in some places than in others.
How is fluoride in drinking water regulated?
Fluoride is not required in all drinking water sources in the United States, but the levels of fluoride in water are regulated by several government agencies.
Starting in 1962, the United States Public Health Service (PHS) recommended that public water supplies contain between 0.7 and 1.2 milligrams of fluoride per liter (mg/L) of drinking water to help prevent tooth decay. This recommendation was updated in 2015 to a fluoride level of 0.7 mg/L, The change was made in part to account for the fact that people now get more fluoride from other sources (such as toothpaste) than in the past. (Natural drinking water sources in the US have an average fluoride level of about 0.2 mg/L, although in some places it can be much higher.)
The US Environmental Protection Agency (EPA) has set a maximum amount of fluoride allowable in drinking water of 4.0 mg/L. Long-term exposure to levels higher than this can cause a condition called skeletal fluorosis, in which fluoride builds up in the bones. This can eventually result in joint stiffness and pain, and can also lead to weak bones or fractures in older adults.
The EPA has also set a secondary standard of no more than 2.0 mg/L to help protect children (under the age of 9) from dental fluorosis. In this condition, fluoride collects in developing teeth, preventing tooth enamel from forming normally. This can cause permanent staining or pitting of teeth. (The secondary standard is a guideline, as opposed to an enforceable regulation, but public water systems must tell their customers if the fluoride level goes above it.)
States can set maximum fluoride levels in drinking water that are lower than the national 4.0 mg/L standard.
Bottled water standards are set by the US Food and Drug Administration (FDA). The fluoride levels allowed vary based on the annual average air temperature in the place where the water is sold.
For bottled water with no fluoride added, the maximum fluoride level allowed is 2.4 mg/L (in places with colder temperatures).
For water in which fluoride is added, the maximum allowed is 1.7 mg/L (in colder climates). However, if fluoride is added, the FDA recommends that manufacturers not go above 0.7 mg/L, which is in line with