Sewage treatment to the environment can lead to a buildup of nutrients, called eutrophication, which can in turn encourage the overgrowth of weeds, algae, and cyanobacteria (blue-green algae). This may cause an algal bloom, a rapid growth in the population of algae. The algae numbers are unsustainable and eventually most of them die. The decomposition of the algae by bacteria uses up so much of the oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose. In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water
Natural foods the term if the food does not contain added color, artificial flavors, or synthetic substances." Furthermore, the FDA has not developed any rules or regulations on the defining features of what qualifies a product as "natural." The FDA does reference a definition of "natural" in their informal policy (Ref. 53) that defines "natural" as "nothing artificial or synthetic (including colors regardless of source) is included in, or has been added to, the product that would not normally be expected to be there." The Food, Drug, and Cosmetic Act prohibits labeling that is false or misleading. The USDA's Agricultural Marketing Service