Seaweed farming needs tighter regulation to limit damage to the environment after booming into a $6.4 billion business with uses in everything from sushi to toothpaste, a United Nations study said Sunday.

Led by China, South Korea, Indonesia and the Philippines, seaweed's surge in recent years has seemed environmentally friendly since it needs no fertilizers and has created both jobs and food in remote coastal areas of developing nations. Japan is the fifth-largest producer of seaweed, harvesting about 440,000 tons in 2012, or 1.85 percent of the global share, according to the U.N. Food and Agriculture Organization.

But emerging evidence shows that seaweed can sometimes cause harm and spread diseases and pests, the U.N. report said. One type of Asian seaweed brought to Hawaii has smothered some coral reefs by out-competing local plants.