Officials from 150 governments have agreed to ban the production of nine of the world’s most toxic and dangerous chemicals. These chemical join a list of 12 other chemicals called persistent organic pollutants, or POPS, that are prohibited under a 2001 international Stockholm Convention treaty. The meeting was held by the United Nations Environment Program.

The newly targeted chemicals include products that are widely used in pesticides and flame-retardants, and in a number of other commercial uses. These pollutants are harmful because they cross boundaries and travel long distances, from the Equator to the Arctic. They persist in the atmosphere and can take decades to degrade.

Donald Cooper, executive secretary of the Stockholm Convention, said this about the chemicals that have been banned, and their effect on human bodies “It bio-accumulates in more than just humans. It bio-accumulates up the food chain. So, it goes from the plankton on up to the squid to the fish to you. So, you are not only exposed to them in the environment, you are eating them…The affects of the chemicals are wide-ranging from the negative impact reproductive systems and mental capacity, growth and intelligence. They cause cancers. So, it is a whole array of these things,” he said during the conference.

These harmful chemicals pose the most threats to the environment and human health, especially to young people, farmers, pregnant women and babies they carry.