A group of African countries is moving to halt the import of chemical and other hazardous materials, saying they are determined to prevent Africa from becoming the world’s waste dump.

Countries that are parties to the Bamako Convention agreed to enact stringent laws and to develop national hazardous waste disposal policies and action plans to prevent the continent from becoming a dumping ground for developed countries.

Delegates at the Jan. 28–Feb. 1 Second Meeting of the Conference of the Parties...