The Domestic Substances List (DSL) is an inventory of substances manufactured in, or imported into Canada on a commercial scale. DSL, published in the Canada Gazette, Part II, in May 1994, includes approximately 23,000 substances believed to have been traded in Canada between January 1984 and December 1986. DSL is modified 12 times a year to add, update, or remove substances. Currently, there are more than 28,000 substances on the DSL.