The European Union banned the sale of snus in 1992, after a 1985 World Health Organization (WHO) study concluded that "oral use of snuffs of the types used in North America and western Europe is carcinogenic to humans", but a WHO committee on tobacco has also acknowledged the evidence is inconclusive regarding health consequences for snus consumers. Only Sweden and European Free Trade Association (EFTA)-member Norway are exempt from this ban. A popular movement during the run-up to the 1994 referendum for Sweden's EU membership made exemption from the EU sale ban of snus a condition of the membership treaty.