The S&P/TSX composite index fell 74.7 points to 12,361.8, with the energy, mining and materials sectors leading the way down.
The Canadian dollar shed 0.75 of a cent to 100.03 cents US, after earlier falling below parity as investors retreated to the perceived safety of the greenback.
Gold bullion lost $7.80 to US$1,642.50 an ounce, while copper fell eight cents to US$3.77 a pound. Oil for May delivery was down $1.92 to US$105.35 on the New York Mercantile Exchange.
Investors also took in disappointing data on Canadian retail trade and employment insurance claims from January.
Meanwhile, Wall Street also closed lower on anxiety over China's slowing growth, with the Dow Jones industrial average falling 78.5 points to 13,046.1. The Nasdaq index down 12 points to 3,063.3 and the S&P 500 index fell 10.1 points to 1,392.8.