Free trade deals can cause immense environmental damage by allowing companies to shift their manufacturing facilities to nations with few or no environmental regulations and by increasing access to natural resources in those nations. Before the North American Free Trade Agreement became law in 1993, there was little demand for timber or metal ores from Mexico. In a 2014 report, the Sierra Club asserts that NAFTA stimulated the creation of poorly regulated, highly destructive mining operations in Mexico that would not have existed without the trade agreement.
Read more : http://www.ehow.com/list_6113059_disadvantages-trade-agreements.html