Some countries already practice the precautionary principle,removing potentially harmful products from the market until scientific tests can be completed to determine whether the products are dangerous.For example,in 2010,Canada listed bisphenol-A(BPA), a common compound in plastic bottles and plastic-lined cans,as a toxin. This move made selling products that included BPA illegal.Research continues on exactly whether and how BPA affects humans,with some early studies suggesting it functions as an endocrine disruptor.