What are the conditions under which a country may use the unsafe products argument to block imports?

Imports are blocked, more often than not to promote and support the domestic producers. There are many arguments by which countries restrict imports like Infant Industry Argument, Environmental Degradation Argument, etc. One such argument is Unsafe Products Argument.

Under Unsafe Products Argument, countries tend to restrict imports and put up trade barriers by stating that the product imported is not safe and healthy for the consumers.

It can be acceptable if-

1) It should not be discriminatory and can not be blocked for the sake of promoting trade with certain countries only.

2) It must treat both the foreign producers and the domestic industry in the same way, i.e. the safety measures imposed must bind the domestic manufacturers as well.

3) The argument should be scientifically proven.