Traditionally safe and adequately tested products may still harm consumers and thus create ethical issue because

Traditionally safe and adequately tested products may still harm consumers and thus create ethical issue because of illiteracy, unsanitary conditions, or cultural values.

There are numerous tests that each product has to go through in order to be placed on the market, but these tests cannot predict everything that may happen or that the consumers will think about them. So there is the risk of offending consumers in some way that will create some ethical issues.