How much responsibility do we have as a food supplement trader?

Hi there, we are a small nutraceutical trader, purchasing raw materials from within as well as outside of the EU and subsequently selling them onto our customers in the UK. I have been ensuring that we comply with EC 629/2008, EC 1881/2006 and the European Pharmacopoeia in terms of acceptable limits of contaminants and microbes in supplements. However, how much responsibility do we actually hold in terms of these limits as many suppliers don't test many of the parameters such as heavy metals until we ask. Even then, in the past they weren't even checked, as long as our customer was happy with the CoA they were sold the product as it is their responsibility. This makes it feel as if a lot of my hard work is of no use. However, after reading 'If you import and sell goods from other non-EU countries, you are legally responsible for all aspects of those goods, including composition, safety and labelling of the products.' I am wondering how much responsibility we have and if my hard work has been for nothing. So what I am asking is how much responsibility do we have if our customer accepts a product which doesn't state any heavy metal limits for example.

Not sure about the UK but in Canada-the imported is on the hook for everything and they would be the ones to seek compensation from the supplier.

If there are federal requirements for heavy metals et all, then I would imagine you should test to see if your supplier conforms.  In this case, ignorance would not be bliss