All batches of raw materials are tested and supplied with a Certificate of Analysis that certifies that raw material meets specifications (heavy metals and many other things beside). This is how all food and medicine manufacturing works in MHRA sites and ISO9001 / GMP sites like ours which indeed is even FDA registered. Basically manufacturers rely on the Certificates of Analysis from other quality (ISO9001 or GMP etc) manufacturers and suppliers because every manufacturer along the supply chain performing the same tests would be lot of duplicated time, cost and effort.
Our products are sold to stores such as Planet organic which has one of the strictest regulations. Having said all that, as part of further validation of product and process we may look to random test finished product batches as a further check on QC but this additional step is not currently in place.