I know you posted this question over a month ago but I've just heard a 30 minute documentary, on BBC World Service, about the problems faced by Brazilian nut producers, so I thought I'd pass on some information.
When consignments of unshelled Brazil nuts are received in the EU, they can't be distributed until samples of the nuts have been tested. This is done by crushing the unshelled nuts and checking for the presence of toxins caused by fungal growths. The acceptable limit is 4 parts per billion. The majority of consignments were showing levels many times the permitted limits. (Up to 400 parts per billion). When a consignment fails the test, the producer either has to pay for his shipload of (probably unsaleable) nuts to be sent back to Brazil or they're destroyed without any compensation being paid.
This means that it is no longer viable for Brazilian nut producers to send unshelled nuts to the EU. Shelled nuts are hand-sorted and any suspect nuts are removed. Consignments of shelled nuts are thus able to pass the toxins test and to be placed on sale in EU shops.
Chris