Sorry, DMcG: I take that back.
Mr Maruyama did go on to mention chlorinated chicken, but it came after the comments by Jeremy Corbyn, so I did not connect the two.

“A customs union presupposes a single tariff for all members and presupposes the illumination of all regulatory barriers within the union, and that implies a degree of harmonisation between UK and UK,” he said.

“If the UK is bound to precautionary principles and food standards, that’s a big problem and the US is watching that closely.

“You would be stuck with some of the EU’s restrictive policies that would preclude the importation of GMOs (genetically modified organisms), chlorinated chicken, hormone treated beef.”