Colourlessness of dyed plastic materials

According to the 24th Communication on the Examination of Plastics, Bundesgesundheitsblatt 15 (1972), there are "(...) no objections to the use of colourants for colouring plastics and other polymers for consumer goods (...) provided that the colourants (...) do not pass on to the foodstuffs even in visible proportions (...) when the consumer goods are used as intended". This requirement can be easily checked with the test available here.