Artifact spots on cloudy plastic

[KimEurope]

Hello, Guys! If I use green translucent plastic, then on the render artifact points appear. With other colors this is not observed. How do i get rid of them?

Turning off caustics, turning off the cache, increasing samples, increasing global illumination - do not help

Thanks.
P.S Sorry for my English

[Will Gibbons]

How long are these rendering for? How many samples have you set for material samples (if you've changed it?)