If you look carefully at the ingredients of most heavy duty granulated workshop hand cleaners they use plastic beads as the abrasive medium. That's even some of the ones that market themselves as 'natural'. I used Swarfega for years without fully realising and thinking about what polygrains actually were. Shame on you guys at Swarfega et al for ever thinking that it was a cool thing to be washing tons of tiny plastic grains down the sink.
Of course recently there has been a move away from microbeads, polygrains or whatever the marketing folk care to call the tiny lumps of plastic they sneak in to their products but many still contain them.
Nowadays there are several products on the market that are more friendly to the environment - to the extent that they don't contain actual plastic and really it's a no-brainer to buy these ones and avoid the others like the plague. After searching around I settled on 'Zalpon Zorange' by Rozalex, it is fairly easy to find and the abrasive medium is ground up pumice stone.
The good news is that Zorange is a pretty similar hand washing product to others on the market. It works just as well as Swarfega Tough or any of the others.
Personally I'd like to find something more enviro-friendly still, in packaging and biodegradable non-toxic nature of the ingredients. Any suggestions welcome. But until then Zorange will suit me fine.