It's probably off gassing aromatics from the molded plastics parts. Anything aromatic (in an organic chem context) is possibly carcinogenic. Past that its semi-volatile phthalates and other possible additives and light volatiles that may be off gassing especially from the unit's heat generation/dissipation.

Offgassing testing is common (think new car smell...Yeah unfortunately that's carcinogenic too, but we're testing for stuff now). I'm pretty surprised they didn't either invest in the right types of plastics that wouldn't have potentially toxic emissions...unless they did and didn't care until someone noticed and spread the word.