They weren't sued because there was carcinogens in the chicken, but they were sued because of California's Proposition 65, which stated that if there's anything dangerous in the products then the companies had to give a clear warning.
No fueron demandados porque hubiese carcinógenos en el pollo, sino debido a la Propuesta 65 de California, que establece que si hay algo peligroso en los productos las empresas tienen que brindar una advertencia clara.