Most have no excretory structures, but rely on the diffusion of ammonia across their tissues to rid themselves of nitrogenous waste, though some have a simple excretory system.
Inorganic mercury has a wide spectrum of toxicological effects that include damage to the respiratory, nervous, immune and excretory systems in humans.
Since cestodes are devoid of any digestive and excretory systems, the tegument with its microtriches constitute the principal site of absorption of nutrients and elimination of waste materials.