@bobby newmark está correto, está em Para além do Horizonte de Eventos Azul .
Página 166
Also silently - it not seem so bad to talk to oneself, as long as it was not aloud - he defended himself. It was not unjustified, he thought. It was only because of the example of the bioassay unit in the toilet was always before him. For three and a half years it had been monitoring every waste product of their bodies. Of course, so it must! How else to keep tabs on their health? And if it was proper for a machine to weigh and evaluate one's excrement, why not for the excrement's author?