In an oral reproductive study in mice using the continuous breeding protocol, decreased numbers of live pups per litter and decreased numbers of litters per pair were observed when they were administered a daily dose of TCEP. This study included crossover mating trials; the results showed adverse effects on sperm in males (decreased sperm counts and motility, increased number of abnormal sperm). In 18-week studies on rats and mice, testicular toxicity was observed in both species (decreased relative testes weight and increased number of abnormal sperm in mice; decreased sperm motility in rats).