As discussed above, the primary degradate of chlorpyrifos is TCP. Toxicity data for TCP are available for three bird, one mammal, three fish, four aquatic invertebrate and three aquatic plant species (Table B 1-9.2). TCP has been shown to form at up to roughly one third of the applied parent and is more mobile and more persistent than chlorpyrifos. TMP is expected to have similar toxicity as TCP (due to their structural similarities) and is expected to form at lower concentrations in the environment than TMP. The potential exposure to TCP or TMP is not expected to contribute significantly to the overall risk because TCP and TMP are expected to be generally orders of magnitude less toxic than chlorpyrifos.