A couple. Some basic neuro papers have found that it's directly neurotoxic. Others have found that it exacerbates the neurotoxicity of certain other compounds

A couple. Some basic neuro papers have found that it's directly neurotoxic. Others have found that it exacerbates the neurotoxicity of certain other compounds (e.g., lead). And other studies have found that pthalate exposure increases urinary output of quinolinic acid, a neurotoxic metabolite of the tryptophan metabolic pathway to which pthalates are structurally similar. This suggests a couple of things: (1) that pthalates are neurotoxic via the excitotoxic pathway that quinolinic acid acts through, and (2) that pthalates induce higher quinolinic acid production (we've confirmed this is true in humans). Essentially, we've confirmed pthalates to be neurologically harmful in a number of animal studies, found a candidate pathway, and confirmed that that pathway is in fact affected in the prediction direction in humans experimentally exposed to higher doses of pthalates. (That last bit slipped by the ethics boards because there are meds that already include pthalates, so patients were randomized to get higher- or lower- pthalate containing formulations of the med, which were otherwise equivalently dosed.) It's a pretty reasonable conclusion at this point, if one isn't already wedded to the idea of the compound's safety.