In another case, phthalates in pregnant women’s urine was linked to subtle, but specific, genital changes in their male infants – a shorter, more female-like anogenital distance and associated incomplete descent of testes and a smaller scrotum and penis.  The science behind this study has been questioned by phthalate industry consultants.  As of June 2008, there are only five studies of anogenital distance in humans,  and one researcher has stated "Whether AGD measures in humans relate to clinically important outcomes, however, remains to be determined, as does its utility as a measure of androgen action in epidemiologic studies." 
The neurotoxin MPTP had been known earlier to cause PD-like symptoms (in humans and other primates, though not in rats) by interfering with complex I in the electron transport chain and killing dopaminergic neurons in the substantia nigra. However, further studies involving MPTP have failed to show development of Lewy bodies , a key component to PD pathology. Therefore, the mechanism behind MPTP as it relates to Parkinson's disease is not fully understood.  Because of these developments, rotenone was investigated as a possible Parkinson-causing agent. Both MPTP and rotenone are lipophilic and can cross the blood–brain barrier .