Dispositions of di- and mono-(2-ethylhexyl) phthalate in newborn infants subjected to exchange transfusions.

The dispositions of the plasticizer di-(2-ethylhexyl) phthalate (DEHP) and its primary metabolite mono-(2-ethylhexyl) phthalate (MEHP) were studied in newborn infants subjected to exchange transfusions. During a single exchange transfusion the amounts of DEHP and MEHP infused ranged from 0.8-3.3 and 0.05-0.20 mg kg-1 body weight, respectively. There were indications that about 30% of the infused DEHP originated from parts of the transfusion set other than the blood bag. Approximately 30% of the infused amount of DEHP was withdrawn during the course of each transfusion. Immediately after the transfusions the plasma levels of DEHP ranged between 5.8 and 19.6 micrograms ml-1, and subsequently they declined rapidly. This decline, probably reflecting distribution of DEHP within the body, was followed by a slower elimination phase. The half-life of this phase was approximately 10 h. The maximal plasma levels of MEHP were about 5 micrograms ml-1. In one pre-term infant the elimination of MEHP was slower than its formation, whereas in one full-term newborn the formation appeared to be rate-limiting for the elimination.