A Comparative Evaluation of Three Washing Procedures for Minimizing Exogenous Trace Element Contamination in Fetal Scalp Hair of Various Obstetric Outcomes

Abstract

A comparative evaluation of three washing methods for removing exogenous elemental contamination from fetal scalp hair is described. A total of 12 samples, including 6 from normal pregnancies and 6 from abruptio placentae (AP) cases, were used. Each was divided into four subsamples, with one left unwashed for comparison, while three were subjected to one of the three washing methods. The first consisted of agitating hair for 5 min in sequential and equal measures (30 ml) of acetone and water, followed by rinsing with acetone, and the process repeated twice. In the second and third, hair was agitated for 30 min in aqueous solutions of sodium lauryl sulfate (0.5%, w/v), and Triton X-100 (0.5%, v/v), respectively, followed by sequential rinsing with deionized water and acetone. After drying and microwave-assisted digestion in concentrated nitric acid, the subsamples' concentrations of zinc, copper, cadmium, lead, mercury and selenium were determined using inductively coupled mass spectrometry. All washed subsamples, irrespective of washing method used, had lower elemental concentrations than the corresponding, unwashed subsamples. These differences, taken as presumptive indicators of exogenous contamination, showed only small variations (<5%) between the three washing methods, irrespective of element, mode of delivery, and obstetric outcome. However, the contamination levels elicited by each of the three methods varied in magnitude according to individual elements, with those of copper being highest, followed by those of zinc, cadmium, mercury, selenium, and lead. They also varied according to obstetric outcome, being highest in the AP subsamples, while in the normal pregnancy group, copper and zinc contamination levels in the subsamples from neonates delivered by elective caesarean section were higher than in those from normal-delivery neonates. The data from this study suggest that the three washing methods used have comparable efficacies in removing exogenous elemental contamination from fetal hair, further inferring that it is probably a simple biological matrix to decontaminate. Possible contributory factors are discussed and contrasted with those affecting adult hair.