Assessment of asbestos burden in the placenta and tissue digests of stillborn infants in South Texas

The primary aim of this prospective study was to examine the tissues and placentas of autopsied stillborn infants for presence of asbestos fibers, Asbestos burden of lung, liver, skeletal muscle, and placenta digests of 82 stillborn infants was determined using standard bleach digestion technique. The digests were examined by electron microscopy, and the types of fibers determined using energy dispersive x-ray analysis and selected area diffraction analysis. Digests of 45 placentas collected from deliveries of liveborn healthy infants were processed and examined similarly as controls. Asbestos fibers were detected in 50% of the fetal digests and 23% of the placental digests of stillborn infants. Of the fibers present, 88% were chrysotile, 10% were tremolite, and 2% were actinolite and anthophyllite. Fibers measured 0.5-16.73 mu m in length (mean 1.55 mu m), and 0.03-0.8 mu m in width (mean 0.098 mu m). Lungs were most frequently positive for fibers (50%), followed by muscle (37%), placenta (23%), and liver (23%). Mean fiber counts were highest in the liver (58,736 f/g), followed by placenta (52,894 f/g), lungs (39,341 f/g), and skeletal muscle (31,733 f/g). Digests of 15% of the control placentas also showed asbestos fibers, although in very small numbers. The mean fiber count of the stillborn placentas (52,894 f/g) was significantly higher than the mean fiber count of the control placentas (mean 19 f/g) (p = 0.001). A highly significant association was found between fiber presence in stillborns and a maternal history of previous abortions (p = 0.007). A significant association was also found between fiber presence and placental diseases (p = 0.041). An association was suggested between working mothers and fiber presence (p = 0.19), although it did not reach statistical significance. The study documents the presence of small and thin asbestos fibers in stillborn fetal tissues and placenta. Significantly higher number of fibers were found in stillborn tissues compared to controls (liveborn placenta). The absence of a maternal history of asbestos-related occupations suggests that the fibers may have been acquired through environmental exposure.