Comparative toxicity of five dispersants to coral larvae.

Oil spill responders require information on the absolute and relative toxicities of chemical dispersants to relevant receptor species to assess their use in spill response. However, little toxicity data are available for tropical marine species including reef-building corals. In this study, we experimentally assessed the sub-lethal toxicity of five dispersants to larvae of the coral Acropora millepora over three short exposure periods (2, 6 and 24 h) reflecting real-world spill response scenario durations. Inhibition of larval settlement increased rapidly between 2 and 6 h, and was highest at 24 h: EC50 Corexit EC9500A = 4.0 mg l-1; Ardrox 6120 = 4.0 mg l-1; Slickgone LTSW = 2.6 mg L-1; Slickgone NS = 11.1 mg L-1 and Finasol OSR52 = 3.4 mg L-1. Coral larvae were more sensitive to dispersants than most other coral life stages and marine taxa, but the toxic thresholds (EC10s) exceeded most realistic environmental dispersant concentrations. Estimating toxic threshold values for effects of dispersants on coral should benefit the decision-making of oil spill responders by contributing to the development of species sensitivity distributions (SSDs) for dispersant toxicity, and by informing net environmental benefit assessment (NEBA) for dispersant use.

Umbilical cord length and intrapartum complications.

The length of umbilical cords was studied in 536 term deliveries to test the hypothesis that a short or long umbilical cord is more frequently associated with certain intrapartum complications. The mean umbilical cord length was 55 cm (range, 14 to 129 cm). A short cord was defined as 35 cm or less (lower sixth percentile). Umbilical cord accidents were most frequent in the presence of a long cord (20 of 32 cases, 62%). Inadequate fetal descent was significantly more common when a long cord or an excessively short cord (25 cm or less, lower first percentile) was found. Fetal heart rate (FHR) abnormalities that primarily reflected cord compression patterns were significantly more frequent in the presence of a short (17 of 27 cases, 63%) or a long cord (28 of 32 cases, 87%), as compared with a normal length cord (145 of 393 cases, 37%). The measurement of umbilical cord length requires minimal effort, no expense, and may explain certain intrapartum FHR abnormalities or an arrest of fetal descent.