Limited mobility of dioxins near San Jacinto super fund site (waste pit) in the Houston Ship Channel, Texas due to strong sediment sorption.

Sediments from a waste pit in Houston Ship Channel (HSC) were characterized using a number of molecular markers of natural organic matter fractions (e.g., pyrogenic carbon residues, PAHs, lignins), in addition to dioxins, in order to test the hypothesis that the dispersal and mobility of dioxins from the waste pit in the San Jacinto River is minimal. Station SG-6, sampled at the site of the submerged waste pit, had the highest dioxin/furan concentrations reported for the Houston Ship Channel/Galveston Bay (HSC/GB) system (10,000-46,000 pg/g), which translated into some of the highest reported World Health Organization Toxic Equivalents (TEQs: 2000-11,000 pg/g) in HSC sediments. Using a multi-tracer approach, this study confirmed our hypothesis that sludges from chlorinated pulps are a very likely source of dioxins/furans to this pit. However, this material also contained large quantities of additional hydrophobic organic contaminants (PAHs) and pyrogenic markers (soot-BC, levoglucosan), pointing to the co-occurrence of petroleum hydrocarbons and combustion byproducts. Comparison of dioxin/furan signatures in the waste pit with those from sediments of the HSC and a control site suggests that the remobilization of contaminated particles did not occur beyond the close vicinity of the pit itself. The dioxins/furans in sediments outside the waste pit within the HSC are rather from other diffuse inputs, entering the sedimentary environment through the air and water, and which are comprised of a mixture of industrial and municipal sources. Fingerprinting of waste pit dioxins indicates that their composition is typical of pulp and paper sources. Measured pore water concentrations were 1 order of magnitude lower than estimated values, calculated from a multiphase sorption model, indicating low mobility of dioxins within the waste pit. This is likely accomplished by co-occurring and strong sorbing pyrogenic and petrogenic residues in the waste pit, which tend to keep dioxins strongly sorbed to particles.

Major histocompatibility class I antigens in the Lebanese population

Except for two reports on Lebanese immigrants, there have been no studies on the major histocompatibility [MHC] antigens in the Lebanese population. We describe the frequency and distribution of MHC class I antigens present in the A, B and C loci based on data obtained from 200 healthy unrelated individuals from different parts of Lebanon. The highest gene frequencies were as follows: A2 [24.8%], B35 [17.9%] and Cw4 [18.6%], making this haplotype the commonest. Comparison of genetic distances revealed a pattern closer to the Caucasoid population than to the Mongoloid, Oriental or Black populations

The management of labor in women with more than one uterine scar: is a repeat cesarean section really the only "safe" option?

A prospective trial to investigate feasibility of vaginal delivery after more than one cesarean section, and the safety of vaginal delivery for mother and neonate. Twenty-six pregnant women with a history of two or more cesarean sections were admitted to the delivery room and accepted trial of labor under internal fetal and uterine monitoring. Epidural anesthesia and oxytocin were applied when needed. A similar group of patients (controls) preferred repeated cesarean section. Nineteen women (73%) were successfully delivered by the vaginal route. There were no cases of uterine rupture or perinatal loss. The maternal complication rate was lower than that of the control group. Trial of labor in selected cases of two or more low-segment cesarean sections may be considered safe for mother and fetus.