TThe Syva MicroTrak Chlamydia enzyme immunoassay (EIA; Syva Company, San Jose, Calif.) with cytospin and direct fluorescent-antibody assay (DFA) confirmation was evaluated on 43,630 urogenital specimens over a 1-year period in the Provincial Laboratory in Regina, Saskatchewan, Canada. This was a two-phase study intended to define a testing algorithm for Chlamydia trachomatis that would be both highly accurate and cost-effective in our high-volume (> 3,000 tests per month) laboratory. The prevalence of C. trachomatis infection in our population is moderate (8 to 9%). In phase 1, we tested 6,022 male and female urogenital specimens by EIA. All specimens with optical densities above the cutoff value and those within 30% below the cutoff value were retested by DFA. This was 648 specimens (10.8% of the total). A total of 100% (211 of 211) of the specimens with optical densities equal to or greater than 1.00 absorbance unit (AU) above the cutoff value, 98.2% (175 of 178) of the specimens with optical densities of between 0.500 and 0.999 AU above the cutoff value, and 83% (167 of 201) of the specimens with optical densities within 0.499 AU above the cutoff value were confirmed to be positive. A total of 12% (7 of 58) of the specimens with optical densities within 30% below the cutoff value were positive by DFA. In phase 2, we tested 37,608 specimens (32,495 from females; 5,113 from males) by EIA. Only those specimens with optical densities of between 0.499 AU above and 30% below the cutoff value required confirmation on the basis of data from phase 1 of the study. This was 4.5% of all specimens tested. This decrease in the proportion of specimens requiring confirmation provides a significant cost savings to the laboratory. The testing algorithm gives us a 1-day turnaround time to the final confirmed test results. The MicroTrak EIA performed very well in both phases of the study, with a sensitivity, specificity, positive predictive value, and negative predictive value of 96.1, 99.1, 90.3, and 99.7%, respectively, in phase 2. We suggest that for laboratories that use EIA for Chlamydia testing, a study such as this one will identify an appropriate optical density range for confirmatory testing for samples from that particular population.
Waste landfills are a potential hazard to health. Public concern exists about this potential hazard and researchers agree that further research is required on this field. The objective of the study was to investigate the association between waste landfill location and congenital anomalies risk in Denmark. The study was a multisided epidemiological geographical comparison study of risk of congenital anomalies combined and congenital anomalies of the cardiovascular and nervous systems with maternal residence in the vicinity of 48 Danish waste landfills compared with those living further away in the years 1997 to 2001. We used routine health and population data in Geographical Information System (GIS) to investigate the risk. The subjects were 2,477 live birth with congenital anomalies. All relative risks in the proximal zones of 0-2 km were set to 1 for comparison. For all anomalies combined relative risk in the middle zones of 2-4 km joint was 0.991 and in the distal zones of 4-6 km joint the relative risk was 1.013. For congenital anomalies of the nervous system, the relative risk in the middle zones was 1.226 and in the distal zones 1.113. For congenital anomalies of the cardiovascular system, the relative risk in the middle zones was 0.926 and in the distal zones 0.854. This result was not supported by the aggregated risk ratio mean. We found no association between waste landfill location and congenital anomalies combined or of the nervous system. However, we found small excess risk for congenital anomalies of the cardiovascular system. No causal mechanisms are available to explain these findings, but alternative explanations include approximated birth rates and residual confounding. It is our recommendation that more comprehensive multisided studies will be executed to examine the safety of waste landfills.
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; Institute of Soil Science and Land Evaluation, Soil Biology Department, University of Hohenheim, Emil-Wolff-Str. 27, 70599 Stuttgart, Germany; Department of Soil Science, Research Institute of Organic Agriculture FiBL, Ackerstrasse 113, 5070 Frick, Switzerland.
Chromated copper arsenates (CCA) have been extensively used as wood impregnation agents in Europe and North America. Today, CCA contaminated sites remain abundant and pose environmental risks that need to be properly managed. Using a TRIAD approach that combined chemical, ecotoxicological and ecological assessment of soil quality, we investigated the abilities of biochar and zero-valent iron (ZVI) to remediate CCA contaminated soil in a microcosm experiment. Soil samples from a highly contaminated CCA site (1364, 1662 and 540?µg?g-1 of As, Cu and Cr, respectively) were treated with two different biochars (fine and coarse particle size; 1% w?w-1) and ZVI (5% w?w-1), both as sole and as combined treatments, and incubated for 56?days at 15?°C. In general, bioavailable As (Asbio) and Cu (Cubio) determined by whole-cell bacterial bioreporters corresponded well to water-extractable As and Cu (Aswater and Cuwater). However, in biochar treatments, only Cubio and not Cuwater was significantly reduced. In contrast, under ZVI treatments only Cuwater and not Cubio was reduced, demonstrating the value of complementing analytical with bacterial bioreporter measurements to infer bioavailability of elements to soil microorganisms. The combined fine particle size biochar and ZVI treatment effectively reduced water extractable concentrations of Cr, Cu, and As on site by 45%, 45% and 43% respectively, and led to the highest ecological recovery of the soil bacterial community, as measured using the [3H]leucine incorporation technique. We conclude that the combined application of biochar and ZVI as soil amendments holds promise for in-situ stabilization of CCA contaminated sites.