Agreement between breast milk dioxin levels by CALUX bioassay and chemical analysis in a population survey in Hong Kong

Chemically-activated luciferase gene expression (CALUX) bioassay and gas chromatography/mass spectrometry (GC/MS) are used to determine dioxin levels in food and humans. Valid measures of the agreement between the two methods would improve interpretation of bioassay results. Paired breast milk samples from 250 mothers, as 11 pooled samples, were analysed by GC/MS for total WHO-TEQ (7 polychlorinated dibenzo-para-dioxins, 10 polychlorinated dibenzofurans and 12 dioxin-like polychlorinated biphenyls) and as individual samples by CALUX. Mean difference between total WHO-TEQ (weighted by TEF system derived in 1997) and mean CALUX-TEQ in each pool was 1.6 pg/g fat (95% CI: 0.7, 2.4), indicating a statistically significant overestimation of CALUX-TEQ compared to WHO-TEQ, probably due to the presence of Ah-receptor agonists. CALUX estimated toxicity of 13 pg/g fat was greater than the WHO-TEQ by 0.9, 3.1 and 0.3 pg/g fat for mothers from Hong Kong, mainland China and overseas territories, respectively. When the 2005 TEF system was applied, a reduction of 14-26% in the WHO-TEQ and a larger but less disperse discrepancy between WHO-TEQ and CALUX-TEQ (3.9 pg/g fat, 95% CI: 3.5, 4.4) were observed. Our study suggested that the mothers' place of residence explained the discrepancy between CALUX-TEQ and WHO-TEQ and should be considered in inter-country comparisons for CALUX-TEQ. For regulatory purposes bioassays for detecting quantitative dioxin contents in any setting must be combined with adequate extraction, clean-up and validation with WHO-TEQs. The larger difference between the two measurements after using the new TEF system warrants further investigation.     

Comparison of semipermeable membrane device (SPMD) and large-volume solid-phase extraction techniques to measure water concentrations of 4,4'-DDT, 4,4'-DDE, and 4,4'-DDD in Lake Chelan, Washington

Semipermeable membrane devices (SPMDs) spiked with the performance reference compound PCB29 were deployed 6.1 m above the sediments of Lake Chelan, Washington, for a period of 27 d, to estimate the dissolved concentrations of 4,4'-DDT, 4,4'-DDE, and 4,4'-DDD. Water concentrations were estimated using methods proposed in 2002 and newer equations published in 2006 to determine how the application of the newer equations affects historical SPMD data that used the older method. The estimated concentrations of DDD, DDE, and DDD calculated using the older method were 1.5-2.9 times higher than the newer method. SPMD estimates from both methods were also compared to dissolved and particulate DDT concentrations measured directly by processing large volumes of water through a large-volume solid-phase extraction device (Infiltrex 300). SPMD estimates of DDD+DDE+DDT (SigmaDDT) using the older and newer methods were lower than Infiltrex concentrations by factors of 1.1 and 2.3, respectively. All measurements of DDT were below the Washington State water quality standards for the protection of human health (0.59 ng l(-1)) and aquatic life (1.0 ng l(-1)).     

An assessment of coastal land-use and land-cover change from 1974–2008 in the vicinity of Mobile Bay,Alabama

The purpose of this research is to quantify and assess geospatial land-use and land-cover (LULC) changes in the coastal counties of Mobile and Baldwin, Alabama using nine Landsat images from 1974–2008. A study-specific classification scheme was devised comprising upland herbaceous, upland forest, non-woody and woody wetlands, open water, and urban categories. Upland forest was the most dominant terrestrial cover type. Wetlands averaged 17% and urban averaged 7%. A majority of the urban expansion occurred between 1974 and 1979 (26%). Thirty-four percent of the 2008 urban areas were upland forest in 1974. Watershed-scale analysis of Three Mile Creek and D’Olive Bay highlights the temporal and spatial differences of urbanization for watersheds found within the same region. This study is a Gulf of Mexico Alliance (GOMA) Application Pilot project that uses NASA data products to benefit coastal environmental managers and community members. Results have led to increased effectiveness of coastal conservation decision-making, increased understanding of post-hurricane LULC change, continued research on habitat change impacts, and contributed to timely conservation planning efforts. This study has benefited the development of watershed management plans by the Mobile Bay National Estuary Program, which is especially important given projected climate change.     

Association between low fetal fraction in cell-free DNA screening and fetal chromosomal aberrations: A systematic review and meta-analysis

Objective

To perform a systematic review and meta-analysis of the available literature on low fetal fraction (LFF) in cell-free DNA (cfDNA) screening and the risk of fetal chromosomal aberrations.

Method

We searched articles published between January 2010 and May 2021 in PubMed and EMBASE databases. Risk of bias was assessed using QUADAS-2.

Results

Twenty-seven studies met the inclusion criteria, comprising data of 243,700 singleton pregnancies. Compared to normal fetal fraction, LFF was associated with a higher risk of trisomy 13 (OR 5.99 [3.61–9.95], I ² of heterogeneity = 0%, n = 22 studies), trisomy 18 (OR 4.46 [3.07–6.47], I ² = 0%, n = 22 studies), monosomy X (OR 5.88 [2.34–14.78], I ² = 18%, n = 10 studies), and triploidy (OR 36.39 [9.83–134.68], I ² = 61%, n = 6 studies), but not trisomy 21 (OR 1.25 [0.76–2.03], I ² = 36%, n = 23 studies). LFF was also associated with a higher risk of various other types of fetal chromosomal aberrations (OR 4.00 [1.78–9.00], I ² = 2%, n = 11 studies). Meta-analysis of proportions showed that absolute rates of fetal chromosomal aberrations ranged between 1% and 2% in women with LFF. A limitation of this review is the potential risk of ascertainment bias because of differences in outcome assessment between pregnancies with LFF and those with normal fetal fraction. Heterogeneity in population characteristics or applied technologies across included studies may not have been fully addressed.

Conclusion

An LFF test result in cfDNA screening is associated with an increased risk of fetal trisomy 13, trisomy 18, monosomy X, and triploidy, but not trisomy 21. Further research is needed to assess the association between LFF and other specific types of fetal chromosomal aberrations.     

Prenatal exclusion of homocystinuria (cystathionine β-synthase deficiency) by assay of phytohaemagglutinin-stimulated fetal lymphocytes

Homocystinuria due to cystathionine β-synthase deficiency was excluded in a fetus at 23 weeks' gestation by demonstrating activity of the enzyme in fetal lymphocytes after stimulation by phytohaemagglutinin. Fetal blood sampling was carried out because two determinations of enzyme activity on cultured amniotic cells gave low, not fully diagnostic values.     

The recovery of selenious acid aerosols on glass fiber filters

Previous workers have shown that selenium is only partially trapped on a filter during air sampling. In some cases, these losses have been attributed to volatilization of selenium dioxide. Our results demonstrate that selenium dioxide, in the presence of moist air, is completely recovered (apparently as selenious acid aerosols) and that the previous shortfalls must be due to other selenium species as yet unidentified. Selenious acid aerosols in our study were formed by volatilizing selenium dioxide (approximately 3 mg) into a stream of moist ambient air (relative humidity, greater than 50%), and trapped on glass fiber filters using a high-volume air sampler. Selenium(IV) was ultrasonically extracted from the filter with water and analyzed by atomic absorption spectrometry. Selenious acid aerosols were trapped on the filters with high efficiency (105 +/- 5 percent) using a 50 minute sampling period. With an extended sampling period (24 hours) the recovery was 103 +/- 6 percent.