Maternal exposure to high levels of dioxins in relation to birth weight in women affected by Yusho disease

Background

Studies on the association of maternal exposure to polychlorinated dibenzo-p-dioxin (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) with decreased birth weight in humans have produced conflicting results. In Japan in 1968, an accidental human exposure to rice oil contaminated with PCDDs, PCDFs, and PCBs, led to the development of Yusho disease.

Objective

The Yusho cohort was used to evaluate the effect of maternal exposure to PCDDs, PCDFs, and PCBs on birth weight.

Methods

Blood samples, obtained from 101 Yusho women (190 births) who gave birth after exposure, were analyzed for congeners of seven PCDDs, ten PCDFs, and four non-ortho PCBs.

Results

Total PCDD TEQ (adjusted beta = − 161.9 g; 95% CI, −265.3 to − 58.6), total PCDF TEQ (adjusted beta = − 105.9 g; 95% CI, −179.5 to − 32.2), and total non-ortho PCBs (adjusted beta = − 178.4 g; 95% CI, −318.3 to − 38.5) levels were inversely associated with birth weight. Significant inverse associations with birth weight were also found for total PCDD TEQ, total PCDF TEQ, and total non-ortho PCB TEQ levels among male, but not female, infants. Significant inverse associations with birth weight were also found for nine congeners among all infants; the adjusted beta coefficients were largest for 1,2,3,6,7,8-HxCDD and smallest for 2,3,4,7,8-PeCDF.

Conclusion

In the setting of exposure to high levels of dioxins, maternal blood levels of PCDDs, PCDFs and PCBs are associated with lower birth weight in Yusho patients. The association exhibited gender-specific differences, as male infants are more susceptible than females to growth restriction induced by in utero dioxin exposures.     

Comparison of the concentrations of polychlorinated biphenyls and dioxins in mothers affected by the Yusho incident and their children

Accumulated maternal dioxins are passed onto the fetus and neonate via the placenta and maternal milk. In Japan in 1968, an accidental human exposure to rice oil contaminated with polychlorinated biphenyls (PCBs) and other dioxin-related compounds, such as polychlorinated dibenzofurans (PCDFs), led to development of Yusho oil disease. We investigated differences in blood dioxin concentrations in mother-children pairs affected by the Yusho incident. From 2002 to 2008, blood samples were collected from 26 pairs of Yusho mothers and their children (19 mothers, 26 children). Specific congeners of seven polychlorinated dibenzo-p-dioxins (PCDDs), ten PCDFs, and four non-ortho PCBs were analyzed. The children had significantly lower TEQ concentrations of PCDDs, PCDFs, and coplanar PCBs compared to their mothers. The mother-child difference in blood concentrations varied with the congeners; the largest for 2,3,4,7,8-pentaCDF and the smallest for 1,2,3,4,6,7,8-heptaCDD. The level for 2,3,4,7,8-pentaCDF, which characterizes Yusho oil disease, was approximately 17-30 times higher in the mothers than in the general population, whereas there were no significant differences between children in the formula-fed group and the general population. In contrast, the mean level for 2,3,4,7,8-pentaCDF in the breast-fed group was approximately 1.5 times, (range 0.5-6.5 times) higher than that in the general population. Over 30 years after the Yusho incident, the mean blood dioxin levels in the offspring were only a fraction of the levels in their mothers. This is more consistent with exposure via breast milk than via transplacental transfer in the Yusho incident.     

Automobile exhaust gas as a source of aqueous phase OH radical in the atmosphere and its effects on physiological status of pine trees

Free radical generation potential of automobile exhaust gas was examined by measuring hydroxyl (OH) radical photo-formation rates in exhaust gas-scrubbing water. Effects of automobile exhausts on physiological status of Japanese red pine trees (Pinus densiflora Sieb. et Zucc.) were also investigated to elucidate the mechanism how the free radicals derived from exhaust gas damage higher plants. Gasoline and diesel exhaust gases were scrubbed into pure water. Potential photo-formation rates of OH radical in aqueous phase (normalized to sun light intensity of clear sky midday on May 1 at 34°N) for gasoline and diesel cars were ave. 51 and 107 μM h⁻¹ m⁻³ of exhaust gas, respectively. Nitrite was a dominant source (ca. 70-90%) of photochemical formation of OH radical in both gasoline and diesel car exhausts. The scrubbed solution of diesel car exhaust gas was sprayed for six times per week to needles of pine tree seedlings in open top chambers. Control, exhaust + mannitol (added as OH radical scavenger), and nitrite + nitrate standard solution (equivalent levels existed in the exhaust gas) were also sprayed. Two months sprays indicated that the sprayed solutions of diesel exhaust and nitrite + nitrate caused a decrease of maximum photosynthetic rate and stomata conductance in pine needles while the control and exhaust + mannitol solution showed no effects on photosynthetic activities of pine needles. These results indicated that OH radicals generated mainly from photolysis of nitrite occurring in the scrubbing solution of exhaust gas are responsible for the decrease of photosynthetic activities of pine needles.     

Enhanced remediation of dioxins-spiked soil by a plant-microbe system using a dibenzofuran-degrading Comamonas sp. and Trifolium repens L

In this study, rhizoremediation technology was applied to dioxins-spiked soil. A dibenzofuran-degrading bacterium Comamonas sp. strain KD7, reported in the previous paper, was used in combination with white clover (Trifolium repens L.). First, the effect of strain KD7 on clover seed germination and root elongation was examined in the presence of dioxins compounds. As a result, the white clover seeds inoculated with strain KD7 exhibited a higher germination efficiency and increased root elongation compared with uninoculated white clover. Next, the recovery efficiency of two extraction methods were considered for analyzing the dioxin concentration in soil samples, then, the potential of the plant-microbe combination was evaluated for the remediation of dioxins-spiked soil. After 12 week of growth, significant reductions in the soil were confirmed for most compounds. Our results demonstrated that clover can function as a carrier in order to increase the dioxin-degrading activity of strain KD7. The association of clover and strain KD7 is considered to be a potential tool in the remediation of dioxin-contaminated soil.     

Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil

Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, ρ(b), and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (D(p)/D(o), ratio of gas diffusion coefficients in soil and free air) and air permeability (k(a)) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting ρ(b) values ranging from 1.40 to 2.10 g cm(-3). Results showed that D(p) and k(a) values for the '+gravel' fraction (<35 mm) became larger than for the '-gravel' fraction (<2mm) under variably-saturated conditions for a given soil-air content (ε), likely due to enhanced gas diffusion and advection through less tortuous, large-pore networks. The effect of dry bulk density on D(p) and k(a) was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity D(p)/D(f), the ratio of measured D(p) to D(p) in total porosity (f), (ii) for air permeability k(a)/k(a)(,pF4.1), the ratio of measured k(a) to k(a) at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content (ε) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for D(p)(ε/f) and k(a)(ε/f) models were developed based on a single parameter (water blockage factor M for D(p) and P for k(a)). The water blockage factors, M and P, were found to be linearly correlated to ρ(b) values, and the effects of dry bulk density on D(p) and k(a) for both '+gravel' and '-gravel' fractions were well accounted for by the new models.     

Organic acids and aldehydes in throughfall and dew in a Japanese pine forest

We analyzed low molecular weight organic acids and aldehydes in throughfall under pine forest, and organic acids in dew on chemically inert surfaces and pine needle surfaces at urban- and mountain-facing sites of pine forest in western Japan. Low molecular weight organic acids and aldehydes accounted for less than 5% of the dissolved organic carbon in throughfall at both sites. Formaldehyde at both sites and formate at the mountain-facing site were found at significantly lower concentrations in throughfall than in rainfall, which may be explained by the degradation and/or retention of these components by the pine canopy as the incident precipitation passed through it. The oxalate concentration in throughfall was significantly higher than those in rainfall at both sites, suggesting that oxalate was derived from leaching from the pine foliage. At both sites, organic acid concentrations were higher in dew on the pine needles than in throughfall or dew on chemically inert surfaces. This could be due to the long contact time of dew on pine needles, during which leached substances from pine needles and dry deposits accumulated on their surfaces can dissolve into the small volume of dew. The role of enhanced concentrations of oxalate in an aqueous phase on the plant surfaces (e.g., dew) is discussed in relation to hydroxyl radical formation via the photo-Fenton reaction.     

Comparative fertilizer properties of digestates from mesophilic and thermophilic anaerobic digestion of dairy manure: focusing on plant growth promoting bacteria (PGPB) and environmental risk

The fertilizer properties of anaerobic digestate depend on the feedstock and operating conditions of digestion. In this study, the comparative fertilizer properties of mesophilic and thermophilic digestates from dairy manure were evaluated for plant nutrient contents, and special attention was paid to plant growth promoting bacteria (PGPB). Two digestates contained similar plant nutrient contents, while the thermophilic digestate contained higher contents of NH₄⁺–N. The quantity of Bacillus and Pseudomonas in the mesophilic digestate was significantly higher than in the thermophilic digestate. Furthermore, Bacillus showed siderophore production and antifungal activity (43.5–75.3%), and Pseudomonas showed siderophore and phytohormone production (4.2–75.2 µg ml^?1). One phosphate solubilizing isolate was also detected in the mesophilic digestate. These results indicated that two digestates showed different fertilizer properties with respect to nutrient contents and PGPB, and digestates had the potential to increase the availability of phosphorus and iron in the soil, both to provide phytohormones to plant roots and protect plants from fungal phytopathogens. The contents of indicator bacteria and heavy metals were analyzed to determine their environmental risk, and the results showed a high reduction in indicator bacteria and lower levels of heavy metals than in other feedstocks.     

Association of serum levels of polychlorinated biphenyls with IL-8 mRNA expression in blood samples from asthmatic and non-asthmatic Japanese children

Background

One of the suggested health outcomes of PCB exposure is childhood asthma.

Objectives

This study was conducted to find health relevant biomarkers providing the molecular epidemiological evidence for the positive relationship between exposure to PCBs and childhood asthma.

Methods

Blood samples from fifteen asthmatic children as well as an equal number of non-asthmatic children (average 2 year old) were collected, and were analyzed for PCBs and their select marker expression by using qRT-PCR.

Results

Among biomarkers examined IL-8 expression was significantly correlated to serum levels of PCB #163 + 164 (P = 0.022), #170 (P = 0.046), #177 (P = 0.022), #178 (P = 0.022) and #180 + 193 (P = 0.046) in a dose-dependent manner, which was found only among asthmatic children. In contrast, COX-2 correlations to individual congener levels were recognized only among control subjects, not among asthmatic subjects.

Conclusion

Serum concentrations of PCB#163 + 164, #170, #177, #178 and #180 + 193 correlate significantly with IL-8 mRNA expressions among asthmatic children.     

The relationship between seasonal variations of total-nitrogen and total-phosphorus in rainfall and air mass advection paths in Matsue,Japan

We collected rainwater samples from every rainfall in Matsue, Japan in order to study variations of nitrogen and phosphorus concentrations over time. The seasonal average concentration by magnitude order of Total Nitrogen (here after T-N) was highest in winter, then in spring, fall, and summer and that of Total Phosphorus (here after T-P) was highest in spring, then in winter, fall, and summer. These seasonal variations were examined in relation to the transportation paths of arrived air masses by using a backward trajectory and rainfall patterns from a surface synoptic weather chart. In winter, continental air masses frequently flow from China or Siberia and the resultant winter rainfall is on many occasions of a continental type. In summer, maritime air masses frequently arrive from the Pacific Ocean and this resultant rainfall therefore was often of maritime type. Looking at average concentrations of T-N and T-P for each rainfall type, continental types were high range and maritime types were low. It was therefore concluded that the monthly average concentration of T-N was affected by continental air masses from northern China in winter and by maritime ones from the Pacific Ocean in summer. The maximum deposition of T-N was caused by this concentration in winter and rainfall depth in summer. Seasonal variation of T-P showed a different fluctuation tendency from T-N, with a maximum concentration in spring, and minimum in summer and fall. T-P was susceptible to the yellow sand phenomenon which maximised T-P deposition in spring.