Health risk of fluorine in soil from a phosphorus industrial area based on the in-vitro oral, inhalation, and dermal bioaccessibility

Health risk of F in soil is of special concern due to the continuously elevated concentration of F in soil. However, there is still a dearth of risk assessments of F in soil based on in-vitro bioaccessibility posed by multiple exposure routes. Herein, the oral, inhalation, and dermal bioaccessibility of F in soil was firstly obtained by adapting and combining in-vitro methods, which then was introduced to remedy an information gap of a comprehensive risk of F in soil posed by a multi-exposure pathway. Combined in-vitro tests indicate the oral, inhalation, and dermal bioaccessibility of F was 13.15 ± 2.63%, 16.55 ± 2.63%, and 1.27 ± 0.73%, respectively. Plasma yielded a detoxic potential for the absorbed F after digesting in small intestine, while effects of enzymes, sweat, and food on the oral bioaccessibility of F were insignificant. Different with metals, the major dissolving phase of F was the interstitial fluid in the deep lung instead of in the alveolar macrophages intracellular environment. A potentially major release of F in the exocrine sweat was noted than in the apocrine sweat. Risk assessments based on the daily exposure incorporated with the in-vitro bioaccessibility suggested that compared with inhalation and dermal contact, oral ingestion was the main exposure route of F in soil to human. Present findings provide insights into the bioaccessibility and health risk of F in soil by multiple exposure routes, which are crucial for the risk control of F contamination in soil.

Mechanism of vanadium(IV) resistance of the strains isolated from a vanadium titanomagnetite mining region

Microbial treatment for vanadium contamination of soils is a favorable and environment-friendly method. However, information of the resistant mechanism of the strains in soils to vanadium, especially to tetravalent vanadium [vanadium(IV)], is still limited. Herein, potential of the vanadium(IV) biosorption and biotransformation of the strains (4K1, 4K2, 4K3 and 4K4) which were capable of tolerating vanadium(IV) was determined. For biosorption, the bioadsorption and the bioabsorption of vanadium(IV) occur on the bacterial cell wall and within the cell, respectively, were taken into consideration. Comparison of the vanadium(IV) adsorbed on the bacterial cell walls and remained in the cells after sorption indicated the major bacterial vanadium(IV) sorption role of the bioadsorption which was at least one order of magnitude higher than the bioabsorption amount. Isotherm study using various isotherm models revealed a monolayer and a multilayer vanadium(IV) biosorption by 4K2 and the others (4K1, 4K3 and 4K4), respectively. Higher biosorption was observed in acidic conditions than in alkaline conditions, and the maximum biosorption was 2.41, 9.35, 7.76 and 8.44 mg g^-1 observed at pH 6 for 4K1, at pH 3 for 4K2, and at pH 4 for 4K3 and 4K4, respectively. At the present experimental range of the initial vanadium(IV) concentration, optimal biosorption capacity of the bacteria was observed at the vanadium(IV) level of 100-250 mg L^-1. Different biotransformation level of vanadium(IV) in soils by the stains was observed during a 28-d pot incubation of the soils mixed with the strains, which can be attributed to the discrepancy of both soil properties and bacterial species. Present study can help to fill up the gaps of the insufficient knowledge of the vanadium(IV) resistant mechanism of the strains in soils.

Seroprevalence of Toxoplasma gondii infection in people in southeast Hubei province, China

Toxoplasma gondii is a world-widely spread zoonotic parasite. However, scarce knowledge is known about the prevalence of T. gondii infection in people in Hubei province, China. This study herein was to perform epidemiological investigation of T. gondii infection in people in this region. A total 12527 blood samples were obtained during 2015-2018, and were assayed for T. gondii antibodies of IgG and IgM, respectively by employing an indirect hemagglutination test (IHA). The results discovered that the prevalence of T. gondii in people was 2.44% and 6.1%, respectively based on antibodies of IgG and IgM, respectively. The prevalence was ranged from 0.3% to 5.4% during 2015-2018 based on IgM antibodies. For genders, the prevalence was 0.7% and 2.6% in males and females, respectively based on IgM antibodies. In different years, the prevalence was ranged from 4.9% to 14.0% based on IgG antibodies. The prevalence of T. gondii was 4.9% and 6.6% in males and femalesy based on IgG antibodies. The current results may be helpful for the implementation of preventive measures against Toxoplasma infection among people living in this region.

Adsorption-desorption and co-migration of vanadium on colloidal kaolinite

Vanadium (V) pollution in soil has been widely noted, while knowledge about the effect of soil colloid on migration of V is scarce. Batch adsorption-desorption and transportation of the colloid-adsorbed V in columns packed with quartz sand under various environment conditions were carried out to explore the retention and transportation of V by colloidal kaolinite. Batch adsorption-desorption studies show that the adsorption of V by the colloidal kaolinite was mainly specific adsorption and redox played a limited role in the adsorption process. The maximum adsorption capacity of the colloidal kaolinite was 712.4 mg g^-1, and about 5.9-8.7% of the adsorbed V could be desorbed. Both the adsorption-desorption and migration of V with colloidal kaolinite were highly ambient condition dependent. The column studies show that V was highly mobile in the saturated porous media. An easier transfer of V with an increase in pH, IS, and velocity of flow was noted. However, the increase of IS lead to the blockage of the colloidal kaolinite transportation. The recovery rate of the colloidal kaolinite at pH 7 and 9 was 2.0 and 2.1 times that at pH 5, respectively. The migration of colloidal-adsorbed V in sand column preceded that of V ion, but more colloidal-bound V than V ion remained in the column. Lack of consideration of the combination and co-transportation of V and colloidal kaolinite will lead to an overestimation of the risk of V to deeper soil profiles and groundwater. Graphical abstract.

Fluorine in the environment in an endemic fluorosis area in Southwest, China

Soils in large areas of China are enriched in fluorine (F). The present study analyzed F concentrations in cultivated soil, water, chemical fertilizer, and human hair, and metal concentrations in soils from an endemic fluorosis area in Southwest, China. In order to reveal the effects of industry on F concentration in the environment, 3 towns mainly with agriculture production and another 3 towns with developed phosphorus chemical industry in a same city were selected for sample collection. The total F concentrations of the 277 surface agricultural soil samples were 378.79-1576.13 μg g^-1, and F concentrations of nearly 95% of the soil samples were higher than the Chinese average topsoil F concentration (480 μg g^-1). Only a small fraction (0.75%) of total F was water soluble. The average total F, water soluble F, Ca, Cr, Fe, K, Mn, Rb, and Sr concentrations in soil samples from towns with intensive industry were higher than those from towns mainly with agriculture. Significant correlations were found between soil pH with total F (p < 0.01) and with water soluble F concentration (p < 0.1). Low F concentrations (<0.5 mg L^-1) were found in irrigation water, well water and tap water in a town where the industry is dense. The phosphorus fertilizer and compound fertilizer had hundreds of times of contribution to soil F increment than the nitrogen fertilizer and potassium fertilizer. Nearly half percent of F in the human hair samples was of exogenic origin. Based on soil ingestion pathway, the health risk for adults exposure to F in soils was acceptable, however, F may pose possible health risks to children in high F concentration areas.

Characteristic of adsorption, desorption, and co-transport of vanadium on humic acid colloid

Understanding the interactions between humic acid colloid (HAC) and vanadium (V) in soils is of great importance in forecasting the behaviors and fates of V in the soil and groundwater systems. This study investigated the characteristics and factors that affect V adsorption-desorption by the HAC; meanwhile, we also explored the co-transport of the HAC and V in a saturated porous media. Scanning Electronic Microscopy micrographs showed the variation of morphological features on the surface of the HAC before and after V adsorption. Fourier transform infrared spectroscopy spectra revealed that the presence of hydroxyl, carboxyl, carbonyl, carbon-carbon double bond, amino, and aromatic ring on the HAC participated in V adsorption. The adsorption isotherms were well described by the Langmuir model, and the adsorption kinetics of the HAC was better described by the pseudo-first-order kinetic models. The adsorption-desorption was strongly dependent on the initial V concentration, solution pH, and temperature. The maximum adsorption amount was 861.17 mg g^-1 by 200 mg L^-1 HAC at the initial V concentration of 500 mg L^-1, and the corresponding desorption amount was 15.13 mg g^-1. These results showed that the HAC had high fixation capacity of V in soil. In addition, the HAC sped up the mobility of V; however, it decreased mass of migration of V in the saturated quartz sand column. These results are expected to provide insight into the potential impact of HAC on geochemical behaviours of V in vulnerable ecosystems.

Epidemiological investigation and risk factors of Peste des petitis ruminants (PPR) in yaks (Bos grunniens) and cattle in five regions of China

To investigate the prevalence of Peste des petitis ruminants in yaks and cattle in poorly studied areas of China. A total of 1202 and 560 blood samples were collected from yaks and cattle, respectively and processed using a commercial ELISA kit. Multivariable logistic regression model was piloted to find the variables, potentially associated with exposure of PPR infection in yaks and cattle. Results indicated that the overall prevalence of PPR in yaks was 11.2%. A total 66 (11.8%) out of 560 were examined out to be positive to PPR in cattle in Jiangxi province. According to conditional stepwise logistic regression, region, age and gender were found to be the more influencing risk factors in yaks, while region and age were found to be the potential risk factors in cattle. The current results reported the prevalence and associated risk factors of PPR in bovine for the first time in China.

Prevalence, associated risk factors, and phylogenetic analysis of Echinococcus granulosus isolated from freerange Tibetan pigs in Tibet, China

The current study was performed to investigate the prevalence, associated risk factors exploration and phylogenetic analysis of Echinococcus granulosus (E. granulosus) genotypes isolated from Tibetan pigs. A total 373 Tibetan pigs were examined during 2014 and 2015, and the variables potentially associated with E. granulosus infection were explored with a multivariable logistic regression model. E. granulosus cysts (n=37) were collected from Tibetan pigs (lungs or livers). Fragments amplification of mitochondrial (mt) DNA of cox1 (shorter and longer) and atp6 were employed. The genotype of E. granulosus were identified by sequence and phylogenetic analysis. Results showed the prevalence of E. granulosus in Tibetan pigs was 9.9%. The prevalence of E. granulosus in male and female Tibetan pigs was 6.8% and 13.3%, with a significant difference in the two genders (P<0.05). In different seasons, the infection rate of E. granulosus in Tibetan pigs were ranged from 5.8% to 12.3%. E. granulosus infection rates in different growing stages of Tibetan pigs were ranged from 4.4% to 15.9%, with a statistical difference in the three stages (P<0.01). The prevalence of E. granulosus in Tibetan pigs were 7.9% in 2014 and 13.0% in 2015. Genders and growing stages were demonstrated to be risk factors to influence the prevalence significantly through multivariable logistic regression model. All the three fragments were successfully amplified from each of the 37 cysts. E. granulosus genotypes of G4 and G6 were identified by comparing with reference sequences of E. genotypes available at NCBI database and phylogenetic analysis by using MEGA software.

Molecular characterization of ascaris from Tibetan pigs by three mitochondrial markers of nad1, cox1 and cox2

Ascaris is a helminthic parasite, which infects a wide range of host species causing ascariasis, a predominant disease worldwide. This parasite causes significant economic losses to the pig industry. The current study was designed to determine the Ascaris nematode by the genetic characterization of three mitochondrial (mt) genes namely NADH dehydrogenase subunit 1 (nad1), cytochrome oxidase subunit 1 (cox1) and cytochrome oxidase subunit 2 (cox2). A high infection rate of Ascaris nematode has been found in Tibetan pigs at the slaughter houses in Tibet Autonomous Region of China. The nad1, cox1 and cox2 genes sequences collected from adult Ascaris individuals were amplified by polymerase chain reaction. The cloned-amplicons and the positive products were sequenced and phylogenetic analysis was performed. The results indicated that the Ascaris infecting the Tibetan pigs were Ascaris suum (A. suum). This is the first report on the isolation, identification and genetic characterization of three mitochondrial genomes (nad1, cox1, and cox2) of A. suum originated from Tibetan pigs at high altitudes in Tibet.

Seroprevalence of bluetongue virus infection in goats in the central China

Seroprevalence of Bluetongue virus (BTV) in goats from Hubei was investigated by a commercial competitive enzyme-linked immunosorbent assay kits. Blood samples (n= 1157) were collected during the year 2014 and 2015. The results showed that 13.31% (CI 95% 11.4%-15.4%) serum samples were positive for BTV antibodies in goats in Hubei. The prevalence of BTV antibodies in each region ranged from 1.32% to 27.70%, and differences among the regions were statistically significant (p < 0.01). The prevalence of BTV in male and female goats was 14.23% (95% CI: 11.3, 17.6) and 12.58% (95% CI: 10.1, 15.4), respectively, no significant difference in genders (p > 0.05). In different seasons, the seroprevalence were 8.94% (95% CI: 5.6, 13.3) in spring; 18.31% (95% CI: 14.5, 22.7) in summer; 23.08% (95% CI: 17.0, 30.2) in autumn and 6.98% (95% CI: 4.6, 10.0) in winter, respectively with a significant difference of the prevalence in the different seasons (p < 0.01).

Seroepidemiology of Toxoplasma gondii and Neospora caninum infections in goats in Hubei province, China

Scarce information is available about the seroprevalence of Toxoplasma gondii (T. gondii) and Neospora caninum (N. caninum) infections in goats in Hubei province, China. In the present study, the prevalence of T. gondii and N. caninum infections in goats were investigated in Hubei province, China between 2014 and 2015. A total 2007 serum samples were collected from 6 counties of Hubei province, China and were tested for antibodies to N. caninum and T. gondii by an enzyme-linked immunosorbent assay (ELISA) and an indirect agglutination test (IAT), respectively. Antibodies against T. gondii and N. caninum were detected in 13.4% and 3.9%, respectively in goats. 2% (41) serum samples were positive to both parasites. There was no apparent association of T. gondii and N. caninum infection with gender of the animals. There were significant differences of T. gondii (p < 0.01), N. caninum (p < 0.05) and both parasites (p < 0.01) infection with season. This is the first time that antibodies to T. gondii and N. caninum have been detected in goats in Hubei province, China.

[Observation on the persistence period and transmission of residual microfilaremia with medium and higher density]

OBJECTIVE

To explore the persistence period of medium and higher density of microfilaremia and its role in the transmission of filariasis in areas with filariasis basically eradicated.

METHODS

The residual microfilaremia was followed up and the population were regularly examined by thick blood film assay. Culex quinquefaciatus were dissected to determine the natural infection rate and density of filarial larvae. The filarial antibody levels were detected by using IFAT.

RESULTS

Two cases with medium and higher density of microfilaremia were found to be microfilaremia positive for twelve years. The natural infection rate and density of filarial larvae in Culex quinquefasciatus dropped down year by year, one case of new microfilaremia was found in the sixteenth year.

CONCLUSION

The persistence period of residual medium and higher density of microfilaremia lasted for more than twelve years. The individual residual medium and higher density of microfilaremia cases still possess the potential for transmission of filariasis.