Population-wide measures due to the COVID-19 pandemic and exposome changes in the general population of Cyprus in March-May 2020.

Non-pharmacological interventions (e.g., stay-at-home orders, school closures, physical distancing) implemented during the COVID-19 pandemic are expected to have modified routines and lifestyles, eventually impacting key exposome parameters, including, among others, physical activity, diet and cleaning habits. The objectives were to describe the exposomic profile of the general Cypriot population and compliance to the population-wide measures implemented during March-May 2020 to lower the risk of SARS-CoV-2 transmission, and to simulate the population-wide measures' effect on social contacts and SARS-CoV-2 spread. A survey was conducted in March-May 2020 capturing different exposome parameters, e.g., individual characteristics, lifestyle/habits, time spent and contacts at home/work/elsewhere. We described the exposome parameters and their correlations. In an exposome-wide association analysis, we used the number of hours spent at home as an indicator of compliance to the measures. We generated synthetic human proximity networks, before and during the measures using the dynamic-[Formula: see text]1 model and simulated SARS-CoV-2 transmission (i.e., to identify possible places where higher transmission/number of cases could originate from) on the networks with a dynamic Susceptible-Exposed-Infectious-Recovered model. Overall, 594 respondents were included in the analysis (mean age 45.7 years, > 50% in very good health and communicating daily with friends/family via phone/online). The median number of contacts at home and at work decreased during the measures (from 3 to 2 and from 12 to 0, respectively) and the hours spent at home increased, indicating compliance with the measures. Increased time spent at home during the measures was associated with time spent at work before the measures (ß= -0.87, 95% CI [-1.21,-0.53]) as well as with being retired vs employed (ß= 2.32, 95% CI [1.70, 2.93]). The temporal network analysis indicated that most cases originated at work, while the synthetic human proximity networks adequately reproduced the observed SARS-CoV-2 spread. Exposome approaches (i.e., holistic characterization of the spatiotemporal variation of multiple exposures) would aid the comprehensive description of population-wide measures' impact and explore how behaviors and networks may shape SARS-CoV-2 transmission.

Assessment of indoor and outdoor air quality in primary schools of Cyprus during the COVID-19 pandemic measures in May-July 2021.

Combined pollutant effects from indoor and outdoor sources on children's health, while being at school have not been holistically tackled. The aim of the School Temperature and Environmental Pollutants Study (STEPS) was to perform a school population representative assessment of indoor air quality (IAQ) in primary schools of densely and intermediate populated areas of Cyprus (n = 42). The study took place during May-July 2021 when a school-specific COVID-19 protocol was in place. Questionnaire-based characteristics of schools/classrooms were collected along with 24/48-h long IAQ monitoring of air temperature, relative humidity (RH), particulate matter (PM), carbon dioxide (CO2) and volatile organic compounds (VOCs), using low-cost sensors. Mixed effect models assessed the IAQ determinants during school hours. Indoor PM, temperature, RH and VOCs increased with progressing school periods in the day, while indoor CO2 decreased. Indoor RH and CO2 were negatively associated with % open windows, while indoor PM2.5 was positively associated. Most of school time (85%), indoor air temperature exceeded the recommended upper limit (27 °C), while a third of indoor PM2.5 (24-h) measurements exceeded 15 µg/m3. The interplay of clean indoor air with adequate ventilation and adaptation to heat stress in schools is important and its comprehensive characterization requires holistic methodological approaches and tools.

Effect of Calcium and Vitamin D Supplementation With and Without Collagen Peptides on Volumetric and Areal Bone Mineral Density, Bone Geometry and Bone Turnover in Postmenopausal Women With Osteopenia.

Collagen peptides (CPs) have been shown to potentially have a role as a treatment option in osteopenia. In the present randomized prospective study, we examined the effect of calcium, vitamin D with and without CPs supplementation on changes in volumetric bone mineral density (vBMD) and bone geometry assessed by peripheral quantitative computed tomography at the tibia, areal bone mineral density (aBMD) assessed by dual-energy X-ray absorptiometry at the lumbar spine and the hip and bone turnover markers over 12-mo. Fifty-one postmenopausal women with osteopenia were allocated to Group A who received orally 5 g CPs, 500 mg calcium and 400 IU vitamin D3 and Group B who received the same dose of calcium and vitamin D3 per day. The primary endpoint was the change of trabecular bone mineral content (BMC) and vBMD after 12-mo supplementation in Groups A and B. At the trabecular site (4% of the tibia length), Group A had a significant increase of total BMC by 1.96 ± 2.41% and cross-sectional area by 2.58 ± 3.91%, trabecular BMC by 5.24 ± 6.48%, cross-sectional area by 2.58 ± 3.91% and vBMD by 2.54 ± 3.43% and a higher % change of these parameters at 12 mo in comparison to Group B (p < 0.01, p = 0.04, p < 0.01, p = 0.04, p = 0.02, respectively). At the cortical site (38% of the tibia length), total and cortical vBMD increased by 1.01 ± 2.57% and 0.67 ± 1.71%. Furthermore, the mean aBMD at the spine was higher (p = 0.01), while bone markers decreased in Group A compared to Group B. The present study shows improvement of trabecular and cortical parameters as assessed by peripheral quantitative computed tomography at the tibia, prevention of aBMD decline and decrease of bone turnover after 12-mo supplementation with calcium, vitamin D with CPs.

Stakeholders' Perceptions of Environmental and Public Health Risks Associated with Hydrocarbon Activities in and around the Vasilikos Energy Center, Cyprus.

The Vasilikos Energy Center (VEC) is a large hydrocarbon industrial hub actively operating in Cyprus. There is strong public interest by the communities surrounding VEC to engage with all stakeholders towards the sustainable development of hydrocarbon in the region. The methodological framework of the exposome concept would allow for the holistic identification of all relevant environmental exposures by engaging the most relevant stakeholders in industrially contaminated sites. The main objectives of this study were to: (i) evaluate the stakeholders' perceptions of the environmental and public health risks and recommended actions associated with the VEC hydrocarbon activities, and (ii) assess the stakeholders' understanding and interest towards exposome-based technologies for use in oil and gas applications. Methods: Six major groups of stakeholders were identified: local authorities, small-medium industries (SMIs) (including multi-national companies), small-medium enterprises (SMEs), academia/professional associations, government, and the general public residing in the communities surrounding the VEC. During 2019-2021, a suite of stakeholder engagement initiatives was deployed, including semi-structured interviews (n = 32), a community survey for the general public (n = 309), technical meetings, and workshops (n = 4). Results from the semi-structured interviews, technical meetings and workshops were analyzed through thematic analysis and results from the community survey were analyzed using descriptive statistics. Results: Almost all stakeholders expressed the need for the implementation of a systematic health monitoring system for the VEC broader area and its surrounding residential communities, including frequent measurements of air pollutant emissions. Moreover, stricter policies by the government about licensing and monitoring of hydrocarbon activities and proper communication to the public and the mass media emerged as important needs. The exposome concept was not practiced by the SMEs, but SMIs showed willingness to use it in the future as part of their research and development activities. Conclusions: The sustainable development of hydrocarbon exploitation and processing prospects for Cyprus involves the VEC. Continuous and active collaboration and mutual feedback among all stakeholders involved with the VEC is essential, as this may allow future environmental and occupational health initiatives to be formalized.

Teriparatide Treatment in Patients with Pregnancy- and Lactation-Associated Osteoporosis.

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare disease, presenting in most cases with severe back pain due to low energy vertebral fractures (VFs). Our purpose was to assess the effect of teriparatide (TPTD) vs. conventional management on areal bone mineral density (aBMD) and trabecular bone score (TBS) in patients with PLO. A multicenter retrospective cohort study concerning premenopausal women with PLO. Nineteen women were treated with TPTD (20 µg/day) (group A) plus calcium and vitamin D and eight women with calcium and vitamin D only (group B) for up to 24 months. The primary end-point was between group differences in lumbar spine (LS) and total hip (TH) aBMD, and TBS at 12 and 24 months. Patients in group A had sustained a median of 4.0 VFs (3-9) vs. 2.5 VFs (1-10) in group B (p = 0.02). At 12 months, patients on TPTD vs. controls achieved a mean aBMD increase of 20.9  ±  11.9% vs. 6.2  ±  4.8% at the LS (p < 0.001), 10.0  ±  11.6% vs. 5.8  ±  2.8% at the TH (p = 0.43), and 6.7  ±  6.9% vs. 0.9  ±  3.7% in TBS (p = 0.09), respectively. At 24 months, seven patients on TPTD and six controls achieved a mean LS aBMD increase of 32.9  ±  13.4% vs. 12.2  ±  4.2% (p = 0.001). P1NP levels during the first month of TPTD treatment were positively correlated with the 1-year LS aBMD change (r = 0.68, p = 0.03). No new clinical fractures occurred while on-treatment. In patients with PLO, TPTD treatment resulted in significantly greater increases in LS aBMD compared with calcium and vitamin D supplementation at 12 and 24 months.

Recommendations on the measurement and the clinical use of vitamin D metabolites and vitamin D binding protein - A position paper from the IFCC Committee on bone metabolism.

Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function. The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other "molecules" related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results.

Analytical Performance Specifications for 25-Hydroxyvitamin D Examinations.

Currently the 25-hydroxy vitamin D (25(OH)D) concentration is thought to be the best estimate of the vitamin D status of an individual. Unfortunately, its measurement remains complex, despite recent technological advances. We evaluated the biological variation (BV) of 25(OH)D in order to set analytical performance specifications (APS) for measurement uncertainty (MU). Six European laboratories recruited 91 healthy participants. The 25(OH)D concentrations in K3-EDTA plasma were examined weekly for up to 10 weeks in duplicate on a Lumipulse G1200 (Fujirebio, Tokyo, Japan). The linear regression of the mean 25(OH)D concentrations at each blood collection showed that participants were not in a steady state. The dissection of the 10-sample collection into two subsets, namely collections 1-5 and 6-10, did not allow for correction of the lack of homogeneity: estimates of the within-subject BV ranged from 5.8% to 7.1% and the between-subject BV ranged from 25.0% to 39.2%. Methods that would differentiate a difference induced by 25(OH)D supplementation at p < 0.05 should have MU < 13.6%, while at p < 0.01, the MU should be <9.6%. The development of APS using BV assumes a steady state of patients. The findings in this study suggest that patients are not in steady state. Therefore, APS that are based on MU appear to be more appropriate.

Variation in surgical management of primary hyperparathyroidism in the US Department of Veterans Affairs healthcare system: A 15-year observational study.

BACKGROUND: Primary hyperparathyroidism is underdiagnosed and undertreated nationally despite the benefits of parathyroidectomy. However, the degree of hospital-level variation in the management of primary hyperparathyroidism is unknown. METHODS: We performed a national, retrospective study of Veterans with primary hyperparathyroidism using the Veterans Affairs Corporate Data Warehouse from January 2000 to September 2015. The objective was to characterize the extent of hospital-level variation in the use of parathyroidectomy for the management of primary hyperparathyroidism within a national, integrated healthcare system. Rate of parathyroidectomy in patients with primary hyperparathyroidism was stratified by (1) geographic region, (2) facility complexity level, (3) volume of parathyroidectomies per facility, and (4) frequency of parathyroid hormone testing in hypercalcemic patients. RESULTS: Among 47,158 Veterans with primary hyperparathyroidism, 6,048 (12.8%) underwent parathyroidectomy. Rates of parathyroidectomy were significantly higher in the Continental (17.0%) and Pacific (16.0%) regions than in other areas (11.4%, P < .01). The highest complexity referral centers had the highest rate of parathyroidectomy (13.6%) compared with all other facilities (12.1%, P < .01). Centers that performed the highest volume of parathyroidectomies were more likely to offer surgery (13.3%) than low volume centers (8.9%, P < .01). Facilities with higher frequency of parathyroid hormone testing among hypercalcemic patients were more likely to offer parathyroidectomy (15.2%) than those with the lowest parathyroid hormone testing frequency (12.6%, P < .01). CONCLUSION: Although there is notable variation in parathyroidectomy use for definitive treatment of primary hyperparathyroidism between Veterans Affairs facilities, parathyroidectomy rates are low across the entire system. Further research is needed to understand additional local contextual and other patient and clinician-level factors for the undertreatment of primary hyperparathyroidism to subsequently guide corrective interventions.

Standardized Map of Iodine Status in Europe.

Background: Knowledge about the population's iodine status is important, because it allows adjustment of iodine supply and prevention of iodine deficiency. The validity and comparability of iodine-related population studies can be improved by standardization, which was one of the goals of the EUthyroid project. The aim of this study was to establish the first standardized map of iodine status in Europe by using standardized urinary iodine concentration (UIC) data. Materials and Methods: We established a gold-standard laboratory in Helsinki measuring UIC by inductively coupled plasma mass spectrometry. A total of 40 studies from 23 European countries provided 75 urine samples covering the whole range of concentrations. Conversion formulas for UIC derived from the gold-standard values were established by linear regression models and were used to postharmonize the studies by standardizing the UIC data of the individual studies. Results: In comparison with the EUthyroid gold-standard, mean UIC measurements were higher in 11 laboratories and lower in 10 laboratories. The mean differences ranged from -36.6% to 49.5%. Of the 40 postharmonized studies providing data for the standardization, 16 were conducted in schoolchildren, 13 in adults, and 11 in pregnant women. Median standardized UIC was <100 µg/L in 1 out of 16 (6.3%) studies in schoolchildren, while in adults 7 out of 13 (53.8%) studies had a median standardized UIC <100 µg/L. Seven out of 11 (63.6%) studies in pregnant women revealed a median UIC <150 µg/L. Conclusions: We demonstrate that iodine deficiency is still present in Europe, using standardized data from a large number of studies. Adults and pregnant women, particularly, are at risk for iodine deficiency, which calls for action. For instance, a more uniform European legislation on iodine fortification is warranted to ensure that noniodized salt is replaced by iodized salt more often. In addition, further efforts should be put on harmonizing iodine-related studies and iodine measurements to improve the validity and comparability of results.

Effect of calcium and vitamin D supplementation with and without collagen peptides on bone turnover in postmenopausal women with osteopenia.

OBJECTIVES: Collagen peptides (CPs) seem to exert beneficial effects on bone and may have a role as a treatment option. In the present randomized prospective study, we aimed to examine the efficacy, as expressed by changes in P1NP and CTX, and the tolerability of 3-month supplementation of calcium, vitamin D with or without bioactive CPs in postmenopausal women with osteopenia. METHODS: Fifty-one female, postmenopausal women with osteopenia were allocated to two groups: Group A received a sachet containing 5 g CPs, 3.6 g calcium lactate (equivalent to 500 mg of elemental calcium) and 400 IU vitamin D3 and group B received a chewable tablet containing 1.25 g calcium carbonate (equivalent to 500 mg of elemental calcium) and 400 IU vitamin D3 daily. RESULTS: In group A, the P1NP levels significantly decreased by 13.1% (p<0.001) and CTX levels decreased by 11.4% (p=0.058) within 3 months of supplementation. In group B, P1NP and CTX did not change. Group A presented better compliance in comparison to group B and no adverse events contrary to group B. CONCLUSIONS: These findings may reflect the reduction of the increased bone turnover in postmenopausal women with the use of calcium, vitamin D and CPs supplements. The addition of CPs in a calcium and vitamin D supplement may enhance its already known positive effect on bone metabolism. Clinical Trial ID: NCT03999775.

Possible Obesogenic Effects of Bisphenols Accumulation in the Human Brain.

Evidence of bisphenols' obesogenic effects on humans is mixed and inconsistent. We aimed to explore the presence of bisphenol A (BPA), bisphenol F (BPF) and chlorinated BPA (ClBPA), collectively called the bisphenols, in different brain regions and their association with obesity using post-mortem hypothalamic and white matter brain material from twelve pairs of obese (body mass index (BMI) >30 kg/m2) and normal-weight individuals (BMI <25 kg/m2). Mean ratios of hypothalamus:white matter for BPA, BPF and ClBPA were 1.5, 0.92, 0.95, respectively, suggesting no preferential accumulation of the bisphenols in the grey matter (hypothalamic) or white matter-enriched brain areas. We observed differences in hypothalamic concentrations among the bisphenols, with highest median level detected for ClBPA (median: 2.4 ng/g), followed by BPF (2.2 ng/g) and BPA (1.2 ng/g); similar ranking was observed for the white matter samples (median for: ClBPA-2.5 ng/g, BPF-2.3 ng/g, and BPA-1.0 ng/g). Furthermore, all bisphenol concentrations, except for white-matter BPF were associated with obesity (p < 0.05). This is the first study reporting the presence of bisphenols in two distinct regions of the human brain. Bisphenols accumulation in the white matter-enriched brain tissue could signify that they are able to cross the blood-brain barrier.

Video. Transanal specimen retrieval using the transanal endoscopic microsurgery (TEM) system in minimally invasive colon resection.

BACKGROUND: During laparoscopic colectomy, the specimen is retrieved through substantial incisions, which increase postoperative pain, wound infections, and incisional hernias. In the era of natural orifice transluminal endoscopic surgery (NOTES), incisionless transrectal approaches for colon resections have been investigated with promising results [4-6]. Transanal retrieval of the colonic specimen in laparoscopic colectomy has been described but not widely adopted, although it seems to be an appealing step towards NOTES colectomy. We have used the TEM rectoscope (Richard Wolf Medical Instruments Corporation, Vernon Hills, IL, USA) as a retrieval conduit, which facilitates transanal extraction of the specimen, and protects the rectal edge and anal sphincter during laparoscopic left colectomy. TECHNIQUE: After standard laparoscopic dissection and vascular control, the colon is divided distally, whereas the proximal colonic end is ligated to prevent fecal spillage. The TEM rectoscope is advanced through the rectal stump. The proximal colon is grasped and withdrawn through the rectoscope. The colon is stapled off proximally, and the specimen is removed transanally. An anvil is introduced into the pelvis through the rectoscope and inserted in the descending colon through a colotomy, which is subsequently sealed with an endo-loop. The rectoscope is withdrawn, and the rectal stump edge is stapled off. A circular stapler is introduced in the rectum, and end-to-end anastomosis is performed. DISCUSSION: The extraction incisions in laparoscopic colectomy increase invasiveness and compromise the "purity" of the laparoscopic approach. Retrieval of the specimen through natural orifices constitutes a stepping stone in the transition to future incisionless NOTES colectomy. These techniques have not been widely adopted because of technical difficulties and concerns regarding trauma. In our experience, transanal retrieval of the colonic specimen is hampered by friction between the specimen and the rectum, which requires countertraction to the edges of the open rectal stump. These manipulations are time consuming and increase the risk of injury, even when retrieval bags are used. The TEM rectoscope allows gentle dilation of the anus, provides stability during extraction, and protects the edges of the rectum, therefore decreasing the risk of rectal or anal canal injuries. It maintains pneumoperitoneum and eases retrieval of the specimen through the large-caliber metal conduit. Alternative options in the form of a rigid conduit would be the use of the transanal endoscopic operation device (Karl Storz, Tuttlingen, Germany), the plastic McCartney tube (Tyco Healthcare, Norwalk, CT, USA) used for transvaginal operations, or an anecdotally reported, "homemade" rectoscope from a customized polyvinyl chloride tube. Potential limitations of this technique include the increased cost of acquiring and using the TEM rectoscope, although this should not be significant if this reusable system is already available for transanal procedures. The 4 cm diameter of the TEM rectoscope can also be a limiting factor in the case of large, bulky, incompressible specimens or large colonic tumors. We have also avoided using this technique in patients with preexisting anal sphincter dysfunction and fecal incontinence, as well as in the presence of severe perianal disease (i.e., fistulae or fissures). Naturally, the open lumen in the peritoneal cavity raises concerns regarding bacterial contamination and potential tumor cell seeding in cases of cancer. Preliminary evidence on these issues comes from TEM and NOTES research without obvious signs of increased risk currently. We do not perform preoperative bowel preparation for our colectomies, but we do perform rectal enema with Betadine solution at the beginning of the procedure. CONCLUSIONS: Use of the TEM system facilitates transanal removal of the specimen and protects the anorectum during laparoscopic colectomy.

Alternative amendment for soluble phosphorus removal from poultry litter.

BACKGROUND, AIM, AND SCOPE: Alum (aluminum sulfate) is the currently preferred chemical amendment for phosphorus (P) treatment in poultry litter (PL). Aluminum-based drinking-water treatment residuals (Al-WTRs) are the waste by-product of the drinking-water treatment process and have been effectively used to remove P from aqueous solutions, but their effectiveness in PL water extracts has not been studied in detail. Elevated cost associated with alum could be minimized by using the equally effective WTRs to remove soluble P from PL, and they can be obtained at a minimal cost from drinking-water treatment plants. MATERIALS AND METHODS: We set up batch and incubation experiments to determine: (1) the effect of WTR amendment rates on PL water-extractable P (WEP) concentrations and (2) the effects of incubation time, pH, and temperature on WEP concentrations of WTR-amended PL. RESULTS: Removal of PL-soluble P by the WTR was biphasic, showing an initial fast reaction (60% removal within 10 min) followed by a slower reaction that was completed within 12 days (90% removal). Phosphorus removal by the WTR was unaffected by pH changes in the range of 3-8. Incubation experiments showed that all WTR rates (2.5-15 wt.%) significantly (p < 0.001) lowered WEP concentrations in PL to approximately 40% of the unamended PL (no WTR) at 23 degrees C. DISCUSSION: Minimal reduction (20% of the unamended PL) in WEP concentrations for all WTR rates were observed up to 18 days, possibly due to P diffusion limitations. Increasing the temperature to 35 degrees C resulted in overcoming such diffusion limitations by increasing P removal rate of reaction. CONCLUSIONS: Assuming year-round availability of adequate quantities in nearby drinking-water treatment plants, WTR may be a cost-effective treatment to reduce P availability in poultry litter. RECOMMENDATIONS AND PERSPECTIVES: Field experiments are greatly needed in order to demonstrate the excellent performance of WTR in this laboratory-based study to remove soluble P concentrations in animal waste.

Bioavailability and bioaccessibility of arsenic in a soil amended with drinking-water treatment residuals.

Earlier incubation and greenhouse studies in our laboratory confirmed the effectiveness of drinking-water treatment residual (WTR) in decreasing soil arsenic (As) bioaccessibility as determined with in vitro tests, which led us to hypothesize a similar outcome if animal studies were to be conducted. Our objective was to evaluate the potential of WTR in lowering soil As bioavailability by conducting in vivo experiments and compare the in vitro to the in vivo As data. This study was performed using 6-week-old male BALB/c mice that were fed with an As-contaminated soil slurry using the gavage method. Blood and stomach contents were collected at 1 and 24 h after feeding. Urine and excreta were collected at time 0 (before feeding) and 24 h after feeding. Relative As bioavailability (RBA) values calculated from the blood samples of mice fed with WTR and WTR-amended soil samples ranged from 13% to 24% and from 25% to 29%, respectively; both were significantly (p < 0.001) lower than that of the unamended (no-WTR) soil (approximately 100% RBA). Absolute As bioavailability (ABA) in the gastric phase was significantly (p < 0.001) lowered, to 7-16%, in the WTR-amended soil compared with that of the unamended control (26%). A significant (p < 0.001) linear correlation (r = 0.94) was observed between the in vitro (stomach-phase) and the in vivo RBA data. Percentage recovery of As obtained from four mice tissue compartments (i.e., blood, stomach, urine, and fecal matter) after oral and intramuscular administrations was 63-80%. Results illustrate the effectiveness of in situ WTR amendment in decreasing in vivo soil As bioavailability, thereby lowering the potential cancer risk via an oral ingestion pathway.

In vitro model improves the prediction of soil arsenic bioavailability: worst-case scenario.

There is a strong interest in developing an in vitro arsenic (As) model that satisfactorily estimates the variability in in vivo relative oral bioavailability (RBA) measurements. Several in vitro tests have been developed, but none is universally accepted due to their limited success in predicting soil As RBA. A suite of amorphous and crystalline solid As phases were chosen, utilizing a worst-case scenario (WCS) that simulated fasting children's gastric solution chemistry. The objectives of this study were to (i) determine the effects of residence time, pH, and solid-to-solution ratio on As bioaccessibility and speciation in the in vitro gastric test; (ii) provide the fundamental basis for an optimized in vitro model constrained by the WCS; and (iii) validate the optimized in vitro test with the in vivo RBA obtained with BALB/c mice. The gastric pH was the only significant (p < 0.05) factor influencing solid As bioaccessibility. Bioaccessible As retained the oxidation state after its release from the solid into the gastric solution. The optimized in vitro model adequately predicted RBA values for a suite of solid As phases typically encountered in soils, with the exception of aluminum-based solids. This study is an excellent starting point for developing an in vitro test applicable to different As-contaminated soils.

Novel colorimetric method overcoming phosphorus interference during trace arsenic analysis in soil solution.

A sensitive (method detection limit, 2.0 microg As L(-1)) colorimetric determination of trace As(v) and As(iii) concentrations in the presence of soluble phosphorus (P) concentrations in soil/water extracts is presented. The proposed method modifies the malachite green method (MG) originally developed for P in soil and water. Our method relies upon the finding that As(iii) and As(v) do not develop the green color during P analysis using the MG method. When an optimum concentration of ascorbic acid (AA) is added to a sample containing up to 15 times P > As (microM) concentrations, the final sample absorbance due to P will be equal to that of As(v) molecules. The soluble As concentration can then be quantified by the concentration difference between the mixed oxyanion (As + P) absorbance (proposed method) and the MG method absorbance that measures only P. Our method is miniaturized using a 96-well microplate UV-VIS reader that utilizes minute reagent and sample volumes (120 and 200 microL sample(-1), respectively), thus, minimizing waste and offering flexibility in the field. Our method was tested in a suite of As-contaminated soils that successfully measured both As and P in soil water extracts and total digests. Mean% As recoveries ranged between 84 and 117%, corroborating data obtained with high-resolution inductively-coupled plasma mass-spectrometry. The performance of the proposed colorimetric As method was unaffected by the presence of Cu, Zn, Pb, Ni, Fe, Al, Si, and Cr in both neutral and highly-acidic (ca. pH 2) soil extracts. Data from this study provide the proof of concept towards creating a field-deployable, portable As kit.

Long-term phosphorus immobilization by a drinking water treatment residual.

Excessive soluble P in runoff is a common cause of eutrophication in fresh waters. Evidence indicates that drinking water treatment residuals (WTRs) can reduce soluble P concentrations in P-impacted soils in the short term (days to weeks). The long-term (years) stability of WTR-immobilized P has been inferred, but validating field data are scarce. This research was undertaken at two Michigan field sites with a history of heavy manure applications to study the longevity of alum-based WTR (Al-WTR) effects on P solubility over time (7.5 yr). At both sites, amendment with Al-WTR reduced water-soluble P (WSP) concentration by >or=60% as compared to the control plots, and the Al-WTR-immobilized P (WTR-P) remained stable 7.5 yr after Al-WTR application. Rainfall simulation techniques were utilized to investigate P losses in runoff and leachate from surface soils of the field sites at 7.5 yr after Al-WTR application. At both sites, amendment with Al-WTR reduced dissolved P and bioavailable P (BAP) by >50% as compared to the control plots, showing that WTR-immobilized P remained nonlabile even 7.5 yr after Al-WTR amendment. Thus, WTR-immobilized P would not be expected to dissolve into runoff and leachate to contaminate surface waters or groundwater. Even if WTR-P is lost via erosion to surface waters, the bioavailability of the immobilized P should be minimal and should have negligible effects on water quality. However, if the WTR particles are destroyed by extreme conditions, P loss to water could pose a eutrophication risk.

Arsenic immobilization in soils amended with drinking-water treatment residuals.

Use of Fe/Al hydroxide-containing materials to remediate As-contaminated sites is based on the general notion that As adsorption in soils is primarily controlled by Fe/Al (hydr)oxides. A low-cost and potentially effective substitute for natural Fe/Al hydroxides could be the drinking-water treatment residuals (WTRs). Earlier work in our laboratory has shown that WTRs are effective sorbents for As in water. We hypothesized that land-applied WTRs would work equally well for As-contaminated soils. Results showed that WTRs significantly (p<0.001) increased the soil As sorption capacity. All WTR loads (2.5, 5, and 10%) significantly (p<0.001) increased the overall amount of As sorbed by both soils when compared with that of the unamended controls. The amount of As desorbed with phosphate (7500 mg kg(-1) load) was approximately 50%. The WTR effectiveness in increasing soil As sorption capacities was unaffected by differences in both soils' chemical properties.

Physicochemical properties related to long-term phosphorus retention by drinking-water treatment residuals.

Drinking-water treatment residuals (WTRs) are nonhazardous materials that can be obtained free-of-charge from drinking-water treatment plants to reduce soluble phosphorus (P) concentrations in poorly P sorbing soils. Phosphorus sorption capacities of WTRs can vary 1-2 orders of magnitude, on the basis of short-term equilibration times (up to 7 d), but studies dealing with long-term (weeks to months) P retention by WTRs are lacking. Properties that most affect long-term P sorption capacities are pertinent to the efficacy of WTRs as amendments to stabilize P in soils. This research addressed the long-term (up to 80 d) P sorption/desorption characteristics and kinetics for seven WTRs, including the influence of specific surface area (SSA), porosity, and total C content on the overall magnitude of P sorption by seven WTRs. The data confirm a strong but variable affinity for P by WTRs. Aluminum-based WTRs tended to have higher P sorption capacity than Fe-based WTRs. Phosphorus sorption with time was biphasic in nature for most samples and best fit to a second-order rate model. The P sorption rate dependency was strongly correlated with a hysteretic P desorption, consistent with kinetic limitations on P desorption from micropores. Oxalate-extractable Al + Fe concentrations of the WTRs did not effectively explain long-term (80 d) P sorption capacities of the WTRs. Micropore (CO2-based) SSAs were greater than BET-N2 SSAs for most WTRs, except those with the lowest (<80 g kg(-1)) total C content. There was a significant negative linear correlation between the total C content and the CO2/N2 SSA ratio. The data suggest that C in WTRs increases microporosity, but reduces P sorption per unit pore volume or surface area. Hence, variability in C content confounds direct relations among SSA, porosity, and P sorption. Total C, N2-based SSA, and CO2-based SSAs explained 82% of the variability in the long-term P sorption capacities of the WTRs. Prediction of long-term P sorption capacities for different WTRs may be achieved by taking into account the three proposed variables.