Analyzing working time and efficient caries removal using a novel bioactive caries detecting dye and air polisher prophy for caries excavation: randomised clinical trial.

OBJECTIVES: This study aims to analyze the working time consumed during caries excavation and pain perception while using a novel Bioactive caries-detecting dye solution (BCD), an Air Polisher Prophy and a combination. MATERIALS AND METHODS: Four groups (in each group, n = 20 permanent teeth) were selected from 60 people between 17 and 40 years of age. The study included teeth with occlusal dentinal caries in the molars with cavity entrance sizes of less than 2 mm (clinically and radiographically). Randomization software was used to assign patients to various groups. Group A: Conventional Rotary Drilling, Group B: BCD + Mechanical Excavation (Spoon Excavator), Group C: Air Polisher Prophy, and Group D: BCD + Air Polisher Prophy 0.5 mL BCD was applied with a micro brush to the carious tooth surface for 40 s in groups B and D. After that, radiographs were performed to see if the radiopaque extension was visible. For mechanical caries extraction, a spoon excavator was used for group B, and an air polisher prophy was employed for group D. For mechanical caries extraction, a spoon excavator was utilized for group B. An air polisher prophy was employed for group D. Multiple applications of the BCD were used in the event of residual caries. Working time and pain experienced during caries excavation were registered using the Verbal Pain Scale (VPS) (score 0-4), and caries removal was clinically graded using the modified Scale (score 0-5). RESULTS: The time taken was Group A, Group D, Group B, and Group C, according to statistical analysis using ANOVA and the Post Hoc Test (275.02, 403.8, 461.98, 615.41 s, respectively). Group A had the highest mean VPS (1.85), whereas Group B had the most minor pain (0.6), followed by Group D (1.2) and Group C (0.6). (1.45). Group C (2.35), followed by groups D (1.75), B (1.30), and A (1.30), had ineffective caries eradication (0.90). (p < 0.05). CONCLUSIONS: compared to group C, groups B and D took less time and had less/no pain while excavating caries. Compared to traditional mechanized caries removal methods, the chemo-chemical BCD can diagnose and aid in successful caries removal with minimal pain. CLINICAL RELEVANCE: The outcomes of the present study demonstrated that the chemo-chemical bioactive caries detecting dye solution has the potential to identify and help in effective caries removal before mechanized caries removal methods.

Prevalence of obstructive sleep apnoea syndrome in oncological patients: A systematic review and meta-analysis.

BACKGROUND: Obstructive sleep apnoea syndrome (OSAS) has garnered increasing attention in recent years due to its potential association with cancer. This systematic review and meta-analysis aimed to assess the prevalence of OSAS in cancer patients through a comprehensive analysis of existing literature. METHODS: This systematic review and meta-analysis, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, aimed to evaluate the prevalence of OSAS in cancer patients. A comprehensive search of electronic databases was performed to identify relevant studies published up to September 2021. Eligible studies reporting on the prevalence of OSAS in cancer patients, encompassing various study designs, were included in the analysis. Pooled estimates of the odds ratios (OR) with 95% confidence intervals (CIs) were calculated using a random effects model. Heterogeneity among the studies was assessed using the I2 statistic. RESULTS: Seventeen studies fulfilled the inclusion criteria and were subsequently included in the review. The prevalence of OSAS in cancer patients was estimated to have an overall OR of 0.80 (95% CI: 0.75-0.85). In comparison with non-cancer patients, cancer patients had a statistically significant greater risk of OSAS, as indicated by the total estimated RR for the prevalence of OSAS in cancer patients, which was 0.89 (95% CI: 0.86-0.92). Nonetheless, there was a significant amount of heterogeneity (I2 = 96%) among the studies. CONCLUSION: The overall data analysed in this review indicates that patients with cancer had far reduced likelihood of developing OSAS than individuals without cancer. However, the significant variation across the included studies highlights the need for additional investigation to fully clarify the complex association between OSAS and cancer incidence. These results emphasise how critical it is to identify OSAS as a possible comorbidity in cancer patients, one that should be taken into account for clinical management and ongoing research.

Volumetric analysis after caries excavation with caries detecting dyes and chemomechanical caries removal agents using 3D scanner-a randomised clinical trial.

AIM: This research aimed to use an extra-oral 3D scanner for conducting volumetric analysis after caries excavation using caries-detecting dyes and chemomechanical caries removal agents in individuals with occlusal and proximal carious lesions. METHODS: Patients with occlusal (A1, A2, A3) and proximal carious lesions (B1, B2, B3) were treated with the conventional rotary technique, caries detecting dyes (CDD) and chemomechanical caries removal (CMCR) method on 90 teeth (n = 45 for each). Group A1, B1: Excavation was performed using diamond points. Group A2, B2: CDD (Sable Seek™ caries indicator, Ultradent) was applied and left for 10 s, and then the cavity was rinsed and dried. For caries removal, diamond points or excavators were used. Group A3 and B3: BRIX3000 papain gel was applied with a micro-brush for 20 s and was activated for 2 min, and then the carious tissue was removed with a sharp spoon excavator. Post-excavation cavity volume analysis was performed using a 3D scanner. The time required and the verbal pain score (VPS) for pain were scored during excavation. Post-restoration evaluation was performed at 1, 3, and 6 months FDI (Federation Dentaire Internationale) criteria. RESULTS: Comparison of age, time and volume with study groups were made using Independent Sample' t' test and one-way analysis of variance (ANOVA) for two and more than two groups, respectively. Using Cohen's Kappa Statistics, evaluators 1 and 2 agreed on caries removal status aesthetic, functional and biological properties at different follow-ups. The chi-square test revealed that the rotary groups [A1(2.5 ± 0.4 min) B1(4.0 ± 0.4 min)] had significantly less (p = 0.000) mean procedural time than CDD [A2(4.5 ± 0.4 min) B2(5.7 ± 0.4 min)] and CMCR [A3(5.4 ± 0.7 min) B3(6.2 ± 0.6 min)] groups. The CMCR group showed better patient acceptance and less pain during caries excavation than the rotary and CDD groups. CMCR group showed significantly less mean caries excavated volume(p = 0.000). Evaluation of restoration after 1-, 3-, and 6-month intervals was acceptable for all the groups. CONCLUSION: Brix3000 helps effectively remove denatured teeth with less pain or sensitivity. The time required for caries removal was lowest in the rotary method and highest in the brix3000 group, while the volume of caries removed was the lowest for brix3000 and highest for the rotary group.

Effect of co-trimoxazole and N-acetylcysteine alone and in combination on bacterial adherence on ureteral stent surface.

To assess the effect of co-trimoxazole and N-acetylcysteine (NAC), alone and in combination, on bacterial adherence to biofilm formed on ureteral stent surfaces. This prospective randomized study was conducted on 636 patients who underwent double J ureteral stent insertion after variable urological procedures. Patients were randomized into four groups: A (n = 165), no antibiotics or mucolytics during stent indwelling; B (n = 153), oral NAC (200 mg/day for children aged < 12 years old and 600 mg/day for adults) during stent indwelling; C (n = 162), oral co-trimoxazole (2 mg TMP/kg/day) during stent indwelling; and D (n = 156), both oral NAC and co-trimoxazole during stent indwelling. Two weeks following double J stent (JJ stent) insertion, urinalysis was performed on all patients and urine culture was done for all the patients at the day of double J stent removal. The stent was removed 2 weeks postoperatively, and a stent segment sized 3-5 cm from the bladder segment of the stent was sent for culture. Positive stent cultures were found in 63.6% (105/165), 43.1% (66/153), 37% (60/162), and 19.2% (30/156) patients of groups A, B, C, and D, respectively. E. coli was the organism most commonly isolated from the stent culture in all groups. The combination of co-trimoxazole and NAC was more effective in reducing bacterial adherence on ureteral stent surfaces than either alone.

Allosteric Inhibitors of Macrophage Migration Inhibitory Factor (MIF) Interfere with Apoptosis-Inducing Factor (AIF) Co-Localization to Prevent Parthanatos.

Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine and essential signaling protein associated with inflammation and cancers. One of the newly described roles of MIF is binding to apoptosis-inducing factor (AIF) that "brings" cells to death in pathological conditions. The interaction between MIF and AIF and their nuclear translocation stands as a central event in parthanatos. However, classical competitive MIF tautomerase inhibitors do not interfere with MIF functions in parthanatos. In this study, we employed a pharmacophore-switch to provide allosteric MIF tautomerase inhibitors that interfere with the MIF/AIF co-localization. Synthesis and screening of a focused compound collection around the 1,2,3-triazole core enabled identification of the allosteric tautomerase MIF inhibitor 6y with low micromolar potency (IC50 = 1.7 ± 0.1 µM). This inhibitor prevented MIF/AIF nuclear translocation and protects cells from parthanatos. These findings indicate that alternative modes to target MIF hold promise to investigate MIF function in parthanatos-mediated diseases.

Comparative Evaluation of Efficacy of Protaper Universal Retreatment System, R-Endo System and Hedstrom File in Gutta Percha Removal During Root Canal Retreatment- An In Vitro Study.

Background: The complete removal of residual filling materials from the root canal determines the success of root canal retreatment. Aim: To evaluate and correlate the efficacy of ProTaper retreatment system, R-Endo retreatment system, and Hedstrom file in the removal of gutta-percha and sealer from root canal during endodontic retreatment in addition to the period desired for the elimination of gutta-percha and sealer. Methodology: Thirty extracted premolars were prepared and filled by cold lateral compaction with gutta-percha and sealer. Retreatment was finished with ProTaper retreatment files, R-Endo files, Hedstrom files with Endosolv E as the solvent for 10 specimens each. Each half of the root was imaged using the image analyzer software Chroma allied to a stereomicroscope with 10× magnification via a charge-coupled device sensor. For statistical analysis, parametric one-way ANOVA test and Scheffe post hoc multiple range test were utilized at a significance level of P < 0.05. Results: There is no significant difference among the three groups at P < 0.0001 in removing filling material. However, the rotary files needed significantly less time for removing gutta-percha along with sealer than H-file (P < 0.0001). Conclusion: The gutta-percha and sealer were found in the root canal subsequent to all the retreatment techniques, especially in the apical third. Retreatment time was less only for the rotary system.

A Vaccine Construction against COVID-19-Associated Mucormycosis Contrived with Immunoinformatics-Based Scavenging of Potential Mucoralean Epitopes.

Mucormycosis is a group of infections, caused by multiple fungal species, which affect many human organs and is lethal in immunocompromised patients. During the COVID-19 pandemic, the current wave of mucormycosis is a challenge to medical professionals as its effects are multiplied because of the severity of COVID-19 infection. The variant of concern, Omicron, has been linked to fatal mucormycosis infections in the US and Asia. Consequently, current postdiagnostic treatments of mucormycosis have been rendered unsatisfactory. In this hour of need, a preinfection cure is needed that may prevent lethal infections in immunocompromised individuals. This study proposes a potential vaccine construct targeting mucor and rhizopus species responsible for mucormycosis infections, providing immunoprotection to immunocompromised patients. The vaccine construct, with an antigenicity score of 0.75 covering, on average, 92-98% of the world population, was designed using an immunoinformatics approach. Molecular interactions with major histocompatibility complex-1 (MHC-I), Toll-like receptors-2 (TLR2), and glucose-regulated protein 78 (GRP78), with scores of -896.0, -948.4, and -925.0, respectively, demonstrated its potential to bind with the human immune receptors. It elicited a strong predicted innate and adaptive immune response in the form of helper T (Th) cells, cytotoxic T (TC) cells, B cells, natural killer (NK) cells, and macrophages. The vaccine cloned in the pBR322 vector showed positive amplification, further solidifying its stability and potential. The proposed construct holds a promising approach as the first step towards an antimucormycosis vaccine and may contribute to minimizing postdiagnostic burdens and failures.

Comparative evaluation of mechanical and physical properties of a new bulk-fill alkasite with conventional restorative materials.

PURPOSE: The physical and mechanical performance of a newly commercialized dental restorative material (alkasite) was compared with glass ionomer cement (GIC) and nano-hybrid composite. METHODOLOGY: Human extracted premolars were used to investigate the shear bond strength. Restorative materials were placed on the dentine surface and were aged in deionized water for 14 days. The 3-D surface roughness was evaluated before and after chewing simulation cycles (50,000). The samples were fatigued mechanically using a chewing simulator and investigated with a scanning electron microscope (SEM). RESULTS: For shear bond strength, alkasite showed significantly high values than GIC, whereas non-significant difference was observed between alkasite and nano-hybrid composite. After the chewing simulation (50,000 cycles), non-significant difference was found between GIC and nano-hybrid composite, where surface roughness values were highest for GIC and lowest for alkasite. CONCLUSION: The newly developed restorative material (alkasite) has shown better results than existing restorative materials.

Examining the Effect of Gravity on Different Irrigation Systems: An In vitro Study.

BACKGROUND: Periapical extrusion is frequently observed during endodontic therapy. It can lead to acute injury of periapical tissues, resulting in interappointment pain or swelling. The effect is pronounced in teeth with immature apex, which are more susceptible to the extrusion of irrigant. The aim of this study was to evaluate the effect of gravity on the apical extrusion of irrigating solution with different irrigation protocols in single-rooted premolars. METHODOLOGY: A total number of 80 permanent single-rooted teeth (premolars) with same working length (WL) were divided into two main groups: Group A: Penetration depth of irrigation syringe to 2 mm from the WL and Group B: Penetration depth of irrigation syringe to 4 mm from the WL. Each group was subdivided into four subgroups. (n = 10). The extruded debris and irrigants were weighed, and the data were statistically analyzed by the analysis of variance and the Tukey test. RESULTS: Irrespective of the irrigation technique used, the amount of irrigant extruded from the apex showed a statistically significant difference related to the effect of gravity (P < 0.05). There was no statistically significant difference observed between irrigation methods (P > 0.05). CONCLUSION: The degree of apical extrusion of irrigant was dependent on the type of irrigation technique and gravity. Greater caution should be taken during irrigation to prevent postoperative pain.

Synergistic Effect of Plant Extracts on Endodontic Pathogens Isolated from Teeth with Root Canal Treatment Failure: An In Vitro Study.

BACKGROUND AND OBJECTIVES: This study aimed to evaluate the synergistic antimicrobial activity of extracts obtained from Salvadora persica (Miswak), Commiphora molmol (myrrh) and Azadirachta indica (neem) in combination with commercially available antimicrobial agents: penicillin, tetracycline, ofloxacin and fluconazole on endodontic pathogens such as Enterococcus faecalis, Streptococcus mitis,Actinomyces naeslundii and Candida albicans. MATERIALS AND METHODS: Microbiological samples from the root canals of the teeth undergoing retreatment were taken using sterile paper points kept at full length in the canal for 30 s. The disc diffusion method was used to check the susceptibility of microbes to the plant extracts and antimicrobials by measuring the diameter of the inhibition zones. Against the microbes, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) of the plant extracts were assessed. The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of plant extracts combined with antimicrobials against the resistant endodontic microbes. RESULTS: The findings clearly indicate the effectiveness of all the three plant extracts, Commiphora molmol, Azadirachta indica, Salvadora persica, against all the experimental pathogenic microorganisms except for the ineffectiveness of Azadirachta indica, Salvadora persica against Candidaalbicans. Maximum antimicrobial activity was displayed by Azadirachta indica against Enterococcusfaecalis (MIC = 0.09 ± 1.2 mg/mL, MBC = 0.78 ± 1.25 mg/mL) and the minimum antimicrobial activity was displayed by Commiphora molmol against Actinomyces naeslundii (MIC = 12.5 ± 3.25 mg/mL, MBC = 100 ± 3.75 mg/mL). The best synergy was displayed by Commiphora molmol with fluconazole against Candidaalbicans (FICI = 0.45). CONCLUSIONS: The current study delineates the variable antimicrobial activity of plant extracts against the experimental endodontic pathogenic microorganisms. Plant extracts in conjunction with various antimicrobials can be valuable aids in combating relatively resistant endodontic microorganisms that have been the cause of worry in recent years, leading to failure even in treatment procedures following all required protocols.

The influence of long-term ageing on arsenic ecotoxicity in soil.

The ageing of a contaminant in soil influences the bioavailability and toxicity of environmental pollutants. Yet, despite arsenic (As) being an important terrestrial contaminant, the effect of As ageing on phytotoxicity has received relatively little research. Research to date has reported predominantly short term (< 0.5 years) experiments. Here, we studied the influence of ageing over 0.25 and 5 years on the phytotoxicity of As (as arsenate) on Cucumis sativus L. (cucumber). The study showed that increasing ageing time of As from 0.25 to 5 years increased the EC10 and EC50 values by 4.0 and 1.76 fold, respectively. The dependence of ageing on soil properties was also examined, although only Freundlich sorption parameters were correlated to the ageing factor (r = 0.68, P = 0.028). Soils with high adsorption capacity also showed the greatest change in toxicity over 5 years. In addition, data was compiled from relevant literature to develop a model for As ecotoxicity. The combined model (n = 54) showed no relationship with pH but was correlated to the oxalate extractable iron content and %clay. Arsenate ecotoxicity (EC50, mg/kg) in the multivariate model was related to oxalate iron content, %clay and ageing time. Thus, the results of this study have significant implications for risk assessment of long-term As contaminated soils.

Evaluation and Comparison of Antibacterial Efficacy of Herbal Extracts in Combination with Antibiotics on Periodontal pathobionts: An in vitro Microbiological Study.

BACKGROUND: In the past few decades focus of research has been toward herbal medicines because of growing bacterial resistance and side effects of antimicrobial agents. The extract derived from the plants may increase the efficacy of antibiotics when used in combination against pathogenic bacteria. In the current study, the synergistic antibacterial efficacy of plant extracts in combination with antibiotics has been assessed on selected periodontal pathogens. METHODS: Ethanolic extracts were prepared from Salvadora persica (Miswak) and Cinnamomum zeylanicum (Ceylon cinnamon), by the soxhalate method. Plaque samples were collected from clinical periodontitis patients to isolate and grow the periodontal pathobionts under favorable conditions. Susceptibility of bacteria to the extracts was assessed by gauging the diameter of the inhibition zones. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of plant extracts were determined against each bacterium. Synergistic activity of plants extract in combination with antibiotics against the bacteria was also assessed by measuring the diameter of the inhibition zones. RESULTS: Ethanolic extract of both the plants showed an inhibitory effect on the proliferation and growth of all four strains of periodontal pathobionts. Maximum antibacterial activity was exhibited by C. zeylanicum against Tannerella forsythia (MIC = 1.56 ± 0.24 mg/mL, MBC = 6.25 ± 0.68 mg/mL), whereas among all the studied groups the minimum activity was reported by C. zeylanicum against Aggregatibacter actinomycetemcomitans the (MIC = 12.5 ± 3.25 mg/mL, MBC = 75 ± 8.23 mg/mL). Combination of herbal extracts with different antibiotics revealed a synergistic antibacterial effect. The best synergism was exhibited by S. persica with metronidazole against A. actinomycetemcomitans (27 ± 1.78). CONCLUSIONS: Current in vitro study showed variable antibacterial activity by experimented herbal extracts against periodontal pathobionts. The synergistic test showed significant antibacterial activity when plant extracts were combined with antibiotics.

A Comparative Evaluation of Five Obturation Techniques in the Management of Simulated Internal Resorptive Cavities: An Ex Vivo Study.

BACKGROUND: Root resorption is the loss of dental hard tissues as a result of clastic activities. It might be broadly classified into external or internal resorption by the location of the resorption in relation to the root surface. the various techniques used these days for filling internal resorption include warm condensation, vertical condensation, core techniques, thermoplasticized gutta-percha, warm vertical compaction, and cold lateral condensation. OBJECTIVES: The aims and objectives of this study were to compare the quality of root fillings in artificially created internal resorption cavities filled with warm vertical compaction, lateral condensation, Obtura II along with System B, E and Q plus along with System B, and Thermafil, and to calculate the percentage of gutta-percha, sealer, and voids using an ImageJ software. RESULTS: Results between the warm vertical compaction (group I), lateral condensation (group II), Obtura II with System B (group III), E and Q plus with System B (group IV), and Thermafil (group V), group III showed the highest percentage of gutta-percha plus sealer and gutta-percha, and least number of voids, which was statistically significant (P < 0.000). CONCLUSION: It can be concluded that Obtura II along with System B was found to be the most suitable obturation technique for the management of teeth exhibiting internal resorption. Thermafil was found to give the poorest obturation quality when used to fill the teeth with internal resorption. Similarly, lateral condensation technique was observed to show maximum sealer and hence was not ideal for the management of internal resorptive cavities.

Modified roll technique for soft tissue augmentation in prosthetic rehabilitation: A case report.

There are various causes for residual alveolar ridge defects, most common being the collapse of the cortical plate during extraction. Localized defects of alveolar ridge affect prosthetic restoration due to poor emergence profile of the pontic. Various soft tissue augmentation procedures have been recommended for the correction of these defects. Abrams's roll technique has been widely used for soft tissue ridge augmentation in the maxillary anterior region where aesthetics is a prime concern. The original Abrams's roll technique has been modified and revisited by many authors to overcome the limitations. The present clinical case report discusses the modified roll technique as an option to treat alveolar ridge deformity. The current procedure resulted in expectable ridge augmentation, uneventful healing, and good aesthetic outcome. Hence this modified technique can be selected for the treatment of mild to moderate Seibert class I ridge defects in the aesthetic zone.

Comparison of Accuracy in Determining the Root Canal Working Length by Using Two Generations of Apex Locators - An In Vitro Study.

AIM: The present in-vitro study aims to compare the accuracy of root canal working length determination between the third generation and fourth generation electronic apex locators. MATERIAL AND METHODS: Fifty extracted single-rooted single canal teeth were selected for the study, and a definite coronal plane was prepared. Actual working length (AL) was measured using a stereomicroscope under 8X magnification. Electronic working length measurements were recorded using Root ZX (EL1) and Elements Diagnostic Unit (EL2) apex locators. One-way ANOVA test was carried out to analyse the data among the experimental groups. RESULTS: The results of the one-way ANOVA test showed that difference in the working length determined by either apex locators (EL1 and EL2) and actual length determined under a stereomicroscope (AL) was statistically not significant. The independent 't' test comparing between groups EL1 and AL; and EL2 and AL showed that working length determined by either of the apex locators (EL1 and EL2) and actual length determined under a stereomicroscope (AL) was statistically not significant. CONCLUSION: In this in vitro study, the Root ZX and Elements Diagnostic Unit apex locators are equally accurate for determination of working length when compared to actual working length.

Copper interactions on arsenic bioavailability and phytotoxicity in soil.

Arsenic (As) and copper (Cu) are co-contaminants in the environment but little is known about their ecological impact as mixtures in soil. In this study, we investigated the combined As-Cu interactions on toxicity and uptake as binary mixtures in 5 contrasting soils. The study included solubility, contaminant uptake and toxicity in cucumber (Cucumis sativus L.) as a model plant species. Soils were spiked individually and as a mixtures at 10 different As levels (2, 4, 8 up to 1024mgkg-1). Copper was added with As at two effective concentration levels (EC10Cu and EC50Cu). Arsenic uptake was significantly reduced in the presence of Cu and a higher effect was demonstrated with increasing pore-water pH. Copper accumulation was not significantly influenced by As. An additive response on plant growth was predominant overall when expressed from pore-water parameters with root mean square errors of 12.6 and 13.2 for EC10Cu and EC50Cu treatments, respectively.

Zinc-arsenic interactions in soil: Solubility, toxicity and uptake.

Arsenic (As) and zinc (Zn) are common co-contaminants in mining impacted soils. Their interaction on solubility and toxicity when present concurrently is not well understood in natural systems. The aim of this study was to observe their interaction in solubility (soil-solution), bioaccumulation (shoot uptake) and toxicity to cucumber (Cucumis sativa L) conducting 4 weeks pot study in 5 different soils spiked with As (0, 2, 4, 8 to 1024 mg kg-1) individually and with Zn at two phytotoxic doses. The As pore-water concentration was significantly reduced (df = 289, Adjusted R2 = 0.84, p < 0.01) in the presence of Zn in the whole dataset, whereas Zn and Zn2+ activity in pore-water was reduced significantly only in the two alkaline soils. This outcome may be due to adsorption/surface precipitation or tertiary bridging complexation. No homogenous precipitation of zinc arsenate could be established using electron microscopy, XRD or even equilibrium calculations. For bioaccumulation phase, no significant effect of Zn on As uptake was observed except acidic MG soil whereas, Zn uptake was significantly reduced (p < 0.05) by As in whole dataset. However, an additive response was observed mostly except acidic MG soil. The synergistic response (more than additive) was predominant in this soil for a wide range of inhibition concentration (0-80%) at both Zn EC10 and EC50 levels. Since additive response is mostly considered in risk assessment for mixtures, precautions should be implemented for assessment of toxicity for As-Zn mixture in acidic soil due to their synergistic response in some soils.

Toxicity of Inorganic Mercury to Native Australian Grass Grown in Three Different Soils.

In this study, three native Australian grasses namely Iseilema membranaceum (Barcoo), Dichanthium sericeum (Queensland Blue) and Sporobolus africanus (Tussock) were grown in three different soils spiked with different concentrations of inorganic mercury and the root elongation was monitored up to 28 days following the germination. Results showed that mercury at certain concentrations significantly inhibited the root growth of all three tested native grasses grown in three soils, however, the toxicity was less in the soil with high organic carbon content and acidic pH. The calculated EC50 values ranged from 10 to 224 mg/kg total Hg in soil. However, the EC10 values indicated that existing guideline values for mercury may be of protective to the native Australian vegetation. Considering their tolerance to soil mercury, these grass species have the potential for their use in rehabilitation of mercury contaminated sites.

Pore-Water Carbonate and Phosphate As Predictors of Arsenate Toxicity in Soil.

Phytotoxicity of inorganic contaminants is influenced by the presence of competing ions at the site of uptake. In this study, interaction of soil pore-water constituents with arsenate toxicity was investigated in cucumber (Cucumis sativa L) using 10 contrasting soils. Arsenate phytotoxicity was shown to be related to soluble carbonate and phosphate. The data indicated that dissolved phosphate and carbonate had an antagonistic impact on arsenate toxicity to cucumber. To predict arsenate phytotoxicity in soils with a diverse range of soil solution properties, both carbonate and phosphate were required. The relationship between arsenic and pore-water toxicity parameters was established initially using multiple regression. In addition, based on the relationship with carbonate and phosphate we successively applied a terrestrial biotic ligand-like model (BLM) including carbonate and phosphate. Estimated effective concentrations from the BLM-like parametrization were strongly correlated to measured arsenate values in pore-water (R2 = 0.76, P < 0.001). The data indicates that an ion interaction model similar to the BLM for arsenate is possible, potentially improving current risk assessments at arsenic and co-contaminated soils.

Predicting plant uptake of cadmium: validated with long-term contaminated soils.

Cadmium accumulates in plant tissues at low soil loadings and is a concern for human health. Yet at higher levels it is also of concern for ecological receptors. We determined Cd partitioning constants for 41 soils to examine the role of soil properties controlling Cd partitioning and plant uptake. From a series of sorption and dose response studies, transfer functions were developed for predicting Cd uptake in Cucumis sativa L. (cucumber). The parameter log Kf was predicted with soil pHca, logCEC and log OC. Transfer of soil pore-water Cd2+ to shoots was described with a power function (R 2 = 0.73). The dataset was validated with 13 long-term contaminated soils (plus 2 control soils) ranging in Cd concentration from 0.2 to 300 mg kg-1. The series of equations predicting Cdshoot from pore-water Cd2+ were able to predict the measured data in the independent dataset (root mean square error = 2.2). The good relationship indicated that Cd uptake to cucumber shoots could be predicted with Cdpore and Cd2+ without other pore-water parameters such as pH or Ca2+. The approach may be adapted to a range of plant species.