High Level Of Toxicity Research Articles

Impact of silver nanoparticles on secondary metabolite composition and toxicity in anise (Pimpinella anisum L.) callus culture

BackgroundThere are numerous challenges associated with producing desired amounts of secondary metabolites (SMs), which are mostly unique and cannot be chemically synthesized. Many studies indicate that nanoparticles (NPs) can boost the production of SMs. Still, the precise manner in which NPs induce metabolic changes remains unidentified. This study examines the influence of eco-friendly silver NPs (AgNPs) on the chemical makeup and toxicity of Pimpinella anisum L. (anise).ResultsAgNPs were introduced into anise callus cultures at different concentrations (0, 1.0, 5.0, 10, and 20 mg/L). The induced oxidative stress was tracked over intervals of 7, 14, 28, and 35 days. Chemical composition evaluations were carried out on the 35th day. Within the first 14 days, plant stress was evident, though the plant adapted to the stress later on. Notably, the plant showed high tolerance at 1 mg/L and 5 mg/L concentrations despite increased toxicity levels. However, relatively high toxicity levels were identified at 10 and 20 mg/L. The AgNP-induced stress significantly impacted anise SMs, particularly affecting fatty acid content. In the 10 and 20 mg/L AgNP groups, essential metabolites, including palmitic and linoleic acid, showed a significant increase. Polyunsaturated (omega) and monounsaturated fatty acids, vital for the food and pharmaceutical industries, saw substantial growth in the 1 and 5 mg/L AgNP groups. For the first time, vanillyl alcohol and 4-Hydroxybenzoic acid were detected along with various phenolic compounds, such as t-anethole, Salicylic acid, and Thiamazole.ConclusionAgNPs can function as an elicitor to efficiently generate essential SMs such as omegas and phenolic compounds in anise callus culture. This study explores the application of AgNPs as plant elicitors in anise SM production, offering invaluable insight into potential uses.

Baseline study for the total mercury determination in Yemeni fish

The high levels of mercury toxicity in humans make it necessary to monitor mercury levels in food, pharmaceuticals, and the environment to minimize human exposure. Between June 2020 and October 2021, researchers collected 240 fish samples from different locations along the Yemeni coast to evaluate mercury contamination. The Direct Mercury Analyzer was used to determine the concentration of mercury in each sample. To ensure method accuracy, a series of triplicate mercury concentration analyses were conducted. The samples ranged from 2 to 100 ng to determine linearity and repeatability i.e., within-day variation. The results showed a high level of precision, with a correlation coefficient of 0.9990 and a repeatability of 1.34 %–5.62 % RSD range. The method was also highly accurate, as the mercury recovery results from the contaminated fish samples ranged from 96.77 % to 105.14 %. The limits of detection and quantitation of mercury were 0.0015 ppm and 0.0049 ppm, respectively. This allowed the method to detect trace amounts of mercury in fish meat. Mercury concentration in the 240 fish samples did not exceed the FDA, but below the 0.5 ppm specified limit of YSMO.

Relationships between high-concentration toxic metals in sediment and evolution of microbial community structure and carbon-nitrogen metabolism functions under long-term stress perspective.

Microorganisms are highly sensitive to toxic metal pollution and play an important role in the material cycling and energy flow of the water ecosystem. Herein, 13 sediment samples from Junchong Reservoir (Guangxi Province, China) were collected in December 2021. The spatial distribution of pollution levels for toxic metals and the effects of toxic metals on the composition, functional characteristics, and metabolism of microorganisms were investigated. The results demonstrated that the area is a proximate area to industrial zones with severity of toxic metal pollution. Their mean concentrations of As, Cu, Zn, and Pb were up to 128.79mg/kg, 57.62mg/kg, 594.77mg/kg, and 97.12mg/kg respectively. There was a strong correlation between As, Cu, Zn, and Pb, with the highest correlation coefficient reaching 0.94. As the level of toxic metal pollution increases, the diversity and abundance of microorganisms gradually decrease. Compared to those with lower pollution levels, the Shannon index in regions with higher pollution levels decreases by up to 0.373, and the Chao index decreases by up to 143.507. However, the relative abundance of Bacteroidota, Patescibacteria, and Chloroflexi increased by 23%, 20%, and 5%, respectively, indicating their higher adaptability to toxic metals. Furthermore, microbial carbon and nitrogen metabolism were also affected by the presence of toxic metals. FAPROTAX analysis demonstrated an abundant reduction of ecologically functional groups associated with carbon and nitrogen transformations under high toxic metal pollution levels. KEGG pathway analysis indicated that carbon fixation and nitrogen metabolism pathways were inhibited with increasing toxic metal concentrations. These findings would contribute to a better understanding of the effects of toxic metal pollution on sediment microbial communities and function, shedding light on the ecological consequences of toxic metal contamination.

Eco-Friendly Remediation: Tea Leaves and Fibres as Adsorbents for High Cobalt Concentrations; Thermodynamics, Isotherms and Kinetic Studies

Increasing industrialization has produced huge amounts of liquid effluents, which are a key source of ecological unrest in diverse ecosystems. The high toxicity level of cobalt in surface water has drawn a lot ofattention; hence,a low-cost adsorbent made from leaves and fibres of Camellia sinensis has been developed to remove cobalt from wastewater. The kinetics of the pseudo-first and second-order sorption interaction, as well as the physicochemical parameters of the precursor adsorbent, was investigated. There was a linear relationship between Cobalt uptake and biosorbent dosage under ideal conditions; the optimum dosage was 4 g. Between 10 to 40 minutes of contact time, clearance of cobalt was greater than 90 per cent. The Gibb’s free energy (∆Go) at various temperatures ranges from -9980 to -1020, indicating a spontaneous system, viable for both parts of the precursor adsorbent. The entropy change (∆So) was found to be +31.05 and +35.12 for tea leaves and fibre respectively, implying a highly disordered biosorption interface. The enthalpy (∆Ho) was found to be-8.58 and -10.03 for tea leaves and fibres hence, an exothermic system was suggested by the enthalpy with a second order kinetics. Therefore, Camellia sinensis is a suitable adsorbent for the effective removal of high cobalt concentrations in wastewater.

Strategies of NHX antiporters to deal with salt stress

The adverse effects of salinity on plant growth are generally associated with the low osmotic potential of the soil solution and the high level of sodium toxicity (and chlorine toxicity for some species) which cause multiple perturbations on plant metabolism, growth, and development at the molecular, biochemical and physiological levels. The vacuolar NHX and plasma membrane SOS antiporters mediate cation and proton exchange across the tonoplast and plasma membrane, respectively. The SOS transporters allow the excretion of Na+ from the cytoplasm to the outside environment and alternatively, NHXs provide Na+ transport from the cytoplasm to the vacuole. Cellular ion homeostasis is an essential phenomenon for all organisms. Most cells manage to maintain a high level of potassium and a low level of sodium in the cytoplasm through the coordination and regulation of different transporters and channels instead of the NHX-type vacuolar antiport. In this article, some important mechanisms in the regulation of ionic ions such as Na+. will be discussed.

Detecting and locating chemical intrusion in water distribution systems using 911 calls

ABSTRACT Intentional or unintentional chemical contamination of water distribution systems (WDSs) could have severe health and socio-economic consequences. High potency chemicals constituting, in essence, “super poisons” have the potential to be used in such intrusion scenarios. Some of these contaminants are capable of killing the victim in less than 1 h. Due to their high toxicity levels and short time from exposure to onset of symptoms, 911 call centers are likely the first point of contact for victims or their families with the authorities. Information such as 911 calls could be used to identify the ongoing event and potential intrusion locations. In this way, such emergency calls could function as an intrusion warning system. This study employs network hydraulic modelling to synthesize the 911 call patterns in the aftermath of such events. It then defines the scenarios as a multi-label pattern recognition problem. The synthesized data then was used to train a Convolutional Neural Network (CNN). The trained AI was applied to a real-world WDS with approximately 4000 km of pipe and 26,000 demand nodes. The results indicated that CNN is capable of accurately recognizing the pattern and pinpointing the originating location of the intrusion with an accuracy greater than 93%.

Removal of High Concentrations of Arsenite from Aqueous Solutions by the Emulsion Liquid Membrane Technique

AbstractAs(III) is a dangerous species that contaminates groundwater resources and therefore water purification from this element is necessary. In this study, the removal of As(III) was investigated by the emulsion liquid membrane (ELM) technique due to the high toxicity levels of this species. The effect of various parameters such as hydrochloric acid and arsenic concentration in the feed solution, emulsion to feed ratio, surfactant concentration and type of carrier was evaluated on the arsenic separation efficiency. The results showed that the best type of carrier in terms of emulsion stability and separation efficiency of arsenic ions was di‐(2‐ethylhexyl) phosphoric acid (D2EHPA), and its optimal concentration was about 5 % (v/v). In addition, paraffin as the organic solvent performed better than the mixture of paraffin and kerosene in the separation of As(III) ions. The optimal conditions were obtained at 8 and 0.1 M HCl concentrations for the feed and the internal phases, respectively. Also, the emulsion to feed ratio of 1 : 4.5, the volume ratio of the internal phase to the membrane phase of 1 : 1 and the surfactant concentration of 5 % (v/v) led to achieving the maximum removal of arsenic ions. This work presents a broad perspective of removing As(III) ions from wastewater by carefully examining the parameters influencing the separation of this hazardous element through the ELM method.

An approach for collaboratively separation and detection of uranium based on novel plastic scintillating resin

It is extremely significant to monitor the radioactive uranium during the process of nuclear energy mining and disposal because of its high levels of chemical and radiological toxicity. In this work, a novel uranium plastic scintillator resin (U-PSresin) was successfully synthesized by suspension polymerization and used to rapidly enrich and determine uranium by Liquid Scintillation Counting (LSC). The U-PSresin shows excellent irradiation stability, extremely appropriate adsorption capacity of U(VI) (9.35 mg/g), which is convenient for the accurate measurement of LSC. Meanwhile, U-PSresin has a deviation of less than 5 % in adsorption and measurement repeatability and can be utilized to accurately measure more than 1 mg of natural uranium after enrichment. For different types of spiked water samples, the measurement deviation of U-PSresin is less than 15 %. This work demonstrates that U-PSresin can selectively enrich and quantitatively measure uranium in an aqueous environment, showcasing its significant potential in nuclear emergency scenarios and environmental monitoring.

Modulating the immunosuppressive tumor microenvironment: Multi-synergistic cancer therapeutic approach with oncolytic viruses

Most patients with complex malignancies show a high level of toxicity and limited long-lasting responses to current conventional therapies. In contrast, the immune system has the intrinsic potential to distinguish between self and non-self (foreign or different) cells, including cancer cells, and successfully eliminate them. Even after T and NK cells successfully navigate sophisticated surveillance paths studded with diversion networks, processes, and impediments, they must overcome the impacts of a highly neutralizing and immune-suppressive destination known as the tumor microenvironment (TME). A comprehensive understanding of these TME events, immune system stimulative OVs functions, and synergistic possibilities with other immune activating strategies will provide insight and present a unique opportunity for improved therapeutic efficacy against cancer. The synergistic potential of combining oncolytic viruses with immune checkpoint inhibitors merits further exploration. In particular, focusing on the PD-1/PD-L1 (programmed cell death) axis may hold promise in amplifying antitumor immune responses and thereby bolstering therapeutic outcomes.

Poziotinib treatment in patients with HER2-positive advanced breast cancer who have received prior anti-HER2 regimens.

Poziotinib is an irreversible pan-inhibitor of the human epidermal growth factor receptor (HER) that has shown acceptable tolerability and antitumor activity in phase I and II trials in patients with advanced solid tumors. In the present open-label, multicenter phase II study, we demonstrate safety, tolerability, and preliminary efficacy data from two different dosing schedules in patients with HER2-positive advanced breast cancer. Patients who had received at least two prior HER2-directed therapy lines for advanced disease, received 24mg poziotinib on an intermittent dosing schedule (cohort 1) or 16mg poziotinib once daily on a continuous dosing schedule (cohort 2). The primary endpoint was overall response rate (ORR). Secondary endpoints were progression-free survival (PFS), disease control rate (DCR), and time to progression (TTP). Secondary endpoints additionally included safety and pharmacokinetics. A total of 67 patients were enrolled. The ORR was 30% in both groups (p = 0.98). DCR was 60% vs 78% (p = 0.15) and median PFS and TTP were 4.1 vs 4.9months (both p = 0.30) for cohorts 1 and 2, respectively. The most common treatment related adverse events (AEs) of any grade included diarrhea (88% vs 85%, p = 0.76), rash (88% vs 88%, p = 0.96), and stomatitis (64% vs 56%, p = 0.52), with grade 3-4 diarrhea occurring in 33% vs 32% of patients (p = 0.93) and grade 3-4 rash in 27% vs 35% of patients (p = 0.48) in cohort 1 vs cohort 2, respectively. Poziotinib demonstrated evidence of clinical activity in patients with pre-treated HER2-positive advanced breast cancer, although high levels of toxicity may preclude further studies at this time.

Acute myeloid leukemia patient with active disseminated tuberculosis bridged to transplant with reduced 14-day venetoclax and azacitidine schedule

SummaryA 59-year-old female patient was diagnosed with acute myeloid leukemia and tuberculosis. As a further complication, she developed idiopathic bowel perforation. Her infectious and intestinal situation demanded shorter periods of neutropenia and did not permit a high-dose, curative therapy regimen. Moreover, simultaneous administration of venetoclax and antitubercular therapy with rifampicin causes CYP3A4 interactions and thereby higher levels of toxicity. She was treated with a shortened, 14-day therapy regimen with azacitidine and venetoclax as antileukemic treatment together with ethambutol, pyrazinamide, isoniazid, and rifampicin as antitubercular therapy, which resulted in a complete remission and to an improvement of the tuberculosis without any greater toxicity or other adverse events.

Antimicrobial mechanisms of g-C3 N4 @ZnO against oomycetes Phytophthora capsici: from its metabolism, membrane structures and growth.

Phytophthora capsici, a refractory and model oomycete plant pathogen, especially threatens multiple vegetable crops. A limited number of chemical pesticides play a vital role in controlling oomycete plant diseases. However, this approach often leads to excessive use of chemical agent, exacerbates environmental issues and more and more drug-resistant strains of oomycete. Therefore, it is imperative to devise innovative solutions that can effectively address the infection of oomycete while maintaining high levels of environmental sustainability and low toxicity. In this study, g-C3 N4 @ZnO heterostructure was synthesized and characterized. The g-C3 N4 @ZnO showed higher toxicity on Phytophthora capsici than graphitic carbon nitride (g-C3 N4 ) nanosheets and zinc oxide (ZnO) nanoparticles in vitro and in vivo. Except the hyphal growth of Phytophthora capsici, their germination rate of spores, sporangium formation and number of spores were all suppressed by g-C3 N4 @ZnO heterostructure. Furthermore, we found that this g-C3 N4 @ZnO heterostructure has higher photocatalytic activity under visible light, which potentially enhanced the reactive oxygen species (ROS) mediated stress on Phytophthora capsici. Ultrastructural morphology, global changes of gene expression and weighted gene co-expression network analysis all supported that the anti-oomycete activity of g-C3 N4 @ZnO was manifested in the destruction of membrane system and inhibition of multiple metabolisms of Phytophthora capsici under visible irradiation, which also could be attributed to the ROS and zinc ion (Zn2+ ) mediated stress. This works offers a novel oomycete disease management strategy by using g-C3 N4 @ZnO, which were attributed to the ROS stress, destruction of membrane system and inhibition of multiple metabolisms. © 2023 Society of Chemical Industry.

Synergistic potency of ultrasound and solar energy towards oxidation of 2,4-dichlorophenol: a chemometrics approach.

Industrial units based on chemical processes-the textile and paper industries-are major sources of chlorophenols in the environment, and chlorophenolic compounds persist within the environment for a long time with high toxicity levels. The photo-assisted Fenton's and photocatalysis processes were investigated for the degradation of chlorophenols in the present study. Response surface methodology was employed to get optimised conditions for photocatalysis and photo-Fenton process-governing factors, thus, yielding a profound removal efficiency. Under optimised conditions, with a photocatalyst dose of 0.2 g/L, oxidant concentration of 10.0 mM and pH 5.0, complete removal of 2,4-dichlorophenol (2,4-DCP) was observed in 210 minutes in photocatalytic treatment. In the case of the photo-Fenton process, at an H2O2 dose of 5.0 mM and Fe2+ concentration of 0.5 mM, the organic pollutant was eliminated within 5 minutes of reaction time under acidic conditions (pH 3.0). The RSM model reported the perfect fit of experimental data with the predicted response. Among different isotherm models, the Langmuir isotherm was the best fit. The process followed pseudo-first order rate kinetics among various kinetics models. For the obtained optimised conditions, sonication and solar energy-driven processes were incorporated to study enhanced mineralisation. The solar-assisted Fenton process reported maximum mineralisation (90%) and cost-effective ($0.01/litre for 100 mg/L 2,4-DCP) treatment among different hybrid oxidation processes. The work provides insight into harnessing the naturally available solar energy, reducing the overall treatment cost and opting for a sustainable treatment method.

STATUS OF APPLIED PROGRESSION TO TREAT PHARMACEUTICAL WASTEWATER; AN OVERVIEW

In this study, we examined the breakdown of pharmaceutical wastewater, which is complex and contains high levels of organic substances, microbial toxicity, and salt, making it challenging to decompose and posing an environmental risk due to its persistence as a chemical pollutant. To mitigate environmental contamination, the majority of the pharmaceutical sector employs various treatment facilities to clean and recycle wastewater. Through a review of existing literature, we explored the sources, uses, and progress in removing dissolved organic compounds from pharmaceutical wastewater. We discussed several recent methods used for treating pharmaceutical waste. It was found that while effective technologies exist, there is a need for further development within the industry. Integrated treatment strategies hold great potential, such as the common effluent treatment plant (CETP), which is currently experiencing significant growth and success, provided there is a strong commitment from the scientific community and regulatory bodies to enforce policies.

Genomic selection for tolerance to aluminum toxicity in a synthetic population of upland rice.

Over half of the world's arable land is acidic, which constrains cereal production. In South America, different rice-growing regions (Cerrado in Brazil and Llanos in Colombia and Venezuela) are particularly affected due to high aluminum toxicity levels. For this reason, efforts have been made to breed for tolerance to aluminum toxicity using synthetic populations. The breeding program of CIAT-CIRAD is a good example of the use of recurrent selection to increase productivity for the Llanos in Colombia. In this study, we evaluated the performance of genomic prediction models to optimize the breeding scheme by hastening the development of an improved synthetic population and elite lines. We characterized 334 families at the S0:4 generation in two conditions. One condition was the control, managed with liming, while the other had high aluminum toxicity. Four traits were considered: days to flowering (FL), plant height (PH), grain yield (YLD), and zinc concentration in the polished grain (ZN). The population presented a high tolerance to aluminum toxicity, with more than 72% of the families showing a higher yield under aluminum conditions. The performance of the families under the aluminum toxicity condition was predicted using four different models: a single-environment model and three multi-environment models. The multi-environment models differed in the way they integrated genotype-by-environment interactions. The best predictive abilities were achieved using multi-environment models: 0.67 for FL, 0.60 for PH, 0.53 for YLD, and 0.65 for ZN. The gain of multi-environment over single-environment models ranged from 71% for YLD to 430% for FL. The selection of the best-performing families based on multi-trait indices, including the four traits mentioned above, facilitated the identification of suitable families for recombination. This information will be used to develop a new cycle of recurrent selection through genomic selection.

Evaluation of upflow anaerobic sludge blanket (UASB) performance in synthetic vinasse treatment

Vinasse is one of the major sources of environmental pollution because of high organic matter and toxic compound levels (e.g., sulfates and phenols). The more the vinasse treatment is, the less the environmental pollution will be. This study aimed to evaluate the effect of a low-cost and simple anaerobic pretreatment on the COD removal efficiency of the UASB reactor for the treatment of synthetic vinasse. In addition, this system was evaluated through organic loading rate (OLR), hydraulic retention time (HRT), upflow velocity (Vup), mixed liquor volatile suspended solid (MLVSS), mixed liquor suspended solids (MLSS), and pH. In a 155-day trial, the system was fed by synthetic vinasse with an organic loading rate (OLR) ranging from 2.5 to 20.5 kgCOD/m3.d. The results indicated that when a UASB reactor was used for synthetic vinasse treatment, the average COD removal efficiency and methane production were about 80.45% and 56%, respectively. However, the use of an anaerobic unit as a less expensive and simple pretreatment increased COD removal efficiency to 88.4% and methane production to 62.5% (684.6 L/kgCOD). The study result suggested that anaerobic pretreatment is suitable for reducing the environmental pollution of vinasse and can be used as an economical system for real vinasse treatment on an industrial scale.

In Vitro Antibacterial, Antioxidant, Cytotoxicity Activity, and In Silico Molecular Modelling of Compounds Isolated from Roots of Hydnora johannis.

The plant Hydnora johannis has been utilized in folk medicine. Analyzing phytochemical composition of dichloromethane/methanol (1 : 1) root part of Hydnora johannis gave oleic acid (1), caffeic acid-2-hydroxynonylester (2), catechin (3), and a pregnane derivative (4). NMR spectroscopy was used to characterize compounds 1-3, while compound 4 was identified through GC-MS analysis and literature comparison. The cytotoxicity of extracts from roots of H. johannis was conducted against MCF-7 cell lines (human breast cancer) by MTT assay. According to the cytotoxicity study, n-hexane extract exhibited a high level of toxicity with 28.9 ± 5.6% cell viability. Antibacterial activity was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogen. The highest bacterial growth mean inhibition zone was measured for catechin (3) (13.72 ± 0.05 mm)) against P. aeruginosa at 0.25 mg/mL and acceptable related to standard. Antioxidant activity was studied by the DPPH assay. Based on the data from the antioxidant study, DCM/MeOH extract (70.32%) and catechin (3) showed good antioxidant activity (65.61%) (IC50 0.25 μg/mL) relative to that of the positive control (78.21%, IC50 0.014 μg/mL) at 12.5 μg/mL. In each docking pose, catechin (3) scored higher binding affinity of -7.9, -7.2, and -6.4 kcal/mol towards PqsA, DNA gyraseB, and S. aureus PK, respectively, compared to amoxicillin (-8.1, -6.1, and -6.4 kcal/mol). All five Lipinski rules were obeyed by compounds 1-3, which showed an acceptable drug resemblance. The lipophilicity was computed as less than five (1.47-4.01) indicating a lipophilic property. Catechin (3) obeys Veber's rule implying its good oral bioavailability. Binding affinity scores of catechin (3)-protein interactions are in line with those from in vitro tests, indicating its potential antibacterial effect. The obtained cytotoxicity and antibacterial activity results support the utilization of H. johannis in folk medicine.

Improved Targeting and Safety of Doxorubicin through a Novel Albumin Binding Prodrug Approach.

Human serum albumin (HSA) improves the pharmacokinetic profile of drugs attached to it, making it an attractive carrier with proven clinical success. In our previous studies, we have shown that Caveolin-1 (Cav-1) and caveolae-mediated endocytosis play important roles in the uptake of HSA and albumin-bound drugs. Doxorubicin is an FDA-approved chemotherapeutic agent that is effective against multiple cancers, but its clinical applicability has been hampered by its high toxicity levels. In this study, a doxorubicin-prodrug was developed that could independently and avidly bind HSA in circulation, called IPBA-Dox. We first developed and characterized IPBA-Dox and confirmed that it can bind albumin in vitro while retaining a potent cytotoxic effect. We then verified that it efficiently binds to HSA in circulation, leading to an improvement in the pharmacokinetic profile of the drug. In addition, we tested our prodrug for Cav-1 selectivity and found that it preferentially affects cells that express relatively higher levels of Cav-1 in vitro and in vivo. Moreover, we found that our compound was well tolerated in vivo at concentrations at which doxorubicin was lethal. Altogether, we have developed a doxorubicin-prodrug that can successfully bind HSA, retaining a strong cytotoxic effect that preferentially targets Cav-1 positive cells while improving the general tolerability of the drug.

Synthesis of Graphene Quantum Dots: A Comprehensive Review

Semiconductor quantum dots such as CdSe, PbSe, PbS, CdS, CuInS, CuInSe, etc. have been extensively studied for their size-tunable optical absorption and emission properties, which enable their applications in different optoelectronics applications. Although despite having high photoaborption and photosensing properties these semiconductor quantum dots possess certain limitation due to their high level of toxicity and complex synthesis process. Graphene quantum dots (GQDs) are a zero-dimensional (0D) nontoxic nanomaterial of the carbon family, and have sparked a lot of attention in the domains of optoelectronics and electronics. In this review, a number of GQD synthesis methods such as laser ablation, hydrothermal, solvothermal, thermal pyrolysis, electrochemical, chemical oxidation and cutting have been summarized in detail.

Heterogeneity of Harmful Constituent Profiles in Smokeless Tobacco Products from Five African Countries.

Addictive, toxic, and carcinogenic constituents present in smokeless tobacco (SLT) products are responsible for the harmful effects associated with SLT use. There are limited data on levels of such constituents in SLT products used in Africa, a region with high prevalence of SLT use and the associated morbidity and mortality. Manufactured and custom-made SLT products were purchased from five African countries (South Africa, Uganda, Mauritania, Nigeria, and Zambia) using a standard approach for sample collection, labeling, and storage. Moisture content, pH, total and unprotonated (biologically available) nicotine, five tobacco-specific N-nitrosamines (TSNA), 10 polycyclic aromatic hydrocarbons (PAH), five metals and metalloids (As, Cd, Cr, Ni, and Pb), nitrate, and nitrite were analyzed. A total of 54 samples representing 15 varieties of manufactured SLT products and 13 varieties of custom-made SLT products were purchased and analyzed. In all samples, the total nicotine ranged from 1.6 to 20.5 mg/g product and unprotonated nicotine accounted for 5.3-99.6% of the total nicotine content. The sum of all five TSNA ranged from 1.6 to 100 μg/g product, with significant within-country variations observed across both the manufactured and custom-made varieties. Significant variations were also found for PAH, metals and metalloids, nitrates, and nitrites. This is the most comprehensive report on the chemical profiling of products from African countries. This is also the first study illustrating the variability of harmful constituents within the same types and brands of African SLT. Our findings emphasize the need for consumer education and interventions to reduce SLT use in Africa. The data reported here can be useful to regulators in considering measures to prevent the occurrence of high levels of known toxicants and carcinogens in manufactured products.