Explore the vast range of titles available.

Selenium (Se)-dependent enzymes (selenoenzymes) protect brain tissues against oxidative damage and perform other vital functions, but their synthesis requires a steady supply of Se. High methylmercury (CH₃Hg) exposures can severely diminish Se transport across the placenta and irreversibly inhibit fetal brain selenoenzymes. However, supplemental dietary Se preserves their activities and thus prevents pathological consequences. The modified Se health benefit value (HBVSₑ) is a risk assessment criterion based on the molar concentrations of CH₃Hg and Se present in a fish or seafood. It was developed to reflect the contrasting effects of maternal CH₃Hg and Se intakes on fetal brain selenoenzyme activities. However, the original equation was prone to divide-by-zero-type errors whereby the calculated values increased exponentially in samples with low CH₃Hg contents. The equation was refined to provide an improved index to better reflect the risks of CH₃Hg exposures and the benefits provided by dietary Se. The HBVSₑ provides a biochemically based perspective that confirms and supports the FDA/EPA advice for pregnant and breast-feeding women regarding seafoods that should be avoided vs. those that are beneficial to consume. Since Se can be highly variable between watersheds, further evaluation of freshwater fish is needed to identify locations where fish with negative HBVSₑ may arise and be consumed by vulnerable subpopulation groups.

Use of dietary supplements in the U.S. has increased steadily over the last 25 years. While misformulation is uncommon, the consequences can be serious. A March 2008 voluntary market recall removed supplement products responsible for the most serious selenium toxicity outbreak that has occurred in the U.S. We quantified selenium concentrations in the misformulated supplement products, measured the temporal response in the nail biologic monitor, and associated exposure to self-reported selenosis symptoms. Subjects recruited through state health departments and referrals provided samples of the misformulated supplement products, exposure information, monthly toenail and or fingernail clippings or onycholysitic nail fragments, and listed their newly onset adverse health effects attributed to selenium toxicity. Ninety-seven subjects enrolled and submitted at least one test sample. Peak selenium concentrations (up to 18.3 and 44.1 μg/g for toenails and fingernails, respectively) were measured. Multiple samples (52 total) of all six recalled supplement lots were analyzed ranging from 22,300 to 32,200 μg selenium per daily dose. Average consumption was 30.9 ± 13.9 doses; 73 subjects provided follow-up data on selenosis symptoms at 2.50 ± 0.14 years. Nail samples accurately reflect exposure in this selenium toxicity outbreak, which resulted in long-term/permanent adverse health effects.

It has been strongly suggested that two factors are involved in the development of Kaschin–Beck Disease (KBD), namely grains contamination with T-2 toxin and selenium deficiency. So our team undertook a survey about grains and drinking water in three rural KBD endemic villages and one non-KBD village in Qinghai Province. The level of T-2 toxin contamination in 364 grain samples was assayed using an ELISA kit. The selenium concentration in these grains and 15 drinking water samples from three KBD endemic villages were determined using the 2,3-diaminonaphthalene fluorometric assay. The results revealed that the level of T-2 toxin contamination in the samples from three KBD endemic villages was relatively high with an average level of 78.91 ng/g in wheat and 47.47 ng/g in flour. The T-2 toxin level in samples from the non-KBD village (12.23 ng/g) was significantly lower than that of local grains from the three KBD endemic villages. The average selenium content in wheat and flour from KBD areas was 0.0045 and 0.0067 μg/g, respectively. The selenium concentration in local grain samples was significantly lower than that in samples from the non-KBD village (0.0604 μg/g). In addition, the selenium concentration in drinking water from three KBD endemic villages was also low (0.156 μg/L). These results support a potential role of T-2 toxin contamination and selenium deficiency in KBD. Compared with non-KBD endemic areas, health hazards in grains and in the environment of KBD endemic areas were observed.

Baby foods, from the Spanish market and prepared from meat, fish, vegetables, cereals, legumes, and fruits, were analyzed to obtain the concentration of antimony (Sb), arsenic (As), bismuth (Bi), and tellurium (Te) as toxic elements and selenium (Se) as essential element. An analytical procedure was employed based on atomic fluorescence spectroscopy which allowed to obtain accurate data at low levels of concentration. Values of 14 commercial samples, expressed in nanograms per gram fresh weight, ranged for Sb 0.66–6.9, As 4.5–242, Te 1.35–2.94, Bi 2.18–4.79, and Se 5.4–109. Additionally, speciation studies were performed based on data from a non-chromatographic screening method. It was concluded that tellurium and bismuth were mainly present as inorganic forms and selenium as organic form, and antimony and arsenic species depend on the ingredients of each baby food. Risk assessment considerations were made by comparing dietary intake of the aforementioned elements through the consumption of one baby food portion a day and recommended or tolerable guideline values.

Anthropogenic activities resulting in elevated selenium (Se) levels in aquatic ecosystems can result in teratogenic and reproductive effects in fish and waterfowl. However, relationships between observed effects and exposure concentrations or body burdens are ambiguous. Therefore, it is critical to identify factors that affect Se ecotoxicity before defining adequate protective environmental regulations. One important political debate questions if Se ecotoxicity differs between standing (lentic) and flowing (lotic) waters and, if so, how this should be incorporated into the definition of protective criteria. In the present review, we compile and discuss the scarce literature regarding Se ecotoxicity in lotic systems, and we compare it to the substantial body of evidence for lentic systems. General differences between lentic and lotic systems with respect to ecology, hydrology, and biogeochemistry are identified and related to Se ecotoxicity. The limited knowledge regarding Se speciation in the biomagnification process is reviewed and put in context. Fundamental considerations suggest that Se ecotoxicity in lotic systems should be reduced compared to lentic systems, but we conclude that this statement is not substantiated by the existing data. Additionally, we identify critical gaps of knowledge that must be resolved in future studies before the argument can be decided conclusively.

Two previously healthy women developed nausea, vomiting, headache and dizziness for several days, a massive hair loss about 2 weeks later and a discoloration of the fingernails. Detailed diagnostic procedures did not reveal any pathological results. Therapeutic measures did not show any effect. Thallium and arsenic were within normal range in plasma. Delayed quantitative determination of selenium in blood, however revealed toxic values (in case I: 479 μg/L of serum, 8 weeks after ingestion, and in case II 300 μg/L of serum, 9 weeks after ingestion). In retrospect, a relation to the ingestion of paradise nuts could be established.

To determine the selenium intake of adults residing in high and low selenium areas of rural Punjab. All food samples consumed by the subjects were collected and analysed for selenium content. Based on food intake data and selenium content of foods, the selenium intake of the subjects was calculated. Hair, fingernails and urine samples from a sub-sample of subjects were collected and analysed for selenium. Three villages from the selenium-endemic area of Nawan Shahr District and two villages from the non-endemic area of Ludhiana District, Punjab, India, were covered. Forty families from each of the two areas, with one adult male and one adult female in the age range of 20-40 years, were surveyed. Thus a total of 80 men and 80 women constituted the study sample. In the selenium-endemic area, the average selenium intake of both men and women was more than nine times that in the non-endemic area and exceeded the maximum tolerable limit in more than 60% of men. Mean selenium content of the hair, nails and urine of both men and women was tens of times higher than in the non-endemic area. High selenium intake in the endemic area resulted in high selenium content in the hair, nails and urine of men and women. In addition, clinical symptoms of selenium toxicity were also observed in some of the subjects. Selenium intake in the non-endemic area was marginally below the suggested value. Based on the study results, steps need to be taken to educate the public in the endemic area to avoid selenium toxicity.

Two patients, a 36-year-old female and a 36-year-old male, separately experienced new onset nausea, vomiting, diarrhea, abdominal pain, muscle weakness and pallor. Over a period of 14–16 h these symptoms continue and progress to include hypotension refractory to therapy, pulmonary edema and cardiovascular collapse. Autopsies show hemorrhagic pulmonary edema, splenomegaly and lack of anatomical cause for sudden death. Postmortem analysis, in one case post-embalming and exhumation, revealed elevated selenium concentrations and a determination of the cause of death. These two cases present several important features associated with selenium toxicity, two of which are previously unreported: (1) selenium as a potential homicidal agent, (2) the toxidrome and time frame of selenium toxicity, (3) selenium determination in exhumed, embalmed tissues, (4) postmortem urinary selenium concentration, and (5) decrease in tissue concentrations over time.

In order to clarify the historic academic problem of whether or not livestock poisoning in ancient Suzhou of Northwest China, recorded by Marco Polo in 1295, was selenosis, this study deals with the biogeochemistry of selenium in Sunan County in the Hexi Corridor, which is part of ancient Suzhou in China. It was found that quite a number of farm animals had suffered from intoxication and died as a result of grazing poisonous grasses, mostly Oxytropis DC, Stellera chamaejasme, and Achnatheru inebrians. Toxic symptoms of livestock grazing on Oxytropis DC are similar to those of selenium toxicity, for instance, hair loss and hoof lesions as described by Marco Polo. Therefore, we thought that toxic grass, probably Oxytropis DC, led to the intoxication of livestock recorded by Marco Polo. Average Se concentrations in two members of this species were 0.112 ± 0.038 mg/kg for the root of Oxytropis glabra, 0.102 ± 0.027 mg/kg for the stem and leaf of Oxytropis glabra, and 0.066 ± 0.009 mg/kg for Oxytropis ochrocephala. The average soil selenium concentration was 0.205 ± 0.127 mg/kg on grassland producing Oxytropis glabra and 0.152 ± 0.024 mg/kg on grassland producing Oxytropis ochrocephala. The average Se concentration in other plants was 0.076 mg/kg in the root of Ephedra monosperma Mey, 0.029 mg/kg in the root of Rheum palmatum, 0.031 mg/kg in the root of Stellera chamaejasme, 0.037 mg/kg in Achnatherum inebrians, and 0.067 mg/kg in forage grass (Achnatherum splendens ohwi). Selenium concentrations in soils and plants in Sunan County are far less than the thresholds causing selenium toxicity in livestock. As a result, this study concludes that the livestock poisoning recorded by Marco Polo in 1295 might not have been selenosis.