Radiochemical separation by liquid-liquid extraction for the determination of selenium in Mentha pulegium L.: Toxicity monitoring and health study

In Algeria, Data and studies on the non-metal trace element selenium (Se) are presently lacking, therefore, the aim of this investigation is to provide new data on (Se) element via its determination for the first time from Mentha pulegium L. plant. The plant samples were collected in summer of 2012 from Ain-Oussera region, Djelfa province, Algeria; they were dried and powdered. After the neutron irradiation, the samples were digested using high oxidative reagents including H₂SO₄, HNO₃, H₂O₂ and HCl. The end of this process gave two phases, organic and aqueous discard phase. By using a separating funnel, the organic phase was transferred into a vial in order to measure their induce radionuclide ⁷⁵Se using gamma-ray spectrometer. A non-chromatographic and sensitive analytical technique RNAA (Radiochemical Neutron Activation Analysis), was applied in this investigation due to its great significant minor systematic error. Results were determined using two distinguish calculation methods, relative-RNAA and k₀-RNAA, the findings were quite significant, whereas, the average separation yield was about 85% for both calculation methodologies. Moreover, (Se) concentration obtained from M. pulegium L., is close to the minimal FAO (Food and Agriculture Organization of the United Nations) recommended consumption.

The Epidemiology of Selenium and Human Cancer

The relation between the trace element selenium and the etiology of cancer in humans remains elusive and intriguing, despite the number of epidemiologic studies published on the topic. We address some methodologic issues, such as misclassification of exposure, particularly to single selenium compounds, effect modification, confounding, and other sources of bias, which may explain the inconsistencies in the literature. We also review the results of cohort studies, which have yielded either inverse or null or direct associations between selenium exposure and subsequent cancer risk. To date, no beneficial effect on cancer incidence at major sites, including prostate cancer, has emerged from the Finnish program begun in 1984 to increase the average selenium intake in its population. Populations exposed to unusually high or low levels of environmental selenium might offer unique opportunities to investigate if selenium exposure is related to the etiology of human cancer.

Hair analysis as a biomonitor for toxicology, disease and health status

Hair analysis receives a large amount of academic and commercial interest for wide-ranging applications. However, in many instances, especially for elemental or 'mineral' analysis, the degree of success of analytical interpretation has been quite minimal with respect to the extent of such endeavors. In this critical review we address the questions surrounding hair analysis with specific intent of discovering what hair concentrations can actually relate to in a biogenic sense. This is done from a chemistry perspective to explain why and how elements are incorporated into hair and their meaning. This includes an overview of variables attributed to altering hair concentrations, such as age, gender, melanin content, and other less reported factors. Hair elemental concentrations are reviewed with regard to morbidity, with specific examples of disease related effects summarized. The application of hair analysis for epidemiology and etiology studies is enforced. A section is dedicated specifically to the area of population studies with regards to mercury, which highlights how endogenous and exogenous incorporation relies on species dependant metabolism and metabolic products. Many of the considerations are relevant to other areas of interest in hair analysis, such as for drug and isotopic analysis. Inclusion of a table of elemental concentrations in hair should act as a valuable reference (298 references).

Bioaccumulation of PGEs and other traffic-related metals in populations of the small mammal Apodemus sylvaticus

The accumulation of the platinum group elements (PGEs), Pd, Pt, Rh, and other heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, Zn) in the wood mouse Apodemus sylvaticus was investigated in relation to environmental availability, comparing levels in the commonly used target tissues, the liver and kidney, to hair responses. In particular the research aimed to evaluate the suitability of a non-destructive hair-based biomonitoring approach and the responsiveness of PGEs as tracers for the environmental hazard assessment of pollutants linked to traffic in intensively anthropized areas. The four populations considered, inhabiting an urban, a suburban, an agricultural and a reference site, respectively, were shown to be capable of characterizing the differently polluted areas. In particular, multivariate analysis showed a significant correlation between metal levels in tissues and soils. Animals from both the urban and suburban sites, compared to those from the reference site, showed higher levels of those elements (PGEs, Cd, Cr, Ni, Pb and Zn), the availability of which is likely to be related to road traffic. On the contrary, Mn and Cu characterized the animals from the agricultural site. Even though the detected metal concentrations in tissues did not exceed the LOAEL levels, stress indices such as the PGE, Cd and Pb kidney/liver ratios and the kidney/body weight ratios were found to be altered. Significant correlations were established between hair and both internal tissues and soils, for non-essential metals PGEs, Cd, Ni and Pb, and also for biologically essential Zn, the level of which was high in urban soils. Hair proved to be a suitable non-invasive tool for monitoring metal exposure responses in small mammals.

Disposition kinetics of selenium in healthy volunteers following therapeutic shampoo treatment

This study was aimed at documenting the kinetic time courses of selenium (Se) in accessible biological matrices of volunteers following controlled applications of therapeutic shampoo containing Se, to better elucidate the mechanisms by which shampoo-Se accumulates in hair and hence estimate the contribution of this source to total Se body burden. Ten healthy volunteers were exposed to Se-shampoo three times a week over a month. Blood, hair and toenail concentrations along with daily urinary excretions were repeatedly measured over an 18-month period following the onset of application. Over the entire study period, blood concentrations of Se (range: 127-233μg/l) and daily urinary excretions (range: 11.9-150μg/d) remained within baseline range of the general population. Conversely, during shampoo application, mean Se concentrations in hair reached transitional levels of 89μg/g while, following cessation of treatment, a mono-exponential decrease was observed with a mean half-life of 4.5 weeks. Two of the volunteers also exhibited an increase in toenail concentrations of Se during the study period. Results show that Se-shampoo does not contribute significantly to total Se body burden, as assessed from blood and urine levels. Differences observed between blood and urine time courses as compared to hair profiles and the presence of Se on hair grown before treatment indicates an adsorption on hair; however, the gradual decrease in Se concentrations in successive centimeters of hair grown following the application period suggests a concomitant absorption from the scalp during treatment with subsequent excretion in hair.

Selenium interactions with essential and toxic elements in egg yolk from commercial and fortified eggs

The main objective of this work was to evaluate the interaction between selenium concentration in both commercial and Se-enriched eggs and other essential/toxic elements (Ca, Mg, Fe, Zn, Pb, and Cd), taking into account a possible synergic action of iodine. Commercial eggs were purchased from several sale points or directly from the producers (farmyard eggs). Fortified eggs were obtained by supplementing chickenfeed for 6 weeks with Se as sodium selenite (1.0 microg/g Se) or Se plus iodine (1.0 microg/g Se+3.7 microg/g I). Se in experimental egg yolks significantly increased over the basic value by 39% in the Se group and 61% in the Se+I group, suggesting that I addition may enhance Se absorption. Levels of Se in commercial yolks were identical in free-range, barn or battery eggs, but significantly lower in farmyard and higher in organic eggs where the Se content approximated that found in Se fortified eggs. A significant reduction in Cd was observed in Se+I treated yolks compared to both control and Se alone diet, thus suggesting a high sensitivity of Cd to the detoxifying effect of Se combined with I. Furthermore, Se+I supplementation was associated with a significant Zn reduction, a finding which needs clarification to avoid attempts to maximize one component affecting the levels of other essential elements.