Chronic exposure to chromium (Cr) and nickel (Ni) has long been recognized as being capable to increase head and neck cancer (HNC) incidence among exposed human populations. This study represents the first biomonitoring of Cr and Ni exposure in Tunisia and focuses on a possible association with HNC risk. The aim of the present study was to evaluate the concentrations of Cr and Ni in the blood of HNC patients and controls. Metals blood levels of 169 HNC patients and 351 controls were determined using a Perkin-Elmer Analyst 800 Atomic Absorption Spectrometer. Mean blood levels of Cr and Ni in HNC cases (52.15 and 111.60 μg/L, respectively) were significantly higher than those of controls (37.04 and 30.50 μg/L, respectively). Cases' blood levels of Cr and Ni were significantly higher than those of controls after controlling for the other risk factors of HNC, including smoking, shisha consumption, occupational exposure, and nearby environment (P < 0.05). Among these risk factors, smoking and occupational exposure presented the most significant association with HNC (odds ratio (OR) = 6.54 and 7.66, respectively, P < 0.001). Cr and Ni levels in blood sample of cases and controls that are smoker/occupationally exposed were higher than that of non-smoker/non-occupationally exposed (P < 0.05). Smokers who are occupationally exposed present the most significant association with HNC (OR = 25.08, P < 0.0001). High levels of blood Cr (OR = 2.09) and high levels of blood Ni (OR = 8.87) were strongly associated with HNC after other potential confounders were controlled (P = 0.004 and P < 0.0001, respectively). This study suggested a potential role of Cr and Ni in the mechanism of HNC development.

Characterization of groundwater quality allows the evaluation of groundwater pollution and provides information for better management of groundwater resources. This study characterized the shallow groundwater quality and its spatial and seasonal variations in the Lower St. Johns River Basin, Florida, USA, under agricultural, forest, wastewater, and residential land uses using field measurements and two-dimensional kriging analysis. Comparison of the concentrations of groundwater quality constituents against the US EPA’s water quality criteria showed that the maximum nitrate/nitrite (NO ₓ ) and arsenic (As) concentrations exceeded the EPA’s drinking water standard limits, while the maximum Cl, SO ₄ ² ⁻ , and Mn concentrations exceeded the EPA’s national secondary drinking water regulations. In general, high kriging estimated groundwater NH ₄ ⁺ concentrations were found around the agricultural areas, while high kriging estimated groundwater NO ₓ concentrations were observed in the residential areas with a high density of septic tank distribution. Our study further revealed that more areas were found with high estimated NO ₓ concentrations in summer than in spring. This occurred partially because of more NO ₓ leaching into the shallow groundwater due to the wetter summer and partially because of faster nitrification rate due to the higher temperature in summer. Large extent and high kriging estimated total phosphorus concentrations were found in the residential areas. Overall, the groundwater Na and Mg concentration distributions were relatively more even in summer than in spring. Higher kriging estimated groundwater As concentrations were found around the agricultural areas, which exceeded the EPA’s drinking water standard limit. Very small variations in groundwater dissolved organic carbon concentrations were observed between spring and summer. This study demonstrated that the concentrations of groundwater quality constituents varied from location to location, and impacts of land uses on groundwater quality variation were profound.

Mercury (Hg) speciation and mobility were determined in calcines and waste rocks collected from 9 Hg mines in China. Total Hg (THg) concentrations in the mine wastes varied widely in different Hg mines (with a range of 0.369 to 2,620 mg kg(-1)). Cinnabar is the dominant form of Hg in the mine wastes. However, Hg(2+) and Hg(0) concentrations in the calcines were significantly higher than these in the waste rocks, which suggested the retorting can produce large amounts of by-product Hg compounds. The THg and Hg(0) concentrations in certain mine wastes exceeded soil guidelines recommended by US Environmental Protection Agency; while total soluble Hg concentrations of leachates in certain mine wastes exceeded National Surface Water Quality Standard of China. Mine wastes are important Hg pollution sources to the aquatic ecosystem and atmosphere.

Trace metals were examined in the muscle tissue of flatfish species of flounder, Platichthys flesus (Linnaeus, 1758), sediments from two southern Baltic Sea sites (Gdańsk Bay and Ustecko-Łebskie as a reference) and in two areas of the Portuguese Atlantic coast (Douro River estuary and Atlantic fishing ground as a reference) to evaluate spatial differences in trace metals. Additionally, the accumulation of trace metals in flounder of different length classes was assessed. Flounder from the Gdańsk Bay area contained twofold more cupper (Cu), lead (Pb) and mercury (Hg) than did flounder from the Douro River estuary, but zinc (Zn) and cadmium (Cd) were at similar concentrations. The sediments from Gdańsk Bay contained significantly more Zn and threefold more Cd, while concentrations of Cu and Pb were twofold lower. The concentrations of metals in the sediments did not correlate with those in the flounder. Spatial differences were noted in metal concentrations in flounder from the southern Baltic Sea and the Portuguese Atlantic coast as well as within these regions, with higher concentrations in the flounder from the Baltic Sea Gdańsk Bay. The flounder in length class 25-30 cm from Gdańsk Bay contained metal concentrations comparable to those of class 40-45 cm specimens from the Atlantic coast. The accumulation of metals in flounder length classes differed in the two regions.

Because of an increasing exposure to environmental and occupational nanoparticles (NPs), the potential risk of these materials for human health should be better assessed. Since one of the main routes of entry of NPs is via the lungs, it is of paramount importance to further characterize their impact on the respiratory system. Here, we have studied the uptake of fluorescently labeled SiO₂ NPs (50 and 100 nm) by epithelial cells (NCI-H292) and alveolar macrophages (MHS) in the presence or absence of pulmonary surfactant. The quantification of NP uptake was performed by measuring cell-associated fluorescence using flow cytometry and spectrometric techniques in order to identify the most suitable methodology. Internalization was shown to be time and dose dependent, and differences in terms of uptake were noted between epithelial cells and macrophages. In the light of our observations, we conclude that flow cytometry is a more reliable technique for the study of NP internalization, and importantly, that the hydrophobic fraction of lung surfactant is critical for downregulating NP uptake in both cell types.

In the eggs and developing chick livers in the two wild bird species, great cormorant and herring gull, the concentrations of a range of 15 perfluoroalkyl acids (PFAAs) were determined. Eggs of the two species were collected from Lake Vanern, Sweden, and analysed either as undeveloped egg (whole egg or separated into yolk and albumen) or incubated until start of the hatching process when the chick liver was removed and analysed. High levels of PFAAs were found in all matrixes except albumen. The predominant PFAA was perfluorooctane sulfonate (PFOS), which was found in the mu g/g wet weight (ww) range in some samples of cormorant whole egg, yolk and liver and herring gull egg yolk and liver. The average concentration in yolk was 1,506 ng/g ww in cormorant and 589 ng/g ww in herring gull. The average liver concentrations of PFOS were 583 ng/g ww in cormorant and 508 ng/g ww in herring gull. At these concentrations, biochemical effects in the developing embryo or effects on embryo survival cannot be ruled out. For perfluoroalkyl carboxylates (PFCAs), the liver/egg and liver/yolk concentration ratios increased with PFCA chain length in cormorant but not in herring gull, indicating that chain length could possibly affect egg-to-liver transfer of PFCAs and that species differences may exist.

Based on the molecular distribution of bound fatty acid (BFA) compound classes in core sediments of Lake Dianchi combined with the compound-specific δ¹³C values of the straight-chain BFAs, origin and vertical changes of organic matters in the sediments were investigated. The results indicated a significant change of BFA sources over the past 700 years. Contrast to the low concentrations of the terrestrial BFAs, the abundance of BFAs derived from the plankton/bacteria in the top sections (1944–recent) was more than 80 %. The increasing proportions of the branched and unsaturated BFAs in total fatty acids were closely correlated with the heavy eutrophication and the frequent algal blooms in the decades. Furthermore, the positive shift of δ ¹³C of C16 and C18 (~2 ‰) in the upper section might be an indicator of the excess phytoplankton productivity. However, it was found that the plankton/bacteria-derived BFAs were more easily degraded during the early diagenetic process. The special compound carbon isotopic compositions of the long straight-chain BFAs (C24 and C26) in the sediments showed a depletion of heavier δ ¹³C values (ca. −30 ‰) in the midsections (1559–1787), reflecting a relatively growing contribution of C3 plants to C4 plants or that C4 plant growth was inhibited in cold and arid climates during the period.

Caviar (fish roe of sturgeon) may contain high levels of contaminants. An inductively coupled plasma-optical emission spectrometer and a direct mercury analyzer were used to assess the contents of four heavy metals (Hg, Se, Sn, and Ba) in caviar of wild Persian sturgeon sea foods. The levels of Hg ranged from 1.39 to 1.50 μg g(-1), Se from 0.90 to 1.10 μg g(-1), Sn from 0.23 to 0.33, and Ba from 0.71 to 1.17 μg g(-1). Evaluation of these levels showed that except for Hg, the average concentrations of other metals are significantly lower than adverse level for the human consumption when compared with Food and Agricultural Organization of the United Nations and World Health Organization permissible limits. Therefore, their contribution to the total body burden of these heavy metals can be considered as negligibly small given that caviar is a luxury product.

The aim of the present investigation was to exploit the high specific surface area of activated carbons in immobilizing the manganese and iron oxides as to obtain a suitable, efficient and cost effective and environment benign wastewater treatment process in the remediation of cadmium-contaminated waters. The manganese and iron oxides were impregnated in situ onto the surface and pores of the activated carbons precursors to the rice hulls and areca nut wastes. The solids were characterized with the help of Fourier transform infrared spectroscopy and X-ray diffraction analytical data, and the BET specific surface area as obtained. The surface morphology of these solids was discussed with the help of scanning electron microscopic images. The activated carbon samples along with the manganese and iron immobilized activated carbons were further employed in the batch and column reactor operations in the remediation of cadmium-contaminated waters. The batch data showed that an increase in sorptive pH from 2.0 to 10.0 and concentration from 1.0 to 20 mg/L favoured the uptake of cadmium by these solids. Moreover, the 1,000 times increase in background electrolyte concentrations NaNO3 caused an insignificant decrease in cadmium uptake by these solids, which inferred that sorbing ions/species were sorbed specifically and forming 'inner-sphere' complexes onto the solid surface. The concentration dependence data were utilized to model various adsorption isotherms and indicated that Freundlich adsorption isotherm was reasonably fitted well. The kinetic data was fitted well to the pseudo-second-order rate equations; hence, the equilibrium sorption capacity was estimated. Furthermore, the dynamic experiments carried out by the column experiments and the breakthrough data were fitted well to the non-linear Thomas equations; accordingly, the loading capacity of the column was estimated. Iron or manganese immobilized activated carbons showed relatively higher loading capacity compared to its precursor activated carbons hence showing its possible implication in the remediation processes. Moreover, among these modified ACs, IIAC showed higher removal capacity than the MIAC solid.

Triphenyltin chloride (TPTC), which has been extensively used in industry and agriculture, can occur at concentrations in the environment sufficient to be toxic. Here, potency of TPTC to modulate genes in a library containing 1,820 modified green fluorescent protein (GFP)-expressing promoter reporter vectors constructed from Escherichia coli K12 strains was determined. Exposure to TPTC resulted in 22 (fold change > 2) or 71 (fold change > 1.5) differentially expressed genes. The no observed transcriptional effect (NOTEC) and median transcriptional effect concentrations (TEC50) were determined to be 0.036 and 0.45 mg/L in E. coli. These responses were 1,230 and 97 times more sensitive than the acute median effect concentration (EC50) required to inhibit growth of cells, which demonstrated that this live cell array represents a sensitive method to assess toxic potency of chemicals. The 71 differentially expressed genes could be classified into seven functional groups. Of all the altered genes, three groups which encoded for catalytic enzymes, regulatory proteins, and structural proteins accounted for 28 %, 18 %, and 14 % of all altered genes, respectively. The pattern of differential expression observed during this study was used to elucidate the mechanism of toxicity of TPTC. To determine potential relationships among genes that were changed greater than 2.0-fold by exposure to TPTC, a correlation network analysis was constructed, and four genes were related to aroH, which is the primary target for metabolic regulation of aromatic biosynthesis by feedback inhibition in bacteria. The genes rnC, cld, and glgS were selected as potential biomarkers for TPTC, since their expression was more than 2.0-fold greater after exposure to TPTC.