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Archives of Environmental Contamination and Toxicology (v.63, #3)
Application of Zeeman Graphite Furnace Atomic Absorption Spectrometry with High-Frequency Modulation Polarization for the Direct Determination of Aluminum, Beryllium, Cadmium, Chromium, Mercury, Manganese, Nickel, Lead, and Thallium in Human Blood by Natalya B. Ivanenko; Nikolay D. Solovyev; Anatoly A. Ivanenko; Alexander A. Ganeev (pp. 299-308).
Determination of aluminum (Al), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and thallium (Tl) concentrations in human blood using high-frequency modulation polarization Zeeman graphite furnace atomic absorption spectrometry (GFAAS) was performed. No sample digestion was used in the current study. Blood samples were diluted with deionized water or 0.1 % (m/v) Triton X-100 solution for Tl. Dilution factors ranged from 1/5 per volume for Be and Tl to 1/20 per volume for Cd and Pb. For Tl, Cd, and Hg, noble metals (gold, platinum, rhodium, etc.) were applied as surface modifiers. To mitigate chloride interference, 2 % (m/v) solution of NH4NO3 was used as matrix modifier for Tl and Ni assessment. The use of Pd(NO3)2 as oxidative modifier was necessary for blood Hg and Tl measurement. Validation of the methods was performed by analyzing two-level reference material Seronorm. The precision of the designed methods as relative SD was between 4 and 12 % (middle of a dynamic range) depending on the element. For additional validation, spiked blood samples were analyzed. Limits of detection (LoDs, 3σ, n = 10) for undiluted blood samples were 2.0 μg L−1 for Al, 0.08 μg L−1 for Be, 0.10 μg L−1 for Cd, 2.2 μg L−1 for Cr, 7 μg L−1 for Hg, 0.4 μg L−1 for Mn, 2.3 μg L−1 for Ni, 3.4 μg L−1 for Pb, and 0.5 μg L−1 for Tl. The LoDs achieved allowed determination of Al, Cd, Cr, Mn, Ni, and Pb at both toxic and background levels. Be, Hg, and Tl could be reliably measured at toxic levels only. The methods developed are used for clinical diagnostics and biological monitoring of work-related exposure.
Anthropogenic and Authigenic Uranium in Marine Sediments of the Central Gulf of California Adjacent to the Santa Rosalía Mining Region by Evgueni Shumilin; Griselda Rodríguez-Figueroa; Dmitry Sapozhnikov; Yuri Sapozhnikov; Konstantin Choumiline (pp. 309-322).
To investigate the causes of uranium (U) enrichment in marine sediments in the eastern sector of the Gulf of California, surface sediments and sediment cores were collected adjacent to the Santa Rosalía copper mining region in the Baja California peninsula. Three coastal sediment cores were found to display high concentrations of U (from 54.2 ± 7.3 mg kg−1 to 110 ± 13 mg kg−1) exceeding those found in the deeper cores (1.36 ± 0.26 mg kg−1 in the Guaymas Basin to 9.31 ± 3.03 mg kg−1 in the SR63 core from the suboxic zone). The contribution of non-lithogenic U (estimated using scandium to normalize) to the total U content in sediments of three coastal cores varied from 97.2 ± 0.4 % to 98.82 % versus 49.8 ± 3 % (Guaymas Basin) to 84.2 ± 8.2 % (SR62 core) in the deeper cores. The U content record in a lead-210 (210Pb)-dated core had two peaks (in 1923 and 1967) corresponding to the history of ancient mining and smelting activities in Santa Rosalía.
Distribution of Pesticides and PCBs in Sediments of Agricultural Drains in the Culiacan Valley, Sinaloa, Mexico by Luz Ma. García-de la Parra; L. Juleny Cervantes-Mojica; Carolina González-Valdivia; Francisco J. Martínez-Cordero; Gabriela Aguilar-Zárate; Pedro Bastidas-Bastidas; Miguel Betancourt-Lozano (pp. 323-336).
Agriculture is one of the most important economic activities in Sinaloa, Mexico. The Culiacan Valley is an extensive agricultural region characterized by a variety of crops with high-yield productions. In this study, concentrations of organochlorine (OCPs) and organophosphorus (OPs) pesticides and polychlorobiphenyls (PCBs) were determined in sediments of the agricultural drainage system of Culiacan Valley. Overall, 32 compounds were detected, with concentrations widely ranging from 0.03 to 1 294 ng g−1 dry weight. OCP concentrations (15) ranged from 0.1 to 20.19 ng g−1 dw. OP concentrations (8) ranged from 0.03 to 1294 ng g−1 dw, and diazinon was the compound with the highest concentration. PCB concentrations were also determined and varied from 0.05 to 3.29 ng g−1 dw. Other compounds detected included permethrin, triadimefon, and fipronil. The central zone registered the higher concentrations and the greatest number of compounds, which could be related to the occurrence of horticultural fields in this zone. According to sediment quality guidelines, the compounds exceeding the probable effect level were γ-HCH, p,p′-DDT and p,p′-DDE, while the pesticides above the maximum permissible concentration were endosulfan, azinphos methyl, diazinon, dichlorvos, and permethrin. Although Sinaloa is an important agricultural crop producer in northwest Mexico, there are not many studies dealing with pesticide distribution in agricultural areas.
Bioindicators and Biomarkers of Environmental Pollution in the Middle-Lower Basin of the Suquía River (Córdoba, Argentina) by Tamara Maggioni; Andrea Cecilia Hued; Magdalena Victoria Monferrán; Rocío Inés Bonansea; Lucas Nicolás Galanti; María Valeria Amé (pp. 337-353).
The Suquía River middle-lower basin (Córdoba, Argentina) is subject to a strong anthropogenic impact because it receives pollutants from different sources. Recent studies have shown the importance and the need of approaching the monitoring process of water quality from integral perspectives through the use of chemical as well as biological methods. The main goal of this study was to evaluate the fish species Jenynsia multidentata as a bioindicator of environmental pollution in the middle-lower basin of the Suquía River using biotransformation and antioxidant enzymes as well as gill and liver histopathology as biomarkers. We also studied the fish-assemblage characteristics through the fish species pattern variation and the application of a biotic index based on fish data. Our study also included the analysis of a water-quality index, heavy-metal concentrations in sediment and water, and pesticide concentrations in sediment. The chemical analyses of the middle-lower Suquía River basin showed a water-quality degradation gradient. Fish-assemblage structure changed with increasing water pollution, showing a simpler structure at the most polluted area. According to the bioitc index, the variation pattern of fish assemblages reflected the aquatic environmental deterioration. Both molecular and histopathological biomarkers reflected the same trend in relation to water quality. However, enzymes varied with more acute precision between seasons. In addition, each enzyme presented with different sensibility. At tissue level, the histopathological analysis detected chronic contamination at both stations and seasons. The present work, which comprises different levels of biological organization together with chemical analyses, generated particular although complementary information, thus evidencing the same trend of aquatic contamination. Thus, the development of integral investigations gives a comprehensive approach and becomes the most effective tool to construct policies both preventive and palliative. Our study constitutes a good model to be applied in other endorheic basins of South America.
Long-Term Effects of Antibiotics on the Elimination of Chemical Oxygen Demand, Nitrification, and Viable Bacteria in Laboratory-Scale Wastewater Treatment Plants by Susan Schmidt; Josef Winter; Claudia Gallert (pp. 354-364).
Antibiotics and other pharmaceuticals are contaminants of the environment because of their widespread use and incomplete removal by microorganisms during wastewater treatment. The influence of a mixture of ciprofloxacin (CIP), gentamicin (GM), sulfamethoxazole (SMZ)/trimethoprim (TMP), and vancomycin (VA), up to a final concentration of 40 mg/L, on the elimination of chemical oxygen demand (COD), nitrification, and survival of bacteria, as well as the elimination of the antibiotics, was assessed in a long-term study in laboratory treatment plants (LTPs). In the presence of 30 mg/L antibiotics, nitrification of artificial sewage by activated sludge ended at nitrite. Nitrate formation was almost completely inhibited. No nitrification at all was possible in the presence of 40 mg/L antibiotics. The nitrifiers were more sensitive to antibiotics than heterotrophic bacteria. COD elimination in antibiotic-stressed LTPs was not influenced by ≤20 mg/L antibiotics. Addition of 30 mg/L antibiotic mixture decreased COD removal efficiency for a period, but the LTPs recovered. Similar results were obtained with 40 mg/L antibiotic mixture. The total viable count of bacteria was not affected negatively by the antibiotics. It ranged from 2.2 × 106 to 8.2 × 106 colony-forming units per milliliter (CFU/mL) compared with the control at 1.4 × 106–6.3 × 106 CFU/mL. Elimination of the four antibiotics during phases of 2.4–30 mg/L from the liquid was high for GM (70–90 %), much lower for VA, TMP, and CIP (0–50 %), and highly fluctuating for SMZ (0–95 %). The antibiotics were mainly adsorbed to the sludge and not biodegraded.
Effects of Seven Antifouling Compounds on Photosynthesis and Inorganic Carbon Use in Sugar Kelp Saccharina latissima (Linnaeus) by Per Johansson; Karl Martin Eriksson; Lennart Axelsson; Hans Blanck (pp. 365-377).
Macroalgae depend on carbon-concentrating mechanisms (CCMs) to maintain a high photosynthetic activity under conditions of low carbon dioxide (CO2) availability. Because such conditions are prevalent in marine environments, CCMs are important for upholding the macroalgal primary productivity in coastal zones. This study evaluated the effects of seven antifouling compounds—chlorothalonil, DCOIT, dichlofluanid, diuron, irgarol, tolylfluanid, and zinc pyrithione (ZnTP)—on the photosynthesis and CCM of sugar kelp (Saccharina latissima (L.)). Concentration-response curves of these toxicants were established using inhibition of carbon incorporation, whereas their effects over time and their inhibition of the CCM were studied using inhibition of O2 evolution. We demonstrate that exposure to all compounds except ZnTP (< 1000 nM) resulted in toxicity to photosynthesis of S. latissima. However, carbon incorporation and O2 evolution differed in their ability to detect toxicity from some of the compounds. Diuron, irgarol, DCOIT, tolylfluanid, and, to some extent, dichlofluanid inhibited carbon incorporation. Chlorothalonil did not inhibit carbon incorporation but clearly inhibited oxygen (O2) evolution. Photosynthesis showed only little recovery during the 2-h postexposure period. Inhibition of photosynthesis even increased after the end of exposure to chlorothalonil and tolylfluanid. Through changes in pH of the medium, toxic effects on the CCM could be studied isolated from photosynthesis effects. The CCM of S. latissima was inhibited by chlorothalonil, DCOIT, dichlofluanid, and tolylfluanid. Such inhibition of the CCM, or the absence thereof, deepens the understanding the mechanism of action of the studied compounds.
Single Versus Combined Lethal Effects of Three Agricultural Insecticides on Larvae of the Freshwater Insect Chironomus dilutus by Heidi M. K. LeBlanc; Joseph M. Culp; Donald J. Baird; Alexa C. Alexander; Allan J. Cessna (pp. 378-390).
Pesticides are currently regulated individually but are present in aquatic systems as mixtures of toxicants. In this study, the lethal effects of three agricultural insecticides—chlorpyrifos, imidacloprid and dimethoate—on Chironomus dilutus larvae were examined. Ninety-six–hour static bioassays were performed using single, binary, and ternary toxicant mixtures. The effects of the binary mixtures were investigated using the MIXTOX model to determine if the mixtures behaved additively, synergistically, or antagonistically. Dimethoate was much less toxic than chlorpyrifos or imidacloprid. Chlorpyrifos and dimethoate were not additive in mixture despite their common mode of action (MOA) and resulted in opposing effects (synergism and antagonism, respectively) when combined with imidacloprid. Synergism was observed in the ternary mixture. These results suggest that current mixture models based on MOA alone may not always be adequate in describing mixture effects, as in the current situation of mixtures with relatively few components. Other factors, such as water solubility, secondary MOA, and mechanisms of toxicity, should also be considered in future investigations of multichemical-mixture effects.
Acute and Chronic Effects of Sodium Tungstate on an Aquatic Invertebrate (Daphnia magna), Green Alga (Pseudokirchneriella subcapitata), and Zebrafish (Danio rerio) by Leslie N. Clements; Ranulfo Lemus; Alicia D. Butler; Kate Heim; Matthew R. Rebstock; Carmen Venezia; Michael Pardus (pp. 391-399).
Although aquatic toxicity data exists for tungstate substances, insufficient data of high quality and relevancy are available for conducting an adequate risk assessment. Therefore, a series of acute and chronic toxicity tests with sodium tungstate (Na2WO4) were conducted on an aquatic invertebrate (Daphnia magna), green alga (Pseudokirchneriella subcapitata), and zebrafish (Danio rerio). Collectively, the data from these studies suggest that sodium tungstate exhibits a relatively low toxicity to these taxa under these test conditions. All studies were conducted in the same laboratory under good laboratory practice standards using Organisation for Economic Co-operation and Development guidelines with the same stock of test material and the same analytical methods. All results are reported as mg W/L. The following toxicity values were based on mean measured concentrations. For D. magna, the 21 day test no-observable effect concentration (NOEC) was 25.9 mg W/L, and the 48-h median effective concentration (EC50) from the acute test was >95.5 mg W/L (the highest concentration tested). The P. subcapitata test yielded an ErC50 of 31 mg W/L. A 38-day test with zebrafish resulted in an NOEC ≥5.74 mg W/L with no effects at any concentration. The 96-h LC50 from the acute test with zebrafish was >106 mg W/L. The results of the current acute study for daphnids and fish are consistent with published literature, whereas the algae results are different from previously reported values. Transformation/dissolution (T/D) studies, which were conducted according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals protocol, confirmed that the WO 4 −2 anion accounted for most of the tungsten in solution. For classification purposes, the algae ecotoxity reference value was then compared with T/D data and would not classify Na2WO4 as an aquatic toxicant under the European Union Classification, Labelling and Packaging scheme.
Toxicity of Copper to Early-life Stage Kootenai River White Sturgeon, Columbia River White Sturgeon, and Rainbow Trout by E. E. Little; R. D. Calfee; G. Linder (pp. 400-408).
White sturgeon (Acipenser transmontanus) populations throughout western North America are in decline, likely as a result of overharvest, operation of dams, and agricultural and mineral extraction activities in their watersheds. Recruitment failure may reflect the loss of early-life stage fish in spawning areas of the upper Columbia River, which are contaminated with metals from effluents associated with mineral-extraction activities. Early-life stage white sturgeon (A. transmontanus) from the Columbia River and Kootenai River populations were exposed to copper during 96-h flow-through toxicity tests to determine their sensitivity to the metal. Similar tests were conducted with rainbow trout (RBT [Oncorhynchus mykiss]) to assess the comparative sensitivity of this species as a surrogate for white sturgeon. Exposures were conducted with a water quality pH 8.1–8.3, hardness 81–119 mg/L as CaCO2, and dissolved organic carbon 0.2–0.4 mg/L. At approximately 30 days posthatch (dph), sturgeon were highly sensitive to copper with median lethal concentration (LC50) values ranging from 4.1 to 6.8 μg/L compared with 36.5 μg/L for 30 dph RBT. White sturgeon at 123–167 dph were less sensitive to copper with LC50 values ranging from 103.7 to 268.9 μg/L. RBT trout, however, remained more sensitive to copper at 160 dph with an LC50 value of 30.9 μg/L. The results indicate that high sensitivity to copper in early-life stage white sturgeon may be a factor in recruitment failure occurring in the upper Columbia and Kootenai rivers. When site-specific water-quality criteria were estimated using the biotic ligand model (BLM), derived values were not protective of early-life stage fish, nor were estimates derived by water-hardness adjustment.
Distribution and Accumulation of Metals in Tadpoles Inhabiting the Metalliferous Streams of Eastern Chalkidiki, Northeast Greece by Efstratios Kelepertzis; Ariadne Argyraki; Efstratios Valakos; Emmanouil Daftsis (pp. 409-420).
The present study investigates the accumulation of heavy metals [copper (Cu), lead (Pb), zinc (Zn), magnesium (Mn), cadmium (Cd), nickel (Ni), and chromium (Cr)] in tadpoles inhabiting the metalliferous streams flowing within the Asprolakkas River basin (northeast Chalkidiki peninsula, Greece) and the effect of potentially harmful elements in stream water and sediment on the corresponding levels in their tissue. Animals were collected from six sampling sites influenced by a wide range of surface water and stream sediment trace element concentrations. The results of the chemical analyses showed that tadpoles accumulated significant levels of all of the examined metals. The range of whole-body mean measured concentrations were (in dry mass) as follows: Cu (46–182 mg/kg), Pb (103–4,490 mg/kg), Zn (494–11,460 mg/kg), Mn (1,620–13,310 mg/kg), Cd (1.2–82 mg/kg), Ni (57–163 mg/kg), and Cr (38–272 mg/kg). The mean concentrations of Pb, Zn, Mn, Ni, Cr, and Cd in Kokkinolakkas stream, which drains a currently active mining area, were the highest ever reported in tadpoles. Our results indicate that whole-body levels of Pb, Zn, Cu, and Cd increase with stream sediment concentrations and that these organisms tend to accumulate metals bound to Fe and Mn oxides. In addition, high dissolved concentrations and significant concentrations associated with more labile geochemical phases of sediments for specific metals were contributing factors determining whole-body levels. Given the observed bioconcentration factors, as well as the correlation with sediment concentrations, it is proposed that these organisms could be considered as bioindicators of environmental contamination and may be used for monitoring purposes within this metal-rich zone and, perhaps, within other rivers affected by metal mining.
Persistent Increase of Blood Lead Level and Suppression of δ-ALAD Activity in Northern Bobwhite Quail Orally Dosed With Even a Single 2-mm Spent Lead Shot by S. D. Holladay; R. Kerr; J. P. Holladay; B. Meldrum; S. M. Williams; R. M. Gogal Jr. (pp. 421-428).
Birds that display grit ingestion behavior are potentially at risk of lead (Pb) poisoning from mistaken ingestion of spent Pb shot pellets. The majority of available studies designed to assess such risk have used unspent shot pellets rather than field-obtained spent shot, which is oxidized and otherwise changed by weathering. Available studies also often administered more or heavier shot pellets to a bird than it might be expected to ingest. The current study dosed northern bobwhite quail (Colinus virginianus) weighing 194.6 ± 23.1 g (female birds) and 199.3 ± 12.2 g (male birds) with one to three spent no. 9 Pb shot collected from a skeet range, with particular interest in the toxicity that may occur from ingestion of a single 2-mm, 50 mg shot. An 8 week post-dosing clinical observation period was employed, over which feed consumption, body weight, blood Pb levels, and a battery of blood physiological parameters were made. Weight loss occurred in the birds, including male birds dosed with one Pb pellet. Erythrocyte delta aminolevulinic acid dehydratase (δ-ALAD) levels were decreased for the duration of the study across exposures and to levels associated with injury in wild bird populations. Decreased ALAD was particularly severe in female birds dosed with one Pb pellet and was still 92 % decreased at 8 weeks after dosing. Together, these results suggest that inadvertent ingestion of a single no. 9 Pb shot pellet can adversely affect the health of northern bobwhite quail.
Metals, Trace Elements, Polychlorinated Biphenyls, Organochlorine Pesticides, and Brominated Flame Retardants in Tissues of Barrow’s Goldeneyes (Bucephala islandica) Wintering in the St. Lawrence Marine Ecosystem, Eastern Canada by Jean-François Ouellet; Louise Champoux; Michel Robert (pp. 429-436).
The eastern North American population of Barrow’s goldeneyes winters in the St. Lawrence Estuary and Gulf of St. Lawrence where the sediments and food web are known to be contaminated with inorganic and organic compounds. Therefore, there is a potential for contamination of this population, which is designated of Special Concern by the Committee on the Status of Endangered Wildlife in Canada. Specimens were collected during three consecutive winters (2005–2007) in three regions (Manicouagan, Charlevoix, and Chaleur Bay) and analysed for metals, trace elements, polychlorinated biphenyls (PCBs), organochlorine pesticides, and brominated flame retardants (BFRs). Liver mercury levels were greater in the St. Larence Estuary (4.4 mg/kg in Manicouagan, 3.8 mg/kg in Charlevoix) than in Chaleur (2.4 mg/kg), whereas selenium showed the opposite pattern (7.3 mg/kg in Manicouagan, 7.0 mg/kg in Charlevoix, and 36.9 mg/kg in Chaleur). Liver PCB levels were greater in specimens from Manicouagan (236 ng/g) than in those from the two other regions (72 ng/g in Charlevoix, 35 ng/g in Chaleur). DDT was greater in Chaleur (66 ng/g) versus 10 ng/g in Manicouagan and 16 ng/g in Charlevoix. BFRs were not compared among regions because of smaller sample sizes, but mean total concentration was low (4.02 ng/g). Overall, although significant differences were found across regions, levels of all contaminants measured are generally low and not of toxicological concern for this population.
High Exposure Rates of Anticoagulant Rodenticides in Predatory Bird Species in Intensively Managed Landscapes in Denmark by Thomas Kjær Christensen; Pia Lassen; Morten Elmeros (pp. 437-444).
The extensive use of anticoagulant rodenticides (ARs) for rodent control has led to widespread secondary exposure in nontarget predatory wildlife species. We investigated exposure rates and concentrations of five ARs in liver samples from five raptors and six owls from Denmark. A total of 430 birds were analysed. ARs were detected in 84–100 % of individual birds within each species. Multiple AR exposure was detected in 73 % of all birds. Average number of substances detected in individual birds was 2.2 with no differences between owls and raptors. Difenacoum, bromadiolone, and brodifacoum were the most prevalent substances and occurred in the highest concentrations. Second-generation ARs made up 96 % of the summed AR burden. Among the six core species (sample size >30), summed AR concentrations were lower in rough-legged buzzard (Buteo lagopus) and long-eared owl (Asio otus) than in barn owl (Tyto alba), buzzard (B. buteo), kestrel (Falco tinnunculus), and tawny owl (Strix aluco). There was a strong tendency for seasonal variations in the summed AR concentration with levels being lowest during autumn, which is probably related to an influx of less-exposed migrating birds from northern Scandinavia during autumn. High hepatic AR residue concentrations (>100 ng/g wet weight), which have been associated with symptoms of rodenticide poisoning and increased mortality, were recorded high frequencies (12.9–37.4 %) in five of the six core species. The results suggest that the present use of ARs in Denmark, at least locally, may have adverse effects on reproduction and, ultimately, population status in some raptors and owls.
Evaluation of Fetal Skeletal Malformations in Deoxynivalenol-Treated Mice Using Microarray Analysis by Yinghui Zhao; Xiaoming Zhu; Huihui Wu; Dongming Zhuang; Guangfu Yu; Xiaoxia Li; Feng Li; Ailian Yu (pp. 445-452).
Deoxynivalenol (DON [vomitoxin]), one of trichothecene mycotoxins produced by the fungus Fusarium, is commonly detected in cereal foods across the world. DON induces diverse toxic effects in humans and animals, including emesis and diarrhea, anorexia, and immunotoxicity, and impaired maternal reproduction and fetal development. Recently, the teratogenic potential of DON has been shown and has received much attention. DON can cause various skeletal deformities in fetuses, but the underlying mechanisms have not yet been fully examined. In this study, fetal skeletal malformations in DON-treated maternal mice were thoroughly investigated using microarray assay. The results showed that DON administration caused various skeletal defects in fetuses, including misaligned or fused sternebrae and vertebrae, divided or fused ribs and polydactyly, hemivertebrae, short toes, and tail anomalies. Microarray analysis showed that 282 genes, including 148 downregulated and 134 upregulated genes, were abnormally expressed in fetal vertebral bones after maternal DON exposure. These identified genes can be classified into several categories: skeletal development, carcinogenesis, nervous disorders, sperm development and embryogenesis, and inflammation. Of these, 6 genes, mostly related to bone development, were intentionally selected for further validation using real-time reverse transcription-Polymerase Chain Reaction (RT-PCR). It was confirmed that the mRNA expression of 4 genes, i.e., fibrillin-1, Col9A2, 3′-phosphoadenosine 5′-phosphosulfate synthase 2, and Pax1, was upregulated significantly by DON administration, whereas that of 2 other genes, Runx2 and parathyroid hormone-like hormone, was downregulated significantly. Taken together, the results of our study suggest that altered expression of these 6 genes plays a critical role in fetal skeletal deformities induced by DON and thus they are worthy of further investigation.
Pyruvate Kinase Activity and δ-Aminolevulinic Acid Dehydratase Activity as Biomarkers of Toxicity in Workers Exposed to Lead by Luciane Rosa Feksa; Evandro Oliveira; Thereza Trombini; Mateus Luchese; Saiuri Bisi; Rafael Linden; Daiane Bolzan Berlese; Denise Bertin Rojas; Rodrigo Binkowski Andrade; Patricia Fernanda Schuck; Larissa Machado Lacerda; Moacir Wajner; Clovis Milton Duval Wannmacher; Tatiana Emanuelli (pp. 453-460).
Lead (Pb2+) is a heavy metal that has long been used by humans for a wide range of technological purposes, which is the main reason for its current widespread distribution. Pb2+ is thought to enter erythrocytes through anion exchange and to remain in the cell by binding to thiol groups. Pyruvate kinase (PK) is a thiol-containing enzyme that plays a key role in erythrocyte cellular energy homeostasis. δ-aminolevulinic acid dehydratase (δ-ALAD) is the second enzyme in the heme biosynthetic pathway and plays a role in the pathogenesis of Pb poisoning. Our primary objective was to investigate the effect of Pb2+ on the activity of the thiolenzymes δ-ALAD and PK and on the concentration of glutathione (GSH), a nonenzymatic antioxidant defense, in erythrocytes from Pb-exposed workers. The study sample comprised 22 male Pb workers and 21 normal volunteers (15 men and 6 women). The Pb-exposed workers were employed in manufacturing and recycling of automotive batteries. Basic red-cell parameters were assayed and total white blood cell counts performed. PK and δ-ALAD activity and blood Pb (BPb) concentrations were determined in all subjects. Pb-exposed individuals had significantly greater BPb levels than controls. Both PK and δ-ALAD activity levels were significantly lower in Pb-exposed individuals than in controls. Pb significantly inhibited PK and δ-ALAD activity in a dose-dependent manner. We found that erythrocyte GSH levels were lower in Pb-exposed individuals than normal volunteers. Pb-exposed individuals had lower values than controls for several red cell parameters (hemoglobin, hematocrit, red blood cell count, mean corpuscular volume). These results suggest that Pb inhibits δ-ALAD and PK activity by interacting with their thiol groups. It is therefore possible that Pb disrupts energy homeostasis and may be linked with decreased glucose metabolism because it affects the heme synthesis pathway in erythrocytes, contributing to the cell dysfunction observed in these in Pb-exposed individuals. These results indicate an apparent dose-effect relationship between PK activity and BPb. PK activity in human erythrocytes can be used for biological monitoring of Pb exposure. Study of the mechanisms by which Pb acts may contribute to greater understanding of the symptoms caused by Pb.