Inorganic Lead Toxicology

Pets, Genuine Tools of Environmental Pollutant Detection

In a shared environment, our companion animals became unintended sentinels for pollutant exposure consequences, developing even earlier similar conditions to humans. This review focused on the human-pet cohabitation in an environment we all share. Alongside other species, canine and feline companions are veritable models in human medical research. The latency period for showing chronic exposure effects to pollutants is just a few years in them, compared to considerably more, decades in humans. Comparing the serum values of people and their companion animals can, for example, indicate the degree of poisonous lead load we are exposed to and of other substances as well. We can find 2.4 times higher perfluorochemicals from stain- and grease-proof coatings in canine companions, 23 times higher values of flame retardants in cats, and 5 times more mercury compared to the average levels tested in humans. All these represent early warning signals. Taking these into account, together with the animal welfare orientation of today's society, finding non-invasive methods to detect the degree of environmental pollution in our animals becomes paramount, alongside the need to raise awareness of the risks carried by certain chemicals we knowingly use.

The effect of lead exposure on IQ test scores in children under 12 years: a systematic review and meta-analysis of case-control studies

An inevitable exposure to the toxic heavy metal such as lead in our environmental can have irreversible effects on children's mental performance.In this study, 3316 children in 8 case-control studies were selected for review. The case group was exposed to a concentration of lead above 10 μg/dL, and the control group was exposed to a concentration of less than 10 μg/dL, but the duration of exposure was different among studies, and the subgroup analysis was performed based on this variable.In the subgroup with duration of exposure less than the average of 4.5 years, the difference of IQ test score between two groups was significant (MD = -3.53) (P-value <0.05). Also, in the subgroup with more than 4.5 years of duration, the difference of IQ test score was significant (MD = -22.63) (P-value < 0.001).This study demonstrates that the concentration and duration of lead exposure have a large effect on mental function in children.

The Effects of Calcium, Magnesium, Phosphorus, Fluoride, and Lead on Bone Tissue

Bones are metabolically active organs. Their reconstruction is crucial for the proper functioning of the skeletal system during bone growth and remodeling, fracture healing, and maintaining calcium-phosphorus homeostasis. The bone metabolism and tissue properties are influenced by trace elements that may act either indirectly through the regulation of macromineral metabolism, or directly by affecting osteoblast and osteoclast proliferation or activity, or through becoming part of the bone mineral matrix. This study analyzes the skeletal impact of macroelements (calcium, magnesium, phosphorus), microelements (fluorine), and heavy metals (lead), and discusses the concentration of each of these elements in the various bone tissues.

Cadmium, lead and mercury in the blood of psoriatic and vitiligo patients and their possible associations with dietary habits

BACKGROUND

Psoriasis and vitiligo are common, autoimmune skin diseases, their etiology is still unclear. The relationship between environmental factors including diet and various skin diseases has been studied. The general mechanism of cadmium (Cd), lead (Pb) and mercury (Hg) toxicity is through the production of reactive oxygen species which are known to play a role in etiopathogenesis of skin disorders.

OBJECTIVE

The aim of this study was to estimate the influence of dietary habits on the concentration of Cd, Pb and Hg in the peripheral blood samples of patients with psoriasis and vitiligo.

METHODS

In this case-control study, sixty patients with psoriasis, fifty patients with vitiligo and fifty eight healthy people were examined. Blood levels of Cd, Pb and Hg were determined by atomic absorption spectrometry. Food-frequency questionnaires were implemented to collect the dietary data.

RESULTS

Significant differences (p < 0.05) of Cd levels were found between women and men with psoriasis and women and men in the control group. The concentration of Pb was significantly higher among vitiligo patients (50.04 ± 26.54 μg/L) than in healthy controls (36.04 ± 27.35 μg/L). Significantly lower ratio of Se/Pb, Zn/Pb and Cu/Pb was found among psoriatic men. Significantly (p < 0.05) lower values of Se/Hg ratio were observed among vitiligo patients compared to controls.

CONCLUSIONS

The elevated levels of toxic elements could increase oxidative stress which may partly contribute to inflammation in the pathogenesis of psoriasis and vitiligo, which requires further research. Analysis of the influence of frequent consumption of food products on toxic metals concentration showed that the dietary habits have impact on the content of examined toxic metals in the blood of patients. The obtained results may be useful for composing the diet and could be helpful in prevention of psoriasis and vitiligo.

The impact of environmental lead exposure on Whooper swan (Cygnus cygnus): Pathological and immunohistochemical studies

This study was carried out to investigate the pathology of environmental lead (Pb) poisoning in Whooper swans (Cygnus cygnus). A number of 12 out 54 swans (22.2%) randomly collected from Honshu, Japan from June 2005 to July 2007 were affected with Pb poisoning. Affected swans showed stained vent with greenish watery diarrhoea and impacted crop. The presence of Pb shots in the gizzard (50%) was confirmed by X-ray, and all cases showed a dark greenish coloured liver. Microscopically, the pathology of Pb poisoning in swans was multisystemic. The severity of the lesions was the highest in the CNS followed by the liver, kidney, spleen, lungs, gizzard, heart, bone marrow respectively and was the least in the peripheral nervous system. CNS lesions were cerebral haemorrhage, malacia, and spongiosis with astrocytic activation and increased neurofilaments accumulations. In addition, there were hepatic and renal hemosiderosis and apoptosis, hepatic granuloma, interstitial pneumonia, gizzard and myocardial necrosis and bone marrow hypoplasia. Chemical analysis of the Pb content in liver and kidneys ranged from 8.18 to 60.6 µg/g, respectively. The extent and severity of lesions varied among individuals and were mostly dose-dependent. Finally, these findings improved the diagnostic procedure of Pb poisoning in free-living Whooper swans.

Environmental and socioeconomic factors contributing to elevated blood lead levels in children from an industrial area of Upper Silesia

The present study concentrated on a cross-sectional analysis of recent exposure to lead (Pb) and the socioeconomic factors behind increased Pb exposure in Polish children. Lead is one of the most widespread toxic heavy metals in the industrial region of Upper Silesia (Poland). Elevated blood Pb levels in children continue to be a matter of serious concern. The present study involved 4882 children from the Upper Silesia region, aged from 3 yr to 18 yr, over the calendar years 1999 to 2013. The concentration of Pb in blood was determined in each child. The children's parents were asked to answer survey questions about the child's environmental exposure to Pb as well as the socioeconomic condition of the family. Factors that correspond with increased exposure to Pb included: lower level of education of parents, unemployment, parents' occupational Pb exposure, poor socioeconomic status of the family, smoking at home, living on the ground floor of buildings, consumption of locally grown vegetables and fruits, longer outdoor playing periods in a polluted environment, and male gender. Environmental exposure to Pb is the most important factor behind chronic poisoning of children in Upper Silesia. The most important socioeconomic factor associated with concentrations of Pb in children's blood is a lower level of education of a child's mother and father. Environ Toxicol Chem 2016;35:2597-2603. © 2016 SETAC.

The effect of occupational lead exposure on lipid peroxidation, protein carbonylation, and plasma viscosity

The aim of the study was to investigate the influence of occupational lead (Pb) exposure on lipid peroxidation, protein carbonylation, and plasma viscosity in workers. The examined group included 283 healthy male employees of manufacturing facilities using zinc and Pb. The mean blood concentrations of Pb and zinc protoporphyrin as well as the mean urine δ-aminolevulinic acid levels were used as markers of exposure for the examined group. Taking into account the obtained mean values of blood lead level, the examined group was divided into three subgroups. When comparing the control group with the subgroups, Pb exposure markers were significantly elevated in all the three subgroups. Concentrations of conjugated dienes (CD), lipid hydroperoxides, malondialdehyde (MDA), and protein carbonyl groups were also significantly increased. Conversely, the levels of total protein and protein sulfhydryls were significantly decreased in the subgroups compared with the controls. The plasma viscosity was significantly elevated in the subgroups. A dose-response between Pb levels and plasma viscosity was not observed. Pb supposedly elevates MDA and CD in a dose-dependent manner. In conclusion, occupational Pb exposure induces oxidative stress that results in lipid and protein damage. Moreover, Pb-induced oxidative stress is likely the primary factor that elevates plasma viscosity, despite decreased protein levels.

Hybrid quantum dot-fatty ester stealth nanoparticles: toward clinically relevant in vivo optical imaging of deep tissue

Despite broad applications of quantum dots (QDs) in vitro, severe toxicity and dominant liver uptake have limited their clinical application. QDs that excite and emit in the ultraviolet and visible regions have limited in vivo applicability due to significant optical interference exerted by biological fluids and tissues. Hence we devised a new biocompatible hybrid fluorophore composed of near-infrared-emitting PbSe quantum dots encapsulated in solid fatty ester nanoparticles (QD-FEN) for in vivo imaging. The quantum yield and tissue penetration depth of the QD-FEN were characterized, and their biological fate was examined in a breast tumor-bearing animal model. It was found for the first time that chemical modification of the headgroup of QD-encapsulating organic fatty acids was a must as these groups quenched the photoluminescence of PbSe nanocrystals. The use of fatty esters enhanced aqueous quantum yields of PbSe QDs up to ∼45%, which was 50% higher than that of water-soluble PbSe nanocrystals in an aqueous medium. As a result, a greater than previously reported tissue penetration depth of fluorescence was recorded at 710 nm/840 nm excitation/emission wavelengths. The QD-FEN had much lower short-term cytotoxicity compared to nonencapsulated water-soluble QDs. More importantly, reduced liver uptake, increased tumor retention, lack of toxic response, and nearly complete clearance of QD-FEN from the tested animals was demonstrated. With a combination of near-infrared spectral properties, enhanced optical properties,and significantly improved biosafety profile, this novel hybrid nanoparticulate fluorophore system demonstrably provides real-time, deep-tissue fluorescent imaging of live animals, laying a foundation for further development toward clinical application.

Correlation of toxicity with lead content in root tip cells (Allium cepa L.)

The present study determines lead content in onion root tip cells (Allium cepa L.), correlating it with its toxicity. The treatment was carried at 25 +/- 0.5 degrees C using aqueous solutions of lead chloride at 0.1, 0.25, 0.50, 0.75, and 1 ppm for 12, 24, 48, and 72 h. For each treatment, a control where the lead solution was substituted by distilled water was included. After treatment, the meristems were fixed with a mixture of alcohol-acetic acid (3:1) and colored according to the technique of Feulgen. Lead content was quantified by graphite furnace absorption atomic spectrometry. The lead content in the roots ranged from 3.25 to 244.72 microg/g dry weight, with a direct relation with the concentration and time of exposure. A significant negative correlation was presented (r = -0.3629; p < 0.01) among lead content and root growth increment, and a positive correlation (r = 0.7750; p < 0.01) with the induction of chromosomic aberrations. In conclusion, lead is able to induce a toxic effect in the exposed roots, correlated with its content.

Effect of Lead Acetate on Cytosolic Thioredoxin Reductase Activity and Oxidative Stress Parameters in Rat Kidneys

Oxidative stress has been suggested to be an important molecular mechanism of toxic effects of lead in the kidney. Thioredoxin reductase-1 is a selenoprotein involved in many cellular redox processes. This study evaluated the effect of acute and chronic exposure intraperitoneally to lead acetate on thioredoxin reductase-1 activity and on other oxidative stress parameters in the rat kidney, as well as on indicators of renal function commonly used to assess lead poisoning. Acute exposure to 25 mg/kg lead acetate increased superoxide dismutase and thioredoxin reductase-1 activity (after 6, 24 and 48 hr), while exposure to 50 mg/kg lead acetate increased catalase activity (after 48 hr) and inhibited delta-aminolevulinate dehydratase activity (after 6, 24 and 48 hr) in the kidney (P < 0.05). Chronic exposure (30 days) to 5 mg/kg lead acetate inhibited delta-aminolevulinate dehydratase and increased glutathione S-transferase, non-protein thiol groups, catalase, thioredoxin reductase-1 and uric acid plasma levels, while exposure to 25 mg/kg lead acetate reduced body weight and delta-aminolevulinate dehydratase, but increased glutathione S-transferase, non-protein thiol groups and uric acid plasma levels (P < 0.05). No changes were observed in thiobarbituric acid reactive substances, glutathione peroxidase, creatinine or inorganic phosphate levels after either acute or chronic exposure. Our results suggest that thioredoxin reductase-1 may be an early indicator of acute exposure to low lead doses.

Lead promotes abasic site accumulation and co-mutagenesis in mammalian cells by inhibiting the major abasic endonuclease Ape1

Lead is a widespread environmental toxin, found in contaminated water sources, household paints, and certain occupational settings. Classified as a probable carcinogen by the International Agency for Research on Cancer (IARC), lead promotes mutagenesis when combined with alkylating and oxidizing DNA-damaging agents. We previously reported that lead inhibits the in vitro repair activity of Ape1, the major endonuclease for repairing mutagenic and cytotoxic abasic sites in DNA. We investigated here whether lead targets Ape1 in cultured mammalian cells. We report a concentration-dependent inhibition of apurinic/apyrimidinic (AP) site incision activity of Chinese hamster ovary (CHO) AA8 whole cell extracts by lead. In addition, lead exposure results in a concentration-dependent accumulation of AP sites in the genomic DNA of AA8 cells. An increase in the oxidative base lesion 8-oxoguanine was observed only at high lead levels (500 microM), suggesting that non-specific oxidation plays little role in the production of lead-related AP lesions at physiological metal concentrations--a conclusion corroborated by "thiobarbituric acid reactive substances" assays. Notably, Ape1 overexpression in AA8 (hApe1-3 cell line) abrogated the lead-dependent increase in AP site steady-state levels. Moreover, lead functioned cooperatively to promote a further increase in abasic sites with agents known to generate AP sites in DNA (i.e., methyl methansulfonate (MMS) and hydrogen peroxide (H2O2), but not the DNA crosslinking agent mitomycin C. Hypoxanthine guanine phosphoribosyltransferase (hprt) mutation analysis revealed that, whereas lead alone had no effect on mutation frequencies, mutagenesis increased in MMS treated, and to a greater extent lead/MMS treated, AA8 cells. With the hApe1-3 cell line, the number of mutant colonies in all treatment groups was found to be equal to that of the background level, indicating that Ape1 overexpression reverses MMS- and lead-associated hprt mutagenesis. Our studies in total indicate that Ape1 is a member of an emerging group of DNA surveillance proteins that are inhibited by environmental heavy metals, and suggest an underlying mechanism by which lead promotes co-carcinogenesis.

Pica-associated cerebral edema in an adult

Acute cerebral edema due to lead intoxication is an unusual presentation in an adult. Here we describe an adult with pica presenting with severe encephalopathy due to extremely high lead levels (>200 microg/dl) with marked cerebral edema and mild hyperammonemia. Rapid initiation of chelation therapy led to a reduction in serum lead and ammonia levels and a resolution of the cerebral edema and encephalopathy, suggesting a close relationship between lead toxicity and hepatic dysfunction.