Utilization of membrane filtration for preconcentration and determination of Cu(II) and Pb(II) in food,water and geological samples by atomic absorption spectrometry

A method for separation–preconcentration of Cu(II) and Pb(III) ions by membrane filtration has been presented. The analyte ions were collected on acetate membrane filter as their 1-2-pyridylazo 2-naphthol (PAN) complexes. The analytes were determined by flame atomic absorption spectrometry. The analytical parameters including pH, eluent type, sample volume, amount of PAN, etc. were examined in order to gain quantitative recoveries of analyte ions. The effects of foreign ions on the recoveries of analyte ions were also investigated. The detection limits by three sigma were found to be 1.2 and 3.5 μg L⁻¹ for Cu(II) and Pb(II), respectively. The preconcentration factor was 60 for Cu(II) and 20 for Pb(II). The validation of the presented procedure was checked by the analysis of certified reference materials. The optimized method was successfully applied to food, water and geological samples with good results.     

Potential of coffee husk biomass waste for the adsorption of Pb(II) ion from aqueous solutions

The uptake of Pb(II) from the aqueous solution by Coffee Husk Biomass Waste (CHBW) as a green low cost solid phase adsorbent was critically studied. The chemical composition and the surface morphology of the CHBW were determined and fully characterized by FESEM-EDX. In batch mode, the effect of various analytical parameters e.g. adsorbent dose, contact time and analyte concentration on lead(II) ions retention by the biomass CHBW was performed. The adsorption equilibrium of Pb(II) ions was achieved after 60 min with very high percentage 98%, and an adsorption capacity of 19.02 mg/g lead towards the adsorbent was determined. Sorption kinetics data was fitted well with pseudo-second-order model with good correlation coefficient (R² = 1) and (q_e,cal) 19.23 mg/g, (eq_e,exp) 19.07 mg/g. The sorption isotherm fitted better with the Freundlich model (R² is close to the unity). The Langmuir gives maximum adsorption capacity (q_max) of Pb(II) was 37.04 mg/g. These results indicated that, the coffee husk is an efficient, sustainable, and low-cost adsorbent for Pb(II) uptake from wastewater.     

Toxic effects and depuration after the dietary lead(II) exposure on the bioaccumulation and hematological parameters in starry flounder (Platichthys stellatus)

Platichthys stellatus (mean length 20 ± 2 cm, mean weight 160.15 ± 15 g) were exposed to the different levels of dietary lead(II) at the concentrations of 0, 30, 60, 120, 240 mg/kg for 4 weeks. Depuration was conducted for 2 weeks after exposure. The lead exposure over 60 mg Pb/kg induced the significant bioaccumulation in tissues of P. stellatus (5–30 μg/g tissue), except for brain and muscle where the exposure to 240 mg Pb/kg caused the bioaccumulation (2–4 μg/g tissue). The hematological parameters such as red blood cell (RBC) counts, hematocrit (Ht) value and hemoglobin (Hb) concentration were substantially decreased over 60 mg Pb/kg, and lasted even after the depuration period. For plasma components, calcium and magnesium levels in plasma were generally decreased over 60 mg Pb/kg, and glucose level was also mainly increased over 60 mg Pb/kg. Total protein was significantly decreased over 120 mg Pb/kg after 4 weeks exposure. Glucose and total protein showed the restoration after the depuration period in groups of fish exposed previously to over 60 and 120 mg Pb/kg, respectively. However, other parameters that changed during the exposure over 60 mg Pb/kg did not recovered. For enzymatic components in plasma, glutamic oxalate transminase (GOT), glutamic pyruvate transminase (GPT) and alkaline phosphatase (ALP) were significantly increased over 120 mg Pb/kg, and there was only restoration observed after the depuration for ALP over 120 mg Pb/kg.     

Mechanisms of defence from Fe(II) toxicity in human intestinal Caco-2 cells

Iron is used to cure iron-deficient anaemia but can also be toxic to the intestine. Fe(II) toxicity was investigated using differentiated human intestinal Caco-2 cells treated with 15 and 50 μM of Fe(II)/ascorbate for 2 h (acute phase), and followed for 24 h after iron removal and replacement of complete culture medium (late phase). During the acute phase damage to tight junctions occurred as demonstrated by an increase in cell monolayer permeability and by partial delocalization of the tight junction protein claudin 4 from the plasma membrane to an intracellular compartment. At the end of the late phase, cells treated with 15 μM Fe(II) showed full restoration of claudin 4 localization to the plasma membrane and their tight junction permeability returned to values close to those of control cells. Conversely, cells treated with 50 μM Fe(II) showed sustained and irreversible damage to the tight junctions, accompanied by apoptosis and necrosis. Activation of NF-κB occurred at both Fe(II) concentrations after 30 min of Fe(II) treatment, followed, at the end of the acute phase, by a strong induction of mRNA coding for heat shock protein 70 and metallothionein 2A. Our results indicate that intestinal cells respond to iron toxicity by strongly activating two genes involved in cell response to stress, although the outcome in terms of cell survival is different depending on the dose of treatment, namely almost complete restoration of epithelial permeability and cell survival at 15 μM Fe(II), and progressive and irreversible cytotoxicity leading to apoptosis and necrosis at 50 μM Fe(II).     

Safety evaluation of metal exposure from commonly used moisturizing and skin-lightening creams in Nigeria

The concentrations of ten metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn and Al) were measured in some commonly used moisturizing and skin-lightening creams in Nigeria with a view to providing information on the risk of exposure to metals from the use of these products. The metal concentrations in these products were measured by atomic absorption spectrometry after acid digestion of the samples. The measured concentrations of metals in the skin moisturizing creams ranged from <0.15 to 6.3 μg/g Cd, <0.02 to 17.5 μg/g Cu, 2.25 to 6.25 μg/g Cr, <0.25 to 124.3 μg/g Al, 0.2 to 7.3 μg/g Pb, <0.03 to 10.7 μg/g Ni, 17.3 to 372.0 μg/g Zn, <0.02 to 1.0 μg/g Co, 17.75 to 28.8 μg/g Mn, <0.1 to 89.8 μg/g Fe while the concentrations of metals in the skin-lightening products ranged from <0.15 to 16.5 μg/g Cd, <0.02 to 10.0 μg/g Cu, 4.25 to 8.0 μg/g Cr, <0.25 to 128.0 μg/g Al, 0.5 to 4.5 μg/g Pb, <0.03 to 1.65 μg/g Ni, 24.7 to 267.5 μg/g Zn, <0.02 to 2.5 μg/g for Co, 19.3 to 31.8 μg/g Mn, 9.5 to 211.63 μg/g Fe. In a significant number (>93%) of the samples investigated the concentrations of Pb, Cd, Ni and Co were below the specified limit, or the maximal limit for impurities in colour additives in cosmetics for external use. However, Cr was found at concentrations above the allergenic limit of 1 μg/g. The results also showed that skin-lightening creams contained higher concentrations of the studied metals than the moisturizing creams, except for Ni, which indicates that persons who uses skin-lightening creams in preference to moisturizing ones, are exposed to higher concentrations of metals.     

Heavy metal burdens of public primary school children related to playground soils and classroom dusts in Ibadan North-West local government area,Nigeria

Information about heavy metal burden of children in Nigeria related to playground soils and classroom dusts is lacking. Playground soil, classroom dust, blood and spot urine samples (n = 253) were collected from 6 urban and 2 semi-rural public schools in Ibadan North-West, Nigeria. Samples were analysed for Pb, Cu, Zn, Fe and Mn. Mean blood Pb levels in urban area (male, 41.66 ± 8.78 μg/dl vs. female, 40.64 ± 5.46 μg/dl) were twice as high as those in semi-rural area (male, 19.71 ± 3.73 μg/dl vs. female, 20.65 ± 2.26 μg/dl). Concentrations of Pb, Cu, Zn, and Fe in soil and dust samples in the urban schools were between 2- to 4-fold greater than that of semi-rural schools. No correlation was observed between blood and dust metals. A positive correlation (r = 0.168, p = 0.008) was observed between blood Pb and playground soil Pb. Pb burden in the children might be from their schools’ playgrounds and other yet unidentified sources.     

Proposal for a revised Reference Concentration (RfC) for manganese based on recent epidemiological studies

In 1993, based on observations of subclinical neurological effects in workers, the United States Environmental Protection Agency (US EPA) published a Reference Concentration (RfC) of 0.05 μg/m³ for manganese (Mn). The geometric mean exposure concentration, 150 μg/m³ respirable Mn, was considered the lowest observable adverse effect level (LOAEL), and uncertainty factors (UFs) were applied to account for sensitive populations, database limitations, a LOAEL, subchronic exposure, and potential differences in toxicity of different forms of Mn. Based on a review of more recent literature, we propose two alternate Mn RfCs. Of 12 more recent occupational studies of eight cohorts with chronic exposure durations, examining subclinical neurobehavioral effects, predominantly on the motor system, three were considered appropriate for development of an RfC. All three studies yielded no observable adverse effect levels (NOAELs) of approximately 60 μg/m³ respirable Mn. Converting the occupational NOAEL to a human equivalent concentration (HEC) of 21 μg/m³ (for continuous exposure) and applying a UF of 10 to account for intraspecies variability yielded an RfC of 2 μg/m³. We also derived a similar RfC (7 μg/m³) using an Mn benchmark dose (BMD) as the point of departure. Overall confidence in both RfCs is medium.     

Dyslipdemia induced by chronic low dose co-exposure to lead,cadmium and manganese in rats: the role of oxidative stress

Lead (Pb), cadmium (Cd) and manganese (Mn) have many potential adverse health effects in vitro and in animal models of clinical toxicity. The current study investigated the dyslipidaemic and oxidative stress effects of chronic low-dose oral exposure to Pb, Cd and Mn and the combination (Pb + Cd + Mn) in rats for 15 weeks. Chronic exposure to the metals did not significantly (P > 0.05) alter serum lipid profiles. However, the atherogenic index decreased by 32.2% in the Pb + Cd + Mn group, relative to the control. The triglyceride/high-density lipoprotein cholesterol ratio decreased by 39.4% in the Pb + Cd + Mn group, relative to the control, and elevated by 81.8, 94.8 and 20.8%, relative to the Pb, Cd and Mn groups, respectively. While the serum concentrations of malondialdehyde significantly increased in the Mn and Pb + Cd + Mn groups, that of glutathione peroxidase-1 decreased in the Pb + Cd + Mn group, and metallothionein-1 and zinc concentrations markedly decreased in all the metal treatment groups.The results suggest that long-term exposure of rats to Pb + Cd + Mn may result in hypolipidaemia, mediated via oxidative stress and metal interactions. Individuals who are constantly exposed to environmentally relevant levels of the metals may be at risk of hypolipidaemia.     

Chebulinic acid and tellimagrandin I inhibit DNA strand breaks by hydroquinone/Cu(II) and H2O2/Cu(II), but potentiate DNA strand breaks by H2O2/Fe(II)

The effects of two polyphenols, chebulinic acid and tellimagrandin I, on DNA strand breaks mediated by H₂O₂/Cu(II), hydroquinone (HQ)/Cu(II) and H₂O₂/Fe(II) in pBR322 plasmid DNA and genomic DNA of cultured MRC-5 human embryo lung fibroblasts were examined. The results demonstrated that chebulinic acid and tellimagrandin I obviously inhibited HQ/Cu(II)- and H₂O₂/Cu(II)-mediated pBR322 DNA strand breaks. When MRC-5 cells were treated with HQ/Cu(II), the presence of chebulinic acid or tellimagrandin I inhibited HQ/Cu(II)-mediated double strand breaks of genomic DNA. The presence of chebulinic acid or tellimagrandin I did not affect the H₂O₂- and HQ-mediated reduction of Cu(II) to Cu(I). Both polyphenols could slightly inhibit H₂O₂/Fe(II)-mediated plasmid DNA strand break at the lower concentration (1–10 μM), but potentiate the DNA strand break at the higher concentration (over 50 μM). These results demonstrated that chebulinic acid and tellimagrandin I possessed antioxidant action in certain conditions and exerted prooxidant action on DNA strand breaks in other conditions.     

Manganese exposure through drinking water during pregnancy and size at birth: A prospective cohort study

The essential element manganese (Mn) might be toxic at excess exposure. We assessed the impact of elevated Mn exposure through drinking water during pregnancy on birth size in a population-based cohort(n = 1695) in rural Bangladesh. Concentrations of water Mn (median = 236 μg/L, range = 7.1–6336; n = 1177) and erythrocyte Mn (median = 30 μg/kg, range = 6.3–114; n = 758) were measured using ICP-MS. In regression analyses, newborns of women in the highest tertile of water Mn (median = 1495 μg/L) were 0.49 cm (0.20 SD) shorter (B = −0.42; 95% CI: −0.77, −0.08) than those in the lowest tertile (56 μg/L). The inverse association was significant in girls and also in boys of mothers with lowest hemoglobin values, likely due to higher absorption of Mn. Manganese concentrations in water and erythrocytes did not correlate, and the associations of the latter with birth size were less obvious. This study suggests that consumption of water with highly elevated Mn levels during pregnancy may impair fetal growth.     

Apoptogenic and necrogenic effects of mercuric acetate on the chromatin structure of K562 human erythroleukemia cells

Time lapse video photography was used to follow the movement of individual cells after in vitro treatment with Hg(II) acetate. Cellular changes of mercuric ions were characterized by their properties of causing reduced cellular mobility (10–50 μM), and complete lack of cellular movement at higher concentrations (100–1000 μM). Results show that after mercury treatment at subtoxic levels (⩽1 μM): (a) chromatin changes were the earliest signs of cytotoxicity, (b) two major parts in nuclear material of K562 erythroleukemia cells could be distinguished, highly condensed supercoiled and decondensed veil-like chromatin, (c) decondensed chromosomes were rejected as clustered puffs and (d) often the nuclear material was broken down to apoptotic bodies. Nuclear changes caused by Hg(II) acetate in the concentration range between 10 and 50 μM were characterized by apoptosis seen as broken nuclei and apoptotic bodies. High concentration of Hg²⁺ ions (100 μM) initiated necrotic nuclear changes, with enlarged leaky or opened nuclei.     

Prenatal exposure to lead in relation to risk of preterm low birth weight: A matched case–control study in China

We investigated the association between prenatal exposure to lead (Pb) and the risk of preterm low birth weight (PLBW). Pb concentrations in maternal urine collected at birth from 408 subjects (102 cases and 306 matched controls) were analyzed and adjusted by creatinine. The median Pb concentration in the PLBW cases (10.60 μg Pb/g creatinine) was higher than that of the controls (7.28 μg Pb/g creatinine). An adjusted odds ratio (OR) of 2.96 (95% CI = 1.49–5.87) for PLBW was observed when the highest tertile was compared to the lowest tertile of Pb levels. The association was more pronounced among female infants (adjusted OR = 3.67 for the highest tertile; 95% CI = 1.35–9.93) than male infants (adjusted OR = 1.91 for the highest tertile; 95% CI = 0.74–4.95). Our study suggests that prenatal exposure to levels of Pb encountered today in China is associated with an elevated risk of PLBW.     

Dose-dependent folic acid and memantine treatments promote synergistic or additive protection against Aβ(25–35) peptide-induced apoptosis in SH-SY5Y cells mediated by mitochondria stress-associated death signals

Increased dietary folic acid (FA) is associated with reduced risks of Alzheimer’s disease (AD). The AD drug memantine (Mn) has had limited therapeutic effects for the treatment of patients with moderate to severe AD. This study investigated whether and the underlying mechanisms by which the combination of Mn and FA may have synergistic or additive effects in protecting against amyloid-β_(25–35) peptide (Aβ)-induced neurocytotoxicity. Aβ treatment of human neuroblastoma SH-SY5Y cells significantly induced a 6-fold increase of apoptotic cells compared with the Aβ-untreated group. Preincubation of Aβ-exposed cells with FA (500 μM) or Mn (20 μM) caused a 22% and 10% reduction of apoptotic cells, respectively, whereas the combo-treatments at such doses synergistically alleviated Aβ-induced apoptosis by 60% (P < 0.05). The apoptotic protection by the combo-treatments coincided with attenuating Aβ-elicited mitochondrial (mt) membrane depolarization and abolishing Aβ-induced mt cytochrome c release to the cytosol. Increased levels of FA at 1000 μM in combination with 20 μM Mn exerted an additive protection against Aβ_(25–35)-induced-apoptosis as compared to the isolate Mn group (P < 0.05). The combo-treatments reversed Aβ-elicited mt membrane depolarization, attenuated Aβ-elicited mt cytochrome c release to the cytosol, and diminished Aβ-promoted superoxide generation. The apoptotic-protection by such combo-treatments was partially abolished by carbonyl cyanide 3-chlorophenylhydrazone (mt membrane potential uncoupler) and sodium azide (mt cytochrome c oxidase inhibitor). Taken together, the data demonstrated that dose-dependent FA and Mn synergistically or additively protected SH-SY5Y cells against Aβ-induced apoptosis, which was partially, if not completely, mediated by mt stress-associated death signals.     

1-(2-(2-(2-(1-Aminoethyl)phenyl)diselanyl)phenyl)ethanamine: An amino organoselenium compound with interesting antioxidant profile

Free radical scavenging and antioxidant activities of 1-(2-(2-(2-(1-aminoethyl)phenyl)diselanyl)phenyl)ethanamine (compound A) and diphenyl diselenide (PhSe)2 were examined and compared for inhibition of Fe(II) and sodium nitroprusside (SNP) stimulated lipid peroxidation in rat brain, interaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical and their glutathione peroxidase (GPx) like antioxidant activities with H₂O₂ or tBuOOH as substrates and with PhSH as thiol co-substrates as well as their ability to oxidize mono- and di-thiols were also evaluated. This study revealed that an amino group in amino diselenide drastically enhances their catalytic activities in the aromatic thiol (PhSH) assay system. Compound A was ∼2-fold more active than (PhSe)2 in both tBuOOH and H₂O₂ assay systems. In addition, the present results showed that (PhSe)2 exhibited an increased ability to oxidize di-thiols, compound A was not a good substrate for the oxidation of thiol used namely DTT, cystine and DMPS. The antioxidant potency against Fe(II) and SNP-induced brain TBARS were in this order [(compound A); IC₅₀ 2 μM and 4 μM] > [(PhSe)2; IC₅₀ 19 μM and 27.5 μM. Compound A showed DPPH radical-scavenging activity. This study provides in vitro evidence anti-oxidant action of the tested organoselenium compounds, that the nitrogen atom in the organochalcogens can have a profound effect on their antioxidant activity.     

Phthalate and di-(2-ethylhexyl) adipate (DEHA) intake by German infants based on the results of a duplicate diet study and biomonitoring data (INES 2)

Phthalates as well as di-(2-ethylhexyl) adipate (DEHA) are used as plasticizers in diverse applications and are of toxicological concern.The study was conducted with a study population of 25 German subjects aged between 15 and 21 months. Overall, 16 phthalates and DEHA were measured by gas chromatography–mass spectrometry in a total of 171 duplicate diet samples collected over 7 consecutive days, and 20 phthalate metabolites were analyzed in the urine samples collected over 7 consecutive days using a liquid chromatography–tandem mass spectrometry method.The median “high” daily dietary intake based on 95th percentiles was 4.66 μg/kg b.w. for di-2-ethylhexyl phthalate (DEHP), 1.03 μg/kg b.w. for di-isobutyl phthalate (DiBP), and 0.70 μg/kg b.w. for di-n-butyl phthalate (DnBP), and 1.0 μg/kg b.w. for DEHA. The “high” daily total intake from biomonitoring data was 4.9 μg/kg b.w. for DEHP, 2.2 μg/kg b.w. for DnBP, 3.9 μg/kg b.w. for DiBP, and 2.6 μg/kg b.w. for di-isononyl phthalate.The comparison of the two intake estimates indicates that the dominant intake source of DEHP was food ingestion, whereas other sources considerably contributed to the total intake of other phthalates. Using our “high” intake scenario, none of the analyzed phthalates reached the recommended tolerable daily intake levels.     

Effect of prenatal manganese intoxication on [3H]glucose uptake in the brain of rats lesioned as neonates with 6-hydroxydopamine

In the present study we examined the effects of prenatal manganese (Mn) intoxication on [³H]glucose uptake in the brain of rats lesioned as neonates with 6-hydroxydopamine (6-OHDA). MnCl₂ ? 4H2O (10,000 ppm) was added to the drinking water of pregnant Wistar rats for the duration of pregnancy. On the day of parturition, Mn was discontinued as an additive to the drinking water. The control group consisted of rats that consumed water without Mn. Three days after birth, rats in both groups (control and Mn) were pretreated with desipramine hydrochloride (20 mg/kg) and pargyline hydrochloride (50 mg/kg) and injected bilaterally icv with one of three doses of 6-OHDAhydrobromide (15 μg, 30 μg or 67 μg base form in saline on each side) or with saline (control). 6-[³H]-Dglucose (500 μCi/kg, ip) was administered to male offspring in adulthood; after 15 min, brain specimens were taken (frontal cortex, hippocampus, striatum, thalamus with hypothalamus, pons and cerebellum) for determination of radioactivity in a liquid scintillation counter. Low dose 6-OHDA (15 μg icv) increased [³H]glucose uptake in all brain regions (p < 0.05) in both control and Mnintoxicated animals. In rats lesioned with a moderate dose of 6-OHDA(30 μg icv), [3H]glucose uptake was unaltered in both control and Mn-exposed rats. High dose 6-OHDA(67 μg icv) reduced [³H]glucose uptake in all brain regions of Mn-exposed rats (except for cerebellum) compared with the saline group (all, p < 0.05). There was no change in regional brain uptake of [³H]glucose in control rats. In conclusion, this study shows that mild neuronal insult (15 μg icv 6-OHDA) increased glucose uptake in the brain while severe damage (concomitant 60 μg icv 6-OHDA and Mn treatment) significantly diminished this process.     

Essential trace and toxic element concentrations in organic and conventional milk in NW Spain

Dietary composition and husbandry practices largely determine essential trace element status and toxic element exposure of livestock, and consequently their concentrations in animal products. This study evaluates the main essential trace (Co, Cr, Cu, Fe, I, Mn, Mo, Ni, Se and Zn) and toxic (As, Cd, Hg and Pb) element concentrations in milk from organic and conventional farms in NW Spain (n = 50). Milk samples were acid digested and analyzed by ICP-MS. Essential trace element concentrations in organic milk were significantly lower compared to conventional milk, this was especially evident for elements that are routinely supplemented at high concentrations in the conventional concentrate feed: Cu (41.0 and 68.9 μg/L in organic and conventional milk, respectively), Zn (3326 and 3933 μg/L), I (78 and 265 μg/L) and Se (9.4 and 19.2 μg/L). Toxic metal concentrations in milk were in general very low and no statistically significant differences were observed between organic and conventional milk. In addition, the mineral content of organic milk showed a seasonal pattern, the significantly higher As (65%) and Fe (13%) concentrations found in the winter sampling possibly being related to a higher consumption of concentration feed and soil ingestion when grazing.     

Determination of repaglinide in human plasma by high-performance liquid chromatography–tandem mass spectrometry

A rapid and sensitive method based on high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been developed for the determination of repaglinide in human plasma. The analyte and internal standard (I.S.), diazepam, were extracted from plasma (25 μL) by liquid–liquid extraction with diethyl ether–dichloromethane (60:40, v/v) and separated on a XDB-C₁₈ column using acetonitrile–ammonium acetate buffer (pH 6.8, 0.01 mol/L) as mobile phase. The retention times of repaglinide and I.S. were 1.95 and 2.35 min, respectively. Detection was carried out using API 4000 mass spectrometer with an ESI interface operating in the multiple reaction monitoring (MRM) mode. The assay was linear over the concentration range 0.050–50 ng/mL with a limit of detection (LOD) of 0.010 ng/mL. Intra- and inter-day precisions (as relative standard deviation, R.S.D.) were ≤5.07% and ≤11.2%, respectively, and accuracy (as relative error, R.E.) was from ?0.593% to ?1.26%. The assay was successfully applied to a pharmacokinetic study involving a single oral administration of a tablet containing 2 mg repaglinide to each of 10 healthy volunteers.     

Toxic trace metals and human oocytes during in vitro fertilization (IVF)

Trace exposures to the toxic metals mercury (Hg), cadmium (Cd) and lead (Pb) may threaten human reproductive health. The aim of this study is to generate biologically-plausible hypotheses concerning associations between Hg, Cd, and Pb and in vitro fertilization (IVF) endpoints. For 15 female IVF patients, a multivariable log-binomial model suggests a 75% reduction in the probability for a retrieved oocyte to be in metaphase-II arrest for each μg/dL increase in blood Pb concentration (relative risk (RR) = 0.25, 95% confidence interval (CI) 0.03–2.50, P = 0.240). For 15 male IVF partners, each μg/L increase in urine Cd concentration is associated with an 81% decrease in the probability for oocyte fertilization (RR = 0.19, 95% CI 0.03–1.35, P = 0.097). Because of the magnitude of the effects, these results warrant a comprehensive study with sufficient statistical power to further evaluate these hypotheses.     

Silver nanoparticle induced toxicity to human sperm by increasing ROS(reactive oxygen species) production and DNA damage

Silver nanoparticles (AgNPs) have been used in medical products and industrial coatings, due to their antimicrobial properties. Excessive use of AgNPs can have adverse effects on the human body, however, their toxicity characteristics to human sperm and the potential mechanisms are not entirely clear. In this study, we exposed human sperm to different doses of AgNPs (0, 50 μg ml⁻¹, 100 μg ml⁻¹, 200 μg ml⁻¹ or 400 μg ml⁻¹) for various times (15 min, 30 min, or 60 min), followed by analyses of the sperm viability, motility and the ratio of abnormal to normal sperm.Then, transmission electron microscopy(TEM) was used to explore the sperm ultrastructural characteristics. Reactive oxygen species production and DNA fragmentation were tested using standard kits and the sperm chromatin dispersion method, respectively. The results showed a dose- and time-dependent decline in sperm viability and motility and an increased ratio of abnormal to normal sperm after 30 min and 60 min of exposure to AgNPs at 200 μg ml⁻¹ and 400 μg ml⁻¹. The most common abnormalities were sperm heads with disrupted chromatin or absent acrosomes, bent tails, and curved mid-pieces. The ultrastructural characteristics of AgNP-treated sperm included disrupted, swollen, granular and vacuolar defects of the chromatin. In addition, ROS(reactive oxygen species)production and DNA fragmentation were markedly increased after 60 min of exposure to AgNPs at 200 μg ml⁻¹ and 400 μg ml⁻¹. Our results indicated that AgNPs caused detrimental changes in human sperm characteristics, and the excessive use of AgNPs should be carried out with caution.