Evaluation of Seasonal Variability of Toxic and Essential Elements in Urine Analyzed by Inductively Coupled Plasma Mass Spectrometry

Association of urinary and seminal plasma vanadium concentrations with semen quality: A repeated-measures study of 1135 healthy men

Although animal studies have shown the reproductive toxicity of vanadium, less is known about its effects on semen quality in humans. Among 1135 healthy men who were screened as potential semen donors, we investigated the relationships of semen quality with urinary and seminal plasma vanadium levels via inductively coupled plasma-mass spectrometry (ICP-MS). Spearman rank correlation tests and linear regression models were used to assess the correlations between average urinary and within-individual pooled seminal plasma vanadium concentrations (n = 1135). We utilized linear mixed-effects models to evaluate the associations of urinary and seminal plasma vanadium levels (n = 1135) with repeated sperm quality parameters (n = 5576). Seminal plasma vanadium concentrations were not significantly correlated with urinary vanadium concentrations (r = 0.03). After adjusting for possible confounders, we observed inverse relationships of within-individual pooled seminal plasma vanadium levels with total count, semen volume, and sperm concentration (all P values for trend < 0.05). Specifically, subjects in the highest (vs. lowest) tertile of seminal plasma vanadium concentrations had - 11.3% (-16.4%, -5.9%), - 11.1% (-19.1%, -2.4%), and - 20.9% (-29.0%, -11.8%) lower sperm volume, concentration, and total count, respectively; moreover, urinary vanadium levels appeared to be negatively associated with sperm motility. These relationships showed monotonically decreasing dose-response patterns in the restricted cubic spline analyses. Our results demonstrated a poor correlation between urinary and seminal plasma levels of vanadium, and elevated vanadium concentrations in urine and seminal plasma may be adversely related to male semen quality.

Cholesteric Liquid Crystal Photonic Hydrogel Films Immobilized with Urease Used for the Detection of Hg2+

Mercury ion is one of the most widespread heavy metal contaminants which can accumulate in the body through multiple channels, posing a detrimental impact on human health. We demonstrate a simple and low-cost method for the detection of Hg2+ assisted by a cholesteric liquid crystal photonic hydrogel (polyacrylic acid (PAA)) film with immobilized urease (CLC-PAAurease film). In the absence of Hg2+, a significant change in color and an obvious red shift in the reflected light wavelength of the prepared film were observed, since urease can hydrolyze urea to produce NH3, resulting in an increasing pH value of the microenvironment of CLC-PAAurease film. Hg2+ can inhibit the activity of urease so that the color change of the film is not obvious, corresponding to a relatively small variation of the reflected light wavelength. Therefore, Hg2+ can be quantitatively detected by measuring the displacement of the reflected light wavelength of the film. The detection limit of Hg2+ is about 10 nM. This approach has a good application prospect in the monitoring of heavy metal ions in environmental water resources.

Identifying windows of susceptibility to essential elements for semen quality among 1428 healthy men screened as potential sperm donors

BACKGROUND

Essential elements such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), selenium (Se), rubidium (Rb), strontium (Sr), and molybdenum (Mo) are necessary for reproductive health. However, their associations with human semen quality remain inconclusive.

OBJECTIVES

To investigate the associations of urinary Fe, Co, Cu, Zn, Se, Rb, Sr, and Mo concentrations with semen quality in healthy men screened as potential sperm donors and identify critical windows of susceptibility.

METHODS

1428 healthy men provided 3766 urine and 6527 semen samples, which were measured for urinary essential element concentrations and sperm quality parameters, respectively. Linear mixed models and cubic spline curves were used to evaluate associations between urinary essential elements and semen quality. Multiple informant models were used to identify potential critical windows of susceptibility.

RESULTS

Linear mixed models and cubic spline curves showed positive dose-response relationships between urinary Zn and sperm concentration and total count and between urinary Mo and total sperm count [all False Discovery Rate (FDR) adjusted p-value for trend < 0.05]. In the multiple-element linear mixed models, the men in the highest versus lowest quartiles of urinary Zn and Mo had a higher sperm concentration of 17.5% (95% CI: 2.8%, 34.2%; p-value for trend = 0.006) and total sperm count of 18.3% (95% CI: 1.4%, 38.0%; p-value for trend = 0.027), respectively. Urinary Zn was also positively associated with total sperm count in a dose-dependent manner (p-value for trend = 0.036), though the percentile difference in total sperm count between men in the highest and lowest quartile was not statistically significant (16.4%, 95% CI: -1.7%, 37.9%). These associations appeared to be stronger when urinary Zn and Mo were measured at 0-9 days before the date of semen examination (i.e., corresponding to epididymal storage).

CONCLUSIONS

Higher urinary Zn and Mo, particularly during the period of epididymal storage, were associated with greater sperm production.

A new procedure for the determination of 21 macro- and trace elements in human fetal urine using an inductively coupled plasma mass spectrometry with dynamic reaction cell (ICP-DRC-MS) equipped with a micro-flow nebulizer

The procedure for determination of 21 macro- and trace elements - Li, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Cu, Zn, Se, Sr, As, Cd, Sb, Ba, Pb and U - in human fetal urine by inductively coupled plasma mass spectrometry (ICP-MS) was developed and validated. The application of a micronebulizer and a dynamic reaction cell (DRC) allowed to perform a full analysis of small volumes (200 μL) of urine collected from human fetuses without the need for sample digestion with closed microwave systems. The procedure and ICP-MS instrument was thoroughly optimized in order to reliably determine both macroelements and ultra-trace concentrations of elements. The internal standard method (Ge, Rh and Tb) was applied in order to encompass signal drift and non-spectral interferences. The rules of metrology were used in order to ensure the quality of the results: (1) the procedure was validated, (2) the uncertainty of the measurement results was estimated and (3) the traceability of the measurement result was established by using the certified reference material with matching matrix (Seronorm Trace Elements Urine L-1). Also, the analyte addition method to the artificial urine was employed for additional confirmation of trueness of the procedure. The selected parameters of the procedure were as follows: (a) limits of detection - (0.00023-53 μg L^-1) for U and Ca, respectively, (b) recoveries of the reference value - 81%-136% for Mn and Cd, respectively (c) linearity expressed as R - greater than 0.999, and (d) expanded relative uncertainties (k = 2) - 13%-66% for Sr and Cd, respectively. The developed and validated procedure was applied to 58 samples of urine collected from human fetuses. The samples were diluted with nitric acid and analyzed without further treatment. The procedure allowed to reliably determine both macro- and trace elements in very low volume of sample in a single analytical run.

Reproducibility of essential elements chromium, manganese, iron, zinc and selenium in spot samples, first-morning voids and 24-h collections from healthy adult men

Evaluation of Cr, Mn, Fe, Zn and Se in humans is challenged by the potentially high within-individual variability of these elements in biological specimens, which are poorly characterised. This study aimed to evaluate their within-day, between-day and between-month variability in spot samples, first-morning voids and 24-h collections. A total of 529 spot urine samples (including eighty-eight first-morning voids and 24-h collections) were collected from eleven Chinese adult men on days 0, 1, 2, 3, 4, 30, 60 and 90 and analysed for these five elements using inductively coupled plasma-MS. Intraclass correlation coefficients (ICC) were utilised to characterise the reproducibility, and their sensitivity and specificity were analysed to assess how well a single measurement classified individuals’ 3-month average exposures. Serial measurements of Zn in spot samples exhibited fair to good reproducibility (creatinine-adjusted ICC = 0·47) over five consecutive days, which became poor when the samples were gathered months apart (creatinine-adjusted ICC = 0·33). The reproducibility of Cr, Mn, Fe and Se in spot samples was poor over periods ranging from days to months (creatinine-adjusted ICC = 0·01–0·12). Two spot samples were sufficient for classifying 60 % of the men who truly had the highest (top 33 %) 3-month average Zn concentrations; for Cr, Mn, Fe and Se, however, at least three specimens were required to achieve similar sensitivities. In conclusion, urinary Cr, Mn, Fe, Zn and Se concentrations showed a strong within-individual variability, and a single measurement is not enough to efficiently characterise individuals’ long-term exposures.

Variability and exposure classification of urinary levels of non-essential metals aluminum, antimony, barium, thallium, tungsten and uranium in healthy adult men

Arsenic, cadmium and lead are well-known toxic metals, and there are substantial studies on variability of these metals in urine to optimize design of exposure assessment. For urinary levels of other nonessential metals such as aluminum (Al), antimony (Sb), barium (Ba), thallium (Tl), tungsten (W) and uranium (U), however, their within-individual and between-individual variability are unclear. Therefore, we collected 529 samples from 11 healthy adult men on 8 days during a 3-month period. We measured urinary metals and creatinine (Cr) levels, assessed the reproducibility using intraclass correlation coefficients (ICCs), and performed sensitivity and specificity analyses to assess how well 1, 2 or 3 specimens could classify exposure. Al, Sb, Ba, W and U levels measured from spot samples varied greatly over days and months (Cr-adjusted ICCs = 0.01-0.14). Serial measures of Tl levels measured from spot samples had fair-to-good reproducibility over 5 consecutive days (Cr-adjusted ICC = 0.40), but worsened when the specimens were collected months apart (Cr-adjusted ICC = 0.16). To identify men who were highly exposed (top 33%) based on their 3-month averages, tests of single spot samples and tests of first-morning voids had high specificities (0.73-0.85) but relatively low sensitivities (0.27-0.60). Collection of repeated urine specimens from each individual improved the classification.