Urinary chromium as a biological marker of environmental exposure: what are the limitations?

Carcinogenic and non-carcinogenic risks caused by rice contamination with heavy metals and their effect on the prevalence of cardiovascular disease (Using machine learning)

INTRODUCTION

The safety and health of food products are essential in the food industry, and the risk of contamination from various contaminants must be evaluated. Exposure to HMs from the environment (especially food) causes various adverse effects on the body and increases the risk of cardiovascular disease (CVD).

MATERIAL AND METHOD

Volunteers in the study comprised both healthy individuals and those with CVD. Patients were chosen using a cohort database of CVD individuals. A random choice of samples was conducted. Medical information (individuals with CVD) related to the participants was obtained from the Hoveyzeh Cohort Study Center. CVD-HM relationships were assessed using various machine-learning techniques.

RESULT

Based on the results of the GAM statistics approach, the baseline levels (β) of As, Cd, and Cr in rice have been calculated to be 1.05, 1.19, and 1.11, respectively. Based on the investigation's results, rice acts as a mediator between high-magnitude actions and the prevalence of CVD. Eating rice increases the probability of CVD by 0.18 and raises As eating by 0.494. The results showed that rice consumption in the research area is not associated with non-carcinogenic and carcinogenic risk (CRs and ILCRs for both categories were less than 1∗10-6).

CONCLUSION

There was neither a carcinogenic nor non-carcinogenic threat to adults or children and many hazardous HMs existed at the accepted thresholds. A notable relationship was seen between rice contaminated with HM and CVD.

Prospective findings from the Dongfeng-Tongji cohort: Exposure to various metals, the expression of microRNA-4286, and the incidence of acute coronary syndrome

Mounting evidence suggests that metal/metalloid exposure is related to the adverse health effects. Our prior investigation revealed a positive relation between the plasma level of microRNA-4286 (miR-4286) and an increased risk of developing acute coronary syndrome (ACS). However, it is a lack of studies evaluating the connection between metal/metalloid exposure and miRNA expression on ACS. In the prospective Dongfeng-Tongji cohort, we performed a nested case-control study. A total of 480 ACS and 480 controls were carefully selected based on similar age, sex, and blood collection time. Using inductively coupled plasma mass spectrometry, we assessed the plasma concentrations of 24 different metals. Quantitative real-time polymerase chain reaction was used to analyze the plasma miR-4286. We examined the relations of plasma metals with miR-4286 levels, the incidence of ACS, and the potential interactions. Using the multivariate conditional logistic regression models, we observed that the adjusted odds ratios (95% confidence intervals [CI]) for incident ACS were 1.79 (1.03, 3.12; P-trend = 0.03), 0.60 (0.41, 0.87; P-trend = 0.008), and 0.66 (0.46, 0.93; P-trend = 0.02), when comparing the extreme tertiles of aluminum, rubidium, and selenium, respectively. There was a relation between the concentration of rubidium in plasma and a decrease in the level of plasma miR-4286 (percent difference [95% CI]: -13.36% [-22.74%, -2.83%]; P-trend = 0.01). Both multiplicative (P interaction = 0.009) and additive interactions (relative excess risk due to interaction [95% CI]: 0.82 [0.59, 1.06]) were noted in our observation regarding the relationship between plasma aluminum and miR-4286 in incident ACS. The findings indicated that plasma aluminum was positively while plasma rubidium and selenium were negatively linked to an increased risk of developing ACS. Plasma aluminum exposure and plasma miR-4286 expression might synergistically affect the incident ACS risk. Controlling aluminum exposure was important for ACS prevention, especially for individuals with high expression of plasma miR-4286.

Associations between plasma metal/metalloid mixtures and the risk of central obesity: A prospective cohort study of Chinese adults

Central obesity has increased rapidly over the past decade and posed a substantial disease burden worldwide. Exposure to metals/metalloids has been acknowledged to be involved in the development of central obesity through regulation of cortisol, insulin resistance, and glucocorticoid receptor reduction. Despite the importance, it is lack of prospective study which comprehensively evaluate the relations between multiple metals exposure and central obesity. We explored the prospective associations of plasma metal concentrations with central obesity in a prospective study of the Dongfeng-Tongji cohort. The present study included 2127 participants with a 6.87-year mean follow-up duration. We measured 23 plasma metal/metalloid concentrations at baseline. The associations between metals and incident central obesity were examined utilizing the Cox proportional hazard regression in single and multiple metals models. Additionally, we applied elastic net (ENET), Bayesian kernel machine regression (BKMR), plasma metal score (PMS), and quantile-based g-computation (Qgcomp) models to explore the joint associations of metal mixtures with central obesity. After adjusting potential confounders, we found significant associations of plasma manganese (Mn) and thallium (Tl) concentrations with a higher risk of central obesity, whereas plasma rubidium (Rb) concentration was associated with a lower risk of central obesity both in single and multiple metals models (all FDR <0.05). The ENET and Qqcomp models verified similar metals (Mn, Rb, and Tl) as important predictors for central obesity. The results of both BKMR model and PMS suggested cumulative exposure to metal mixtures was associated with a higher risk of central obesity. Our findings suggested that co-exposure to metals was associated with a higher risk of central obesity. This study expands our knowledge that the management of metals/metalloids exposure may be beneficial for the prevention of new-onset central obesity, which may subsequently alleviate the disease burden of late-life health outcomes.

Exploration of Whole Blood Chromium as Biomarker of Hexavalent Chromium Exposure: Based on Literature Review and Monte Carlo Simulation

Hexavalent chromium (Cr(VI)) is a sort of common industrial poison and environmental pollutant posing great health threat to the population. Appropriate biomarkers are indispensable indicative tools in the biological monitoring and health risk assessment of Cr(VI). In this study, we explored the rationality and feasibility of whole blood Cr serving as the biomarker of internal exposure with corroboration drawn from literature review and Monte Carlo simulation. It was indicated that the whole blood Cr had practical operability in the large-scale population researches and robust biological significance with broad association with various Cr(VI)-related effect indices. The simulated distribution of whole blood Cr concentration in exposed populations was about three times higher than that of the control (13.52 ± 24.99 vs. 4.25 ± 11.37 μg/L, P < 0.05; 6.73 ± 10.92 μg/L vs. 1.96 ± 2.05 μg/L in China, P < 0.05), which suggested a great discriminatory ability that might be supported as evidence for its reasonable application.

Prenatal exposure to heavy metal mixtures and anthropometric birth outcomes: a cross-sectional study

BACKGROUND

Numerous studies have suggested significant associations between prenatal exposure to heavy metals and newborn anthropometric measures. However, little is known about the effect of various heavy metal mixtures at relatively low concentrations. Hence, this study aimed to investigate associations between prenatal exposures to a wide range of individual heavy metals and heavy metal mixtures with anthropometric measures of newborns.

METHODS

We recruited 975 mother-term infant pairs from two major hospitals in Israel. Associations between eight heavy metals (arsenic, cadmium, chromium, mercury, nickel, lead, selenium, and thallium) detected in maternal urine samples on the day of delivery with weight, length, and head circumference at birth were estimated using linear and Bayesian kernel machine regression (BKMR) models.

RESULTS

Most heavy metals examined in our study were observed in lower concentrations than in other studies, except for selenium. In the linear as well as the BKMR models, birth weight and length were negatively associated with levels of chromium. Birth weight was found to be negatively associated with thallium and positively associated with nickel.

CONCLUSION

By using a large sample size and advanced statistical models, we could examine the association between prenatal exposure to metals in relatively low concentrations and anthropometric measures of newborns. Chromium was suggested to be the most influential metal in the mixture, and its associations with birth weight and length were found negative. Head circumference was neither associated with any of the metals, yet the levels of metals detected in our sample were relatively low. The suggested associations should be further investigated and could shed light on complex biochemical processes involved in intrauterine fetal development.

Multiple plasma metals, genetic risk and serum complement C3, C4: A gene-metal interaction study

Exposure to metals and metalloids is widely related with human health, and could affect the function of immune system. The complement system links innate and adaptive immunity, and is critically involved in the pathogenesis of inflammatory and immune diseases. The third and fourth components of complement (C3, C4) play key roles in the complement system. However, few studies have examined the relations between multiple metals and complement levels. In this study, based on a total of 2977 participants from the Dongfeng-Tongji cohort, China, we investigated 17 plasma metals and serum C3, C4 levels, and calculated C3/C4-associated genetic risk scores (GRSs) using established single nucleotide polymorphisms. We further explored the potential gene-metal interactions on C3 and C4. After multivariable adjustment, an increment of 10-standard deviation increase in natural log-transformed exposure concentrations of plasma copper was associated with 0.549 (0.489, 0.608) (FDR <0.0001), and 1.146 (0.999, 1.294) (FDR <0.0001) higher natural log-transformed serum C3 and C4 levels, respectively. While each increment of 10-standard deviation of natural log-transformed zinc was associated with a difference of 0.083 (0.024, 0.143) (FDR = 0.049) and 0.007 (-0.138, 0.152) (FDR = 0.935) in log-transformed C3 and C4 levels, respectively. Participants with higher GRS had higher C3 and C4 levels. Furthermore, we found a significant interaction between arsenic exposure and C3-GRS in relation to C3 level (P_interaction = 0.0096). Our results suggested that plasma arsenic would modify the association between C3 genetic predisposition and serum C3 level. We provide new insight into metals exposure on the human immune system. These findings require replication in future research.

Associations of plasma metal levels with type 2 diabetes and the mediating effects of microRNAs

The present study aims to determine the associations of multiple plasma metal levels and plasma microRNAs (miRNAs) with diabetes risk, and further explore the mediating effects of plasma miRNAs on the associations of plasma metal with diabetes risk. We detected plasma levels of 23 metals by inductively coupled plasma mass spectrometry (ICP-MS) among 94 newly diagnosed and untreated diabetic cases and 94 healthy controls. The plasma miRNAs were examined by microRNA Array screening and Taqman real-time PCR validation among the same study population. The multivariate logistic regression models were employed to explore the associations of plasma metal and miRNAs levels with diabetes risk. Generalized linear regression models were utilized to investigate the relationships between plasma metal and plasma miRNAs, and mediation analysis was used to assess the mediating effects of plasma miRNAs on the relationships between plasma metals and diabetes risk. Plasma aluminum (Al), titanium (Ti), copper (Cu), zinc (Zn), selenium (Se), rubidium (Rb), strontium (Sr), barium (Ba), and Thallium (Tl) levels were correlated with elevated diabetic risk while molybdenum (Mo) with decreased diabetic risk (P < 0.05 after FDR multiple correction). MiR-122-5p and miR-3141 were positively associated with diabetes risk (all P < 0.05). Ti, Cu, and Zn were positively correlated with miR-122-5p (P = 0.001, 0.028 and 0.004 respectively). Ti, Cu, and Se were positively correlated with miR-3141 (P = 0.003, 0.015, and 0.031 respectively). In addition, Zn was positively correlated with miR-193b-3p (P = 0.002). Ti was negatively correlated with miR-26b-3p (P = 0.016), while Mo and miR-26b-3p were positively correlated (P = 0.042). In the mediation analysis, miR-122-5p mediated 48.0% of the association between Ti and diabetes risk. The biological mechanisms of the association are needed to be explored in further studies.

Associations of plasma metal concentrations with the risks of all-cause and cardiovascular disease mortality in Chinese adults

BACKGROUND

Exposure to metals/metalloids from both the natural environment and anthropogenic sources have a complex influence on human health. However, relatively few studies have explored the relations of exposure to multiple metals/metalloids with mortality. Therefore, this prospective study aims to examine the relations of multiple metal/metalloids exposures with all-cause and cardiovascular disease (CVD) mortality.

METHODS

A total of 6155 participants within the Dongfeng-Tongji (DF-TJ) cohort were involved in this analysis, which were followed for mortality until December 31, 2018. We applied inductively coupled plasma mass spectrometry (ICP-MS) to measure baseline plasma concentrations of 23 metals. We utilized Cox regression models to calculate the hazard ratios (HRs) for all-cause and CVD mortality associated with metal concentrations. We proposed plasma metal score to assess the simultaneous exposure to multiple metals through summing each metal concentration weighted by the regression coefficients with all-cause mortality.

RESULTS

During the follow-up (mean duration, 9.8 years), we ascertained 876 deaths, including 416 deaths of CVD (157 deaths of coronary heart disease and 259 deaths of stroke). In the multiple-metals model, after adjusting for potential confounders, plasma copper, molybdenum, and vanadium were positively associated with all-cause mortality, whereas manganese, selenium, and thallium were negatively associated with the risk of all-cause mortality, with adjusted HRs (95% Confidence Interval, CI) of the fourth quartiles were 1.73 (1.42-2.11, P-trend < 0.001) for copper, 1.33 (1.09-1.63, P-trend = 0.005) for molybdenum, 1.43 (1.16-1.77, P-trend < 0.001) for vanadium, 0.74 (0.58-0.94, P-trend = 0.005) for manganese, 0.68 (0.56-0.83, P-trend < 0.001) for selenium, and 0.74 (0.59-0.92, P-trend = 0.002) for thallium, respectively. Positive associations were observed between plasma copper, molybdenum, vanadium concentrations and CVD mortality, whereas negative associations were found for plasma selenium and thallium concentrations with CVD mortality in the multiple-metals model. Compared with the first quartiles, the HRs of fourth quartiles were 1.94 (1.45-2.58, P-trend < 0.001) for copper, 1.72 (1.26-2.35, P-trend < 0.001) for molybdenum, 1.81 (1.32-2.47, P-trend < 0.001) for vanadium, 0.67 (0.50-0.89, P-trend = 0.003) for selenium, and 0.58 (0.41-0.81, P-trend < 0.001) for thallium, respectively. The plasma metal score was significantly associated with higher risks of all-cause and CVD death in dose-response fashions. When compared with the first quartiles of plasma metal score, the HRs of fourth quartiles were 2.16 (1.76-2.64; P-trend < 0.001) for all-cause mortality and 3.00 (2.24-4.02; P-trend < 0.001) for CVD mortality.

CONCLUSIONS

The study indicated that several plasma metals/metalloids were key determinants and predictors of all-cause and CVD death in the Chinese population. Our findings highlighted the importance to comprehensively assess and monitor multiple metals/metalloids exposures.

The Effect of Global DNA Methylation on PDCD5 Expression in the PBMC of Occupational Chromate Exposed Workers

OBJECTIVES

To evaluate the alteration of protein of programmed cell death 5 (PDCD5) in peripheral blood mononuclear cells (PBMC) and DNA methylation caused by hexavalent chromium exposure.

METHODS

There were 112 workers and 56 controls in this study. The chromium in RBC and urine, PBMC with PDCD5+, DNA methylation, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and score of DNA damage were measured.

RESULTS

In chromate exposed workers, the percent of PBMC with PDCD5+, urine 8-OHdG, and score of DNA damage were significantly higher, whereas global DNA methylation was significantly lower. The binary logistic regression and generalized linear mixed model analysis showed that the percent of PBMC with PDCD5+ was significantly associated with global DNA hypomethylation.

CONCLUSIONS

The aberrant DNA hypomethylation plays an important role in PBMC apoptosis of occupational hexavalent chromium exposure.

Exposure to environmental neurotoxic substances and neurodevelopment in children from Latin America and the Caribbean

Environmental (and occupational) exposure to neurotoxic substances is a worldwide problem that can affect children's neurodevelopment (ND). In Latin American and Caribbean (LAC) countries there are over 300 million children living under the threat of neurodevelopmental delays due to toxic environmental exposure. Large industrial centers, intense mining and agricultural activities, along with changing complex ecosystems constitute a mosaic that drives contamination of air, water and the food chain. Neurotoxic contaminants such as pesticides (organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, and manganese fungicides), chemicals of industrial use (phthalates), and metals (Hg, Pb, Al, As, F, Cd, Mo, Mn) are at the center of environmental exposure studies. Exposure to neurotoxic substances singly or in combination with other compounds or socioeconomic stressors (maternal education, socio-economic and nutritional status) intertwined with occupational and para-occupational exposure can affect ND (motor, cognition, behavior) of children. Significant negative effects of pesticides and neurotoxic elements on ND were found in all studied countries, affecting especially the less-privileged children from laboring families. Studies showed that exposures to the neurotoxicants in human milk are secondary to their more lasting effects during prenatal exposure. This review integrates exposure (prenatal and breastfeeding), metabolism, and ND effects of neurotoxicants. It highlights the overwhelming evidence showing that current levels of exposures are hazardous and detrimental to children's ND in LAC countries. The evidence indicates that a reduction in neurotoxicant exposure is essential to protect children's ND. Therefore, it is urgent to adopt policies and actions that prevent and remediate region-specific children's ND issues.

Biomarkers, matrices and analytical methods targeting human exposure to chemicals selected for a European human biomonitoring initiative

The major purpose of human biomonitoring is the mapping and assessment of human exposure to chemicals. The European initiative HBM4EU has prioritized seven substance groups and two metals relevant for human exposure: Phthalates and substitutes (1,2-cyclohexane dicarboxylic acid diisononyl ester, DINCH), bisphenols, per- and polyfluoroalkyl substances (PFASs), halogenated and organophosphorous flame retardants (HFRs and OPFRs), polycyclic aromatic hydrocarbons (PAHs), arylamines, cadmium and chromium. As a first step towards comparable European-wide data, the most suitable biomarkers, human matrices and analytical methods for each substance group or metal were selected from the scientific literature, based on a set of selection criteria. The biomarkers included parent compounds of PFASs and HFRs in serum, of bisphenols and arylamines in urine, metabolites of phthalates, DINCH, OPFRs and PAHs in urine as well as metals in blood and urine, with a preference to measure Cr in erythrocytes representing Cr (VI) exposure. High performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was the method of choice for bisphenols, PFASs, the HFR hexabromocyclododecane (HBCDD), phenolic HFRs as well as the metabolites of phthalates, DINCH, OPFRs and PAHs in urine. Gas chromatographic (GC) methods were selected for the remaining compounds, e.g. GC-low resolution MS with electron capture negative ionization (ECNI) for HFRs. Both GC-MS and LC-MS/MS were suitable for arylamines. New developments towards increased applications of GC-MS/MS may offer alternatives to GC-MS or LC-MS/MS approaches, e.g. for bisphenols. The metals were best determined by inductively coupled plasma (ICP)-MS, with the particular challenge of avoiding interferences in the Cd determination in urine. The evaluation process revealed research needs towards higher sensitivity and non-invasive sampling as well as a need for more stringent quality assurance/quality control applications and assessments.

Associations of plasma metal concentrations with the decline in kidney function: A longitudinal study of Chinese adults

Metals are widespread pollutants in the environment which have been reported to be associated with kidney dysfunction in many existing epidemiological studies. However, most of the studies are cross-sectional design and mainly focus on several toxic metals including arsenic, lead and cadmium. Therefore, we conducted this prospective study within the Dongfeng-Tongji cohort to evaluate the associations of plasma multiple metals with the decline in kidney function among Chinese middle-aged and elderly. In total, 1434 participants free of chronic diseases at baseline were included in analysis. We measured baseline plasma concentrations of 23 metals and calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation based on serum creatinine, age, sex and ethnicity. Bonferroni correction was used for multiple testing to reduce the probability of a type I error. Principal component analysis was conducted to evaluate the combined effect of multiple metal co-exposure. Most of the plasma metal concentrations were within the literature reported reference values, whereas the concentration of lead and nickel exceeded the guideline value. We found that plasma concentrations of aluminum, arsenic, barium, lead, molybdenum, rubidium, strontium, vanadium and zinc were significantly associated with the decline in kidney function measured by annual eGFR decline, rapid renal function decline (defined as an annual decline in eGFR ≥ 5 mL/min/1.73 m²) or incident eGFR < 60 mL/min/1.73 m², with the adjusted beta coefficients (95% CI) for annual eGFR decline 0.50 (0.30, 0.69), 0.98 (0.74, 1.23), 0.56 (0.32, 0.79), 0.21 (0.03, 0.39), 0.35 (0.16, 0.54), 0.94 (0.71, 1.17), 0.37 (0.15, 0.60), 0.78 (0.54, 1.02), and 0.74 (0.57, 0.91), respectively. The metals exposures were linked with increased risks of impaired kidney function. Associations of principal components representing these metals with the decline in kidney function were significant and suggest a possible additional health risk by co-exposure. Participants engaged in manufacturing had higher plasma levels of several metals compared with those who had been involved in management- or administration-related work. Our findings suggest that exposure to multiple metals contribute to the decline in kidney function among the middle-aged and elderly. Co-exposure to multiple metals may have synergetic effect on the kidney function. Further studies are warranted to confirm our findings and clarify the potential mechanisms.

Effect of plastic foreign body impaction on rumen function and heavy metal concentrations in various body fluids and tissues of buffaloes

Rumen impaction by plastic waste (PW) is a common condition in the developing countries where ruminants are reared under extensive grazing. As heavy metals (HM) are used in the manufacture of plastic, we hypothesized that buffaloes with PW impaction would have suboptimal rumen function and higher content of HM in the rumen fluid, sera and body tissues. Buffaloes at an abattoir were categorized into impacted with PW or not (Group C and B, respectively; n = 30/group). From the animals of group C and B, rumen fluid and sera were collected ante-mortem, while muscle, liver and kidney were collected after exsanguination. Blood and rumen fluid of stall-fed buffaloes (Group A; n = 15) served as known negative control. Rumen function was assessed by protozoal density, motility, pH, methylene blue reduction time (MBRT) and sedimentation activity time (SAT). Concentration of HM such as mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) in the body fluids, tissues and impacted PW was estimated by atomic absorption spectrometry (AAS). A significant decrease in the rumen protozoal density, motility and increase (P < 0.05) in the rumen fluid pH, MBRT and SAT were observed in group C as compared to group A and B. Concentration of Pb, Hg and Cd showed a moderate to strong significant negative correlation with rumen function indicators. Quantitatively, Cu content (ppm) was highest in PW with 0.9 ± 0.04. The concentration of HM in the body fluids and tissues was significantly (P < 0.05) elevated in group C, but was below the toxic levels. In stall-fed buffaloes, Hg, Pb and Cd were undetectable in body fluids. Collectively, the results indicate that long term exposure of buffaloes to HM from PW affect the health, productivity and increase the risk of entering the food chain.

Multiple plasma metals, genetic risk and serum C-reactive protein: A metal-metal and gene-metal interaction study

Background

C-reactive protein (CRP) is a well-recognized biomarker of inflammation, which can be used as a predictor of cardiovascular disease. Evidence have suggested exposure to multiple metals/metalloids may affect immune system and give rise to cardiovascular disease. However, it is lack of study to comprehensively evaluate the association of multiple metals and CRP, the interactions between metals, and the gene-metal interaction in relation to CRP levels.

Aims

To explore the associations of multiple plasma metals with serum CRP, and to test the interactions between metals, and gene-metal interactions on the levels of serum CRP.

Methods

We included 2882 participants from the Dongfeng-Tongji cohort, China, and measured 23 plasma metals and serum CRP concentrations. The genetic risk score (GRS) was calculated based on 7 established CRP-associated variants. For metals which were associated with the levels of CRP, we further tested the interactions between metals on CRP, and analyzed the gene-metal interactions on CRP.

Results

The median level for CRP in the total population was 1.17 mg/L. After multivariable adjustment, plasma copper was positively associated with serum CRP (FDR < 0.001), whereas selenium was negatively associated with serum CRP (FDR = 0.01). Moreover, selenium and zinc attenuated the positive association between high plasma copper and CRP (P for interaction < 0.001). Participants with a higher GRS had a higher CRP level, with the increase in ln-transformed CRP per increment of 5 risk alleles were 0.64 for weighted GRS, and 0.54 for unweighted GRS (both P < 0.001). Furthermore, the genetic association with CRP was modified by copper concentration (P for interaction < 0.001).

Conclusions

Our results suggest that serum CRP is positively associated with plasma concentration of copper, and inversely associated with selenium. Plasma zinc, selenium and CRP genetic predisposition would modify the associations between plasma copper and serum CRP.

•

We found that serum CRP was positively associated with plasma copper, and inversely associated with selenium.

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The positive association of plasma copper with serum CRP appeared to be attenuated with high plasma zinc and selenium.

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This is the first study that explored the potential gene-metal interactions in relation to CRP levels.

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These novel findings may provide new insights to personalized prevention and interventions for inflammation.

Environmental exposure to low-level lead (Pb) co-occurring with other neurotoxicants in early life and neurodevelopment of children

Lead (Pb) is a worldwide environmental contaminant that even at low levels influences brain development and affects neurobehavior later in life; nevertheless it is only a small fraction of the neurotoxicant (NT) exposome. Exposure to environmental Pb concurrent with other NT substances is often the norm, but their joint effects are challenging to study during early life. The aim of this review is to integrate studies of Pb-containing NT mixtures during the early life and neurodevelopment outcomes of children. The Pb-containing NT mixtures that have been most studied involve other metals (Mn, Al, Hg, Cd), metalloids (As), halogen (F), and organo-halogen pollutants. Co-occurring Pb-associated exposures during pregnancy and lactation depend on the environmental sources and the metabolism and half-life of the specific NT contaminant; but offspring neurobehavioral outcomes are also influenced by social stressors. Nevertheless, Pb-associated effects from prenatal exposure portend a continued burden on measurable neurodevelopment; they thus favor increased neurological health issues, decrements in neurobehavioral tests and reductions in the quality of life. Neurobehavioral test outcomes measured in the first 1000 days showed Pb-associated negative outcomes were frequently noticed in infants (<6 months). In older (preschool and school) children studies showed more variations in NT mixtures, children's age, and sensitivity and/or specificity of neurobehavioral tests; these variations and choice of statistical model (individual NT stressor or collective effect of mixture) may explain inconsistencies. Multiple exposures to NT mixtures in children diagnosed with 'autism spectrum disorders' (ASD) and 'attention deficit and hyperactivity disorders' (ADHD), strongly suggest a Pb-associated effect. Mixture potency (number or associated NT components and respective concentrations) and time (duration and developmental stage) of exposure often showed a measurable impact on neurodevelopment; however, net effects, reversibility and/or predictability of delays are insufficiently studied and need urgent attention. Nevertheless, neurodevelopment delays can be prevented and/or attenuated if public health policies are implemented to protect the unborn and the young child.

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.

Modeling contamination conditions in small-scale industrial areas to estimate health savings benefits associated with remediation

Mercury and dioxin pollution associated with the China Petrochemical Development Corporation's An-shun plant is one of the most severe soil contamination incidents in Taiwan's history. Residents living nearby were exposed to heavy metals and dioxins that led to significant impacts on human health and safety. While many studies related to contamination in large-scale industrial areas have been conducted to evaluate the effects of occupational contaminant exposure, studies related to people who live near small-scale industry areas are less common. In this study, we use the system dynamics modeling to build a media flow pattern for mercury and dioxin in the vicinity of the An-shun plant, simulate the concentrations of the pollutants before and after remediation, and compare the simulated values with the measurements of actual conditions after remediation to evaluate the feasibility and accuracy of the model. This study also estimated the concentration of mercury and dioxin in each food medium to simulate the daily exposure of the human body to these contaminants. Finally, the reduction in mercury and dioxin levels in the study area was used to estimate the total health benefits to the local population. The objective of this study was to evaluate the application of this methodology to small-scale industrial areas as well as improve the decision-making process before, during, and after remediation of contaminated sites. The results of this study revealed the health benefits to residents living in the Annan District after remediation was completed at the An-shun plant were significant.

Associations of multiple plasma metals with incident type 2 diabetes in Chinese adults: The Dongfeng-Tongji Cohort

The long-term associations between multiple metals and incident diabetes are uncertain. We aimed to examine the relationship between plasma concentrations of 23 metals and the incidence of type 2 diabetes among Chinese senior adults. We quantified fasting plasma concentrations of 23 metals by inductively coupled plasma mass spectrometry among 1039 incident diabetes cases and 1039 controls (age and sex matched) nested in a prospective study, the Dongfeng-Tongji cohort. Both cases and controls were free of diabetes at baseline (2008-2010), incident diabetes were identified using the following criteria: fasting glucose ≥ 7.0 mmoL/l; or hemoglobin A1c (HbA1c) ≥ 6.5%; or self-reported physician diagnosis of diabetes or use of anti-diabetic medication during the follow-up visits in 2013. In the conditional logistic regression models, the multivariable adjusted ORs (95% CIs) of diabetes across quartiles (Q1-Q4) of metal concentrations were as follows: titanium, 1.00, 0.92, 1.31, 1.38 (1.00-1.91, P_trend = 0.011); selenium, 1.00, 1.08, 1.45, 1.27 (0.93-1.74, P_trend = 0.05); and antimony, 1.00, 0.79, 0.77, 0.60 (0.44-0.83, P_trend = 0.002). Arsenic was significantly associated with diabetes in the crude model (ORs comparing extreme quartiles 1.30; 1.02-1.65; P_trend = 0.006), but was not significant after adjustment for socio-demographic factors. No significant associations were found for other metals. In conclusion, titanium and selenium were positively while antimony was negatively associated with incident diabetes.

Environmental Exposure of Children to Toxic Trace Elements (Hg, Cr, As) in an Urban Area of Yucatan, Mexico: Water, Blood, and Urine Levels

Merida is the largest urban center in the Mexican State of Yucatan. Here domestic sewage is deposited in poorly built septic tanks and is not adequately treated. Because of contamination from such waste, water from the top 20 m of the aquifer is unsuitable for human consumption. Given this situation and because children are highly vulnerable to environmental pollution, including exposure to toxic trace elements, this study focused on evaluating the exposure of children to arsenic (As), chromium (Cr), and mercury (Hg) in water. It also evaluated the relationship between the levels of these elements in water and their concentrations in urine and blood. Among the 33 children monitored in the study, arsenic surpassed WHO limits for blood in 37% of the cases, which could result from the ingestion of poultry contaminated with organoarsenic compounds. In the case of WHO limits for Mercury, 65% of the water samples analyzed, 28% of urine samples, and 12% of blood samples exceeded them. Mercury exposure was correlated with biological sex, some lifestyle factors, and the zone in Merida in which children live. These data suggest that the levels of some toxic metals in children may be affected by water source, socioeconomic factors, and individual behavior.

The Production of Corporate Research to Manufacture Doubt About the Health Hazards of Products: An Overview of the Exponent Bakelite® Simulation Study

Although corporate sponsorship of research does not necessarily lead to biased results, in some industries, it has resulted in the publication of inaccurate and misleading data. Some companies have hired scientific consulting firms to retrospectively calculate exposures to hazardous products during use that are no longer manufactured or sold. As an example, this paper reviews one such study-a litigation-generated study of Union Carbide Corporation's asbestos-containing product, Bakelite®. This analysis is based on previously secret documents, produced as a result of litigation. The study generated asbestos fiber exposure measurements which resulted in underestimates of actual exposures to create doubt about the hazards associated with manufacture and manipulation of Bakelite®.

Association between maternal urinary chromium and premature rupture of membranes in the Healthy Baby Cohort study in China

Chromium exposure from increasing industrial releases has become a threat for pregnant women due to the potential health effects on vulnerable embryos. Previous studies have suggested that maternal chromium exposure is associated with adverse birth outcomes, but no epidemiological research has been conducted to examine the relationship between chromium exposure and premature rupture of membranes (PROM). This study aimed at investigating the association of maternal urinary chromium exposure levels with PROM and was performed with 5408 pregnant women recruited from 2012 to 2014 in the city of Wuhan, China. Maternal urinary chromium collected before labor was adjusted with creatinine, and its association with PROM was evaluated using logistic regression. Each one unit increase in the natural logarithm transformed maternal urinary chromium concentration (μg/g creatinine), an odds ratio (OR) of 1.47 [95% confidence interval (CI): 1.36, 1.58] for PROM was observed. Compared to the lowest tertile of maternal urinary chromium, PROM was positively correlated with increased urinary levels of chromium (adjusted OR = 1.42; 95% CI: 1.09, 1.84 for the medium tertile; adjusted OR = 2.77; 95% CI: 2.18, 3.52 for the highest tertile). Additionally, the association of chromium with PROM appeared to be more significant among male infants (adjusted OR = 3.52; 95% CI: 2.51, 4.94 for the highest tertile) than female infants (adjusted OR = 2.16; 95% CI: 1.52, 3.06 for the highest tertile) (p for interaction = 0.05). Our large birth cohort showed an association between maternal urinary chromium levels and PROM, and the association may differ by infant gender. Further studies from different populations are needed to confirm the observed association.

Plasma Metal Concentrations and Incident Coronary Heart Disease in Chinese Adults: The Dongfeng-Tongji Cohort

BACKGROUND

Circulating metals from both the natural environment and pollution have been linked to cardiovascular disease. However, few prospective studies have investigated the associations between exposure to multiple metals and incident coronary heart disease (CHD).

OBJECTIVES

We conducted a nested case-control study in the prospective Dongfeng-Tongji cohort, to investigate the prospective association between plasma metal concentrations and incident CHD.

METHODS

A total of 1,621 incident CHD cases and 1,621 controls free of major cardiovascular disease at baseline and follow-up visits were matched on age (±5 years) and sex. We measured baseline fasting plasma concentrations of 23 metals and used conditional logistic regression models to estimate odds ratios (ORs) of CHD for metal concentrations categorized according to quartiles in controls.

RESULTS

Five metals (titanium, arsenic, selenium, aluminum, and barium) were significantly associated with CHD based on trend tests from single-metal multivariable models adjusted for established cardiovascular risk factors. When all five were included in the same model, adjusted ORs for barium and aluminum were close to the null, whereas associations with titanium, arsenic, and selenium were similar to estimates from single-metal models, and ORs comparing extreme quartiles were 1.32 (95% CI: 1.03, 1.69; p-trend=0.04), 1.78 (95% CI: 1.29, 2.46; p-trend=0.001), and 0.67 (95% CI: 0.52, 0.85; p-trend=0.001), respectively.

CONCLUSIONS

Our study suggested that incident CHD was positively associated with plasma levels of titanium and arsenic, and inversely associated with selenium. Additional research is needed to confirm these findings in other populations. https://doi.org/10.1289/EHP1521.

Application of linear mixed-effects model with LASSO to identify metal components associated with cardiac autonomic responses among welders: a repeated measures study

Background

Environmental and occupational exposure to metals is ubiquitous worldwide, and understanding the hazardous metal components in this complex mixture is essential for environmental and occupational regulations.

Objective

To identify hazardous components from metal mixtures that are associated with alterations in cardiac autonomic responses.

Methods

Urinary concentrations of 16 types of metals were examined and ‘acceleration capacity’ (AC) and ‘deceleration capacity’ (DC), indicators of cardiac autonomic effects, were quantified from ECG recordings among 54 welders. We fitted linear mixed-effects models with least absolute shrinkage and selection operator (LASSO) to identify metal components that are associated with AC and DC. The Bayesian Information Criterion was used as the criterion for model selection procedures.

Results

Mercury and chromium were selected for DC analysis, whereas mercury, chromium and manganese were selected for AC analysis through the LASSO approach. When we fitted the linear mixed-effects models with ‘selected’ metal components only, the effect of mercury remained significant. Every 1 µg/L increase in urinary mercury was associated with −0.58 ms (−1.03, –0.13) changes in DC and 0.67 ms (0.25, 1.10) changes in AC.

Conclusion

Our study suggests that exposure to several metals is associated with impaired cardiac autonomic functions. Our findings should be replicated in future studies with larger sample sizes.

Withdrawn: The production of corporate research to manufacture doubt about the health hazards of products: an overview of the Exponent Bakelite™ simulation study

Withdrawal statement Egilman DS. The production of corporate research to manufacture doubt about the health hazards of products: an overview of the Exponent Bakelite™ simulation study. International Journal of Occupational and Environmental Health. 2016;22(1):18–26. DOI: 10.1080/10773525.2015.1123379. This content has been removed by the publishers.

Birth outcomes and background exposures to select elements, the Longitudinal Investigation of Fertility and the Environment (LIFE)

Evidence suggests that trace exposures to select elements may increase the risk for adverse birth outcomes. To investigate further, we used multiple regression to assess associations between preconception parental exposures to Pb, Cd, and total Hg in blood, and 21 elements in urine, with n=235 singleton birth outcomes, adjusted for confounders and partner's exposure. Earlier gestational age at delivery (GA) was associated with higher tertiles of urine maternal W (-1.22 days) and paternal U (-1.07 days), but GA was later for higher tertiles of maternal (+1.11 days) and paternal (+1.30 days) blood Hg. Additional analysis indicated shorter GA associated with higher paternal urine Ba, W, and U, and with higher maternal blood Pb for boys, but GA was longer in association with higher maternal urine Cr. Birth weight (BW) was lower for higher tertiles of paternal urine Cs (-237.85g), U (-187.34g), and Zn (-209.08g), and for higher continuous Cr (P=0.021). In contrast, BW was higher for higher tertiles of paternal urine As (+194.71g) and counterintuitively for maternal blood Cd (+178.52g). Birth length (BL) was shorter for higher tertiles of urine maternal W (-1.22cm) and paternal U (-1.10cm). Yet, higher tertiles of maternal (+1.11cm) and paternal (+1.30) blood Hg were associated with longer BL. Head circumference at delivery was lower for higher tertiles of paternal urine U (-0.83cm), and for higher continuous Mo in boys (-0.57cm). Overall, associations were most consistently indicated for GA and measures of birth size with urine W and U, and paternal exposures were more frequently associated than maternal. Though limited by several factors, ours is the largest multi-element investigation of prospective couple-level trace exposures and birth outcomes to date; the novel observations for W and U merit further investigation.

The effect of social trust on citizens&#8217; health risk perception in the context of a petrochemical industrial complex

Perceived risk of environmental threats often translates into psychological stress with a wide range of effects on health and well-being. Petrochemical industrial complexes constitute one of the sites that can cause considerable pollution and health problems. The uncertainty around emissions results in a perception of risk for citizens residing in neighboring areas, which translates into anxiety and physiological stress. In this context, social trust is a key factor in managing the perceived risk. In the case of industrial risks, it is essential to distinguish between trust in the companies that make up the industry, and trust in public institutions. In the context of a petrochemical industrial complex located in the port of Castellón (Spain), this paper primarily discusses how trust—both in the companies located in the petrochemical complex and in the public institutions—affects citizens’ health risk perception. The research findings confirm that while the trust in companies negatively affects citizens’ health risk perception, trust in public institutions does not exert a direct and significant effect. Analysis also revealed that trust in public institutions and health risk perception are essentially linked indirectly (through trust in companies).

Long-term environmental monitoring of persistent organic pollutants and metals in a chemical/petrochemical area: human health risks

Organic pollutants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polycyclic aromatic hydrocarbons (PAHs), as well as some metals are periodically monitored in soil and vegetation samples collected in Tarragona County (Spain). We here report the temporal trends of the concentrations of the above pollutants between the initial survey (2002) and that recently (2009) performed. The area under evaluation was divided into 4 sections (chemical, petrochemical, urban/residential and unpolluted). In general terms, urban soils presented the highest concentrations of PCDD/Fs, PCNs and PAHs, confirming that traffic is a very important emission source of these pollutants. In addition, substantially higher levels of PAHs and some metals were found in vegetation samples from the petrochemical complex. The assessment of health risks of these contaminants indicated that the current concentrations of micropollutants did not mean additional non-carcinogenic or cancer risks for the population living in the zone.

Chromium ion release from stainless steel pediatric scoliosis instrumentation

STUDY DESIGN

Case-control study.

OBJECTIVE

To determine whether serum metal ion levels and erythrocyte chromium levels in adolescents with stainless steel spinal instrumentation are elevated when compared with 2 control groups.

SUMMARY OF BACKGROUND DATA

Instrumented spinal arthrodesis is a common procedure to correct scoliosis. The long-term consequences of retained implants are unclear. Possible toxic effects related to raised metal ion levels have been reported in the literature.

METHODS

Thirty patients who underwent posterior spinal arthrodesis with stainless steel instrumentation for scoliosis (group 1) were included. Minimum postoperative duration was 3 years. Serum chromium, molybdenum, iron, and ferritin levels were measured. Participants with elevated above normal serum chromium levels (n = 11) also underwent erythrocyte chromium analysis. Comparisons were made with 2 control groups; 10 individuals with scoliosis with no spinal surgery (group 2) and 10 volunteers without scoliosis (group 3). All control group participants underwent serum and erythrocyte analysis.

RESULTS

Elevated above normal serum chromium levels were demonstrated in 11 of 30 (37%) group 1 participants. Elevated serum chromium levels were demonstrated in 0 of 10 participants (0%) in group 2 and 1 of 10 (10%) in group 3. There was a statistically significant elevation in serum chromium levels between group 1 and group 2 participants (P = 0.001). There was no significant association between groups 1, 2, and 3 for serum molybdenum, iron, and ferritin levels. Erythrocyte chromium measurements were considered within the normal range for all participants tested (n = 31).

CONCLUSION

Raised serum chromium levels were detected in 37% of patients following instrumented spinal arthrodesis for correction of scoliosis. This new finding has relatively unknown health implications but potential mutagenic, teratogenic and carcinogenic sequelae. This is especially concerning with most scoliosis patients being adolescent females with their reproductive years ahead.

Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning

Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals.

Chromium in exhaled breath condensate (EBC), erythrocytes, plasma and urine in the biomonitoring of chrome-plating workers exposed to soluble Cr(VI)

Chromium (Cr) levels measured in exhaled breath condensate (EBC-Cr) and urine (Cr-U) at the beginning and end of working shifts were related to those measured in erythrocytes (Cr-RBC) and plasma in 14 non-smoking male chrome-plating workers exposed to Cr(VI) in soluble aerosol form who did not report any significant current or past respiratory disease. Cr-U mainly correlated with Cr-P (Cr in plasma) at the end of the working shift (r(2) = 0.59, p < 0.01), whereas Cr-RBC correlated with EBC-Cr (r(2) = 0.32, p < 0.05); at the beginning of the shift, the only significant correlation was between Cr-U and Cr-RBC (r(2) = 0.74, p < 0.01). The clearance of Cr(iii) arising from Cr(VI) reduction was rapid, thus making Cr-U and Cr-P ideal biomarkers of the most recent exposure, whereas Cr-RBC may represent the fraction of Cr(VI) that reaches the bloodstream in non-reduced form and therefore depends on the airway inhaled dose represented by EBC-Cr. Cr-RBC clearance is slower and not only involves the free diffusion of Cr(iii) from RBC to plasma, but probably also involves more complicated kinetic phenomena involving other tissues and organs, which may explain the correlation between Cr-RBC and Cr-U and the lack of correlation Cr-RBC and Cr-P at least 36 h after the last exposure. In conclusion, our findings reinforce the idea that measuring Cr in EBC can significantly contribute to traditional biomonitoring by providing specific information at the target organ level and integrating our knowledge of Cr toxicokinetics.

CrVI exposure and biomarkers: Cr in erythrocytes in relation to exposure and polymorphisms of genes encoding anion transport proteins

A total of 195 subjects, including 141 exposed workers and 54 farmers, were recruited in China to evaluate the usefulness of chromium (Cr) in erythrocytes as a biomarker of exposure to CrVI. The levels of Cr in red blood cells (RBC) were remarkably elevated even in a group of workers routinely exposed to CrVI as low as 5-15 microg m(-3) and showed a significant exposure-response trend over the exposure range from 0.002 to 1152 microg m(-3) (p <0.0001). Multiple linear regression analyses indicated that age and cigarette smoke were not associated with Cr in RBC. However, female subjects had lower Cr in RBC compared with their male counterparts for about the same exposure levels (p <0.05). The genotypes of band III, which encodes for anion transport protein and may regulate CrO4(-2) across cell membranes, were also identified and included for analysis. The ratios of Cr in RBC to CrVI exposure were higher in subjects with a wild genotype than in those who had heterozygous or homozygous variant alleles. However, the difference was not statistically significant probably due to the limited number of participating subjects. In addition, 15 of the 141 workers were selected for multiple exposure monitoring and blood sample collections to evaluate the inter- and intraindividual variations of Cr in RBC. Compared with the personal exposure levels, Cr in RBC had small intraindividual variations with a reliability coefficient of 0.88. The study suggests that Cr in RBC may serve as a sensitive and reliable biomarker for long-term exposure to CrVI.

Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring

Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, <5% alloys), high alloy steel (HAS, >5% alloys), and stainless steel (SS, >26% alloys), respectively. The median exposures to HCr compounds were 0.23, 0.20, and 0.08 microg/m(3), respectively. Median concentrations of TCr in urine, blood plasma and erythrocytes were elevated in all welders, compared with the corresponding median concentrations in the reference group (p<0.005). The TCr levels observed in plasma were two-fold higher in welders of SS and HAS than in welders of MS (p<0.01). Exposure to HCr as indicated by median total content of Cr in erythrocytes was 10 microg/L in welders of SS, MS and HAS. Uptake of TCr during the shift was confirmed for welders of SS by a median increase of urinary TCr from pre- to post-shift of 0.30 microg/g creatinine. For welders of MS and HAS as a group TCr was not increased.

Biomonitoring of two types of chromium exposure in an electroplating shop

OBJECTIVES

This study is concerned with two specific chromium (Cr) exposure situations at a hard-process electroplating company. Its aims are to define variations in urinary Cr concentration and to clarify their exposure relationships.

METHODS

Airborne chromium exposure and urinary excretion were measured for a-one week period. The majority of the exposed population was divided into two groups distinguishing chromium plating and polishing functions. Analysis of airborne Cr distinguished water soluble Cr(VI), water total soluble Cr and water insoluble Cr. Volunteers provided 6-7 urine samples per day for a monitoring period of 7 days.

RESULTS

Differences between the two groups appear in relation to the type of exposure. Low concentration water soluble Cr(VI) (5.3 microg/m3 maximum) in electroplating shops is practically undetected in other workshops. Water insoluble Cr present in low concentration in electroplating exceeds 1 mg/m3 in polishing shops. Total soluble Cr concentrations are similar in these two activities (3-10 microg/m3). In polishing, 0.4% of the Cr aerosol comprises soluble Cr. Urinary Cr varied according to a 24 h cycle in similar manner in both groups throughout the monitoring week. Minimum values (3-10 microg/g crea) occurred when starting a work shift, following by a rapid rise as soon as exposure commenced, whilst maximum values (12-30 microg/g crea) were recorded towards the end of the work shift.

CONCLUSIONS

Although uncorrelated with soluble Cr(VI), urinary Cr (24 h) is effectively related to the soluble fraction of airborne chromium. In the case of chromium electroplating, correspondence between exposure and excretion appears to be governed by relationships different to those emerging from stainless steel welding, from which current biological limit values have been derived.

Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers

Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers.Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively.The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC.Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI).

Biomonitoring of chromium for residents of areas with a high density of electroplating factories

The high density of electroplating factories in the geographic middle of Taiwan has prompted concern over the potential for exposure to harmful metals. The present study aimed to determine the levels of chromium in whole blood (B-Cr) of residents living in the high vs. low factory-density areas, and to examine the relations to gender and age. A total of 660 residents who had not moved within the 5 years preceding the study were sampled according to the stratified random sampling approach, at ages 35-44, 45-54, and 55-64 years, for both genders. Chromium determinations (n=641) were made using a graphite furnace atomic absorption spectrometer. The geometric mean (95% C.I.) of B-Cr was 0.357 (0.34-0.38) microg/l. The International Federation of Clinical Chemistry (IFCC) nonparametric 0.95 reference limits of B-Cr was estimated to be <0.905 microg/l. B-Cr levels decreased with increasing age. Subjects in the areas with a high density (0.38 microg/l, 95% C.I.: 0.36-0.40) of electroplating factories had significantly higher B-Cr levels, compared to residents of the low-density (0.27, 0.25-0.30) areas and to the general population from western countries. The health significance of the elevated B-Cr remains to be determined.

Increased levels of 8-hydroxy-2 -deoxyguanosine attributable to carcinogenic metal exposure among schoolchildren

Arsenic, chromium, and nickel are reported in several epidemiologic studies to be associated with lung cancer. However, the health effects of arsenic, chromium, and nickel exposures are equivocal for children. Therefore, we performed a cross-sectional study to investigate possible associations between the internal concentrations of arsenic, chromium, and nickel and the level of oxidative stress to DNA in children. We measured urinary levels of arsenic, chromium, and nickel for 142 nonsmoking children using atomic absorption spectrometry. As a biomarker for oxidative stress, urinary 8-hydroxy-2 -deoxyguanosine (8-OHdG) levels were analyzed with an enzyme-linked immunosorbent assay kit. The median urinary 8-OHdG level for our subjects was 11.7 ng/mg creatinine. No obvious relationship between the levels of urinary nickel and 8-OHdG was found. Multiple linear regression analysis showed that children with higher urinary chromium had greater urinary 8-OHdG than did those with lower urinary chromium. Similarly, subjects with higher urinary arsenic had greater urinary 8-OHdG than did those with lower urinary arsenic. Furthermore, children with both high urinary arsenic and high urinary chromium had the highest 8-OHdG levels (mean +/- SE, 16.0 +/- 1.3; vs. low arsenic/low chromium, p < 0.01) in urine, followed by those with low arsenic/high chromium (13.7 +/- 1.6; vs. low arsenic/low chromium, p = 0.25), high arsenic/low chromium (12.9 +/- 1.6 vs. low arsenic/low chromium, p = 0.52), and low arsenic/low chromium (11.5 +/- 1.3); the trend was significant (p < 0.001). Thus, environmental carcinogenic metal exposure to chromium and arsenic may play an important role in oxidative DNA damage to children.

Health risk communication using comparative risk analyses

The ability to communicate effectively the degree or magnitude of public exposures or health risks is essential for risk assessors and risk managers. Various guidelines exist for communicating environmental and public health risks, including recommended approaches for putting risk data into proper context. Although it remains unclear as to which approach is the most useful or appropriate under different circumstances, risk comparisons are a popular choice for conveying the significance of or providing a better perspective on a particular chemical exposure or health risk. In this paper, several different types of risk comparisons are described that are frequently used in the private and public sectors, and these are illustrated using a variety of examples from the literature. These approaches include: (1) intrachemical comparisons, (2) interchemical comparisons, (3) comparisons to background levels of risk, (4) comparisons to theoretical risks or safety levels, and (5) comparisons to other actions or activities. The primary purpose of this paper is to summarize and briefly discuss the advantages and limitations of these risk communication approaches. The evolving field of risk communication is also discussed, including ongoing research on public risk perceptions and alternative methods for communicating risk magnitudes and data uncertainties.

Acute potassium dichromate poisoning: a toxicokinetic case study

CASE REPORT

A 48-year-old man drank 150 mL of an aqueous solution containing potassium dichromate 22.5 g in a suicidal attempt and was admitted 7 hours after the ingestion. Hemodialysis was promptly undertaken and chromium concentrations in serum, erythrocytes, and dialysate were determined during the treatment. Chromium elimination in urine was monitored during hemodialysis and the subsequent 400 hours. The total chromium eliminated via hemodialysis and urine was calculated as 36.7 mg or 0.16% of the ingested dose. Spontaneous urinary elimination proceeded according to an open one-compartment model. The elimination half-life was 71.37 hours +/- 17.13 hours (95% CI). Chromium elimination from serum followed an open two-compartment model, with the half-lives of 3.16 hours +/- 2.63 hours for phase 1 and 50 hours +/- 27 hours (95% CI) for phase 2. Calcium-EDTA therapy had no influence on erythrocyte, serum, or urine chromium level. It contributed, however, to a significant increase in chromium elimination rate in the dialysate. Serum zinc was very low at admission and serum zinc, copper, and magnesium were controlled during the initial 30 hours.

Blood chromium determination in assessing reference values in an unexposed Mediterranean population

Plasma chromium levels were determined in 243 healthy subjects. The study group consisted of 134 men and 109 women, ages 19-71 yr, all residing in Barcelona in northeastern Spain. The study was designed to assess the reference levels for plasma chromium and to investigate its relationships to age and sex. The assays were performed by means of a graphite-furnace atomic absorption spectrometer. The mean plasma chromium concentration was 3.01 +/- 1.45 nmol/L, ranging from 0.6 to 6 nmol/L. The upper reference values in the 0.95 percentile for this population was 5 nmol/L. No significant differences were observed with respect to the subjects' sex.