Biological monitoring of exposure to mixtures

Interactive effect of carbendazim and imidacloprid on buffalo bone marrow derived mesenchymal stem cells: oxidative stress, cytotoxicity and genotoxicity

The effect of a combination of two pesticides, carbendazim (CBZ) and imidacloprid (IMI), was investigated on mesenchymal stem cells derived from the bone marrow of buffalo (bMSCs). The bMSCs were exposed to the CBZ (2.25 µM, 4.49 µM, and 8.98 µM) and IMI (0.81 mM, 1.61 mM, and 3.22 mM) alone as well as in combinations. The bMSCs were found to be positive for the stem cell markers, AP, CD73, and OCT4. The bMSCs showed a significant reduction (p ≤ 0.05) in cell viability, and status of anti-oxidants while a significant increase (p ≤ 0.05) in the level of LDH, ALP, and CK-MB in CBZ and IMI-treated groups. A significant increase (p ≤ 0.05) was noticed in LPO, O^2─ radical, total ROS, loss of ΔΨm, apoptotic index, and DNA damage in CBZ and IMI-treated groups. A low-dose combination group showed an elevated effect compared to the groups treated with the single pesticide. The interaction index was calculated for CBZ-IMI combined treatment groups on various parameters that showed the majority of antagonist effects. Present findings confirmed that CBZ and IMI-induced cytotoxicity in bMSCs was mediated via ROS production, altered ΔΨm and LPO along with depressed antioxidant status which was responsible for cell apoptosis and cell damage. This study suggested that CBZ and IMI had a dose-dependent toxic effect when the pesticides were used alone, while, co-exposure to both the pesticides simultaneously had an antagonist or non-additive effect on buffalo bMSCs at lower dose combinations and they induced a potentiating effect at high-dose combination.

Metabolomics for exposure assessment and toxicity effects of occupational pollutants: current status and future perspectives

INTRODUCTION

Work-related exposures to harmful agents or factors are associated with an increase in incidence of occupational diseases. These exposures often represent a complex mixture of different stressors, challenging the ability to delineate the mechanisms and risk factors underlying exposure-disease relationships. The use of omics measurement approaches that enable characterization of biological marker patterns provide internal indicators of molecular alterations, which could be used to identify bioeffects following exposure to a toxicant. Metabolomics is the comprehensive analysis of small molecule present in biological samples, and allows identification of potential modes of action and altered pathways by systematic measurement of metabolites.

OBJECTIVES

The aim of this study is to review the application of metabolomics studies for use in occupational health, with a focus on applying metabolomics for exposure monitoring and its relationship to occupational diseases.

METHODS

PubMed, Web of Science, Embase and Scopus electronic databases were systematically searched for relevant studies published up to 2021.

RESULTS

Most of reviewed studies included worker populations exposed to heavy metals such as As, Cd, Pb, Cr, Ni, Mn and organic compounds such as tetrachlorodibenzo-p-dioxin, trichloroethylene, polyfluoroalkyl, acrylamide, polyvinyl chloride. Occupational exposures were associated with changes in metabolites and pathways, and provided novel insight into the relationship between exposure and disease outcomes. The reviewed studies demonstrate that metabolomics provides a powerful ability to identify metabolic phenotypes and bioeffect of occupational exposures.

CONCLUSION

Continued application to worker populations has the potential to enable characterization of thousands of chemical signals in biological samples, which could lead to discovery of new biomarkers of exposure for chemicals, identify possible toxicological mechanisms, and improved understanding of biological effects increasing disease risk associated with occupational exposure.

Early molecular markers for retrospective biodosimetry and prediction of acute health effects

Radiation-induced biological changes occurring within hours and days after irradiation can be potentially used for either exposure reconstruction (retrospective dosimetry) or the prediction of consecutively occurring acute or chronic health effects. The advantage of molecular protein or gene expression (GE) (mRNA) marker lies in their capability for early (1-3 days after irradiation), high-throughput and point-of-care diagnosis, required for the prediction of the acute radiation syndrome (ARS) in radiological or nuclear scenarios. These molecular marker in most cases respond differently regarding exposure characteristics such as e.g. radiation quality, dose, dose rate and most importantly over time. Changes over time are in particular challenging and demand certain strategies to deal with. With this review, we provide an overview and will focus on already identified and used mRNA GE and protein markers of the peripheral blood related to the ARS. These molecules are examined in light of 'ideal' characteristics of a biomarkers (e.g. easy accessible, early response, signal persistency) and the validation degree. Finally, we present strategies on the use of these markers considering challenges as their variation over time and future developments regarding e.g. origin of samples, point of care and high-throughput diagnosis.

Longitudinal effects of family psychopathology and stress on pubertal maturation and hormone coupling in adolescent twins

Adolescents experience profound neuroendocrine changes, including hormone "coupling" between cortisol, testosterone, and dehydroepiandrosterone. Emerging research has only begun to elucidate the role of hormone coupling, its genetic and environmental etiology, and the extent to which coupling is impacted by gender, puberty, and family context. We included measures on parent and child mental health, parenting stress, and family conflict of 444 twin pairs and their parents across two timepoints, when youth were on average 8 and 13 years old, respectively. Structural equation models examined the impact of family context effects on coupling during adolescence. Biometric twin models were then used to probe additive genetic, shared, and non-shared environmental effects on hormone coupling. Hormones were more tightly coupled for females than males, and coupling was sensitive to parental depression and co-twin psychopathology symptoms and stress exposure in females. The association between family context and coupling varied across specific neuroendocrine measures and was largely distinct from pubertal maturation. Biometric models revealed robust shared and non-shared environmental influences on coupling. We found that family antecedents modify the strength of coupling. Environmental influences account for much of the variation on coupling during puberty. Gender differences were found in genetic influences on coupling.

The genotoxicity of an organic solvent mixture: A human biomonitoring study and translation of a real-scenario exposure to in vitro

This study aimed to evaluate occupational exposure to a styrene and xylene mixture through environmental exposure assessment and identify the potential genotoxic effects through biological monitoring. Secondly, we also exposed human peripheral blood cells in vitro to both xylene and styrene either alone or in mixture at concentrations found in occupational settings in order to understand their mechanism of action. The results obtained by air monitoring were below the occupational exposure limits for both substances. All biomarkers of effect, except for nucleoplasmic bridges, had higher mean values in workers (N = 17) compared to the corresponding controls (N = 17). There were statistically significant associations between exposed individuals and the presence of nuclear buds and oxidative damage. As for in vitro results, there was no significant influence on primary DNA damage in blood cells as evaluated by the comet assay. On the contrary, we did observe a significant increase of micronuclei and nuclear buds, but not nucleoplasmic bridges upon in vitro exposure. Taken together, both styrene and xylene have the potential to induce genomic instability either alone or in combination, showing higher effects when combined. The obtained data suggested that thresholds for individual chemicals might be insufficient for ensuring the protection of human health.

Technical note: Residues of gaseous air pollutants in rabbit (Oryctolagus cuniculus) tissues

The modern consumer is concerned not only for meat quality, but also about animal welfare and the environment. Studies were conducted to determine the concentration of gaseous residues in the tissues of rabbits. For this purpose, gaseous air pollutants were measured at the height of rabbit cages. Immediately after slaughter, samples were taken for analysis to determine the level of residual pollutants in the tissues (blood, perirenal fat and lung). Headspace gas chromatography was performed on the tissue samples to test for volatile toxic substances. Gas residues of 11 compounds were determined in the samples of blood, perirenal fat and lungs. The same chemicals were present in the air of the farm and the animal tissues, which may indicate their capacity for bioaccumulation. We recommend that the results should be used to develop guidelines regarding the welfare of meat rabbits and requirements for laboratory rabbits.

Toluene and methylethylketone: effect of combined exposure on their metabolism in rat

1. Multiple exposures are ubiquitous in industrial environments. In this article, we highlight the risks faced by workers and complete the data available on the metabolic impact of a common mixture: toluene (TOL) and methylethylketone (MEK). 2. Rats were exposed by inhalation under controlled conditions either to each solvent individually, or to mixtures of the two. How the interaction between the two solvents affected their fate in the blood and brain, their main relevant urinary metabolites (o-cresol, benzylmercapturic acid for TOL and 2,3-butanediols for MEK) and their hepatic metabolism were investigated. 3. Although the cytochrome P450 concentration was unchanged, and the activities of CYP1A2 and CYP2E1 isoforms were not additively or synergistically induced by co-exposure, TOL metabolism was inhibited by the presence of MEK (and vice versa). Depending on the relative proportions of each compound in the mixture, this sometimes resulted in a large increase in blood and brain concentrations. Apart from extreme cases (unbalanced mixtures), the amount of o-cresol and benzylmercapturic acid (and to a lesser extent 2,3-butanediols) excreted were proportional to the blood solvent concentrations. 4. In a co-exposure context, ortho-cresol and benzylmercapturic acid can be used as urinary biomarkers in biomonitoring for employees to relatively accurately assess TOL exposure.

The influence of ochratoxin A on DNA adduct formation by the carcinogen aristolochic acid in rats

Exposure to the plant nephrotoxin and carcinogen aristolochic acid (AA) leads to the development of AA nephropathy, Balkan endemic nephropathy (BEN) and upper urothelial carcinoma (UUC) in humans. Beside AA, exposure to ochratoxin A (OTA) was linked to BEN. Although OTA was rejected as a factor for BEN/UUC, there is still no information whether the development of AA-induced BEN/UUC is influenced by OTA exposure. Therefore, we studied the influence of OTA on the genotoxicity of AA (AA-DNA adduct formation) in vivo. AA-DNA adducts were formed in liver and kidney of rats treated with AA or AA combined with OTA, but no OTA-related DNA adducts were detectable in rats treated with OTA alone or OTA combined with AA. Compared to rats treated with AA alone, AA-DNA adduct levels were 5.4- and 1.6-fold higher in liver and kidney, respectively, of rats treated with AA combined with OTA. Although AA and OTA induced

NAD(P)H

quinone oxidoreductase (NQO1) activating AA to DNA adducts, their combined treatment did not lead to either higher NQO1 enzyme activity or higher AA-DNA adduct levels in ex vivo incubations. Oxidation of AA I (8-methoxy-6-nitrophenanthro[3,4-d]-1,3-dioxole-5-carboxylic acid) to its detoxification metabolite, 8-hydroxyaristolochic acid, was lower in microsomes from rats treated with AA and OTA, and this was paralleled by lower activities of cytochromes P450 1A1/2 and/or 2C11 in these microsomes. Our results indicate that a decrease in AA detoxification after combined exposure to AA and OTA leads to an increase in AA-DNA adduct formation in liver and kidney of rats.

Combined toxic exposures and human health: biomarkers of exposure and effect

Procedures for risk assessment of chemical mixtures, combined and cumulative exposures are under development, but the scientific database needs considerable expansion. In particular, there is a lack of knowledge on how to monitor effects of complex exposures, and there are few reviews on biomonitoring complex exposures. In this review we summarize articles in which biomonitoring techniques have been developed and used. Most examples describe techniques for biomonitoring effects which may detect early changes induced by many chemical stressors and which have the potential to accelerate data gathering. Some emphasis is put on endocrine disrupters acting via epigenetic mechanisms and on carcinogens. Solid evidence shows that these groups of chemicals can interact and even produce synergistic effects. They may act during sensitive time windows and biomonitoring their effects in epidemiological studies is a challenging task.

Amounts and proportion of administered pyrene dose excreted as urinary 1-hydroxypyrene after dietary exposure to polycyclic aromatic hydrocarbons

Although urinary 1-hydroxypyrene (1-OHP) is the most relevant parameter for assessing exposure to polycyclic aromatic hydrocarbons, the inability to further elucidate the intra- and inter-individual variability, specificity and kinetics makes it difficult to enhance its value as an exposure predictor. Therefore, this human control study examined the excretion kinetics of urinary 1-OHP after consuming barbecued meat. Two feeding experiments were conducted, with doses of 15 and 30 g of barbecued meat per kg of body weight for experiments 1 and 2, respectively. All voided urine was collected for 7 days and analyzed for 1-OHP. In both experiments, the amounts of urinary 1-OHP excreted was significantly increased (P < 0.05) at 12 h post exposure but not at 12-24 h post exposure. Mean percentages of administered pyrene doses excreted as urinary 1-OHP at 0-12 h and 12-24 h post exposure were 3.80 and 0.61% in experiment 1 and 1.66 and 0.38% in experiment 2. Excretion ratio was inversely related to dose. A pattern of diurnal fluctuation (P < 0.05) in 1-OHP excretions was also identified. That is, 1-OHP excretions were smaller in the first half of the day (~0:00-12:00) than in the last half of the day (~12:00-24:00). This study demonstrated that, even at large dietary doses, most of the total urinary excretion of 1-OHP occurs within 12 h. Thus, subjects of occupational or environmental studies need only recall their diets for the current or previous day to diminish the influence from dietary pyrene.

Decreased sperm motility in rats orally exposed to single or mixed pesticides

The Brazilian Agency of Sanitary Vigilance (ANVISA) conducted a study that demonstrated the presence of residues of several pesticides in fresh fruits and vegetables that were available for purchase by the general populace. In order to evaluate potential adverse health effects of low-level exposure to agrochemicals, the reproductive toxicity of the pesticides dicofol, dichlorvos, permethrin, endosulfan, and dieldrin was evaluated in rats dosed with these chemicals individually or as mixtures. Sixty male Lewis rats (6 wk old, 200 x g) were randomly allocated to 8 groups: (1) control group, received basal diet; (2) 5 groups designated a to e received the diet containing each pesticide individually, at the respective effective doses: lowest-observed-adverse-effect level (LOAEL) for dieldrin and endosulfan, lowest-observed-effect level (LOEL) for dicofol, and lowest effect level (LEL) for dichlorvos and permethrin, respectively, depending on the published data; (3) effective dose group, which received a mixture of pesticides added to basal diet at the respective doses reported to produce adverse effects; and (4) low dose group, which received a pesticide mixture added to the basal diet, where each pesticide was at its no-observed-effect level (NOEL). After 8 wk of treatment, reproductive parameters were evaluated. Sperm morphology, daily sperm production (DSP), sperm transit time through the epididymis, hormonal levels, and histopathological evaluation of testis and epididymis did not differ significantly among the groups. However, sperm motility was significantly decreased in animals that received a mixture of dieldrin, endosulfan, dicofol, dichlorvos, and permethrin, as well as in the group receiving dicofol alone. Exposure to the individual pesticides endosulfan, dichlorvos, and permethrin did not markedly affect sperm motility. The impairment of sperm motility in the mixture of pesticides at the NOEL level indicates that reproductive effects not seen with individual pesticides may occur in presence of several pesticides due to an additive effect. However, the pesticide mixtures did not appear to affect DSP or spermatogenesis despite reduced sperm motility.

Determinants of urinary 1-hydroxypyrene glucuronide in South Korean children

OBJECTIVES

This study was conducted to investigate the dominant sources of the urinary pyrene metabolite, 1-hydroxypyrene glucuronide (1-OHPG), in South Korean children.

METHODS

Urine samples were collected from 102 non-smoking children (aged 10-14). Urinary 1-OHPG was assayed by synchronous fluorescence spectroscopy, following immuno-affinity purification using monoclonal antibody 8E11. Urinary cotinine, a metabolite of nicotine, was measured by GC/MS. Information on environmental tobacco smoke (ETS) exposure, diet, fuel type for heating home, and other possible sources of PAH exposure was collected by self-administered questionnaires.

RESULTS

Mean (+/-SE) 1-OHPG levels were 1.64 (+/-0.06) ng/ml (range 0.04-3.27 ng/ml). Two multiple linear regression analyses (differing in how ETS was approximated: by parental smoking or urinary cotinine) revealed a positive association between urinary 1-OHPG levels and parental smoking at home (P = 0.007), log urinary cotinine (P = 0.165), frequent grilled (shell)fish consumption (P = 0.061), and living in a commercial/other zone (P = 0.007) versus a residential or industrial zone. No consistent associations were found between 1-OHPG and the child's sex, grilled meat consumption, or fuels used to heat the home.

CONCLUSIONS

These results support that ETS, frequent grilled fish consumption, and the ambient environment are important predictors of urinary 1-OHPG levels in South Korean children.

Extraction of information from laser-induced breakdown spectroscopy spectral data by multivariate analysis

Laser-induced breakdown spectroscopy (LIBS) is being proposed more and more as a high-throughput technology to assess the elemental composition of materials. When a specific element is of interest, semiquantification is possible by building a calibration model using the emission line intensity of this element for known samples. However, a unique element has usually more than one emission line, and there are many examples where several emission lines used in combination give dramatically better results than any of the individual variables used alone. With a multivariate approach, models can be constructed that take into account all the emission lines related to a specific element; therefore more robust models can be developed. In this work, chemometric methods such as principal component analysis and partial least squares are proposed to resolve and extract useful information from the LIBS spectral data collected on biological materials.

Exposure assessment at the workplace: implications of biological variability

Biological monitoring (BM) and biomarkers are widely applied in occupational toxicology. BM is mainly aimed at (i) defining the existence of an occupational exposure; (ii) quantifying the level of internal dose; (iii) verifying that exposure limits (BEI((R)), BAT, BLV) are respected. As compared to ambient monitoring, BM is more expensive and complex. Several biomarkers are available for the same chemical and the meaning of the marker may depend on the sampling time. Therefore, practical issues, including cost and selection of an adequate sampling strategy, should be dealt with when planning a BM program for specific purposes. In addition, several biological and analytical sources of variability may influence biomarker levels, thus making the interpretation of BM data a difficult task. However, we should recognize that the main aim of BM is not to reduce, but to explain biological variance. The decreasing trend in occupational exposure levels highlighted the specificity problems of traditional biomarkers of exposure and prompted the research to the development of new biomarkers, e.g. unchanged volatile compounds in urine, minor metabolites, DNA and protein adducts. Depending on the scope and context (research or routine) different requirements of biomarkers can be envisaged in terms of validation and acceptable variability.

Urinary 1-hydroxypyrene as a biomarker of PAH exposure in 3-year-old Ukrainian children

Urinary 1-hydroxypyrene (1-OHP) is a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure. We measured urinary 1-OHP in 48 children 3 years of age in Mariupol, Ukraine, who lived near a steel mill and coking facility and compared these with 1-OHP concentrations measured in 42 children of the same age living in the capital city of Kiev, Ukraine. Children living in Mariupol had significantly higher urinary 1-OHP and creatinine-adjusted urinary 1-OHP than did children living in Kiev (adjusted: 0.69 vs. 0.34 micromol/mol creatinine, p < 0.001; unadjusted: 0.42 vs. 0.30 ng/mL, p = 0.002). Combined, children in both cities exposed to environmental tobacco smoke in their homes had higher 1-OHP than did children not exposed (0.61 vs. 0.42 micromol/mol creatinine; p = 0.04; p = 0.07 after adjusting for city). In addition, no significant differences were seen with sex of the children. Our sample of children in Mariupol has the highest reported mean urinary 1-OHP concentrations in children studied to date, most likely due to their proximity to a large industrial point source of PAHs.