Serum level of PCBs and OCPs and leukocyte telomere length among adults in Tehran, Iran

Association between rare earth element exposure during pregnancy and newborn telomere length

Telomere length (TL) is considered a marker of biological aging and lifetime health, and some epidemiological studies report that the environmental exposures may influence TL at birth. We aimed to investigate the associations between prenatal rare earth elements (REE) exposure and newborn TL. A total of 587 mother-newborn pairs were recruited during 2013 to 2015 in Wuhan, China. Maternal urinary concentrations of REE collected during three trimesters were measured by inductively coupled plasma mass spectrometry. Quantitative real-time polymerase chain reaction was used to measure relative cord blood TL. The trimester-specific associations between prenatal REE exposure and cord blood TL were evaluated using multiple informant models. Weighted quantile sum regression was used to estimate the mixture effect of urinary REE on cord blood TL. After adjustment for potential confounders, per doubling of urinary REE (Dy, Yb, Pr, Nd, and Tm) concentrations (μg/g creatinine) during the second trimester was respectively associated with 1.94% (95% CI 0.19%, 3.72%), 2.10% (95% CI 0.31%, 3.92%), 2.11% (95% CI 0.35%, 3.89%), 2.08% (95% CI 0.01%, 4.20%), and 1.38% (95% CI 0.09%, 2.70%) increase in cord blood TL. Furthermore, exposure to the mixture of REE during the second trimester was also significantly associated with increased cord blood TL (percent change 1.20%, 95% CI 0.30%, 2.11%). However, these associations were not statistically significant in the first and third trimesters. This study provides new evidence on the potential effect of prenatal REE exposure on the initial (newborn) setting of offspring's telomere biology. Further epidemiological studies are warranted to confirm our findings.

Persistent organic pollutant exposure contributes to Black/White differences in leukocyte telomere length in the National Health and Nutrition Examination Survey

Despite racial disparities in diseases of aging and premature mortality, non-Hispanic Black Americans tend to have longer leukocyte telomere length (LTL), a biomarker of cellular aging, than non-Hispanic White Americans. Previous findings suggest that exposure to certain persistent organic pollutants (POPs) is both racially-patterned and associated with longer LTL. We examine whether Black/White differences in LTL are explained by differences in exposure to 15 POPs by estimating the indirect effect (IE) of self-reported race on LTL that is mediated through nine polychlorinated biphenyls (PCBs), three furans, and three dioxins, as well as their mixtures. Our study population includes 1,251 adults from the 1999-2000 and 2001-2002 cycles of the cross-sectional National Health and Nutrition Examination Survey. We characterized single-pollutant mediation effects by constructing survey-weighted linear regression models. We also implemented various approaches to quantify a global mediation effect of all POPs, including unpenalized linear regression, ridge regression, and examination of three summary exposure scores. We found support for the hypothesis that exposure to PCBs partially mediates Black/White differences in LTL. In single-pollutant models, there were significant IEs of race on LTL through six individual PCBs (118, 138, 153, 170, 180, and 187). Ridge regression (0.013, CI 0.001, 0.023; 26.0% mediated) and models examining summative exposure scores with linear combinations derived from principal components analysis (0.019, CI 0.009, 0.029; 34.8% mediated) and Toxic Equivalency Quotient (TEQ) scores (0.016, CI 0.005, 0.026; 28.8% mediated) showed significant IEs when incorporating survey weights. Exposures to individual POPs and their mixtures, which may arise from residential and occupational segregation, may help explain why Black Americans have longer LTL than their White counterparts, providing an environmental explanation for counterintuitive race differences in cellular aging.

Association between telomere length in human umbilical cord tissues and polychlorinated biphenyls in maternal and cord serum

Environmental exposure to persistent organic pollutants during pregnancy has potential adverse health effects on the fetus. One of the environmental pollutants is polychlorinated biphenyl (PCB). Earlier, we reported the presence of PCBs in fetal tissues such as the umbilical cord. Telomere length (TL) is a biomarker of aging because it shortens with each cell division. According to the Developmental Origins of Health and Disease hypothesis, fetal exposure to environmental pollutants during pregnancy affects the occurrence of non-communicable diseases in later life. In the current study, we investigated the association between cord tissue TL and serum levels of PCBs. The subjects were 114 mother-child pairs participating in a birth cohort study, the Chiba Study of Mother and Child Health (C-MACH). Maternal serum was collected during pregnancy, and cord serum and tissue were obtained at birth. TL was assessed by qPCR using genomic DNA extracted from the cord tissue. Maternal and cord serum PCB congener levels were assessed using gas chromatography and negative ion chemical ionization qMS. In male fetuses, serum levels of PCB74 in the cord blood were significantly associated with TL following covariate adjustment, but no significant association was found in female fetuses. These data suggest that the TL of the umbilical cord is affected by fetal exposure to PCBs.

Exposure sources of polychlorinated biphenyls (PCBs) and health risk assessment: a systematic review in Iran

This systematic review aims to identify the sources of exposure to polychlorinated biphenyls (PCBs), portioning, and human health risk assessment in Iran. The literature was searched in the international databases of Web of Science, PubMed, Scopus, Google Scholar, and the national databases of SID and MagIran up to November 14, 2020. Among all 153 articles, 21 eligible papers were identified. Among them, only one article was related to drinking water, the rest was related to food and soil, and no article was found on ambient air. The corrected portion of each exposure source was determined to be 90% for food, 9% for water, and 1% for air. The total hazard quotient (HQ) was determined to be within an unsafe range, and the total excess lifetime cancer risk (ELCR) was determined to be at a high risk of oral carcinogenesis. It is suggested that a comprehensive study be conducted in a specific period for all sources of exposure in all counties of Iran. Moreover, it is recommended that the policymakers set national standards for this pollutant in near future in some sources of exposure (e.g., drinking water) which have no standards in Iran.

Path Analysis Reveals the Direct Effect of PCB28 Exposure on Cognitive Dysfunction in Older Chinese Females

Background: Research indicates that exposure to polychlorinated biphenyls (PCBs) can cause neurobehavioral impairments in neonates and adults, but the way specific PCBs’ congeners impact cognition functions at a low exposure level in a real-life co-exposure system remains poorly understood. This study aimed to investigate the association of PCBs burden with cognition function among elderly adults. Methods: Based on the Weitang Geriatric Diseases study (2014−2015), the current study measured the plasma concentrations of six indicator-PCBs by GC-MS/MS and assessed the cognitive dysfunction (CoD) via an Abbreviated Mental Test in 266 participants (ages 61−90). Sequential logistic regression was used to analyze the effects of PCBs on cognition functions. Female participants aged less than or equal to 80 years were selected, and path analysis was used to determine the direct or indirect impacts of co-exposure PCBs on CoD by structural equation modeling. Results: After sequential adjustments to potential confounding factors and correction by the Bonferroni, no statistically significant correlation between PCBs exposure and CoD was found in participants (p > 0.05). However, in the co-exposure system, after controlling for co-exposures and confounders, exposure to PCB28 had a direct effect on CoD in females aged between 61 and 80, with a factor load of 0.670. Conclusions: After adjusting for the co-exposures and confounders, exposure to PCB28 can directly increase the risk of cognitive impairment in older Chinese females.

Dietary Exposure to Polychlorinated Biphenyls and Dioxins and Its Relationship to Telomere Length in Subjects Older Than 55 Years from the SUN Project

Exposure to persistent organic pollutants (POPs) may influence telomere length (TL), which is considered as a marker of biological age associated with the risk of chronic disease. We hypothesized that dietary exposure to polychlorinated biphenyls (PCBs) and dioxins could affect TL. Our aim was to evaluate the association of dietary exposure to PCBs and dioxins with TL. In this cross-sectional study of 886 subjects older than 55 y (mean age: 67.7; standard deviation (SD): 6.1; 27% women) from the “Seguimiento Universidad de Navarra” (SUN) project. TL was determined by real-time quantitative polymerase chain reaction and dietary PCBs and dioxins exposure was collected using a validated 136-item Food Frequency Questionnaire. Multivariable linear regression models were used to control for potential confounding factors. Shorter TL was associated with dietary total PCBs (SD of T/S ratio/(ng/day) = −0.30 × 10⁻⁷; 95% CI, −0.55 × 10⁻⁷ to −0.06 × 10⁻⁷), dioxin-like PCBs (DL-PCBs) (SD of T/S ratio/(pg WHO TEQ (Toxic Equivalents)/day) = −6.17 × 10⁻⁷; 95% CI, −11.30 × 10⁻⁷ to −1.03 × 10⁻⁷), and total TEQ exposure (SD of T/S ratio/(pg WHO TEQ/day) = −5.02 × 10⁻⁷; 95% CI, −9.44 × 10⁻⁷ to −0.61 × 10⁻⁷), but not with dioxins (SD of T/S ratio/(pg WHO TEQ/day) = −13.90 × 10⁻⁷; 95% CI, −37.70 × 10⁻⁷ to 9.79 × 10⁻⁷). In this sample of middle-aged and older Spanish adults, dietary exposure to total PCBs and DL-PCBs alone and together with dioxins was associated with shorter TL. Further longitudinal studies, preferably with POPs measured in biological samples, are needed to confirm this finding.

Biomonitoring of 89 POPs in blood serum samples of Czech city policemen

In this biomonitoring study, we evaluated the concentrations of 8 polychlorinated biphenyls (PCBs), 11 organochlorinated pesticides (OCPs), 33 brominated flame retardants (BFRs), 7 novel brominated and chlorinated flame retardants (novel FRs) and 30 per- and polyfluoroalkylated substances (PFAS) in human serum samples (n = 274). A total of 89 persistent organic pollutants (POPs) were measured in blood serum samples of city policemen living in three large cities and their adjacent areas (Ostrava, Prague, and Ceske Budejovice) in the Czech Republic. All samples were collected during the year 2019 in two sampling periods (spring and autumn). The identification/quantification of PCBs, OCPs, BFRs, novel FRs and PFAS was performed by means of gas chromatography coupled to (tandem) mass spectrometry (GC-MS/(MS)) and ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). The most frequently detected pollutants were perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), 2,2',3,4,4',5'-hexachlorobiphenyl (CB 138), 2,2',4,4',5,5'-hexachlorobiphenyl (CB 153), 2,2',3,3',4,4',5-heptachlorobiphenyl (CB 170), 2,2',3,4,4',5,5'-heptachlorobiphenyl (CB 180), hexachlorobenzene (HCB), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) quantified in 100% of serum samples. In the serum samples, the concentrations of determined POPs were in the range of 0.108-900 ng g^-1 lipid weight (lw) for PCBs, 0.106-1016 ng g^-1 lw for OCPs, <0.1-618 ng g^-1 lw for FRs and <0.01-18.3 ng mL^-1 for PFAS, respectively. Locality, sampling season, and age were significantly associated with several POP concentrations. One of the important conclusions was that within the spring sampling period, statistically significant higher concentrations of CB 170 and CB 180 were observed in the samples from Ostrava (industrial area) compared to Prague and Ceske Budejovice. Older policemen had higher concentrations of five PCBs and two OCPs in blood serum.

Spatiotemporal variability of exposure to secondhand smoke in Iran during 2009-2020: a systematic review

The present study aimed to provide a systematic review of studies on the prevalence of secondhand smoke (SHS) exposure in the Iran population as a serious indoor health hazard. A literature review of studies that considered SHS exposure, available in multiple electronic databases including Web of Science, PubMed, and Scopus published 2009-2020 in English and two Persian databases (SID and Magiran), was carried out following the PRISMA recommendations. A total of 55 studies were included based on the inclusion and exclusion criteria and the quality assessment. The results showed no specific decrease in the prevalence of exposure to secondhand smoke in Iran; however, it appeared that the exposure has been increasing. Distribution of studies in terms of age group revealed that most studies (38%) investigated adults (more than 18 years old), while 34% of the studies considered less than 18 years of age group and a single article considered infants (6-24 months). Based on the present study results, a large population of Iran was exposed to SHS. Moreover, based on Iran's STEPs 2016 (Stepwise Non-communicable Diseases Risk Factors Survey in Iran) study, the overall prevalence of SHS exposure at home (57.5%) was higher than in workplaces (49.2%). The results of the present study recommended that protection measures should be comprehensive in terms of exposure places, and since the exposure prevalence in some provinces was higher than the others, it is especially important to consider the local measures and cultural aspects in SHS control programs.

Development in the European flounder (Platichthys flesus) of a q-PCR assay for the measurement of telomere length, a potential biomarker of pollutant effects for biomonitoring studies

Telomeres protect the coding sequence of chromosome ends and Telomere Length (TL) has been proposed as a biomarker of cellular aging, cumulative stress exposure and life-span in humans. With the aim to propose new biomarkers, a q-PCR protocol was adapted for the measurement of TL in the European flounder Platichthys flesus. The protocol was then applied in 2-year-old flounders from the Seine Estuary. The absolute TL in the flounder is 54 ± 13 kbp per genome (mean ± standard error). Considering relative or absolute TL, no correlation was observed with DNA damage and any of the measured contaminant concentrations (trace elements, metabolites of polycyclic aromatic hydrocarbons, polychlorobiphenyls, organochlorinated pesticides, polybrominated diphenyl ethers, perfluoroalkyl substances). Because sampling was limited, further investigations are required to state a possible impact of chemical pollution on flatfish telomeres. This is motivated by correlations observed with organochlorinated compounds when decreasing statistical significance (p ≤ 0.10).

Telomeres as targets for the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) in rats

Telomere length (TL) can be affected by various factors, including age and oxidative stress. Changes in TL have been associated with chronic disease, including a higher risk for several types of cancer. Environmental exposure of humans to PCBs and dioxins has been associated with longer or shorter leukocyte TL. Relative telomere length (RTL) may serve as a biomarker associated with neoplastic and/or non-neoplastic responses observed with chronic exposures to TCDD and PCBs. RTL was measured in DNA isolated from archived frozen liver and lung tissues from the National Toxicology Program (NTP) studies conducted in female Harlan Sprague Dawley rats exposed for 13, 30, and 52 weeks to TCDD, dioxin-like (DL) PCB 126, non-DL PCB 153, and a mixture of PCB 126 and PCB 153. RTL was assessed by quantitative polymerase chain reaction (qPCR). Consistent with literature, decreased liver and lung RTL was seen with aging. Relative to time-matched vehicle controls, RTL was increased in both the liver and lung tissues of rats exposed to TCDD, PCB 126, PCB 153, and the mixture of PCB 126 and PCB 153, which is consistent with most epidemiological studies that found PCB exposures were associated with increased leukocyte RTL. Increased RTL was observed at doses and/or time points where little to no pathology was observed. In addition to serving as a biomarker of exposure to these compounds in rats and humans, increases in RTL may be an early indicator of neoplastic and non-neoplastic responses that occur following chronic exposure to TCDD and PCBs.

Association Between Leukocyte Telomere Length and Serum Concentrations of PCBs and Organochlorine Pesticides

Exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) through food, water, and air occurred during the life, which may change telomere length (TL) in peripheral blood leukocytes. The present study was designed to investigate the association between TL and serum levels of PCBs and OCPs in Tehran male's population. Whole blood samples were randomly taken from 300 adult males, aged between 25 and 40 years. TL was determined by real-time PCR to measure the number of the telomere (T) repeats to the number of a single-copy gene (S). We applied the multivariate linear regression model to compare the effect of each lipid adjusted serum levels of PCBs and OCPs congener on the TL, with adjustment for age, body mass index, education, smoking, and food patterns. Each doubling of the nondioxin-like PCBs, dioxin-like PCBs, and OCPs levels were associated with 1.9% [95% confidence interval (CI) - 0.70 to 5.40%], 2.5% (95% CI 0.30-8.3%), and - 2.4% (95% CI - 0.70 to - 6.2%) variation in the TL, respectively. The percent difference in the TL with exposure to nondioxin-like PCBs, dioxin-like PCBs, and OCPs for participants with older than age 37 years were 6.45% (95% CI  2.81-16.50%), 4.52% (95% CI  1.60-10.54%), and - 7.44% (95% CI - 1.55 to - 15.51%), respectively. Exposures to nondioxin-like PCBs (except for PCB 28 and 52) with high chlorine in structure and dioxin-like PCBs were related to longer TLs. Conversely, serum levels of OCPs can be associated with oxidative stress and systemic inflammation that lead to telomere shortening.