Different associations of albuminuria with total and cardiovascular mortality by concentrations of persistent organic pollutants in the elderly

Background exposure to polychlorinated biphenyls and all-cause, cancer-specific, and cardiovascular-specific mortality: A systematic review and meta-analysis

BACKGROUND

Polychlorinated biphenyls (PCBs) are a large family of man-made organic, ubiquitous, and persistent contaminants with endocrine-disrupting properties. PCBs have been associated with numerous adverse health effects and were classified as carcinogenic to humans, but their long-term impact on mortality risk in the general population is unknown.

OBJECTIVE

To conduct a systematic review and meta-analysis in order to assess whether background exposure levels of PCBs increase all-cause and cancer- and cardiovascular-specific mortality risk in the general population.

METHODS

We searched the Pubmed, Web of Science, Cochrane Library, and Embase databases for eligible studies up to 1st of January, 2021. We included cohort and nested-case control studies comparing the lowest vs. the highest background exposure level of PCBs in the general population and reporting data for all-cause mortality and/or cancer-/cardiovascular-specific mortality. Studies reporting occupational and accidental exposures were excluded. Random-effects meta-analysis was used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs). Heterogeneity across studies was assessed by I2 statistics, and publication bias both graphically and using Egger's and Begg's tests. Quality of included studies was assessed using the National Toxicology Program/Office of Health Assessment and Translation (NTP/OHAT). Confidence in the body of evidence and related level of evidence were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) based on the NTP/OHAT framework. The protocol was registered in PROSPERO (CRD42020178079).

RESULTS

The initial search led to 2,132 articles. Eight prospective cohort studies met our inclusion criteria, leading to 72,852 participants including 17,805 deaths. Overall exposure to PCBs was not statistically significantly associated with all-cause mortality (SRR = 1.13, 95% CI = 0.90-1.41, n = 7 studies, low certainty); however, dietary exposure to PCBs was associated with an increased risk of cardiovascular-specific mortality (SRR = 1.38, 95% CI = 1.14-1.66, n = 3 studies, moderate certainty), while no association was found with cancer-specific mortality (SRR = 1.07, 95% CI = 0.72-1.59, n = 5 studies, low certainty).

CONCLUSION

Our meta-analysis suggests that background exposure to PCBs is associated with an increased risk of cardiovascular-specific mortality in the general population with a "moderate" level of evidence. These findings should be interpreted with caution given the small number of studies on mortality in the general population.

Can Habitual Exercise Help Reduce Serum Concentrations of Lipophilic Chemical Mixtures? Association between Physical Activity and Persistent Organic Pollutants

BACKGROUND

Low-dose persistent organic pollutants (POPs), especially organochlorine pesticides (OCPs), have emerged as a new risk factor of many chronic diseases. As serum concentrations of POPs in humans are mainly determined by both their release from adipose tissue to circulation and their elimination from circulation, management of these internal pathways may be important in controlling the serum concentrations of POPs. As habitual physical activity can increase the elimination of POPs from circulation, we evaluated whether chronic physical activity is related to low serum POP concentrations.

METHODS

A cross-sectional study of 1,850 healthy adults (age ≥20 years) without cardio-metabolic diseases who participated in the U.S. National Health and Nutrition Examination Survey 1999 to 2004 was conducted. Information on moderate or vigorous leisure-time physical activity was obtained based on questionnaires. Serum concentrations of OCPs and polychlorinated biphenyls were investigated as typical POPs.

RESULTS

Serum concentrations of OCPs among physically active subjects were significantly lower than those among physically inactive subjects (312.8 ng/g lipid vs. 538.0 ng/g lipid, P<0.001). This difference was maintained after adjustment for potential confounders. When analyses were restricted to physically active subjects, there were small decreases in the serum concentrations of OCPs with increasing duration of physical activity, showing a curvilinear relationship over the whole range of physical activity (Pquadratic <0.001). In analyses stratified by age, sex, body mass index, and smoking status, a strong inverse association was similarly observed among all subgroups.

CONCLUSION

Physical activity may assist in decreasing serum concentrations of lipophilic chemical mixtures such as OCPs.

Endosulfan induces cardiotoxicity through apoptosis via unbalance of pro-survival and mitochondrial-mediated apoptotic pathways

Although the associations between endosulfan and adverse cardiovascular health have been reported, the toxic effects and underlying mechanism of endosulfan on the heart are not well understood. In this study, we examined the cardiotoxicity induced by endosulfan using Wistar rats and human cardiomyocytes (AC16) cells. Wistar rats were divided into control group (received corn oil alone) and three concentrations of endosulfan groups (1, 5 and 10 mg/kg·bw) by gavage. The AC16 cells were treated with three various concentrations (0, 1.25, 5, and 20 μg/mL) of endosulfan. The results showed that endosulfan induced cytotoxicity through damaging myocardial structure, decreasing the viability of cardiomyocytes, and elevating the serum levels of cardiac troponin I, heart fatty acid binding protein, aspartate aminotransferase, and reactive oxygen species (p < 0.05). Moreover, measurement of mitochondrial function showed that endosulfan could significantly decrease adenosine triphosphate levels and cytochrome c oxidase IV expression in AC16 cells (p < 0.05). In addition, endosulfan obviously inhibited Bcl-2 expression, activated the expressions of cytochrome c/Caspase-9/Caspase-3 signaling pathway, and induced the apoptosis of AC16 cells (p < 0.05). Furthermore, endosulfan significantly increased the expression of Bim, and inhibited the expressions of PI3K/Akt/FoxO3a signaling pathways in cardiomyocytes (p < 0.05). These results suggest that endosulfan may induce cardiotoxicity by inducing myocardial apoptosis resulting from activation of mitochondria-mediated apoptosis pathway and inhibition of pro-survival signaling pathways, which might be helpful in elucidating the mechanism of cardiac dysfunction induced by endosulfan.

Persistent organic pollutants and mortality in the United States, NHANES 1999-2011

BACKGROUND

Persistent organic pollutants (POPs) are environmentally and biologically persistent chemicals that include polybrominated diphenyl ethers (PBDEs), per- and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and organochlorine (OC) pesticides. Currently, data on the associations between exposure to POPs and the risk of mortality in the U.S. population is limited. Our objective was to determine if higher exposure to POPs is associated with greater risk of all-cause, cancer, heart/cerebrovascular disease, or other-cause mortality.

METHODS

Analyses included participants aged 60 years and older from the 1999-2006 National Health and Nutrition Examination Surveys (NHANES). We included 483 participants for analyses of PBDEs, 1043 for PFASs, and 461 for PCBs, and 1428 for OC pesticides. Exposures to POPs were estimated using biomarkers measured in serum. Mortality status through December 31, 2011 was obtained from public-use, linked mortality files. We used Cox proportional hazard models to quantify the associations of interest. Where we observed an association, we explored effect modification by sex, body mass index, smoking status, and albuminuria. We also explored the combined effect of PBDEs and OC pesticides in the subsample of participants with measures of both analytes.

RESULTS

Serum measurements of PBDEs, PFASs, and PCBs were not clearly associated with increased all-cause or cause-specific mortality in older Americans. Beta-hexachlorocyclohexane was associated with an increased risk of all-cause mortality [HR per 1 SD increase =1.18, 95% CI = 1.01, 1.38]. Oxychlordane [HR = 1.15 95% CI 1.06, 1.25], p,p'-DDE [HR = 1.12, 95% CI = 1.02, 1.23], trans-nonachlor [HR = 1.11, 95% CI = 1.04, 1.18], and beta-hexachlorocyclohexane [HR = 1.25, 95% CI = 1.03, 1.52] were associated with increased risk of other-cause mortality. Exploratory analyses suggested associations between OC pesticides and other-cause mortality were modified by sex. Exploratory analyses also suggested that the combination of high PBDE and high OC pesticide exposure had a stronger than expected adverse effect on all-cause mortality.

CONCLUSION

Higher exposure to beta-hexachlorocyclohexane, an OC pesticide, is associated with increased all-cause mortality and higher exposure to four OC pesticides is associated with increased non-cancer, non-heart/cerebrovascular disease mortality in U.S. adults 60 years or older. These associations may be modified by sex or exposure to other POPs.