Influence of dioxin exposure upon levels of prostate-specific antigen and steroid hormones in Vietnamese men

Effects of dioxin exposure on reproductive and thyroid hormone levels and male sexual function in airbase military workers in Vietnam

Dioxins are endocrine disruptors that may disturb male sexual and reproductive function. Studies on human populations are limited, and their results are controversial. This study evaluated the impact of dioxin exposure on reproductive and thyroid hormone levels and sexual function in men. A total of 140 men working in four military airbases (three bases were formerly contaminated with dioxin by the herbicide spraying campaign in the Vietnam War) were recruited to measure the serum dioxin levels. Four reproductive hormones (testosterone, follicle-stimulating hormone, luteinizing hormone (LH), and prolactin) and three thyroid hormones (free triiodothyronine (FT3), free thyroxin (FT4), and thyroid stimulating hormone) were measured. Male sexual function endpoints including sexual drive, erection, ejaculation, problems, and overall satisfaction were assessed by the Brief Male Sexual Function Inventory. The percentage of subjects with low testosterone and LH levels was 19.6% and 16.7%, respectively. Dioxins, especially 2,3,7,8-tetrachlorodibenzo-P-dioxin and toxic equivalent concentrations of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans, were inversely associated with testosterone and prolactin levels, but positively associated with FT3 and FT4, and showed adverse relationships with sexual function, such as sexual drive, problems, and overall satisfaction. Our results suggested that exposure to dioxin disrupts the homeostasis of reproductive and thyroid hormones leading to adverse effects on male sexual function.

Ten years after: findings from the medical surveillance program on Health Effects in High-Level Exposure to PCB (HELPcB)

After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in 2010, the multidisciplinary medical surveillance program "HELPcB" (Health Effects in High-Level Exposure to PCB) was established for former PCB-exposed workers of the company, their family members, employees of surrounding companies, and area residents to investigate potential adverse health effects by PCB exposure in a longitudinal study approach with up to seven examination time points between 2010 and 2019. More than 300 individuals were enrolled into the program. Assessments particularly included plasma and urine concentrations of PCB congeners and their metabolites, clinical laboratory parameters, Comet assay, analysis of telomere length, neuropsychological examinations, psychological screening, abdominal and thyroid ultrasound examination. This review summarizes the main results of the studies conducted in the HELPcB program yielding relevant new data on potential adverse effects of PCB exposure in humans and potential mechanisms that underlie these effects. Even larger studies in PCB-exposed individuals are warranted to confirm the results of this program and to further establish causality between PCB exposure and clinical effects in humans.

Meta-Analysis of Body Concentration of Polychlorinated Biphenyls and Prostate Cancer

Prostate Cancer (PCa) is the second most common hormone-sensitive neoplasm among men and the fifth cause of death due to malignancy in developed countries. Moreover, studies have shown the links between polychlorinated biphenyls (PCBs) and hormone-related cancers such as prostate cancer. Hence, we conducted a systematic review and meta-analysis to evaluate the potential relationship between the PCBs and developing PCa. In this meta-analysis study, the relevant databases such as Web of Science, PubMed, and Scopus were studied for English research. The Newcastle-Ottawa Scale was applied to evaluate the quality of the selected publications. The GRADE method was used to assess the risk of bias studies. After reviewing the relevant studies, a cohort and seven case-control studies entered the meta-analysis. These articles were published during 2003-2021 with 2989 participants and 1212 PCa cases. The heterogeneity among the studies was significant (p = 0.001, I² = 70.61). Using a random-effects model, the association between the serum and plasma levels of PCBs and the risk of PCa was not shown to be significant (OR = 1.12; 95% CI: 0.90-1.39). The results of Egger's test showed no trace of publication bias in the studies (P of bias = 0.573). This systematic review and meta-analysis was presented based on relatively strong evidence and has confirmed negatively significant associations between PCa risk and some PCBs congeners (PCB 44, 52, and 101). This study does not provide strong evidence that total PCB exposure is a risk factor for PCa development in humans.

Cross-Sectional and Longitudinal Effects of PCB Exposure on Human Stress Hormones in the German HELPcB Surveillance Program

Multiple pathological associations are attributed to PCBs (polychlorinated biphenyls). Research shows a positive association of PCBs with dehydroepiandrosterone sulfate (DHEAS) concentration but the results on the stress hormone cortisol have been inconsistent so far. This study is the first to examine not only the cross-sectional but also the longitudinal effects of PCB exposure on the stress hormones DHEAS and cortisol. Over a period of three years, 112 former employees occupationally exposed to PCBs were tested for their body burden with different types of PCBs (lower and higher chlorinated, dioxin-like and hydroxylated) and for their stress hormone concentration. Highly exposed employees showed a significantly higher risk for higher DHEAS values. Multiple linear regression analysis revealed a positive relationship between the exposure to lower chlorinated PCBs and DHEAS. Mixed models also revealed a significantly positive correlation between lower chlorinated PCBs with DHEAS when controlled for a cross-section. However, an effect for cortisol was not found. These results suggest a causal pathophysiological relationship between PCB exposure and DHEAS concentration, but not with cortisol. The health consequences of high DHEAS concentrations are discussed.

Serum dioxin and DNA methylation in the sperm of operation ranch hand veterans exposed to Agent Orange

BACKGROUND

Exposure to the herbicide Agent Orange during the Vietnam War was widespread and is associated with numerous adverse health outcomes. A continuing concern of veterans is the possibility that exposure to the dioxin-containing herbicide might induce adverse reproductive outcomes. We sought to assess whether exposure to Agent Orange in Vietnam was associated with changes in DNA methylation in sperm in a subset of Vietnam veterans who participated in the Air Force Health Study (AFHS).

METHODS

We studied 37 members of the AFHS chosen to have no, low, medium or high exposure to Agent Orange, based upon serum dioxin levels obtained during a series of examinations. DNA from stored semen was extracted and DNA methylation assessed on the Illumina 450 K platform.

RESULTS

Initial epigenome-wide analysis returned no loci that survived control for false discovery. However, the TEAD3 gene had four different CpG sites that showed loss of DNA methylation associated with dioxin exposure. Analysis assessing regional DNA methylation changes revealed 36 gene regions, including the region of the imprinted gene H19 to have altered DNA methylation associated with high exposure compared to the low exposure group. Additional comparison of our data with sperm DNA methylation data from Russian boys exposed to dioxin found an additional 5 loci that were altered in both studies and exhibited a consistent direction of association.

CONCLUSIONS

Studying a small number of sperm samples from veterans enrolled in the AFHS, we did not find evidence of significant epigenome-wide alterations associated with exposure to Agent Orange. However, additional analysis showed that the H19 gene region is altered in the sperm of Agent Orange-exposed Ranch Hand veterans. Our study also replicated several findings of a prior study of dioxin-exposed Russian boys. These results provide additional candidate loci for further investigation and may have implications for the reproductive health of dioxin-exposed individuals.

The relationship between dioxins exposure and risk of prostate cancer with steroid hormone and age in Vietnamese men

Although Vietnam's massive herbicide exposure in 1960s and 1970s was clearly injurious to health, not all causal relationships have been clarified. We therefore explored associations among dioxins, steroid hormones, age and prostate cancer risk in men. We compared serum levels of dioxin, steroid hormones and prostate specific antigen (PSA) in men aged 56-81years from herbicide-exposed hotspots (n=50) with those from non-sprayed regions (n=48). Mean serum levels of dioxin congeners in the hotspot group were 1.5-11.3 times higher than the non-sprayed group depending on specific compound. Levels of testosterone, estradiol and 3β-hydroxysteroid dehydrogenase (3β-HSD) activity in the hotspot group were also significantly higher than in non-sprayed group. Estradiol levels were significantly related to levels of several specific dioxin derivatives in both group. Significant positive correlations were also found between DHT and 1234678-HpCDD or 1234678-HpCDF; and between 3β-HSD activity and 123678-HxCDD, 123478-HxCDF, 123678-HxCDF, or HxCB#169. After adjusting for age, body mass index, and tobacco use, multiple linear regressions showed levels of dihydrotestosterone (DHT), estradiol, testosterone and 3β-HSD activity were not associated with dioxins in the two groups; however, levels of DHT, testosterone and 3β-HSD activity increased significantly with age in the hotspot group. The hotspot and non-sprayed groups did not significantly differ in PSA levels. But six of the hotspot subjects had PSA levels >3ng/mL, 3 of whom were suspected to have prostate cancer (PC) after digital rectal examination. Our findings suggest that dioxin exposure can lead to increased levels of several sex steroid hormones with age. The correlation of dioxin with steroid hormone levels and prostate cancer risk should be studied further.

The use of ultrasound-assisted anaerobic compost tea washing to remove poly-chlorinated dibenzo-p-dioxins (PCDDs), dibenzo-furans (PCDFs) from highly contaminated field soils

The remediation of dioxin-contaminated soil of a specific coastal area previously employed for the manufacture of pentachlorophenol (PCP) in southern Taiwan's Tainan City has attracted much attention of researchers there. This work addresses the possibility of providing an effective and environmentally friendly option for removing PCDD/Fs from soil in that field. Soil screening/sieving was first conducted to assess particle distribution. Fine sand was observed to be the major component of the soil, accounting for more than 60% of the total mass. A combination of ultrasonification and mechanical double-blade agitation was used to facilitate the washing of the soil using the biosurfactant anaerobic compost tea. More than 85 and 95% of total removal efficiencies were achieved for moderately and highly contaminated soils after 6 and 10 washing cycles, respectively, under ambient temperature, a soil/liquid ratio 1:2.5, 700 rpm, and over a relatively short duration. These results were achieved through the collision and penetration effects of this combined treatment as well as PCDD/F partitioning between the particles and anaerobic compost tea. This study represents the first to report the use of anaerobic compost tea solvent to wash soil highly contaminated by dioxin. It was concluded that anaerobic compost tea, rich in non-toxic bio-surfactants (e.g., alcohols, humic acids), can be used to improve bioavailability and bioactivity of the soil making bio-attenuation and full remediation more efficient.