The relationship between dioxin-like polychlorobiphenyls and IGF-I serum levels in healthy adults: evidence from a cross-sectional study

The Effect of Environmental Disasters on Endocrine Status, Hematology Parameters, Body Composition, and Physical Performance in Young Soccer Players: A Case Study of the Aral Sea Region

The Aral Sea region (Uzbekistan) is infamous because of the ecological disaster characterized by the disappearance of the Aral Sea due to excessive uncontrolled water intake for agriculture needs. A new desert occurrence, soil and climate aridization led to pesticide and toxic metals environment pollution. The impact of environmental conditions in some areas of Uzbekistan on the health of soccer players is not as noticeable as, for example, the effectiveness of training, so it is not widely discussed in scientific papers. The aim of the present study was to study the features of endocrine status, hematology parameters (e.g., red blood cells (RBC) and hemoglobin (Hb)), and their influence on body composition and physical fitness performance in local young soccer players of the Aral Sea region as the territory of ecological disaster. The study involved 60 male soccer players aged from 18 to 22 years. Participants were divided into two groups: the experimental group (EG), which consisted of 30 soccer players living on the territory of the Aral ecological disaster region, and the control group (CG), which included 30 soccer players, natives of the ecologically favorable region of Uzbekistan. All volunteers had anthropometric measurements, concentrations of insulin-like growth factor-1 (IGF-1), total testosterone (TT), estradiol (E2), cortisol (C), RBC, and Hb count. Moreover, Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1) and professional skills tests such as dribbling shuttle test (DSt) and goal accuracy test (GAt) were assessed. When comparing the CG group to the EG group, it was observed that the EG group exhibited statistically significantly reduced levels of TT and E2 (p < 0.05). No significant statistical difference was observed between the two groups in terms of IGF-1 and C (p > 0.05). Regarding hematological parameters, Hb, Ht, and mean corpuscular volume (MCV) were found to be significantly lower in the EG compared with the CG (p < 0.05). Moreover, the distance covered in the YYIR1 test was found to be significantly lower in soccer players within the EG compared with the CG (p < 0.05). Additionally, it was determined that there was no significant difference between the groups in terms of DSt and GAt values (p > 0.05). Lastly, significant differences were observed between the EG and CG in terms of anthropometric characteristics (diameters, skinfold, and somatotype profile) (p < 0.05). The present study showed that the changes in evaluated characteristics might result from the complex influence of endocrine-disrupting chemicals, the content of which is high in the environment of the Aral Sea region. The results obtained may help monitor the health of athletes living in an environmentally unfriendly environment.

The insulin-like growth factor system: A target for endocrine disruptors?

The insulin-like growth factor (IGF) system is a critical regulator of growth, especially during fetal development, while also playing a central role in metabolic homeostasis. Endocrine disruptors (EDs) are ubiquitous compounds able to interfere with hormone action and impact human health. For example, exposure to EDs is associated with decreased birthweight and increased incidence of metabolic disorders. Therefore, the IGF system is a potential target for endocrine disruption. This review summarises the state of the science regarding effects of exposure to major classes of endocrine disruptors (dioxins and dioxin-like compounds, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, phthalates, perfluoroalkyl substances and bisphenol A) on the IGF system. Evidence from both experimental models (in vitro and in vivo) and epidemiological studies is presented. In addition, possible molecular mechanisms of action and effects on methylation are discussed. There is a large body of evidence supporting the link between dioxins and dioxin-like compounds and IGF disruption, but mixed findings have been reported in human studies. On the other hand, although only a few animal studies have investigated the effects of phthalates on the IGF system, their negative association with IGF levels and methylation status has been more consistently reported in humans. For polybrominated diphenyl ethers, perfluoroalkyl substances and bisphenol A the evidence is still limited. Despite a lack of studies for some ED classes linking ED exposure to changes in IGF levels, and the need for further research to improve reproducibility and determine the degree of risk posed by EDs to the IGF system, this is clearly an area of concern.

Persistent organic pollutants and risk of diabetes and obesity on healthy adults: Results from a cross-sectional study in Spain

Environmental exposure to persistent organic pollutants (POPs) has been reported to be relevant in the population of the Canary Islands (Spain), especially that of organochlorine pesticides. On the other hand, the population of this archipelago presents a high prevalence of type 2 diabetes (T2D), and it has been recently reported that environmental chemical contamination could play a role in the development of this disease. We performed a cross-sectional study in a representative sample from this archipelago to evaluate whether serum levels of selected POPs could be considered as risk factors for diabetes in this population. Serum levels of 30 POPs were determined in 429 adults (9.3% with T2D). We found that serum levels of p,p'-DDE (DDE), PCB-153 and PCB-118 were significantly higher among subjects having diabetes than in non-diabetic subjects (p=0.001, p=0.046, and p<0.0001, respectively). We observed a positive correlation between serum p,p'-DDE and glucose levels. Serum p,p'-DDE was identified as a risk factor for diabetes in univariate analysis in the whole series, and it remained as an independent risk factor for diabetes in subjects with serum glucose <126mg/dL (multivariate analysis, Exp(B)=1.283, CI 95% (1.023-1.611), p=0.031). Those normoglycemic subjects that are most exposed to p,p'-DDE (95th percentile: serum p,p'-DDE>5μg/L) seem to be those people at higher risk. Our results showed that p,p'-DDE levels were significantly higher among subjects having diabetes. These findings should be considered by public health Authorities to implement measures devoted to minimize human exposure to pollutants that could be harmful to the population.

Relationship of polychlorinated biphenyls (PCBs) with parasitism, iron homeostasis, and other health outcomes: Results from a cross-sectional study on recently arrived African immigrants

Polychlorinated biphenyls (PCBs) are toxic and persistent chemicals produced between 1930s and 1980s, which accumulate in humans and wildlife. Although a decreasing trend of PCB levels in humans has been described in developed countries, mainly as a consequence of strict regulations and remediation plans, an inverse trend has been recently reported in people from developing countries. We had the opportunity of sampling a series of African immigrants recently arrived to the Spanish archipelago of the Canary Islands, in which high levels of PCBs have been described, and we studied the relationships between their level of contamination and health status. A total of 570 subjects who underwent a complete medical examination and a face-to-face interview were recruited for this study. Hematological and biochemical parameters (blood and urine) were determined in all participants. Serology for the diagnostic of infectious diseases was also performed, and direct identification of parasites was performed in feces, urine or blood samples when appropriate. It is remarkable that up to 26.0% of the population had intestinal parasites, and we found an inverse relationship between PCB levels and parasitism and parasitic diseases: median values of PCBs were lower in parasitized subjects than in subjects without parasites in stool (237.6ng/g fat vs. 154.4ng/g fat for marker PCBs, p=0.015) and median values of dioxin-like PCBs were lower in subjects carrying pathogen parasites than among subjects showing non-pathogen parasites in stool (0.0 ng/g fat vs. 13.1ng/g fat, respectively; p=0.001). Although this inverse association had been described in some vertebrates this is the first study reporting such an association in humans. Furthermore, it has been also recently described that PCBs may disrupt iron metabolism, and we found a direct relationship between serum iron and total PCBs burden (r=0.231, p=0.025), suggesting that PCBs, although at subclinical level, could play a role on iron homeostasis. Although the role of PCBs in parasitism and in the iron metabolism needs future research, our findings may help to understand the adverse health outcomes associated to environmental exposure to PCBs and they might be used in exposed populations as indicators of subtle effects due to environmental insult.

Mercury and selenium status of bottlenose dolphins (Tursiops truncatus): A study in stranded animals on the Canary Islands

The mercury (Hg) level in the marine environment has tripled in recent decades, becoming a great concern because of its high toxic potential. This study reports Hg and selenium (Se) status, and the first Se/Hg molar ratio assessment in bottlenose dolphins (Tursiops truncatus) inhabiting the waters of the Canary Islands. Total Hg and Se concentrations were determined in the blubber and liver collected from 30 specimens stranded along the coasts of the archipelago from 1997 to 2013. The median values for total Hg in the blubber and liver were 80.83 and 223.77 μg g(-1) dry weight (dw), and the median levels for Se in both tissues were 7.29 and 68.63 μg g(-1) dw, respectively. Hg concentrations in the liver were lower than 100 μg g(-1) wet weight (ww), comparable to those obtained in bottlenose dolphins from the North Sea, the Western Atlantic Ocean and several locations in the Pacific Ocean. The Mediterranean Sea and South of Australia are the most contaminated areas for both elements in this cetacean species. In addition, it must be stressed that the levels of Hg and Se in the liver showed an increasing trend with the age of the animals. As expected, a strong positive correlation between Hg and Se was observed (rs=0.960). Surprisingly, both younger and older specimens had a Se/Hg molar ratio different from 1, suggesting that these individuals may be at greater toxicological risk for high concentrations of both elements or a deficiency of Se without a protective action against Hg toxicity.

PCB related effects thresholds as derived through gene transcript profiles in locally contaminated ringed seals (Pusa hispida)

Causal evidence linking toxic injury to polychlorinated biphenyl (PCB) exposure is typically confounded by the complexity of real-world contaminant mixtures to which aquatic wildlife are exposed. A local PCB "hotspot" on the Labrador coast provided a rare opportunity to evaluate the effects of PCBs on the health of a marine mammal as this chemical dominated their persistent organic pollutant (POP) burdens. The release of approximately 260 kg of PCBs by a military radar facility over a 30 year period (1970-2000) contaminated some local marine biota, including the ringed seal (Pusa hispida). The abundance profiles of eight health-related gene transcripts were evaluated in liver samples collected from 43 ringed seals in the affected area. The mRNA transcript levels of five gene targets, including aryl hydrocarbon receptor (Ahr), interleukin-1 β (Il1b), estrogen receptor α (Esr1), insulin like growth factor receptor 1 (Igf1), and glucocorticoid receptor α (Nr3c1) correlated with increasing levels of blubber PCBs. PCB threshold values calculated using best-fit hockey-stick regression models for these five genes averaged 1,680±206 ng/g lw, with the lowest, most conservative, being 1,370 ng/g lw for Il1b. Approximately 14% of the seals in the region exceeded this threshold. The dominance of PCBs in the seals studied enabled an assessment of the effects of this chemical on gene transcripts involved in regulating the health of a highly mobile predator, something that is rarely possible in the world of complex mixtures.

Blood pressure in relation to contamination by polychlorobiphenyls and organochlorine pesticides: Results from a population-based study in the Canary Islands (Spain)

BACKGROUND

Epidemiological studies have reported significant associations between exposure to persistent organic pollutants (POPs) and increased blood pressure (BP). Environmental exposure to POPs, mainly organochlorine pesticides, is of concern to the population of the Canary Islands, who display a high prevalence of diseases associated with hypertension such as metabolic syndrome, obesity and cardiovascular disease.

OBJECTIVE

We performed this population-based study in a representative population sample from this archipelago to evaluate whether serum levels of selected POPs could be considered as hypertension risk factors.

METHODS

BP and several other well-known factors related to hypertension (gender, age, smoking, BMI, and total lipids) were recorded in 428 adult participants from the Canary Islands Nutritional Survey. In total, 28 POPs (including 18 polychlorinated biphenyl (PCB) congeners and 10 organochlorine pesticides and metabolites) were measured in the serum of the population enrolled in this survey.

RESULTS

In total, 167 subjects (39%) demonstrated hypertension or used antihypertensive medication. We observed a positive association between systolic and diastolic BP and p,p'-DDE (r=0.222; p<0.001, and r=0.123; p=0.015, respectively). Conversely, an inverse association between systolic BP and aldrin was observed (r=-0.120; p=0.017). After adjusting for known confounders, only aldrin was inversely related to hypertension risk [OR: 0.28 (95% CI: 0.09-0.92); p=0.037]. After excluding subjects undergoing anti-hypertensive treatment, we also observed that aldrin was inversely associated with systolic BP in multivariate analyses, especially in men [OR: 0.126 (95% CI: 0.021-0.763); p=0.024].

CONCLUSION

Although it has been postulated that background POPs exposure may play a relevant role on elevated BP, we did not observed increased hypertension risk in relation to serum POPs in this cross-sectional study. Conversely, the cyclodiene pesticide aldrin was negatively associated with hypertension, suggesting that cyclodienes could exert an effect opposite of the DDT metabolites. These findings agree with other previous works indicating that POPs may induce divergent actions on BP and suggest that the direction of the association between BP and POPs could be dependent on the chemical structure as well as concentration of the evaluated POP. Prospective studies are needed to clarify the effect exerted by POPs on BP.