Pesticides and polychlorinated biphenyl residues in human adipose tissue

Exposure to pesticides in Chile and its relationship with carcinogenic potential: a review

Background

The widespread application of pesticides in agriculture and the consequent heightened human exposure to these potentially harmful substances present considerable environmental and health risks. The potential link to cancer is particularly concerning, underscoring the urgent need for more sustainable and health-conscious agricultural practices. Pesticides are pervasive global contaminants, with exposure occurring through various routes. Improper use is associated with genotoxicity, neurobehavioral problems, thyroid dysfunction, reproductive issues, and cancer, among other deleterious damages. While pesticide exposure is evident in Chile, a direct link to cancer remains uncertain.

Objective

To examine the scientific evidence on pesticides exposure in the environment and human populations, and its relationship with cancer in Chilean territory.

Methods

The search for original articles was performed in international peer-reviewed scientific databases, including Scopus, Web of Science (WoS), and PubMed Advanced Search Builder. Following the PRISMA extension for review guidelines, the search included studies on environmental pesticide exposure, human biomarker assessments, experimental investigations, and the potential pesticide-cancer associations in Chile. Foreign studies, systematic reviews, and meta-analyses were excluded.

Results

Among the 83 qualifying studies conducted between 1996 and 2024, elevated pesticide exposure risks were documented, with 71% indicating high concentrations that may pose health risk. Additionally, 20% of studies reported significant chlorinated compounds, including organochlorines (OCs) and polychlorinated biphenyls (PCBs), while 79.5% identified carcinogenic to humans classified by the International Agency for Research on Cancer. The review emphasizes the urgent need to update pesticide-related regulations in Chile, including implementing bans or restrictions on carcinogenic pesticides and establishing stricter standards for allowable pesticide residue levels in food.

Conclusion

Long-term epidemiological studies are essential to establishing concrete links between pesticide exposure and specific types of cancer. Additionally, investigating epigenetic markers associated with pesticide exposure, especially in occupational settings, is critical. Furthermore, allocating resources and prioritizing further research is fundamental, particularly in regions with substantial agricultural exposure.

Theoretical Study on the Metabolic Mechanism of Heptachlor in Human Cytochrome P450 Enzymes

Heptachlor (HEP) is an insecticide metabolized by cytochrome P450 (CYP) enzymes in the human liver, resulting in the formation of heptachlor epoxide (HEPX). HEPX can persist in the human body for a long duration. Therefore, it can be extremely harmful. A comprehensive understanding of HEP's metabolic fate may provide a theoretical basis for mitigating associated hazards. However, the specific human CYP isoforms that metabolize HEP, and their metabolic mechanisms, remain unclear. In this study, eight human CYP isoforms were used as catalytic enzymes to investigate the metabolic mechanism of HEP using molecular docking, molecular dynamics simulations, and quantum mechanical calculations. These results indicate that HEP primarily binds to CYP enzymes through hydrophobic interactions, and that the binding positions of HEP are determined by the composition and shape of the hydrophobic pockets near the active site. Based on the reaction distance, CYP2A6, CYP3A4, and CYP3A5 were the only three enzymes that could metabolize HEP. The epoxidation of HEP catalyzed by the doublet state of compound I was effectively concerted, and the rate-determining step was the electrophilic attack of the oxygen atom on HEP. The energy barriers of the rate-determining step vary significantly among different enzymes. A comparison of these energy barriers suggested that CYP3A5 is the most likely enzyme for HEP catalysis in humans.

Protective effects of selenized yeast on the combination of cadmium-, lead-, mercury-, and chromium-induced toxicity in laying hens

The objective of this study was to investigate the toxic effects of a combination of cadmium (Cd), lead (Pb), mercury (Hg), and chromium (Cr) on laying performance, egg quality, serum biochemical parameters, and oxidative stress of laying hens, as well as the alleviating action of dietary supplementation of selenized yeast. A total of 160 Lohmann pink-shell laying hens (63-week-old) were randomly divided into four treatments with 10 replicates of four hens each. The treatments were the corn–soybean meal basal diet (control; CON), the CON diet supplemented with 0.4 mg selenium (Se)/kg from selenized yeast (Se); combined heavy metals group: the basal diet supplemented with 5 mg Cd/kg, 50 mg Pb/kg, 3 mg Hg/kg, and 5 mg Cr/kg (HEM), and the HEM diet supplemented with 0.4 mg Se/kg from selenized yeast (HEM+Se). The experimental period lasted for 12 weeks. The HEM diet decreased hen-day egg production, feed conversion ratio (FCR), and egg white quality (P < 0.05), but increased (P < 0.05) glutamic oxalacetic transaminase (AST) activity in the serum. HEM induced higher malondialdehyde (MDA) and reactive oxygen species (ROS) in the serum, liver, and ovary and significantly decreased (P < 0.05) the activity of total superoxide dismutase (SOD) and tended to decrease glutathione S-transferase (GST) (P = 0.09) in the serum. Meanwhile, HEM significantly decreased (P < 0.05) activity of SOD, GST, glutathione peroxidase (GPX), and glutathione (GSH) in the liver, and the activity of GPX and GSH in the ovary. Se addition of 0.4 mg/kg significantly (P < 0.05) improved hen-day egg production and FCR and decreased AST concentration and increased some enzyme activity in the serum, liver, and ovary. In conclusion, dietary HEM exposure depressed laying performance, and egg white quality was likely due to an impaired antioxidant capacity, disrupted hepatic function, and elevated HEM accumulation in the egg yolk and egg white of laying hens. Se addition of 0.4 mg/kg ameliorated toxic effects of HEM on laying performance, oxidative stress, and hepatic function.

The role of adipose tissue analysis on Environmental Pollutants Biomonitoring in women: The European scenario

Humans are exposed every day to assorted environmental pollutants namely, polychlorinated biphenyls (PCB), organochlorine pesticides (OCP), brominated flame-retardants (BFR), polycyclic aromatic hydrocarbons (PAH), synthetic musks, heavy metals (e.g. cadmium) and plastic additives (e.g. bisphenol A, BPA). Besides environmental persistence, biomagnification and bioaccumulative properties, these pollutants are classified as endocrine disruptors (EDs), metabolic disruptors, neurologic disruptors. These compounds affect the normal function of several mechanisms in the human body being linked to human health issues as cancer development (e.g. breast, uterine and endometrial), miscarriage, birth defects, premature delivery and infertility. In order to prevent future health issue of women and possible progeny, the assessment of EDs accumulated is essential, particularly in adipose tissue. These samples have been referred as the ideal matrix to establish over time accumulation and long-term exposure of persistent and non-persistent lipophilic EDs. However, the invasive sample collection procedure and methodology processing discourages the usage of this matrix for biomonitoring studies. In this review, a Web of Science search without any publishing year restriction on the analysis in adipose tissue of PCB, OCP, BPA, cadmium, BFR and synthetic musks was performed. A total of 313 studies were found, 158 were European studies from which the studies with data on women EDs accumulation were selected for detailed analysis (n = 90). The results were structured and presented in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The present paper is an overview on the existent EDs analytical methods and levels accumulated in women adipose tissue, with the correspondent health implications across Europe. The limits of detection and quantification were compared and a discussion with results obtained about the presence of ED was performed.

Organochlorine pesticides and polychlorinated biphenyls in human adipose tissue from northern Tunisia: Current extent of contamination and contributions of socio-demographic characteristics and dietary habits

The aims of the present study were to investigate the current exposure levels of persistent organochlorine compounds (OCs) in adipose tissues intraoperatively collected from 40 patients over 20 years undergoing non-cancer-related surgery residing in Northern region of Tunisia (Bizerte), which constitutes an exemplary case, and examined association between levels of contamination and both socio-demographic characteristics and dietary habits. Concentration of hexachlorobenzene (HCB), hexachlorocyclohexane isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), dichlorodiphenyltrichloroethane isomers (p,p'-DDT and o,p'-DDT) and metabolites (p,p'-DDE, o,p'-DDE, p,p'-DDD and o,p'-DDD) and 12 polychlorinated biphenyls (PCBs) congeners were measured using capillary gas chromatography with electron capture detector. Overall, residue levels of OCs followed the decreasing order of DDTs > PCBs > HCB > HCHs. DDTs levels ranged from 74.49 to 1834.76ngg^-1 lipid and contributing to more than 90% to the sum of organochlorine pesticides (OCPs). p,p'-DDE was the most abundant in all samples and the p,p'-DDT/p,p'-DDE ratio (range between 1.85% and 58.45%) suggesting recent and ongoing exposure to banned commercial DDT products. PCB concentrations varied from 29.27 to 322.58ngg^-1 lipid and PCB-180, PCB-153 and PCB-138 were the dominant congeners accounting for 70% of total PCBs. We did not find significant correlations between OC exposure levels and sex, parity, habitat areas and smoking habits. In females, the adipose tissue concentrations of DDTs, HCB and PCB-118 were positively correlated with age. There was statistically significant relationship between body mass index (BMI) changes and the adipose tissue levels of HCB and HCHs. No association was found between OCPs levels and dietary factors. However, our study suggests that fish consumption may be an important contributor of PCBs adipose tissue content of PCBs in Tunisian people. The presented work is highly significant, being the first study pointing out the chronic exposure to OCs in Bizerte.

Exposure to priority organochlorine contaminants in the Italian general population. Part 1. Eight priority organochlorinated pesticides in blood serum

Despite extensive use of organochlorinated pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT) in Italy in the 1940s to 1970s, especially for public health control of malaria mosquitoes, information on their exposure levels among the general population is limited. These OCPs can be a source of health risk to human. A total of 137 blood samples were collected from residents of the general population of three Italian towns, Novafeltria, Pavia and Milan, to determine the levels of eight OCPs in blood serum. The concentrations of beta-hexachlorocyclohexane, hexachlorobenzene (HCB), 1,1-dichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)ethylene, 1,1-dichloro-2,2-bis( p-chlorophenyl)-ethylene ( p, p' -DDE), 1,1-dichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)ethane, 1,1-dichloro-2,2-bis (4-chlorophenyl)ethane, 1,1,1-trichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)-ethane and 1,1,1-trichloro-2,2-bis( p-chlorophenyl) ethane were measured by gas chromatography–mass spectrometry. Variations in serum concentrations of OCPs with respect to place of residence, gender, age and body mass index (BMI) were evaluated by non-parametric tests. p, p' -DDE and HCB were the most abundant and major contributors of total OCP concentration. Their levels differed significantly between the three towns with a trend Milan > Novafeltria > Pavia (  p < 0.0001). Females had significantly higher concentrations of HCB and p, p'-DDE than males in the overall population sample. HCB concentrations were significantly higher in females than in males of Milan ( p = 0.029). We observed positive correlations of p, p'-DDE and HCB with age in Novafeltria subjects ( r = 0.468, p = 0.004). Total OCP concentrations differed significantly across BMI categories ( p = 0.018) in overall population. We have demonstrated a clear pattern of the main OCPs in a fairly large population. Generally, our study provides information on OCPs exposure among the Italian general population and provides indications for further investigations.

Persistent organic pollutants in human milk from central Italy: levels and time trends

Persistent organic pollutants (POPs) such as HCB, p,p'-DDE, and PCBs were measured in Italian breast milk. This work is part of a study on human milk, adipose tissues, and food carried out in the same area over the last 20 years. The results showed the prevalence of p,p'-DDE and PCBs over HCB. Comparison of our results with those of previous studies carried out in the same area showed that concentrations are decreasing. No statistically significant differences in organochlorine levels were found when the samples were divided into maternal age classes and into the categories "primiparae" and "multiparae". In order to quantify the amount of the molecules of interest transmitted by mother to child during breast feeding, we estimated the daily intake of each class of compounds: our results indicated that HCB and p,p'-DDE were several times lower than the safety thresholds.

Polychlorinated biphenyls and organochlorine pesticides in human adipose tissue and breast milk collected in Hong Kong

Contamination from persistent organic pollutants is a pervasive global problem that urgently demands global concern and action. In the present study, concentrations of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) were determined in 37 samples of female adipose tissue collected in Hong Kong hospitals. Among the pollutants analyzed, DDTs (2.79 ng/g fat), HCHs (0.72 ng/g fat), and PCBs (0.19 ng/g fat) were prominent compounds in most of the adipose tissue. p,p'-DDE and hexachlorinated biphenyls were found in all samples, whereas heptachlor epoxide and dieldrin were found only in some samples. An estimation of toxic equivalency concentration (TEQ) due to dioxin-like coplanar PCBs was also performed. The estimated TEQ(PCBs) was 2.01 pg/g fat. This study also compared our previous results obtained from the milk samples of the same donors. Significant correlations are obtained for DDTs and HCHs between milk and adipose tissue. Detailed review of available information concerning OC pesticides and PCBs in different ecological compartments indicated that bioconcentration and biomagnification of these contaminants are common phenomena of the Pearl River Delta region, which has undergone rapid socioeconomic change in the past 20 years. It is suggested to establish a regional organization in order to coordinate the monitoring of persistent organic pollutants in the region.