An Adverse Outcome Pathway Network for Chemically Induced Oxidative Stress Leading to (Non)genotoxic Carcinogenesis

Nongenotoxic (NGTX) carcinogens induce cancer via other mechanisms than direct DNA damage. A recognized mode of action for NGTX carcinogens is induction of oxidative stress, a state in which the amount of oxidants in a cell exceeds its antioxidant capacity, leading to regenerative proliferation. Currently, carcinogenicity assessment of environmental chemicals primarily relies on genetic toxicity end points. Since NGTX carcinogens lack genotoxic potential, these chemicals may remain undetected in such evaluations. To enhance the predictivity of test strategies for carcinogenicity assessment, a shift toward mechanism-based approaches is required. Here, we present an adverse outcome pathway (AOP) network for chemically induced oxidative stress leading to (NGTX) carcinogenesis. To develop this AOP network, we first investigated the role of oxidative stress in the various cancer hallmarks. Next, possible mechanisms for chemical induction of oxidative stress and the biological effects of oxidative damage to macromolecules were considered. This resulted in an AOP network, of which associated uncertainties were explored. Ultimately, development of AOP networks relevant for carcinogenesis in humans will aid the transition to a mechanism-based, human relevant carcinogenicity assessment that involves a substantially lower number of laboratory animals.

Electrochemical and Optical Sensors for the Detection of Chemical Carcinogens Causing Leukemia

The incidence and mortality due to neoplastic diseases have shown an increasing tendency over the years. Based on GLOBOCAN 2020 published by the International Agency for Research on Cancer (IARC), leukemias are the thirteenth most commonly diagnosed cancer in the world, with 78.6% of leukemia cases diagnosed in countries with a very high or high Human Development Index (HDI). Carcinogenesis is a complex process initiated by a mutation in DNA that may be caused by chemical carcinogens present in polluted environments and human diet. The IARC has identified 122 human carcinogens, e.g., benzene, formaldehyde, pentachlorophenol, and 93 probable human carcinogens, e.g., styrene, diazinone. The aim of the following review is to present the chemical carcinogens involved or likely to be involved in the pathogenesis of leukemia and to summarize the latest reports on the possibility of detecting these compounds in the environment or food with the use of electrochemical sensors.

Assessment of the inhibition risk of chlorophenol substances on cytochrome P450 via cocktail inhibition assays

Chlorophenols (CPs) are widespread pollutants in nature. CPs have raised significant concern due to their potential hepatotoxic effects on humans. This research aimed to ascertain the inhibitory potential of eleven CPs (2-CP, 3-CP, 4-CP, 2,4-DCP, 2,3,4-TCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,5-TeCP, 2,3,4,6-TeCP, 2,3,5,6-TeCP, and PCP) on nine human CYP isoforms (CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4). The CPs that inhibit the activity of CYP isoforms were detected with human liver microsomes (HLM) using a cocktail approach in vitro. The results demonstrated that trichlorophenols, tetrachlorophenols, and PCP strongly inhibited CYP2C8 and CYP2C9. The half inhibition concentration (IC₅₀) value of 2,3,4,6-TeCP and PCP for CYP2C8 inhibition was 27.3 μM and 12.3 μM, respectively. The IC₅₀ for the inhibition of 2,4,6-TCP, 2,3,4,6-TeCP and PCP towards CYP2C9 were calculated to be 30.3 μM, 5.8 μM and 2.2 μM, respectively. 2,3,4,6-TeCP, and PCP exhibited non-competitive inhibition towards CYP2C8. 2,4,6-TCP, 2,3,4,6-TeCP, and PCP exhibited competitive inhibition towards CYP2C9. The inhibition kinetics parameters (Ki) were 51.51 μM, 22.28 μM, 37.86 μM, 7.27 μM, 0.68 μM for 2,3,4,6-TeCP-CYP2C8, PCP-CYP2C8, 2,4,6-TCP-CYP2C9, 2,3,4,6-TeCP-CYP2C9, PCP-CYP2C9, respectively. This study also defined clear structure-activity relationships (SAR) of CPs on CYP2C8, supported by molecular docking studies. Overall, CPs were found to cause inhibitory effects on CYP isoforms in vitro, and this finding may provide a basis for CPs focused on CYP isoforms inhibition endpoints.

Working conditions in low risk nulliparous women in The Netherlands: are legislation and guidelines a guarantee for a healthy working environment? A cohort study

Objective

Hazardous working conditions increase the risk of adverse pregnancy outcomes. In this study, we examine adherence to legislation and guidelines aimed at improving working conditions in pregnancy.

Methods

Between 2014 and 2016, we recruited a prospective cohort of low-risk nulliparous pregnant women in paid employment or self-employed in 16 community midwifery practices in The Netherlands. Participants completed two questionnaires concerning demographics, education, general health and working conditions between 10–16 and 20–24 weeks of pregnancy. We calculated the proportion of participants with work-related risk factors not in accordance with legislation and/or guidelines.

Results

Of 269 participants included, 214 (80%) completed both questionnaires. At 10–16 weeks 110 (41%) participants and at 20–24 weeks 129 (63%) participants continued to work under circumstances that did not meet recommendations. Employers provided mandated information on work adjustment to 37 (15%) participants and 96 (38%) participants received no information about the potential hazards while working with biological and chemical hazards. Participants with lower educational attainment (aOR 2.2 95%CI 1.3–3.9), or employment in healthcare (aOR 4.5, 95%CI 2.2–9.0), education/childcare and social service (aOR 2.6, 95%CI 1.1–6.0 2),, catering (aOR 3.6, 95%CI 1.1–12) and industry, construction and cleaning (aOR 3.3, 95%CI 1.1–10.3) more often continued work which did not meet recommendations.

Conclusion

There is poor adherence to national legislation and guidelines for safe working in pregnancy in The Netherlands: 50% of the pregnant women worked under hazardous conditions. Given the impact on adverse pregnancy outcomes as well as on the public purse, action to improve compliance must be taken by all stakeholders.

A brief review of the current knowledge on environmental toxicants and risk of pediatric cancers

The incidence of pediatric cancers has steadily increased since 1975, which could suggest that other exogenous factors are accounting for an increasing proportion of cases. There has been growing concern over environmental exposures (i.e., toxicants) the on development of pediatric cancers. However, identifying environmental exposures on childhood cancer risk has been challenging because these outcomes are infrequent compared to cancer in adults, and it is difficult to estimate exposure during specific critical periods of development (e.g., pre-conception, in utero, early childhood) that are likely more important for childhood cancer development. Here, we summarize the International Agency for Research on Cancer (IARC) Group 1 agents (toxicants known to be carcinogenic to humans), their routes of exposure, current methods for risk mitigation, and what is known of their associations with pediatric cancer risk. Our review suggests that environmental toxicants are important and potentially modifiable risk factors that need to be more fully explored in children and adolescents.

Cyclodextrin-Based Polymer-Supported Bacterium for the Adsorption and in-situ Biodegradation of Phenolic Compounds

Dual function polymer materials with immobilized Sphingobium Chorophenolicum (SpC) bacterium cells are reported herein that undergo tandem adsorption and biodegradation of phenolic compounds. The cross-linked polymer materials contain β-cyclodextrin (β-CD) with incremental hexamethylene diisocyanate (HDI) cross-linker at variable mole ratios (X = 1, 3, or 6), denoted as HDI-X systems. The adsorptive uptake properties of the insoluble HDI-X polymers (X = 3 and 6) with various phenolic compounds [pentachlorophenol (PCP), 2,4,6-trichlorophenol (TCP), and 2,4,6-trimethylphenol (TMP)] were studied using batch adsorption isotherms. The molecular selective phenol removal (S_R) capacity of the HDI-3 and HDI-6 materials was evaluated by electrospray ionization mass spectrometry (ESI-MS). The results were compared against granular activated carbon (GAC) and native β-CD, where 1D/2D ¹H NMR spectral characterization of the complexes formed between phenolic guests and a soluble polymer (HDI-1) in aqueous solution provide insight on the intermolecular interactions and the role of cross-linking effects. Immobilization of SpC onto HDI-3 was shown to form a composite polymer/bacterium material. The composite system displays synergistic removal effects due to tandem PCP adsorption and SpC biodegradation to yield by-products such as 2,6-dichloro-1,4-hydroquinone (DCHQ). Apoptosis and cytotoxicity of DCHQ were evaluated using three breast cancer cell lines.

A three-act play: pentachlorophenol threats to the cork oak forest soils mycobiome

Atmospheric release of persistent organic pollutants (POPs) constitutes a silent threat through chronic contamination of soils at global scale; yet fundamental understanding of their occurrence, sources and fate is still largely lacking. Similar to a three act play, this review comprises Setup, Confrontation and Resolution. The first emphasises the eighty years of the history of pentachlorophenol (PCP) usage, only recently classified as POP. The second focus on active sources of PCP pollution, including inside cork oak forests in N.W. Tunisia; a threat partially neutralised by the soil microbial diversity, especially fungi. As Resolution, the need for improved knowledge on the global distribution and impacts of PCP in soil microbial diversity as means to preserve the multi-functionality of terrestrial ecosystem is emphasised.

Investigating paternal preconception risk factors for adverse pregnancy outcomes in a population of internet users

BACKGROUND

Paternal preconception risk factors such as smoking, exposure to environmental substances, medication use, overweight and advanced age correlate with the occurrence of malformations and birth defects in the offspring. Nonetheless, the prevalence of risk factors for adverse pregnancy outcomes in the male population has been scarcely investigated and no report on preconception interventions targeting prospective fathers is available. We conducted a web-based survey to measure the prevalence of paternal preconception risk factors for adverse pregnancy outcomes in an Italian population of Internet users.

METHODS

Prospective or expectant fathers were enrolled during a four-week period through two of the main Italian web-sites dedicated to preconception, pregnancy, childhood and family care. Participants filled in a web questionnaire regarding preconception risk factors for adverse pregnancy outcomes. Logistic regression analysis was used to explore the predictors of paternal preconception risk factors.

RESULTS

We enrolled 131 prospective and 205 expectant fathers. More than half of the total participants used medications during the preconception period, 35% were smokers and 8% were obese. Exposure to environmental substances was declared by almost 20% of the participants, with the group including pesticides/herbicides/professional paints being the most prevalent. More than a half of the study sample included men aged over 35 years. According to the multivariate analysis, smoking and exposure to environmental toxics were less frequent among individuals with a university degree (respectively: OR = 0.52; 95% CI 0.32-0.84; OR = 0.52; 95% CI 0.29-0.93). Paternal obesity and medication use in the preconception period were not associated with any of the independent variables.

CONCLUSIONS

The prevalence of preconception risk factors among male population should not be neglected when planning preconception interventions, confirming that preconception health must be focused on the couple, rather than on women only.

A paternal environmental legacy: evidence for epigenetic inheritance through the male germ line

Literature on maternal exposures and the risk of epigenetic changes or diseases in the offspring is growing. Paternal contributions are often not considered. However, some animal and epidemiologic studies on various contaminants, nutrition, and lifestyle-related conditions suggest a paternal influence on the offspring's future health. The phenotypic outcomes may have been attributed to DNA damage or mutations, but increasing evidence shows that the inheritance of environmentally induced functional changes of the genome, and related disorders, are (also) driven by epigenetic components. In this essay we suggest the existence of epigenetic windows of susceptibility to environmental insults during sperm development. Changes in DNA methylation, histone modification, and non-coding RNAs are viable mechanistic candidates for a non-genetic transfer of paternal environmental information, from maturing germ cell to zygote. Inclusion of paternal factors in future research will ultimately improve the understanding of transgenerational epigenetic plasticity and health-related effects in future generations.