Biomonitoring and Biomathematical Modeling of Health Risks Associated with Dumpsite Grown Vegetables in Lagos State

Conversion of dumpsites to farm lands in several communities is a usual practice in Nigeria. Wastes accumulate heavy metals in a variety of forms. This study assessed the concentration, degrees of contamination, and attendant health risk of heavy metals (HMs), using two major indigenous vegetables (Amaranthus viridis and Talinum triangulare) grown on five major dumpsites in Lagos state. After wet digestion, the mean concentrations of the HMs in the vegetable samples were evaluated using atomic absorption spectrophotometer (AAS). Daily intake of metals (DIM), target hazard quotient (THQ), and hazard index (HI) biomathematics were employed in the assessment of non-carcinogenic health risk. Incremental lifetime cancer risk (ILCR) assessment was used to assess carcinogenicity. The obtained result shows that the concentrations of HMs fell within the following ranges: (0.37 to 0.59), (0.07 to 1.36), (0.30 to 1.92), (0.00 to 0.03), and (0.00 to 0.04) mg/kg; for zinc (Zn), lead (Pb), Iron (Fe), cadmium (Cd), and chromium (Cr), respectively, with low to moderate variability. At Ikorodu dumping site, the Pb concentration was above the World Health Organization (WHO) permissible range and has the highest contamination factor. DIM for Pb was also above threshold values (> 1) in both adults and children, while the THQ values for Fe, Pb, and Cd were above 1 (> 1) in both adults and children. HI values for the vegetables exceeded WHO normal range (> 1), except Abule-Egba dumps' samples (70% HI greater than 1 in adults and 90% HI greater than 1 in children). Additionally, the ILCR values of above 50% of the samples were above the WHO (10-6) limits, with the highest value in children (Cd, 1.064 × 10-3) indicating high risk of carcinogenicity over a life time of exposure. Thus, the results revealed great health risk from consumption of vegetables from the four major dumping sites, with children being at greater risk.

Muller and mutations: mouse study of George Snell (a postdoc of Muller) fails to confirm Muller's fruit fly findings, and Muller fails to cite Snell's findings

In 1931, Hermann J. Muller's postdoctoral student, George D. Snell (Nobel Prize recipient--1980) initiated research to replicate with mice Muller's X-ray-induced mutational findings with fruit flies. Snell failed to induce the two types of mutations of interest, based on fly data (sex-linked lethals/recessive visible mutations) even though the study was well designed, used large doses of X-rays, and was published in Genetics. These findings were never cited by Muller, and the Snell paper (Snell, Genetics 20:545-567, 1935) did not cite the 1927 Muller paper (Muller, Science 66:84, 1927). This situation raises questions concerning how Snell wrote the paper (e.g., ignoring the significance of not providing support for Muller's findings in a mammal). The question may be raised whether professional pressures were placed upon Snell to downplay the significance of his findings, which could have negatively impacted the career of Muller and the LNT theory. While Muller would receive worldwide attention, and receive the Nobel Prize in 1946 "for the discovery that mutations can be induced by X-rays," Snell's negative mutation data were almost entirely ignored by his contemporary and subsequent radiation genetics/mutation researchers. This raises questions concerning how the apparent lack of interest in Snell's negative findings helped Muller professionally, including his success in using his fruit fly data to influence hereditary and cancer risk assessment and to obtain the Nobel Prize.

Risk assessment of Benzene, Toluene, Ethyl benzene, and Xylene (BTEX) in the atmospheric air around the world: A review

Volatile organic compounds, such as BTEX, have been the subject of numerous debates due to their detrimental effects on the environment and human health. Human beings have had a significant role in the emergence of this situation. Even though US EPA, WHO, and other health-related organizations have set standard limits as unhazardous levels, it has been observed that within or even below these limits, constant exposure to these toxic chemicals results in negative consequences as well. According to these facts, various studies have been carried out all over the world - 160 of which are collected within this review article, so that experts and governors may come up with effective solutions to manage and control these toxic chemicals. The outcome of this study will serve the society to evaluate and handle the risks of being exposed to BTEX. In this review article, the attempt was to collect the most accessible studies relevant to risk assessment of BTEX in the atmosphere, and for the article to contain least bias, it was reviewed and re-evaluated by all authors, who are from different institutions and backgrounds, so that the insights of the article remain unbiased. There may be some limitations to consistency or precision in some points due to the original sources, however the attempt was to minimize them as much as possible.

Severe Disease Burden and the Mitigation Strategy in the Arsenic-Exposed Population of Kaliprasad Village in Bhagalpur District of Bihar, India

The present study was carried out in the village Kaliprasad of Bhagalpur district of Bihar to know the arsenic exposure effect in the exposed population. A total of n = 102 households were studied, and their water and biological samples such as urine and hair were collected and analyzed in a graphite furnace atomic absorption spectrophotometer (GF-AAS). The assessment of arsenic-exposed village population reveals that the villagers were suffering from serious health-related problems such as skin manifestations (hyperkeratosis and melanosis in their palm and soles), breathlessness, general body weakness, mental disorders, diabetes, hypertension (raised blood pressure), hormonal imbalance, neurological disorders, and few cancer cases. About 77% of household hand pump water had arsenic level more than the WHO recommended level of 10 µg/L, with highest level of 523 µg/L. Moreover, in 60% individual's urine samples, arsenic concentration was very high with maximum 374 µg/L while in hair 64% individuals had arsenic concentration above the permissible limit with maximum arsenic concentration of 11,398 µg/kg. The hazard quotient (HQ) was also calculated to know the arsenic risk percentage in children as 87.11%, in females as 83.15%, and in males as 82.27% by groundwater. This has surpassed the threshold value of 1 × 10 - 6 for carcinogenic risk (CR) in children, female, and male population group in the village. Hence, the exposed population of Kaliprasad village are at very high risk of the disease burden.

Retrospective chart analysis to determine the impact of a patient-facing digital risk stratification tool combined with a clinical screener for hereditary cancer genetic risk assessment triage in a community oncology clinic

The purpose of this study was to evaluate the utility of adding a clinical screener to the patient-facing digital risk stratification tool triage process for the identification of patients eligible for a genetic risk assessment for hereditary cancer. Digital risk stratification entries were retrospectively reviewed to determine the overall number of patients eligible for genetic risk assessment. These were also analyzed to determine how many patients were re-contacted by the clinical screener, and how many of those recontacted patients met criteria after their personal and family history was revised by the clinical screener. There was an 89.9% digital risk stratification triage tool completion rate, with 22.6% requiring contact from the clinical screener. Of the 640 patients who completed the digital tool, 5.9% met criteria for testing after their personal and/or family history was revised by the clinical screener. Overall, 51.1% of patients met criteria for a genetic risk assessment. The addition of a clinical screener further increased identification of patients eligible for genetic risk assessment. About half of patients who met criteria after being contacted by the clinical screener met criteria based on their personal diagnosis of cancer alone. Incorporation of a clinical screener to the digital screening process may serve to reduce barriers to patient completion of the tool and increase rates of patient identification for cancer genetic services.

Comet assay and hormesis

The paper provides the first assessment of the occurrence of hormetic dose responses using the Comet assay, a genotoxic assay. Using a priori evaluative criteria based on the Hormetic Database on peer-reviewed comet assay experimental findings, numerous examples of hormetic dose responses were obtained. These responses occurred in a large and diverse range of cell types and for agents from a broad range of chemical classes. Limited attempts were made to estimate the frequency of hormesis within comet assay experimental studies using a priori entry and evaluative criteria, with results suggesting a frequency in the 40% range. These findings are important as they show that a wide range of genotoxic chemicals display evidence that is strongly suggestive of hormetic dose responses. These findings have significant implications for study design issues, including the number of doses selected, dose range and spacing. Likewise, the widespread occurrence of hormetic dose responses in this genotoxic assay has important risk assessment implications.

Hereditary cancer testing in a diverse sample across three breast imaging centers

PURPOSE

Up to 10% of all breast cancers (BC) are attributed to inherited pathogenic variants (PV) in BC susceptibility genes; however, most carriers of PVs remain unidentified. Here, we sought to determine the yield of hereditary cancer gene PVs among diverse women attending breast imaging centers, who could benefit from enhanced surveillance and/or risk reduction interventions.

METHODS

This cross-sectional retrospective cohort study included consecutive women, unselected for personal or family cancer history, who were offered genetic testing for hereditary cancer genes at the time of breast imaging at three centers (November 2020-March 2022).

RESULTS

Among 1943 patients (median age: 66 years), self-reported race/ethnicity was White (34.5%), Hispanic (27.7%), African American (17.9%), Asian (4.5%), Ashkenazi Jewish (0.6%), Other (3.5%), and missing (13.0%). Thirty-nine patients (2%) were identified as carriers of a PV in an autosomal dominant clinically actionable hereditary breast and ovarian cancer (HBOC)-related or Lynch syndrome gene, most frequently, BRCA2 (6/39; 15.4%), PALB2 (8/39; 20.5%), CHEK2 (10/39; 25.6%), and PMS2 (5/39; 12.8%). Of the 34 PVs with known race/ethnicity, 47% were detected among non-White patients. Overall, 354/1,943 (18.2%) of patients met NCCN guidelines for HBOC gene testing and only 15/39 (38.5%) patients with an autosomal dominant clinically actionable PV met guidelines.

CONCLUSION

This population health approach extended the reach of genetic cancer risk assessment in a diverse population and highlighted the limits of a guideline-based approach. This may help address inequity in access to risk-appropriate screening and cancer prevention.

Hermann Muller and his LNT scientific and policy leadership: Private communication reveals uncertainties

The present paper highlights numerous publications of Hermann J. Muller with a focus on his opinions concerning the validity of the linear no-threshold dose response model for hereditary and cancer risk assessment. These comments reflect a very consistent and powerfully supporting position for the LNT model. However, newly discovered correspondence between Muller and Robley D. Evans reveals that Muller was highly uncertain about the supportive science, and therefore hid his real opinions, deliberately misleading the scientific community and governmental agencies. Of further historical value is that in the correspondence with Evans, Muller proposed what might be the first articulation of an environmentally based Precautionary Principle. These perspectives have remained unknown since Muller requested Evans to keep this letter private.

Background radiation and cancer risks: A major intellectual confrontation within the domain of radiation genetics with multiple converging biological disciplines

This paper assesses the judgments of leading radiation geneticists and cancer risk assessment scientists from the mid-1950s to mid-1970s that background radiation has a significant effect on human genetic disease and cancer incidence. This assumption was adopted by the National Academy of Sciences (NAS) Biological Effects of Atomic Radiation (BEAR) I Genetics Panel for genetic diseases and subsequently applied to cancer risk assessment by other leading individuals/advisory groups (e.g., International Commission on Radiation Protection-ICRP). These recommendations assumed that a sizeable proportion of human mutations originated from background radiation due to cumulative exposure over prolonged reproductive periods and the linear nature of the dose-response. This paper shows that the assumption that background radiation is a significant cause of spontaneous mutation, genetic diseases, and cancer incidence is not supported by experimental and epidemiological findings, and discredits erroneous risk assessments that improperly influenced the recommendations of national and international advisory committees, risk assessment policies, and beliefs worldwide.

How self-interest and deception led to the adoption of the linear non-threshold dose response (LNT) model for cancer risk assessment

This paper clarifies scientific contributions and deceptive/self-serving decisions of William L. Russell and Liane Russell that led to the adoption of the linear non-threshold (LNT) model for cancer risk assessment by the US EPA. By deliberately failing to report an extremely large cluster of mutations in the control group of their first experiment, and thereby greatly suppressing its mutation rate, the Russells incorrectly claimed that the male mouse was 15-fold more susceptible to ionizing-radiation-induced gene mutations as compared with fruit flies. This self-serving error not only propelled their research program into one of great prominence, but it also promoted the LNT-based doubling dose (DD) concept in radiation genetics/cancer risk assessment, by the US National Academy of Sciences (NAS) Biological Effects of Atomic Radiation (BEAR) I Genetics Panel (1956). The DD concept became a central element in their recommendation that regulatory agencies switch from a threshold to an LNT model. This error occurred because of a decision by W. Russell not to report that a large cluster of control group mutations found in an experiment for which preliminary results were reported in 1951. This failure to report that cluster and similar clusters continued throughout the careers of the Russells, resulting in massive overestimation of low dose radiation risks supporting the LNT. The Russell database and the repeated claim that those data show that there is no threshold dose rate for mutation in irradiated mouse stem-cell spermatogonia, have provided mechanistic validation supporting the epidemiological LNT hypothesis for radiation-induced leukemias and cancers. This reanalysis supports the threshold model for both males and females, thereby rebutting epidemiological extrapolations from the NAS and EPA claiming support for the LNT hypothesis for cancer risk assessment. The implications of the Russell errors/deceptions, how/why they occurred, and their impact upon society are enormous and need to be addressed by scientific/regulatory agencies, affecting regulatory and litigation activities.

Confirmation that Hermann Muller was dishonest in his Nobel Prize Lecture

In his Nobel Prize Lecture of December 12, 1946, Hermann J. Muller argued that the dose-response for ionizing radiation-induced germ cell mutations was linear and that there was ''no escape from the conclusion that there is no threshold''. However, a newly discovered commentary by the Robert L. Brent (2015) indicated that Curt Stern, after reading a draft of part of Muller's Nobel Prize Lecture, called Muller, strongly advising him to remove reference to the flawed linear non-threshold (LNT)-supportive Ray-Chaudhuri findings and strongly encouraged him to be guided by the threshold supportive data of Ernst Caspari. Brent indicated that Stern recounted this experience during a genetics class at the University of Rochester. Brent wrote that Muller refused to follow Stern's advice, thereby proclaiming support for the LNT dose-response while withholding evidence that was contrary during his Nobel Prize Lecture. This finding is of historical importance since Muller's Nobel Prize Lecture gained considerable international attention and was a turning point in the acceptance of the linearity model for radiation and chemical hereditary and carcinogen risk assessment.

New and legacy pesticidal persistent organic pollutants in the agricultural region of the Sultanate of Oman

Comprehensive air and surface soil monitoring was conducted for new and legacy organochlorine pesticides (OCPs) to fill the knowledge and data gap on the sources and fate of pesticidal persistent organic pollutants (POPs) in the Sultanate of Oman. DDTs in agricultural soil samples ranged from 0.013 to 95.80 ng/g (mean: 8.4 ± 25.06 ng/g), with a median value of 0.07 ng/g. The highest concentration was observed at Shinas, where intensive agricultural practice is prevalent. The dominance of p,p'-DDT in soil and air reflected technical DDT formulation usage in Oman. Among newly enlisted POPs, pentachlorobenzene had the maximum detection frequency in air (47%) and soil (41%). Over 90% of sites reflected extensive past use of hexachlorobenzene. Major OCP isomers and metabolites showed net volatilisation from the agricultural soil, thereby indicating concurrent emission and re-emission processes from the soil of Oman. However, the cleansing effect of oceanic air mass is the possible reason for relatively lower atmospheric OCP levels from a previous study. Although DDT displayed maximum cancer risk, the level is below the permissible limit. DDT primarily stemmed from obsolete stock and inadequate management practices. Hence, we suggest there is a need for DDT regulation in Oman.

Development of a framework for risk assessment of dietary carcinogens

Although there are a number of guidance documents and frameworks for evaluation of carcinogenicity, none of the current methods fully reflects the state of the science. Common limitations include the absence of dose-response assessment and not considering the impact of differing exposure patterns (e.g., intermittent, high peaks vs. lower, continuous exposures). To address these issues, we have developed a framework for risk assessment of dietary carcinogens. This framework includes an enhanced approach for weight of evidence (WOE) evaluation for genetic toxicology data, with a focus on evaluating studies based on the most recent testing guidance to determine whether a chemical is a mutagen. Included alongside our framework is a discussion of resources for evaluating tissue dose and the temporal pattern of internal dose, taking into account the chemical's toxicokinetics. The framework then integrates the mode of action (MOA) and associated dose metric category with the exposure data to identify the appropriate approach(es) to low-dose extrapolation and level of concern associated with the exposure scenario. This framework provides risk managers with additional flexibility in risk management and risk communication options, beyond the binary choice of linear low-dose extrapolation vs. application of uncertainty factors.

Muller mistakes: The linear no-threshold (LNT) dose response and US EPA's cancer risk assessment policies and practices

This paper identifies the occurrence of six major conceptual scientific errors of Hermann Muller and describes how these errors led to the creation of the linear no-threshold (LNT) dose response historically used worldwide for cancer risk assessments for chemical carcinogens and ionizing radiation. The paper demonstrates the significant role that Muller played in the environmental movement, affecting risk assessment policies and practices that are in force even now a half century following his death. This paper lends support to contemporary research that shows significant limitations of the LNT model for cancer risk assessment.

Effect of beef patties fortification with black garlic on the polycyclic aromatic hydrocarbons (PAHs) content and toxic potency

Nine different black garlic samples aged at varying temperatures and durations were added to the patties at 0.5% and 1% ratios and compared with raw garlic in terms of polycyclic aromatic hydrocarbons (PAHs) formation. The results showed that black garlic caused a reduction in the patties' content of ∑PAH8 by 38.17% to 94.12% compared to raw garlic, with the highest reduction percent in the patties fortified with 1% black garlic aged at 70 °C for 45 days. Beef patties fortified with black garlic reduced human exposure to PAHs from beef patties (from 1.66E to 01 to 6.04E-02 ng-TEQ_BaP kg^-1 bw per day). The negligible cancer risk associated with exposure to PAHs through the consumption of beef patties was confirmed by very low ILCR (incremental lifetime cancer risk) values of 5.44E-14 and 4.75E-12. Finally, patty fortification with black garlic could be suggested as an effective way to reduce PAHs formation and exposure from patties.

Error-corrected next generation sequencing - Promises and challenges for genotoxicity and cancer risk assessment

Error-corrected Next Generation Sequencing (ecNGS) is rapidly emerging as a valuable, highly sensitive and accurate method for detecting and characterizing mutations in any cell type, tissue or organism from which DNA can be isolated. Recent mutagenicity and carcinogenicity studies have used ecNGS to quantify drug-/chemical-induced mutations and mutational spectra associated with cancer risk. ecNGS has potential applications in genotoxicity assessment as a new readout for traditional models, for mutagenesis studies in 3D organotypic cultures, and for detecting off-target effects of gene editing tools. Additionally, early data suggest that ecNGS can measure clonal expansion of mutations as a mechanism-agnostic early marker of carcinogenic potential and can evaluate mutational load directly in human biomonitoring studies. In this review, we discuss promising applications, challenges, limitations, and key data initiatives needed to enable regulatory testing and adoption of ecNGS - including for advancing safety assessment, augmenting weight-of-evidence for mutagenicity and carcinogenicity mechanisms, identifying early biomarkers of cancer risk, and managing human health risk from chemical exposures.

Beyond the cancer slope factor: Broad application of Bayesian and probabilistic approaches for cancer dose-response assessment

Traditional cancer slope factors derived from linear low-dose extrapolation give little consideration to uncertainties in dose-response model choice, interspecies extrapolation, and human variability. As noted previously by the National Academies, probabilistic methods can address these limitations, but have only been demonstrated in a few case studies. Here, we applied probabilistic approaches for Bayesian Model Averaging (BMA), interspecies extrapolation, and human variability distributions to 255 animal cancer bioassay datasets previously used by governmental agencies. We then derived predictions for both population cancer incidence and individual cancer risk. For model uncertainty, we found that lower confidence limits from BMA and from U.S. Environmental Protection Agency (EPA)'s Benchmark Dose Software (BMDS) correlated highly, with 86% differing by <10-fold. Incorporating other uncertainties and human variability, the lower confidence limits of the probabilistic risk-specific dose (RSD) at 10-6 population incidence were typically 3- to 30-fold lower than traditional slope factors. However, in a small (<7%) number of cases of highly non-linear experimental dose-response, the probabilistic RSDs were >10-fold less stringent. Probabilistic RSDs were also protective of individual risks of 10-4 in >99% of the population. We conclude that implementing Bayesian and probabilistic methods provides a more scientifically rigorous basis for cancer dose-response assessment and thereby improves overall cancer risk characterization.

Grape Seed Components as Protectors of Inflammation, DNA Damage, and Cancer

PURPOSE OF REVIEW

Oxidative stress is related to the pathogenesis of several chronic diseases, including inflammatory processes. Free radicals excess increase not only oxidative stress but also genomic instability. Polyphenols are non-enzymatic antioxidants that act as a defense barrier against free radicals and non-radical oxidants. The purpose of this article was to review published articles relating dietary polyphenols contained in grape seed proanthocyanidin extracts with its potential for reversing DNA damage.

RECENT FINDINGS

Proanthocyanidin components exert pleiotropic actions having several biological, biochemical, and significant pharmacological effects and showed the ability to reduce cytotoxicity and genotoxicity. Grape seed proanthocyanidin extracts showed the ability to reduce cytotoxicity and genotoxicity through the comet assay and the micronucleus technique.

Implementing digital systems to facilitate genetic testing for hereditary cancer syndromes: An observational study of 4 clinical workflows

PURPOSE

National efforts have prioritized the identification of effective methods for increasing case ascertainment and delivery of evidence-based health care for individuals at elevated risk for hereditary cancers.

METHODS

This study examined the uptake of genetic counseling and testing following the use of a digital cancer genetic risk assessment program implemented at 27 health care sites in 10 states using 1 of 4 clinical workflows: (1) traditional referral, (2) point-of-care scheduling, (3) point-of-care counseling/telegenetics, and (4) point-of-care testing.

RESULTS

In 2019, 102,542 patients were screened and 33,113 (32%) were identified as at high risk and meeting National Comprehensive Cancer Network genetic testing criteria for hereditary breast and ovarian cancer, Lynch syndrome, or both. Among those identified at high risk, 5147 (16%) proceeded with genetic testing. Genetic counseling uptake was 11% among the sites with workflows that included seeing a genetic counselor before testing, with 88% of patients proceeding with genetic testing after counseling. Uptake of genetic testing across sites varied significantly by clinical workflow (6% referral, 10% point-of-care scheduling, 14% point-of-care counseling/telegenetics, and 35% point-of-care testing, P < .0001).

CONCLUSION

Study findings highlight the potential heterogeneity of effectiveness attributable to different care delivery approaches for implementing digital hereditary cancer risk screening programs.

Cancer risk assessment and source apportionment of the gas- and particulate-phase of the polycyclic aromatic hydrocarbons in a metropolitan region in Brazil

A risk assessment and a source apportionment of the particulate- and gas-phase PAHs were conducted in a high vehicular traffic and industrialized region in southeastern Brazil. Higher concentrations of PAHs were found during summer, being likely driven by the contributions of PAHs in the vapor phase caused by fire outbreaks during this period. Isomer ratio diagnostic and Principal Component Analysis (PCA) identified four potential sources in the region, in which the Positive Matrix Factorization (PMF) model confirmed and apportioned as gasoline-related (31.8%), diesel-related (25.1%), biomass burning (23.4%), and mixed sources (19.6%). The overall cancer risk had a tolerable value, with ∑CR = 4.6 × 10^-5, being ingestion the major via of exposure (64% of the ∑CR), followed by dermal contact (33% of the ∑CR) and inhalation (3%). Mixed sources contributed up to 45% of the overall cancer risk (∑CR), followed by gasoline-related (up to 35%), diesel-related (up to 15%), and biomass burning (up to 10%). The risk assessment for individual PAH species allowed identifying higher CR associated with BaP, DBA, BbF, BaA, and BkF, species associated with gasoline-related and industrial sources. Higher risks were associated with PM_2.5-bound PAHs exposure, mainly via ingestion and dermal contact, highlighting the need for measures of mitigation and control of PM_2.5 in the region.

Health and economic gain attributable to the introduction of the World Health Organization's drinking water standard on arsenic level in Hungary: A nationwide retrospective study on cancer occurrence and ischemic heart disease mortality

The World Health Organization (WHO) estimates that 140 million individuals are at risk from consumption of drinking water containing arsenic at concentrations above the WHO guideline value of 10 μg/l. Arsenic mitigation is considered to be the most effective way to prevent arsenic related diseases. After joining the European Union, Hungary implemented a Drinking Water Quality Improvement Programme (DWQIP) to reduce levels of arsenic in drinking water below the WHO guideline value. But what impact did this have on health? We estimated the change in lifetime excess skin, lung, and bladder cancer risks and mortality from ischaemic heart disease (IHD) associated with chronic arsenic intake among those exposed before (2004-2007) and after (2014-2017) the implementation of DWQIP. A population-based risk assessment approach was used to assess lifetime excess cancer risk applying two scenarios for lung and bladder cancers. The economic benefits of the DWQIP were estimated by the combination of cost of illness and value per statistical life methods. Compared to the period before the DWQIP, its implementation was associated with a significant reduction in arsenic in drinking water [median: 3.0 μg/l interquartile range (IQR): 1.5-12.0 μg/l to median: 2.15 μg/l IQR: 1.0-5.79 μg/l]. The two scenarios were estimated to be associated with 225.2 and 35.9 fewer cancer cases each year. The number of annually prevented IHD deaths was estimated to be 88.9. It was estimated that the benefits of the DWQIP will outweigh its costs. We conclude that reducing arsenic levels in drinking water to 10.0 μg/l resulted in significant health and economic benefits. Our study goes beyond the existing research, offering both new insights into the impact of arsenic mitigation and providing a methodological template for similar studies in the many parts of the world that have yet to reduce arsenic exposure.

Assessment of Pb and Ni and potential health risks associated with the consumption of vegetables grown on the roadside soils in District Swat, Khyber Pakhtunkhwa, Pakistan

Vegetables cultivated near roads absorb toxic metals from polluted soil, which enter the human body through the food chain and cause serious health problems to humans. The present study investigated the concentration of lead (Pb) and nickel (Ni) in soils and vegetables grown along the roadside of District Swat, Pakistan, and the health risks associated with the consumption of the tested vegetables. In results, Pb concentration was higher in plants located at the distance between 0-10 m away from the roadside than the WHO permissible limit. In such plants, Pb concentration was higher than Ni. Rumex dentatus contained the highest concentration of Pb (75.63 mg kg^-1 DW) among the tested vegetables while Ni concentration (27.57 mg kg^-1 DW) was highest in Trachyspermum ammi as compared to other plants. Concentration and accumulation of both the metals decreased in soil and plants with increasing distance from the road. Similarly, target hazard quotient values noted for Pb (up to 3.37) were greater than unity, which shows that there is a potential risk associated with the consumption of tested vegetables near the road. Moreover, the values of target cancer risk (up to 0.8413) were greater than 0.0001, which shows that there is a risk of cancer with the consumption of tested vegetables. In conclusion, the consumption of tested vegetables was very dangerous as it may lead to higher risks of cancer. Strict regulatory control is recommended on the cultivation of these vegetables along the roadside to avoid any contamination due to roadside exhaust.

Can the Indian national ambient air quality standard protect against the hazardous constituents of PM2.5?

Globally, exposure to ambient fine particulate matter (PM_2.5) pollution claims ∼9 million lives, yearly, and a quarter of this deaths occurs in India. Regulation of PM_2.5 pollution in India is based on compliance with its National Ambient Air Quality Standard (NAAQS) of 40 μg/m³, which is eight times the revised global air quality guideline (AQG) of 5 μg/m³. But, whether the NAAQS provides adequate protection against the hazardous components in PM_2.5 is still not clear. Here, we examined the risk to health associated with exposure to PM_2.5-bound polychlorinated biphenyls (PCB), heavy metals and polycyclic aromatic hydrocarbons (PAHs) in an Indian district averaging below the NAAQS. The annual average concentrations of PM_2.5 mass, Σ₂₈PCB and Σ₁₃PAHs were 34 ± 17 μg/m³, 21 ± 12 ng/m³ and 458 ± 246 ng/m³, respectively. Concentrations of As, Cr, Mn and Ni in PM_2.5 surpassed the screening levels for residential air. Substantial level of risks to health were associated with exposure to dioxin-like PCBs (Σ₁₂dlPCB), PAHs, As, Cr and Ni. The hazard index or lifetime cancer risk were 240, or 9 cases per 1000 population, respectively. The estimated risks to health through exposure to hazardous components, except Ni, were greatest in rural areas, having a lower average PM_2.5 concentration, than urban or peri-urban areas, suggesting higher toxicity potential of rural combustion sources. The large disparity between the estimated risk values and the acceptable risk level suggests that it would take a more stringent standard, such as the global AQG, to protect vulnerable populations in India from hazardous components in PM_2.5.

Ethical challenges of the linear non-threshold (LNT) cancer risk assessment revolution: History, insights, and lessons to be learned

This paper provides historical review and evaluation of the development, adoption, and advocacy of the linear non-threshold (LNT) dose response model for cancer risk assessment as applied in practices and policies worldwide. It extends previous historical assessments and provides novel insights regarding: 1) how LNT bias became institutionalized in US governmental agencies, 2) how improper editorial practices at the journal Science promoted the adoption of LNT, 3) how a Nobel Prize winning scientist unjustifiably espoused and influenced support for replacing the threshold dose response model with the LNT model, 4) how the cover-up of striking and substantial experimental cancer data by US government scientists reduced support for the threshold dose response model at a critical period of cancer risk assessment policy adoption, and 5) how these events have negatively influenced cancer risk assessment practices and environmental and public health decisions for decades. These findings are presented to illustrate how profound and recognized mistakes, biases and unethical activities, inclusive of frank scientific misconduct, converged, and should motivate regulatory agencies worldwide to critically evaluate any existing policies that apply the LNT model as well as to serve as object lessons for current and future ethical conduct of research, and the provision of ethico-legal education in and across scientific curricula and institutions.

Determination of whole mixture-based potency factors for cancer risk assessment of complex environmental mixtures by in vitro testing of standard reference materials

Whole mixture-based testing using in vitro new approach methodologies (NAMs) has been suggested to facilitate the hazard and risk assessment of complex environmental mixtures. Previous studies have shown that phosphorylation of DNA damage signaling proteins checkpoint kinase 1 (pChk1) and histone 2AX (γH2AX) are sensitive markers that can be used for estimating carcinogenicity potencies in vitro. Here, and with the aim to better validate the applicability, in vitro-based Mixture Potency Factors (MPFs) of Standard Reference Materials (SRMs) from environmental polycyclic aromatic hydrocarbon (PAH)-containing mixtures were determined and compared to published mutagenicity and tumorigenicity data. Also, genotoxicity was assessed by a flow cytometry-based micronucleus (MN) assay which showed that only benzo[a]pyrene (B[a]P) and coal tar SRM (SRM1597a) caused dose-dependent increases of MN formation, while extracts of diesel particulate matter (SRM1650b), diesel particulate extract (SRM1975), and urban dust (SRM1649b) did not. However, a dose-dependent activation of DNA damage signaling was observed for all PAHs and SRMs. The results demonstrated that all SRMs were more potent than B[a]P, at B[a]P-equivalent concentrations, to induce pChk1 and γH2AX, and that western blot was more sensitive than the In-Cell Western assay in detecting their activation in response to these complex mixtures. Relative MPFs, based on dose-response modelling of pChk1 and γH2AX, ranged 113 - 5270 for the SRMs, indicating several orders of magnitude higher genotoxic potential than B[a]P. Moreover, these MPFs were in good agreement with potency values based on published data from Salmonella mutagenicity and in vivo carcinogenicity studies. In conclusion, these comparisons further validate the feasibility of applying in vitro NAMs, such as whole-mixture based MPFs, in cancer risk assessment of complex mixtures.