An evolution of risk assessment for potential carcinogens in food: Scientific session proceedings.

Modern perspectives on the risk assessment of carcinogenic potential of chemicals have taken shape within the last two decades. This has been due to both developments in the understanding of the biology and etiology of cancer and by advances in in silico and in vitro assays. Moving away from a conventional binary carcinogen/non-carcinogen model, modern frameworks offer more nuanced classification structures based on the understanding of mechanisms involved or potentially involved in rodent carcinogenicity. Given these developments, a scientific session at the 2020 Winter Meeting of the Toxicology Forum was organized to explore the impact these innovative approaches will have on food safety assessments and what considerations should be addressed in developing a new carcinogenic risk assessment approach for substances in foods. The session reviewed challenges faced by food toxicologists and risk assessors, current standard approaches for evaluating carcinogenic risk of food substances, limitations of these standard approaches, and potential methods to implement next generation assays and modern carcinogenic frameworks into food safety assessments. Current perspectives of US regulatory, industry, and academic stakeholders were represented during speaker presentations and a moderated Panel Discussion. This Workshop Report provides an overview of key themes and information presented during the session. Summary statements were prepared by the authors and reviewed by the presenters but do not necessarily represent the position or policy of the FDA, the EPA, or other affiliations.

Carcinogens in Products: Inadequate Protections Raise Cancer Risks.

Evidence shows, that over their life cycle, chemicals used in everyday products contribute to raising cancer risks, especially for vulnerable populations such as children and communities of color. This article outlines how US policies have not yet incorporated current science in relation to environmental carcinogenesis and recommends improvements to protect public health.

Probabilistic risk assessment of occupational exposure to volatile organic compounds in the rendering plant of a poultry slaughterhouse.

In this study, occupational exposure to volatile organic compounds (VOCs) in the rendering plant of poultry slaughterhouse was determined and subsequently, carcinogen and non-carcinogenic risks were assessed using the US Environmental Protection Agency (USEPA). National Institute for Occupational Safety and Health (NIOSH) methods of 1501 and 1600 were used to measure VOCs in the breathing zone of the workers. Samples were analyzed by GC/MS. Carcinogenic and non-carcinogenic risks and sensitivity analysis were carried out using Monte Carlo simulations technique. The concentration of benzene and CS2 was higher than the occupational exposure limits (OEL). The hazard quotient (HQ) values for all measured compounds was more than 1, which indicating the high potential for non-carcinogenic risks. Furthermore, the calculated Lifetime Cancer Risks (LCR) for carcinogenic compounds revealed that cancer risk due to benzene is higher than the maximum acceptable level provided by USEPA (10-6). Based on the sensitivity analysis, the concentration and exposure frequency are the most important variable influencing both carcinogen and non-carcinogenic risks. Therefore, the concentration levels of the VOCs and exposure frequency should be controlled using engineering control measures.

Potential impurities in drug substances: Compound-specific toxicology limits for 20 synthetic reagents and by-products, and a class-specific toxicology limit for alkyl bromides.

This paper provides compound-specific toxicology limits for 20 widely used synthetic reagents and common by-products that are potential impurities in drug substances. In addition, a 15 µg/day class-specific limit was developed for monofunctional alkyl bromides, aligning this with the class-specific limit previously defined for monofunctional alkyl chlorides. Both the compound- and class-specific toxicology limits assume a lifetime chronic exposure for the general population (including sensitive subpopulations) by all routes of exposure for pharmaceuticals. Inhalation-specific toxicology limits were also derived for acrolein, formaldehyde, and methyl bromide because of their localized toxicity via that route. Mode of action was an important consideration for a compound-specific toxicology limit. Acceptable intake (AI) calculations for certain mutagenic carcinogens assumed a linear dose-response for tumor induction, and permissible daily exposure (PDE) determination assumed a non-linear dose-response. Several compounds evaluated have been previously incorrectly assumed to be mutagenic, or to be mutagenic carcinogens, but the evidence reported here for such compounds indicates a lack of mutagenicity, and a non-mutagenic mode of action for tumor induction. For non-mutagens with insufficient data to develop a toxicology limit, the ICH Q3A qualification thresholds are recommended. The compound- and class-specific toxicology limits described here may be adjusted for an individual drug substance based on treatment duration, dosing schedule, severity of the disease and therapeutic indication.

Development of an inhalation unit risk factor for ethylene dibromide.

The Texas Commission on Environmental Quality (TCEQ) follows standard scientific methods to develop up-to-date toxicity factors for chemicals emitted in the state of Texas. An inhalation unit risk factor (URF) was developed for ethylene dibromide (EDB, CAS 106-93-4) based on an increased incidence of nasal cavity adenocarcinomas observed in female rats in a 2-year inhalation cancer bioassay conducted by the National Toxicology Program (NTP). The NTP study provided evidence of several EDB-induced tumors in male and female rats and in female mice. Tumor incidences that were statistically increased at the low dose and that showed a statistically significant increasing trend were considered in identifying the critical effect. Following benchmark concentration (BMC) modeling and animal-to-human dosimetric adjustments, the increased incidence of nasal cavity adenocarcinomas observed in female rats was determined to be the most sensitive tumorigenic effect in the most sensitive species and sex and was utilized as the carcinogenic endpoint for the development of the URF. The 95% lower confidence limit of the BMC at the 10% excess risk level (BMCL10 of 292.8 ppb) was determined for calculation of the URF. The resulting URF based on increased nasal cavity adenocarcinomas observed in female rats is 3.4E-04 per ppb (4.4E-05 per µg/m3). The lifetime air concentration corresponding to a no significant excess risk level of one in 100,000 is 0.029 ppb (0.22 µg/m3), which is considered sufficiently health-protective for use in protecting the general public against the potential carcinogenic effects of chronic exposure to EDB in ambient air.

An Integrated Experimental Design for the Assessment of Multiple Toxicological End Points in Rat Bioassays.

BACKGROUND: For nearly five decades long-term studies in rodents have been the accepted benchmark for assessing chronic long-term toxic effects, particularly carcinogenicity, of chemicals. The European Food Safety Authority (EFSA) and the World Health Organization (WHO) have pointed out that the current set of internationally utilized test methods capture only some of the potential adverse effects associated with exposures to these agents over the lifetime. OBJECTIVES: In this paper, we propose the adaption of the carcinogenicity bioassay to integrate additional protocols for comprehensive long-term toxicity assessment that includes developmental exposures and long-term outcomes, capable of generating information on a broad spectrum of different end points. DISCUSSION: An integrated study design based on a stepwise process is described that includes the priority end points of the Economic Co-operation and Development and the National Toxicology Program guidelines on carcinogenicity and chronic toxicity and developmental and reproductive toxicity. Integrating a comprehensive set of relevant toxicological end points in a single protocol represents an opportunity to optimize animal use in accordance with the 3Rs (replacement, reduction and refinement). This strategy has the potential to provide sufficient data on multiple windows of susceptibility of specific interest for risk assessments and public health decision-making by including prenatal, lactational, neonatal exposures and evaluating outcomes over the lifespan. CONCLUSION: This integrated study design is efficient in that the same generational cohort of rats used for evaluating long-term outcomes can be monitored in satellite parallel experiments to measure biomarkers and other parameters related to system-specific responses including metabolic alterations and endocrine disturbances. Citation: Manservisi F, Babot Marquillas C, Buscaroli A, Huff J, Lauriola M, Mandrioli D, Manservigi M, Panzacchi S, Silbergeld EK, Belpoggi F. 2017. An integrated experimental design for the assessment of multiple toxicological end points in rat bioassays. Environ Health Perspect 125:289-295; http://dx.doi.org/10.1289/EHP419.

[Studies on an efficient method for determining 3,3'-dimethylbenzidine in the workplace air]. / Badania nad skuteczna metoda oznaczania 3,3'-dimetylobenzydyny w powietrzu na stanowiskach pracy.

BACKGROUND: 3,3'-Dimethylbenzidene (DMB) is a substance classified into the group of carcinogens. The value of maximum admissible concentration for this substance in the workplace air is not specified in Poland. Bearing in mind that DMB is used in domestic companies there is a need to develop a sensitive method for determining 3,3'-dimethylbenzidine in the work environment. MATERIAL AND METHODS: The method consists in passing DMB-containing air through sulfuric acid-treated glass fiber filters, washing out the substance settled on the filter, using water and solution of sodium hydroxide, liquid-liquid extraction with toluene, replacing dissolvent with acetonitrile and analyzing the obtained solution. Studies were performed using high-performance liquid chromatography (HPLC) technique. An Agilent Technologies chromatograph, series 1200, with a diode-array detector (DAD) and a fluorescence detector (FLD) was used in the experiment. In the test, an Ultra C18 column of dimensions: 250×4.6 mm, particle diameter (dp) = 5 µm (Restek) was applied. RESULTS: The method is linear (r = 0.999) within the investigated working range of concentration 1.08-21.6 µg/ml, which is equivalent to air concentrations 2-40 µg/m3 for a 540 l air sample. The limit of detection (LOD) of quantification determination is 5.4 ng/ml and the limit of quantification (LOQ) - 16.19 ng/ml. CONCLUSIONS: The analytical method described in this paper allows for selective determination of 3,3'-dimethylbenzidine in the workplace air in the presence of 1,4-phenylenediamine, benzidine, aniline, 3,3'-dimethoxybenzidine, 2-nitrotoluene, 3,3'-dichlorobenzidine and azobenzene. The method is characterized by good precision and good accuracy, it also meets the criteria for procedures involving the measurement of chemical agents, listed in EN 482:2012.

Key Characteristics of Carcinogens as a Basis for Organizing Data on Mechanisms of Carcinogenesis.

BACKGROUND: A recent review by the International Agency for Research on Cancer (IARC) updated the assessments of the > 100 agents classified as Group 1, carcinogenic to humans (IARC Monographs Volume 100, parts A-F). This exercise was complicated by the absence of a broadly accepted, systematic method for evaluating mechanistic data to support conclusions regarding human hazard from exposure to carcinogens. OBJECTIVES AND METHODS: IARC therefore convened two workshops in which an international Working Group of experts identified 10 key characteristics, one or more of which are commonly exhibited by established human carcinogens. DISCUSSION: These characteristics provide the basis for an objective approach to identifying and organizing results from pertinent mechanistic studies. The 10 characteristics are the abilities of an agent to 1) act as an electrophile either directly or after metabolic activation; 2) be genotoxic; 3) alter DNA repair or cause genomic instability; 4) induce epigenetic alterations; 5) induce oxidative stress; 6) induce chronic inflammation; 7) be immunosuppressive; 8) modulate receptor-mediated effects; 9) cause immortalization; and 10) alter cell proliferation, cell death, or nutrient supply. CONCLUSION: We describe the use of the 10 key characteristics to conduct a systematic literature search focused on relevant end points and construct a graphical representation of the identified mechanistic information. Next, we use benzene and polychlorinated biphenyls as examples to illustrate how this approach may work in practice. The approach described is similar in many respects to those currently being implemented by the U.S. EPA's Integrated Risk Information System Program and the U.S. National Toxicology Program. CITATION: Smith MT, Guyton KZ, Gibbons CF, Fritz JM, Portier CJ, Rusyn I, DeMarini DM, Caldwell JC, Kavlock RJ, Lambert P, Hecht SS, Bucher JR, Stewart BW, Baan R, Cogliano VJ, Straif K. 2016. Key characteristics of carcinogens as a basis for organizing data on mechanisms of carcinogenesis. Environ Health Perspect 124:713-721; http://dx.doi.org/10.1289/ehp.1509912.

Potential toxic effects of glyphosate and its commercial formulations below regulatory limits.

Glyphosate-based herbicides (GlyBH), including Roundup, are the most widely used pesticides worldwide. Their uses have increased exponentially since their introduction on the market. Residue levels in food or water, as well as human exposures, are escalating. We have reviewed the toxic effects of GlyBH measured below regulatory limits by evaluating the published literature and regulatory reports. We reveal a coherent body of evidence indicating that GlyBH could be toxic below the regulatory lowest observed adverse effect level for chronic toxic effects. It includes teratogenic, tumorigenic and hepatorenal effects. They could be explained by endocrine disruption and oxidative stress, causing metabolic alterations, depending on dose and exposure time. Some effects were detected in the range of the recommended acceptable daily intake. Toxic effects of commercial formulations can also be explained by GlyBH adjuvants, which have their own toxicity, but also enhance glyphosate toxicity. These challenge the assumption of safety of GlyBH at the levels at which they contaminate food and the environment, albeit these levels may fall below regulatory thresholds. Neurodevelopmental, reproductive, and transgenerational effects of GlyBH must be revisited, since a growing body of knowledge suggests the predominance of endocrine disrupting mechanisms caused by environmentally relevant levels of exposure.

Use of mode of action data to inform a dose-response assessment for bladder cancer following exposure to inorganic arsenic.

In the recent National Research Council report on conducting a dose-response assessment for inorganic arsenic, the committee remarked that mode of action data should be used, to the extent possible, to extrapolate below the observed range for epidemiological studies to inform the shape of the dose-response curve. Recent in vitro mode of action studies focused on understanding the development of bladder cancer following exposure to inorganic arsenic provide data to inform the dose-response curve. These in vitro data, combined with results of bladder cancer epidemiology studies, inform the dose-response curve in the low-dose region, and include values for both pharmacokinetic and pharmacodynamic variability. Integration of these data provides evidence of a range of concentrations of arsenic for which no effect on the bladder would be expected. Specifically, integration of these results suggest that arsenic exposures in the range of 7-43 ppb in drinking water are exceedingly unlikely to elicit changes leading to key events in the development of cancer or noncancer effects in bladder tissue. These findings are consistent with the lack of evidence for bladder cancer following chronic ingestion of arsenic water concentrations <100 ppb in epidemiological studies.

Derivation of a No-Significant-Risk-Level (NSRL) for diethanolamine (DEA).

Diethanolamine (DEA) has been listed on the State of California's Proposition 65 List. This listing is based in part on tumors reported in a National Toxicology Program (NTP) 2-year dermal carcinogenicity study in mice which found clear evidence of carcinogenic activity in B6C3F1 mice based on increased incidences of liver neoplasms in both sexes, and increased incidences of renal tubule neoplasms in males. Although considerable controversy exists on the relevance of the NTP study to humans, industries are obligated to comply with the Proposition 65 labeling requirement and drinking water discharge prohibition, unless they are able to demonstrate that DEA levels in their products are below a specific No Significant Risk Level (NSRL). The State of California has not published an NSRL for DEA. In this article, a NSRL of 5.6 µg/day and a life-stage-adjusted NSRL(adj) of 1.4 µg/day are derived from the NTP carcinogenicity study using a benchmark dose modeling method based on the incidence of hepatocellular carcinomas in female mice, in accordance with the guidelines of California EPA.

International Conference on Harmonisation; final recommendation for the revision of the permitted daily exposure for the solvent cumene according to the maintenance procedures for the guidance Q3C Impurities: Residual Solvents; availability. Notice.

The Food and Drug Administration (FDA) is announcing the availability of a final recommendation for the revision of the permitted daily exposure (PDE) for the solvent cumene according to the maintenance procedures for the guidance for industry entitled ``Q3C Impurities: Residual Solvents.'' The recommendation was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH).

First report on development of quantitative interspecies structure-carcinogenicity relationship models and exploring discriminatory features for rodent carcinogenicity of diverse organic chemicals using OECD guidelines.

Different regulatory agencies in food and drug administration and environmental protection worldwide are employing quantitative structure-activity relationship (QSAR) models to fill the data gaps related with properties of chemicals affecting the environment and human health. Carcinogenicity is a toxicity endpoint of major concern in recent times. Interspecies toxicity correlations may provide a tool for estimating sensitivity towards toxic chemical exposure with known levels of uncertainty for a diversity of wildlife species. In this background, we have developed quantitative interspecies structure-carcinogenicity correlation models for rat and mouse [rodent species according to the Organization for Economic Cooperation and Development (OECD) guidelines] based on the carcinogenic potential of 166 organic chemicals with wide diversity of molecular structures, spanning a large number of chemical classes and biological mechanisms. All the developed models have been assessed according to the OECD principles for the validation of QSAR models. Consensus predictions for carcinogenicity of the individual compounds are presented here for any one species when the data for the other species are available. Informative illustrations of the contributing structural fragments of chemicals which are responsible for specific carcinogenicity endpoints are identified by the developed models. The models have also been used to predict mouse carcinogenicities of 247 organic chemicals (for which rat carcinogenicities are present) and rat carcinogenicities of 150 chemicals (for which mouse carcinogenicities are present). Discriminatory features for rat and mouse carcinogenicity values have also been explored.

Biomonitoring Equivalents for benzene.

Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline such as a reference dose (RfD) or tolerable daily intake (TDI). BE values can be used as a screening tool for the evaluation of population-based biomonitoring data in the context of existing risk assessments. This study reviews available health based risk assessments and exposure guidance values for benzene from the United States Environmental Protection Agency (US EPA), Texas Commission on Environmental Quality (TCEQ), California's Office of Environmental Health Hazard Assessment (OEHHA) and the Agency for Toxic Substances and Disease Registry (ATSDR) to derive BE values for benzene in blood and urine. No BE values were derived for any of the numerous benzene metabolites or hemoglobin and albumin adducts. Using existing physiologically based pharmacokinetic (PBPK) models, government risk assessment values were translated into corresponding benzene levels in blood assuming chronic steady-state exposures. BEs for benzene in urine were derived using measured correlations between benzene in urine with benzene in blood. The BE values for benzene in blood range from 0.04 to 1.29 µg/L, depending upon the underlying non-cancer risk assessment used in deriving the BE. Sources of uncertainty relating to both the basis for the BE values and their use in evaluation of biomonitoring data, including the transience of the biomarkers relative to exposure frequency, are discussed. The BE values derived here can be used as screening tools for evaluation of population biomonitoring data for benzene in the context of the existing risk assessment and can assist in prioritization of the potential need for additional risk assessment efforts for benzene relative to other chemicals.

Research opportunities related to establishing standards for tobacco products under the Family Smoking Prevention and Tobacco Control Act.

INTRODUCTION: This paper was written in response to a request from the U.S. National Cancer Institute. The goal is to discuss some research directions related to establishing tobacco product standards under the Family Smoking Prevention and Tobacco Control Act, which empowers the U.S. Food and Drug Administration to regulate tobacco products. Potential research related to tobacco product ingredients, nicotine, and harmful or potentially harmful constituents of tobacco products is discussed. DISCUSSION: Ingredients, which are additives, require less attention than nicotine and harmful or potentially harmful constituents. With respect to nicotine, the threshold level in tobacco products below which dependent users will be able to freely stop using the product if they choose to do so is a very important question. Harmful and potentially harmful constituents include various toxicants and carcinogens. An updated list of 72 carcinogens in cigarette smoke is presented. A crucial question is the appropriate levels of toxicants and carcinogens in tobacco products. The use of carcinogen and toxicant biomarkers to determine these levels is discussed. CONCLUSIONS: The need to establish regulatory standards for added ingredients, nicotine, and other tobacco and tobacco smoke constituents leads to many interesting and potentially highly significant research questions, which urgently need to be addressed.

[Improvement of the organization of oncological aid under conditions of specific technogenic load on the population].

Social and economic disbenifits due to mortality from malignant neoplasms were estimated taking into account the losses of man-years of work, mean life expectancy for the sick, losses from temporary disablement and invalidization caused by malignancies, and the cost of oncological aid. The study was based at an area in Uzbekistan subjected to pollution by industrial wastes from an uranium-extracting enterprise. A special purpose-oriented program has been elaborated for the correction of oncological aid currently provided to the workers of the Navoi mining and metallurgical works and the local population. Its implementation resulted in a 13% reduction of standardized mortality from malignant neoplasm in 2004 compared with 1999 and another 24% in 2009. The disbenefit prevented by the reduction of mortality at active ages is estimated at 60,6 mln rubles.

An analysis of pharmaceutical experience with decades of rat carcinogenicity testing: support for a proposal to modify current regulatory guidelines.

Data collected from 182 marketed and nonmarketed pharmaceuticals demonstrate that there is little value gained in conducting a rat two-year carcinogenicity study for compounds that lack: (1) histopathologic risk factors for rat neoplasia in chronic toxicology studies, (2) evidence of hormonal perturbation, and (3) positive genetic toxicology results. Using a single positive result among these three criteria as a test for outcome in the two-year study, fifty-two of sixty-six rat tumorigens were correctly identified, yielding 79% test sensitivity. When all three criteria were negative, sixty-two of seventy-six pharmaceuticals (82%) were correctly predicted to be rat noncarcinogens. The fourteen rat false negatives had two-year study findings of questionable human relevance. Applying these criteria to eighty-six additional chemicals identified by the International Agency for Research on Cancer as likely human carcinogens and to drugs withdrawn from the market for carcinogenicity concerns confirmed their sensitivity for predicting rat carcinogenicity outcome. These analyses support a proposal to refine regulatory criteria for conducting a two-year rat study to be based on assessment of histopathologic findings from a rat six-month study, evidence of hormonal perturbation, genetic toxicology results, and the findings of a six-month transgenic mouse carcinogenicity study. This proposed decision paradigm has the potential to eliminate over 40% of rat two-year testing on new pharmaceuticals without compromise to patient safety.