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Papers by John Bucher

ISEE Conference Abstracts, 2021

NAM-based approach informs reasonable, conservative screening and prioritization Part I: Retrospe... more NAM-based approach informs reasonable, conservative screening and prioritization Part I: Retrospective case study Katie Paul Friedman l paul-friedman.katie@epa.gov This poster does not necessarily reflect ECHA, EPA, Health Canada, or NTP policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 1737/P113 March 12, 2019 Society of Toxicology Annual Meeting Baltimore, MD Use of high-throughput, in vitro bioactivity data in setting a point-of-departure (POD) has the potential to accelerate the pace of human health risk assessments by chemical prioritization. Advancement toward this goal requires confidence that in vitro bioactivity data, in conjunction with high-throughput toxicokinetic information, can be used to estimate administered equivalent doses at or below the PODs from traditional animal studies. Further, hazard and exposure predictions, combined as a bioactivity:exposure ratio (BER) for use in risk-based prioritization, s...

Journal of Food and Drug Analysis, 2020

Journal of Clinical Epidemiology, 2021

Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, Jan 4, 2018

I. Introduction Dietary supplements, as defined by the Dietary Supplement Health and Education Ac... more I. Introduction Dietary supplements, as defined by the Dietary Supplement Health and Education Act of 1994 (DSHEA) in the United States, are products intended to supplement the diet that contain vitamins, minerals, amino acids, other dietary substances, and/or herbs or other botanicals (Abdel-Rahman et al., 2011). They are further defined as only including products intended for ingestion, not representing a conventional food or complete nutritional source, and requiring labeling as a dietary supplement. The DSHEA legislation was aimed at balancing access to dietary supplements with public safety and amended the Federal Food, Drug, and Cosmetic Act (FD&C Act) to provide a clear definition of dietary supplements and a regulatory framework for evaluating safety and claims associated with activity (Abdel-Rahman et al., 2011). The focus herein is on a subset of dietary supplements, those containing herbs or other botanicals, that are collectively referred to as botanical dietary supplements or, simply, botanicals. It is important to note that use patterns and regulatory guidance for botanical dietary supplements differ around the world. While this manuscript focuses primarily on the United States, recent reviews offer comparisons of global regulatory paradigms (Enioutina et al., 2017; Low et al., 2017). Furthermore, the challenges in assessing the safety of botanical dietary supplements discussed within are universally relevant. Botanical dietary supplements are generally available as whole plants, plant parts, powdered plant material, or plant extracts. These supplements are marketed in various forms, including as powders, tablets, capsules, gummies, teas, tinctures, and essential oils. A variety of botanical dietary supplements are used in complementary and integrative health practices

Bioelectromagnetics, 2018

Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. ... more Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. To characterize the effects of RFR exposure on body temperature in relation to animal size and pregnancy, a series of short-term toxicity studies was conducted in a unique RFR exposure system. Young and old B6C3F1 mice and young, old, and pregnant Harlan Sprague-Dawley rats were exposed to Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA) RFR (rats = 900 MHz, mice = 1,900 MHz) at specific absorption rates (SARs) up to 12 W/kg for approximately 9 h a day for 5 days. In general, fewer and less severe increases in body temperature were observed in young than in older rats. SAR-dependent increases in subcutaneous body temperatures were observed at exposures ≥6 W/kg in both modulations. Exposures of ≥10 W/kg GSM or CDMA RFR induced excessive increases in body temperature, leading to mortality. There was also a significant increase in the number of resorptio...

Toxicology and Applied Pharmacology, 1995

Fundamental and Applied Toxicology, 1987

Environmental health perspectives, 2016

In the history of modern toxicology, few years have been more consequential than 1978-the year th... more In the history of modern toxicology, few years have been more consequential than 1978-the year the National Toxicology Program (NTP) came into being. On 7 August 1978, following months of reports of serious health problems near a chemical dump site at Love Canal, New York, former President Jimmy Carter declared a federal health emergency to facilitate clean up and the relocation of nearby families.

Advances in Experimental Medicine and Biology, 1986

Active forms of oxygen are becoming increasingly implicated in the etiology of numerous disease s... more Active forms of oxygen are becoming increasingly implicated in the etiology of numerous disease states and the toxicities of various drugs and chemicals. Among the former are the initiation and promotion of tumors (Petkau, 1980) and rheumatoid arthritis (Rowley et al., 1984), while the latter includes toxicities such as that associated with anthracycline antibiotics (Goodman and Hochstein, 1977), and paraquat (Bus et al., 1974). The generation of active oxygen species during normal cellular metabolism such as prostaglandin and leukotriene biosynthesis (Kalyanaraman and Sivarajah, 1984) or by stimulated polymorphonuclear leukocytes or macrophages (Babior and Peters, 1981) is now widely recognized.

The U.S. National Toxicology Program (NTP) has carried out extensive rodent toxicology and carcin... more The U.S. National Toxicology Program (NTP) has carried out extensive rodent toxicology and carcinogenesis studies of radiofrequency radiation (RFR) at frequencies and modulations used in the U.S. telecommunications industry. This report presents partial findings from these studies. The occurrences of two tumor types in male Harlan Sprague Dawley rats exposed to RFR, malignant gliomas in the brain and schwannomas of the heart, were considered of particular interest and are the subject of this report. The findings in this report were reviewed by expert peer reviewers selected by the NTP and National Institutes of Health (NIH). These reviews and responses to comments are included as appendices to this report, and revisions to the current document have incorporated and addressed these comments. When the studies are completed, they will undergo additional peer review before publication in full as part of the NTP's Toxicology and Carcinogenesis Technical Reports Series. No portion of ...

Fundamental and Applied Toxicology, 1994

Environmental Health Perspectives, 2015

Reproductive Toxicology, 2015

Bisphenol A (BPA) is a chemical used in the production of numerous consumer products resulting in... more Bisphenol A (BPA) is a chemical used in the production of numerous consumer products resulting in potential daily human exposure to this chemical. The FDA previously evaluated the body of BPA toxicology data and determined that BPA is safe at current exposure levels. Although consistent with the assessment of some other regulatory agencies around the world, this determination of BPA safety continues to be debated in scientific and popular publications, resulting in conflicting messages to the public. Thus, the National Toxicology Program (NTP), National Institute of Environmental Health Sciences (NIEHS), and U.S Food and Drug Administration (FDA) developed a consortium-based research program to link more effectively a variety of hypothesis-based research investigations and guideline-compliant safety testing with Published by Elsevier Inc. This is an open access article under the CC BY license.

Toxicology and Applied Pharmacology, 1997

Journal of Toxicology and Environmental Health, 1990

Toxicology and carcinogenicity studies of N‐methylolacrylamide were conducted by administering th... more Toxicology and carcinogenicity studies of N‐methylolacrylamide were conducted by administering the chemical by gavage in water to both sexes of F344/N rats and B6C3F1 mice 5 times per week for 76 d, 13 wk, or 2 yr. In 16‐d studies, rats receiving doses of 200 mg/kg or higher and mice receiving 400 mg/kg died. In 13‐wk studies, all rats given 100 mg/kg or higher doses died. Rats receiving 50 mg/kg or higher doses developed hindlimb ataxia progressing to paralysis. In neurobehavioral assessments, decreased forelimb and hindlimb grip strength occurred in rats at doses as low as 12.5 mg/kg. Landing footspread was also increased in dosed rats compared to controls. Axon filament and myelin sheath degeneration in the spinal cord and/or peripheral nerves occurred in rats receiving doses of 25 mg/kg or higher. Necrosis in the granular cell layer of the cerebellum was seen in rats given 200 mg/kg. Mice receiving 200 mg/kg in 13‐wk studies died. Decreased grip strength was noted in mice at doses as low as 25 mg/kg, and rotarod performance was also affected by H‐methylolacrylamide administration, but no neuropathology was seen microscopically. Testicular weights were decreased at doses as low as 12.5 mg/kg, and hepatocellular necrosis, thymic lymphocyte necrosis, and hemorrhage, necrosis, and mineralization of the zona reticularis of the adrenal gland were seen in mice that died (200 mg/kg).In 2‐yr studies, survival and weight gains in male and female rats receiving doses of 6 or 12 mg/kg/d were minimally affected. No biologically important clinical signs or neoplastic or nonneoplastic lesions were attributed to N‐methylolacrylamide administration to rats, suggesting that higher doses could have been tolerated. In mice, survival was not different between dosed and control groups (0, 25, or 50 mg/kg/d). Body weights were higher by as much as 25% in dosed compared to control groups. No compound‐related clinical signs were observed, but increases in neoplasms of the harderian gland, liver, and lung were clearly related to chemical administration in both sexes of mice. Benign granulosa‐cell neoplasms of the ovary were also increased in dosed female mice.

Toxicology, Jan 17, 2015

Occupational exposure to cobalt is of widespread concern due to its use in a variety of industria... more Occupational exposure to cobalt is of widespread concern due to its use in a variety of industrial processes and the occurrence of occupational disease. Due to the lack of toxicity and carcinogenicity data following exposure to cobalt and questions regarding bioavailability following exposure to different forms of cobalt, the NTP conducted two chronic inhalation exposure studies in rats and mice, one on soluble cobalt sulfate heptahydrate, and a more recent study on insoluble cobalt metal. Herein, we compare and contrast the toxicity profiles following whole-body inhalation exposures to these two forms of cobalt. In general, both forms were genotoxic in the Salmonella T98 strain in the absence of effects on micronuclei. The major sites of toxicity and carcinogenicity in both chronic inhalation studies were the respiratory tract in rats and mice, and the adrenal gland in rats. In addition, there were distinct sites of toxicity and carcinogenicity noted following exposure to cobalt me...

Toxicologic pathology, 2008

Helicobacter hepaticus (H. hepaticus) infection causes hepatitis and increased hepatocellular neo... more Helicobacter hepaticus (H. hepaticus) infection causes hepatitis and increased hepatocellular neoplasms in male mice; although females are also infected, liver lesions are not typically expressed. In the 1990s, B6C3F1 mice from some chronic National Toxicology Program (NTP) studies were found to be infected with H. hepaticus. In these studies, there was hepatitis in many of the males, and there were more hepatocellular neoplasms in control males compared to studies with uninfected mice. In one of these studies, increased hepatocellular neoplasms at the high doses in male and female mice exposed topically to triethanolamine (TEA) provided the only evidence of carcinogenic activity. This study was repeated in mice free of H. hepaticus.However, the NTP mouse production colony and the diet differed between studies; these differences were the result of NTP programmatic decisions. In repeat study males, although control incidences were similar between studies, exposure did not result in i...

Toxicological sciences : an official journal of the Society of Toxicology, 2004

The National Toxicology Program (NTP) has over 25 years of experience in the design, performance,... more The National Toxicology Program (NTP) has over 25 years of experience in the design, performance, and interpretation of assays for identifying carcinogenic hazards to humans. Through the years we have examined alternative assays and adjunct assays to the standard rodent cancer bioassay including batteries of genetic toxicity tests and genetically modified mouse models. As our collective understanding of carcinogenesis advances, toxicologists and regulatory scientists will at some point begin to rely on mechanism-based biological observations rather than the two-year rodent bioassay to predict human cancer hazards. The goal of the NTP Vision for the 21st Century is to develop the science base that will advance the use of mechanism-based biological observations, eventually providing a replacement for disease-specific toxicology models in the protection of public health.