Toxicology Certification: The Need, the Value, and an Evolving Landscape

Certification in toxicology remains a subject of interest to those in the field, as evidenced by the number of presentations at major meetings and publications in the past decade. In 2009, Brock and colleagues summarized the certifications available in the field of toxicology and provided an international perspective of the pros and cons of gaining certification. Though that article has been viewed thousands of times, the certification processes have evolved over the past decade. Therefore, the purpose of the article is to build upon the prior work and present current information for toxicologists seeking certification with the American Board of Toxicology (DABT), Academy of Toxicological Sciences (ATS), as a European Registered Toxicologist (ERT), as a Diplomate, Japanese Society of Toxicology (DJSOT), and as a Diplomate of the Chinese Society of Toxicology (DCST). In addition, other certifications are presented, but available details are limited.

Nonclinical Safety Assessment of Lipid Nanoparticle-and Emulsion-Based Self-Amplifying mRNA Vaccines in Rats

Vaccines containing mRNA with the capacity to self-amplify represent an alternative to the mRNA vaccines that came to prominence during the COVID-19 pandemic. To gain further insights on the safety profile of self-amplifying mRNA- (SAM-) vaccines, this preclinical toxicology study in rats evaluated the effect of (i) the type of delivery system (lipid nanoparticle [LNP] vs cationic nano-emulsion [CNE]); (ii) antigen-encoding sequence (rabies glycoprotein G vs SARS-CoV-2 Spike); and (iii) RNA amplification. Further analyses also evaluated gene expression in peripheral blood after vaccination, and the biodistribution of vaccine RNA. The SAM vaccines administered as two doses 2-weeks apart had acceptable safety profiles in rats, with respect to clinical signs, blood biochemistry, and macroscopic and microscopic pathology. A transient increase in ALT/AST ratio occurred only in female rats and in the absence of muscle and liver damage was dependent on RNA amplification and appeared related to the greater quantities of vaccine RNA in the muscle and livers of female rats vs male rats. The RNA and delivery-vehicle components, but not the nature of the antigen-coding sequence or the requirement for RNA amplification, affected aspects of the stimulation of innate-immune activity, which was consistent with the transient activation of type I and type II interferon signaling. The delivery vehicle, LNP, differed from CNE as vaccine RNA in CNE compositions appeared independently to stimulate innate-immune activity at 4 hours after vaccination. Our analysis supports further studies to assess whether these differences in innate-immune activity affect safety and efficacy of the SAM vaccine.

alpha-Glycosyl Isoquercitrin (AGIQ) and its lack of carcinogenicity in rasH2 mice

alpha-Glycosyl Isoquercitrin (AGIQ), is used in Japan as a food additive and was granted generally recognized as safe (GRAS) status in 2005 (FEMA) and 2007 (FDA). The safety and toxicity information for AGIQ is sparse and therefore, the carcinogenicity potential of AGIQ was examined in the CByB6F1-Tg(HRAS)2Jic (rasH2) model. One hundred female and male rasH2 mice, each, were allocated to one of four designated dose groups; 0 (control)%, 1.5%, 3.0% or 5.0% AGIQ. Animals were administered the diets for six months and an additional 10 females and 10 males, each, were administered a positive control, N-methyl-N-nitrosourea (MNU). Body weights and clinical observations were collected. A full screen necropsy, organ weights, clinical chemistry, urinalysis and histopathology were performed. The positive control animals elicited appropriate responses specific to this strain (rasH2) of mice. There were statistically significant sporadic non-dose-dependent changes in clinical chemistries without corresponding pathological correlation. No microscopic AGIQ-related findings were noted; the range of pathology observations were all considered background findings, either specific to rasH2 mice or common to inbred strains of mice. Therefore, under the study conditions, the no-observed-adverse-effect level (NOAEL) was determined to be more than 5.0% (7215.4 mg/kg BW/day in male mice and 14685.5 mg/kg/day in female mice).

Embryo-fetal developmental toxicity study of alpha-glycosyl isoquercitrin administered orally to New Zealand White rabbits

An embryo-fetal survival and development study was conducted to augment the toxicity database for alpha-glycosyl isoquercitrin (AGIQ), a generally recognized as safe (GRAS) additive and flavor in food and beverages. In Phase I, 24 naturally mated New Zealand white (NZW) female rabbits per group were administered AGIQ by oral gavage at 0, 250, 500, or 1000 mg/kg/day once daily during gestation days 6–28, followed by necropsy. There was no evidence of maternal or fetal toxicity except for equivocal findings of unilateral absent kidney and ureter in one and two unrelated fetuses at 500 and 1000 mg/kg/day, respectively. To more thoroughly assess fetal kidney/ureter development, in Phase II groups of time mated NZW rabbits were administered AGIQ at 0, 500, or 1000 mg/kg/day, under the same conditions as Phase I. No occurrences of absent kidney/ureter were noted in the AGIQ-treated Phase II dams or fetuses; although, one control fetus had unilateral missing kidney/ureter. Given the lack of reproducibility following treatment with AGIQ in Phase II using 48 animals per group, the missing kidney/ureter observations in Phase I were considered unrelated to treatment. Since oral gavage administration of AGIQ to pregnant female NZW rabbits at dose levels of 250, 500, or 1000 mg/kg/day was well-tolerated with no adverse treatment-related effects on the maternal animal, pregnancy, or the developing conceptus, the no-observed-adverse-effect-level (NOAEL) for maternal toxicity and embryo-fetal survival, growth, and development was 1000 mg/kg/day.

Confirmation of in vitro and clinical safety assessment of behentrimonium chloride-containing leave-on body lotions using post-marketing adverse event data

Behentrimonium chloride (BTC) is a straight-chain alkyltrimonium chloride compound commonly used as an antistatic, hair conditioning, emulsifier, or preservative agent in personal care products. Although the European Union recently restricted the use of alkyltrimonium chlorides and bromides as preservatives to ≤0.1%, these compounds have been safely used for many years at ≤5% in hundreds of cosmetic products for other uses than as a preservative. In vitro, clinical, and controlled consumer usage tests in barrier-impaired individuals were conducted to determine if whole body, leave-on skin care products containing 1-5% BTC cause dermal irritation or any other skin reaction with use. BTC-containing formulations were predicted to be non-irritants by the EpiDerm® skin irritation test and the bovine corneal opacity and permeability (BCOP)/chorioallantoic membrane vascular assay (CAMVA) ocular irritation test battery. No evidence of allergic contact dermatitis or cumulative dermal irritation was noted under the exaggerated conditions of human occlusive patch tests. No clinically assessed or self-reported adverse reactions were noted in adults or children with atopic, eczematous, and/or xerotic skin during two-week and four-week monitored home usage studies. These results were confirmed by post-marketing data for five body lotions, which showed only 0.69 undesirable effects (mostly skin irritation) reported per million shipped consumer units during 2006-2011; a value consistent with a non-irritating body lotion. No serious undesirable effects were reported during in-market use of the products. Therefore, if formulated in appropriate conditions at 1-5%, BTC will not cause dermal irritation or delayed contact sensitization when used in a whole-body, leave-on product.

Negligible penetration of incidental amounts of alpha-hydroxy acid from rinse-off personal care products in human skin using an in vitro static diffusion cell model

Alpha-hydroxy acids (AHAs), primarily glycolic and lactic acids, are widely used in cosmetics to alleviate dyspigmentation, photodamage, and other aging skin conditions and as pH adjusters. Glycolic acid reportedly enhances skin damage after repeated ultraviolet light exposure, e.g., increased sunburn cell formation. This study assessed potential in vitro skin penetration of lactic acid and malic acid incorporated into rinse-off personal care products, compared with rinse-off and leave-on exposures to glycolic acid (10%, pH 3.5) in a reference lotion. Radiolabeled AHA-fortified shampoo, conditioner, and lotion were evenly applied as single doses to human epidermal membranes mounted in static diffusion cells (not occluded). Exposures were 1-3 min (rinse-off) or 24 h (leave-on). Epidermal penetration of malic acid and lactic acid from the rinse-off shampoo and conditioner, respectively, was negligible, with >99% removed by rinsing, a negligible portion remaining in the stratum corneum (≤0.15%), and even less penetrating into the viable epidermis (≤0.04%). Glycolic acid penetration from the leave-on reference lotion was 1.42 μg equiv./cm2/h, with total absorbable dose recovery (receptor fluid plus epidermis) of 2.51%, compared to 0.009%, 0.003%, and 0.04% for the rinse-off reference lotion, shampoo (malic acid), and conditioner (lactic acid) exposures, respectively. Dermal penetration of AHAs into human skin is pH-, concentration-, and time-dependent. Alpha-hydroxy acids in rinse-off shampoos and conditioners are almost entirely removed from the skin within minutes by rinsing (resulting in negligible epidermal penetration). This suggests that ultraviolet radiation-induced skin effects of AHA-containing rinse-off products are negligible.

Influence of a combination of two tetrachlorobiphenyl congeners (PCB 47; PCB 77) on thyroid status, choline acetyltransferase (ChAT) activity, and short- and long-term memory in 30-day-old Sprague-Dawley rats

The important role of thyroid hormones in growth and development, maintenance of body temperature, digestion, cardiac function, and normal brain development can be disrupted by environmental contaminants like polychlorinated biphenyls (PCB). Polychlorinated biphenyls are environmental contaminants that are widespread, persistent, lipophilic, and bioaccumulate through food webs, concentrating in adipose tissue. Placental and lactational PCB exposure of offspring causes metabolic and endocrine disruptions including hypothyroxinemia, spatial learning and memory deficits, neurochemical and neurobehavioral alterations, and reproductive problems. Previous studies in our lab using the individual congeners PCB 47 (2,2',4,4'-tetrachlorobiphenyl, ortho-substituted) and PCB 77 (3,3',4,4'-tetrachlorobiphenyl, non-ortho-substituted) have demonstrated alterations in thyroid hormone levels, alterations in brain choline acetyltransferase (ChAT) activity, and spatial learning deficits. In the present study, pregnant Sprague-Dawley rats were fed a diet with or without a mixture of PCB 47/77 at 1.25 ppm, 12.5 ppm or 25.0 ppm (w/w). Rat pups were swum in the Morris water maze four times a day on days 21-29 in order for the animals to learn the position of a submerged fixed platform. A probe test was run on day 24 (30 min after last swim) for short-term memory, and on day 29 (24 h after the last swim) for long-term memory after removal of the platform. Time spent in the quadrant previously containing the platform was recorded. Rats were decapitated on day 30, serum collected and frozen at -20 degrees. ChAT activity was measured radiometrically in basal forebrain and hippocampus. All PCB-treated animals experienced a depression in both triiodothyronine (T3) and thyroxine (T4). The present study found that all doses of PCB depressed ChAT activity in hippocampus with no significant alteration in the basal forebrain. In PCB-treated animals, short-term memory showed a trend toward improvement and long-term memory toward depression, but these trends were not significant. The consequences likely stem from endocrine disruption, especially with regard to the thyroid.

An encounter-based analysis of the nature of teaching and learning in a 3rd-year medical school clerkship

BACKGROUND

Much of medical education has shifted from the hospital to ambulatory settings where each student works with a preceptor.

PURPOSE

Our objectives were to describe the nature of community-based learning and to explore how learning experiences vary by type of health care visit.

METHODS

This prospective study used both paper- and computer-based documentation systems to collect information on student-patient-preceptor encounters. A consecutive sample of 3rd-year medical students contributed data on 1 full clinical day each week as they rotated through a required 8-week family medicine clerkship. The main measures of interest included patient age, gender, health care visit type (acute, acute exacerbation of chronic, chronic, and health maintenance), method of learning in history taking and physical examinations (observing preceptor, being observed by preceptor, performing unobserved, or working jointly with preceptor), content of physical examinations, amount of preceptor feedback, and preceptor teaching content.

RESULTS

Sixty-three students contributed data on 4,083 patient encounters. The majority of visits concerned acute complaints (37.7%) or health maintenance (26.4%). Many encounters involved students conducting the cardiovascular and pulmonary exams (33.2% each); fewer encounters involved neurologic (6.9%), gynecological (4.5%), and genitourinary (2.2%) exams. Students reported being observed performing histories and physical exams in 4% and 6% of encounters respectively. The most common student experiences were performing histories and performing physical exams unobserved during acute visits, which accounted for 65.8% and 52.4% of encounters overall.

CONCLUSIONS

This system is useful for determining educational content and processes that occur in ambulatory settings. Important differences were found in teaching and learning by type of health care visit. This factor can and should be used when considering how students meet educational objectives in community-based ambulatory settings.