Guidance on classification for reproductive toxicity under the globally harmonized system of classification and labelling of chemicals (GHS)

An oral developmental toxicity study of generic pesticide pinoxaden in rabbits

The safety assessment of pinoxaden by the Joint Meeting on Pesticide Residues (JMPR) established a NOAEL of 30 mg/kg bw/day for maternal and embryo/fetal toxicity from a rabbit developmental toxicity study. However, the Pesticide Peer Review Expert meeting (EFSA) lowered the NOAEL to 10 mg/kg bw/day due to observed diaphragm malformations in one developmental toxicity study in rabbits, proposing a classification for developmental effects as Category 2 R63 or H361d. Both JMPR and EFSA set the Acceptable Daily Intake (ADI) at 0.1 mg/kg bw/day, derived from a 2-year rat study NOAEL with a safety factor of 100, but EFSA also supported ADI by teratology study in rabbits. The current prenatal developmental toxicity study on pinoxaden aimed to elucidate and clarify the potential teratogenic effects and could provide supplementary data for determining the ADI for pinoxaden. The study design exceeded the OECD TG 414 by including an assessment of internal organs. The test item was orally administered by gavage daily from day 6 to day 28 of gestation to three groups of animals, each composed of 21 females, in dose levels of 0, 10 and 30 mg/kg/bw/day. One female from the 30 mg/kg/bw/day dose group was euthanized in extremis on Day 27 post-coitum due to premature delivery, likely induced by poor general condition and was therefore considered to be an indirect effect of the test item. One female at 30 mg/kg/bw/day had entirely dead litters except for one live male pup (9 non-live implants vs 1 live fetus). Since the incidence of post-implantation loss or mean number of the dead pups within the remaining dams at 30 mg/kg/ bw/day that survived to necropsy was not significantly increased, we assume that the toxic effect was on the dam, rather than on the conceptus. No pinoxaden-related skeletal or visceral variations or malformations were observed. No evidence of developmental toxicity was observed. Under the conditions of the study, the pinoxaden produced maternal toxicity at a high dose tested; thus, NOAEL for maternal toxicity was determined to be 10 mg/kg bw/day. NOAEL for developmental toxicity was established at 30 mg/kg bw/day. The obtained results may supplement the overall safety and toxicity profile of pinoxaden. Nevertheless, the NOAEL determined in this study does not affect the previously established ADI.

A diagnostic strategy for pulmonary fat embolism based on routine H&E staining using computational pathology

Pulmonary fat embolism (PFE) as a cause of death often occurs in trauma cases such as fractures and soft tissue contusions. Traditional PFE diagnosis relies on subjective methods and special stains like oil red O. This study utilizes computational pathology, combining digital pathology and deep learning algorithms, to precisely quantify fat emboli in whole slide images using conventional hematoxylin-eosin (H&E) staining. The results demonstrate deep learning's ability to identify fat droplet morphology in lung microvessels, achieving an area under the receiver operating characteristic (ROC) curve (AUC) of 0.98. The AI-quantified fat globules generally matched the Falzi scoring system with oil red O staining. The relative quantity of fat emboli against lung area was calculated by the algorithm, determining a diagnostic threshold of 8.275% for fatal PFE. A diagnostic strategy based on this threshold achieved a high AUC of 0.984, similar to manual identification with special stains but surpassing H&E staining. This demonstrates computational pathology's potential as an affordable, rapid, and precise method for fatal PFE diagnosis in forensic practice.

Does REACH provide sufficient information to regulate substances toxic to reproduction?

Hazard classification and risk assessment of substances, is essential to protect workers and consumers from hazardous substances including reproductive toxicants. The ability to classify substances for reproductive toxicity under the current REACH information requirements has been assessed. For low tonnage substances (<10 ton per annum (tpa)) information for classification is insufficient. When only a reproductive screening study is available (10-100 tpa), substances are mostly not classified in Category 1B as developmental and non-potent fertility effects may be missed. The information requirements could be improved by automatic triggering of follow-up studies in case of a Category 2 classification based on a screening study. Additionally, a study could be added to the information requirements for substances produced at 1-10 tpa. Performing a risk assessment is often problematic due to the limited study requirements at low tonnage levels. Only for substances produced at more than 100 tpa, there is a high likelihood to detect reproductive effects and perform accurate risk assessment provided that the extended-one-generation-reproductive-toxicity-study and/or extra cohorts are triggered where required. Regardless of the tonnage level, no specific studies on lactation are required. With this paper we intend to contribute to the discussion on the information requirements for reproductive toxicity in view of the REACH revision.

Hepatotoxic Evaluation of N-(2-Hydroxyphenyl)-2-Propylpentanamide: A Novel Derivative of Valproic Acid for the Treatment of Cancer

Valproic acid (VPA) is a drug that has various therapeutic applications; however, it has been associated with liver damage. Furthermore, it is interesting to propose new compounds derived from VPA as N-(2-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA). The HO-AAVPA has better antiproliferative activity than the VPA in different cancer cell lines. The purpose of this study was to evaluate the liver injury of HO-AAVPA by acute treatment (once administration) and repeated doses for 7 days under intraperitoneal administration. The median lethal dose value (LD50) was determined in rats and mice (females and males) using OECD Guideline 425. In the study, male rats were randomly divided into 4 groups (n = 7), G1: control (without treatment), G2: vehicle, G3: VPA (500 mg/kg), and G4: HO-AAVPA (708 mg/kg, in equimolar ratio to VPA). Some biomarkers related to hepatotoxicity were evaluated. In addition, macroscopic and histological studies were performed. The LD50 value of HO-AAVPA was greater than 2000 mg/kg. Regarding macroscopy and biochemistry, the HO-AAVPA does not induce liver injury according to the measures of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, glutathione peroxidase, glutathione reductase, and catalase activities. Comparing the treatment with HO-AAVPA and VPA did not show a significant difference with the control group, while malondialdehyde and glutathione-reduced levels in the group treated with HO-AAVPA were close to those of the control (p ≤ 0.05). The histological study shows that liver lesions caused by HO-AAVPA were less severe compared with VPA. Therefore, it is suggested that HO-AAVPA does not induce hepatotoxicity at therapeutic doses, considering that in the future it could be proposed as an antineoplastic drug.

Determining the endocrine disruption potential of industrial chemicals using an integrative approach: Public databases, in vitro exposure, and modeling receptor interactions

Environmental and occupational exposure to industrial chemicals has been linked to toxic and carcinogenic effects in animal models and human studies. However, current toxicology testing does not thoroughly explore the endocrine disrupting effects of industrial chemicals, which may have low dose effects not predicted when determining the limit of toxicity. The objective of this study was to evaluate the endocrine disrupting potential of a broad range of chemicals used in the petrochemical sector. Therefore, 139 chemicals were classified for reproductive toxicity based on the United Nations Globally Harmonized System for hazard classification. These chemicals were evaluated in PubMed for reported endocrine disrupting activity, and their endocrine disrupting potential was estimated by identifying chemicals with active nuclear receptor endpoints publicly available databases. Evaluation of ToxCast data suggested that these chemicals preferentially alter the activity of the estrogen receptor (ER). Four chemicals were prioritized for in vitro testing using the ER-positive, immortalized human uterine Ishikawa cell line and a range of concentrations below the reported limit of toxicity in humans. We found that 2,6-di-tert-butyl-p-cresol (BHT) and diethanolamine (DEA) repressed the basal expression of estrogen-responsive genes PGR, NPPC, and GREB1 in Ishikawa cells, while tetrachloroethylene (PCE) and 2,2'-methyliminodiethanol (MDEA) induced the expression of these genes. Furthermore, low-dose combinations of PCE and MDEA produced additive effects. All four chemicals interfered with estradiol-mediated induction of PGR, NPPC, and GREB1. Molecular docking demonstrated that these chemicals could bind to the ligand binding site of ERα, suggesting the potential for direct stimulatory or inhibitory effects. We found that these chemicals altered rates of proliferation and regulated the expression of cell proliferation associated genes. These findings demonstrate previously unappreciated endocrine disrupting effects and underscore the importance of testing the endocrine disrupting potential of chemicals in the future to better understand their potential to impact public health.

Reproductive and developmental toxicity study of caffeic acid in mice

Caffeic acid is an antioxidant commonly used to promote hematopoiesis and hemostasis. However, little is known about its systemic safety profile in reproduction and development. Here, we focused on the reproductive and developmental toxicity of caffeic acid in F0 female mice and F1 offspring. In the three-segment study, the F0 female mice were continuously exposed to 0, 0.15, 5 or 150 mg/kg/day of caffeic acid by gavage. We found that 5 mg/kg/day and 150 mg/kg/day of caffeic acid affected implantation of embryos when administered before gestation day 6. In addition, 150 mg/kg/day of caffeic acid affected fetal weight gain. No maternal toxicity, fetal teratogenesis or post-natal effects on pup development were observed. The no-observed-adverse-effect-level was 0.15 mg/kg/day for pregnant mice under the conditions of this study.