Retrospective evaluation of the eye irritation potential of agrochemical formulations.

Multiple in vitro eye irritation methods have been developed and adopted as OECD health effects test guidelines. However, for predicting the ocular irritation/damage potential of agrochemical formulations there is an applicability domain knowledge gap for most of the methods. To overcome this gap, a retrospective evaluation of 192 agrochemical formulations with in vivo (OECD TG 405) and in vitro (OECD TG 437, 438, and/or 492) data was conducted to determine if the in vitro methods could accurately assign United Nations Globally Harmonized System for Classification and Labelling of Chemicals (GHS) eye irritation hazard classifications. In addition, for each formulation the eye irritation classification was derived from the classification of the contained hazardous ingredients and their respective concentration in the product using the GHS concentration threshold (CT) approach. The results herein suggest that the three in vitro methods and the GHS CT approach were highly predictive of formulations that would not require GHS classification for eye irritation. Given most agrochemical formulations fall into this category, methods that accurately identify non-classified agrochemical formulations could significantly reduce the use of animals for this endpoint.

Assessment of Urothelial Cytotoxicity at Morphological and Molecular Levels: Urinary Bladder as Target Organ.

The urinary bladder is a target organ of several toxic agents. Exposure to those agents induces mild-to-severe changes, which can be evaluated by different methods. Among them, the scanning-electron microscopy (SEM) is the "gold standard" for characterizing urothelial damage since it provides high-definition images, making it possible to detect early lesions on the surface of the urinary bladder. In addition, molecular technologies allow detecting changes in genetic material and investigating the interaction between genes and environmental stress in disease causation. The urinary bladder epithelium is where the most common type of bladder cancer occurs in humans, that is, the transitional-cell carcinoma (TCC). In animal models, the TCC can be similar to the disease in humans. Techniques to evaluate urothelium in experimental models aid in the comprehension of risk factors for urothelial carcinogenesis.

Implementing a globally harmonized risk assessment-based approach for regulatory decision-making of crop protection products.

A global, harmonized evaluation system for crop protection chemicals based on exposure and risk will improve the ability to inform risk management decisions and better support innovation. This would be achieved through harmonized risk assessment-based regulatory decision-making realized through the application of the best available science, via integration of new methods and traditional data to create tailored exposure-driven risk assessments. A requirement to achieve success is a structure that encourages direct communication between the regulatory community and the regulated industry, which would enable a more rapid incorporation of new technologies and advancing science. An approach that emulates the International Conference of Harmonization (ICH) for pharmaceuticals would bring together regulatory authorities and the regulated industry along with relevant experts from academia and Non-Governmental Organizations to discuss scientific and technical advances and their implementation. These discussions would also encourage the elimination of outmoded practices that no longer serve a purpose resulting in more uniform testing requirements and best practices for data evaluation to support safe use and scientifically defensible human health and environmental risk assessments. New and developing technologies offer exciting opportunities to improve the current toxicity testing paradigms to provide better solutions and diminish animal testing. Implementation of a harmonized approach will increase the speed, efficiency and accuracy of regulatory decision-making for human health and environmental protection while increasing the efficiency of providing safe and effective innovative products to the agriculture community. © 2020 Society of Chemical Industry.

Non-relevance of acute dermal toxicity testing for assessing human health protection in the regulatory decision-making for agrochemical formulated products.

Compared to oral toxicity tests, dermal toxicity tests offer little or no additional scientific information or public health protection for agrochemical-formulated products (US EPA, 2016). Based on that, a retrospective analysis of the results of acute oral and dermal LD50 studies of agrochemical products registered in Brazil was carried out by the Technical Group on Toxicological Risk Assessment (GT-ART) of the Brazilian Crop Protection Association (ANDEF). The data were obtained from 6 agrochemical industries that are associated to ANDEF, following these considerations: only rat studies were selected; only paired studies were chosen; only studies performed with top doses ≥2,000 mg/kg were selected; biological products were excluded. The dataset includes 342 formulated products in 21 formulation types. Among these 342 formulated products, 228 have a single active ingredient, 107 have 2 and 7 have 3 or more. The comparison of acute oral to dermal toxicity studies of agrochemical-formulated products registered in Brazil corroborates the United States Environmental Protection Agency (US EPA) conclusion on waiving acute dermal toxicity tests, which will result in avoiding unnecessary use of time and resources, data generation costs and animal testing.

Dose and temporal effects on gene expression profiles of urothelial cells from rats exposed to diuron.

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is a substituted urea herbicide that at high dietary levels (2500 ppm) induces rat urinary bladder hyperplasia after 20 weeks of exposure and neoplasia after 2 years. The effects on the urothelium after short-term exposure have not been described. The present 7-day study evaluated the dose-dependency of urothelial alterations in the urinary bladder using light microscopy, scanning electron microscopy, and genome-wide transcriptional profiling. Male Wistar rats were fed 0, 125, 500, 2500 ppm diuron for 7 days. The urinary bladder and isolated urothelial cells of these animals were processed for microscopic examination and gene expression profiling, respectively. No significant treatment-related morphologic effects were observed. The number of differentially expressed genes (DEGs) in the exposed groups increased with diuron levels. Diuron-altered genes involved in cell-to-cell interactions and tissue organization were identified in all treatment groups. After 7 days of diuron exposure, transcriptional responses were observed in the urothelium in the absence of clear morphologic changes. These morphological findings are different from those observed in a previous study in which 20 weeks of diuron exposure was associated with simple hyperplasia secondary to the persistent cytotoxicity and necrosis associated with continuous cellular regeneration. Comparison of the gene expression profiles of rats exposed to the 2500 ppm carcinogenic diuron dose for 7 days versus 20 weeks revealed few similarities between these two time points at the gene or pathway level. Taken together, these data provide insight into the dose- and temporal-dependent morphological and transcriptional changes associated with diuron exposure that may lead to the development of tumors in the rat urinary bladder.

Diuron-induced rat urinary bladder carcinogenesis: mode of action and human relevance evaluations using the International Programme on Chemical Safety framework.

Diuron, a high volume substituted urea herbicide, induced high incidences of urinary bladder carcinomas and low incidences of kidney pelvis papillomas and carcinomas in rats exposed to high doses (2500 ppm) in a 2-year bioassay. Diuron is registered for both occupational and residential uses and is used worldwide for more than 30 different crops. The proposed rat urothelial mode of action (MOA) for this herbicide consists of metabolic activation to metabolites that are excreted and concentrated in the urine, leading to cytotoxicity, urothelial cell necrosis and exfoliation, regenerative hyperplasia, and eventually tumors. We show evidence for this MOA for diuron using the International Programme on Chemical Safety (IPCS) conceptual framework for evaluating an MOA for chemical carcinogens, and the United States Environmental Protection Agency (USEPA) and IPCS framework for assessing human relevance.

STEAP1 protein overexpression is an independent marker for biochemical recurrence in prostate carcinoma.

AIMS: To investigate the prognostic value of expression levels of the genes STEAP1 and STEAP2, and of STEAP1 protein, in prostate carcinomas (PCa). METHODS AND RESULTS: STEAP1 and STEAP2 transcript levels were evaluated by RT-qPCR in samples from 35 PCa, 24 adjacent non-neoplastic prostate (AdjP) tissues, five cases of benign prostatic hyperplasia (BPH), and two histologically normal prostates (N). STEAP1 expression was assessed by immunohistochemistry in samples from 198 PCa, 76 AdjP, 22 BPH, and two N. The findings were compared with clinical and pathological parameters and patient outcome. STEAP1 and STEAP2 transcript analysis showed no differences between the groups tested. Although not significant, higher STEAP1 mRNA levels were detected in tumours with high Gleason scores and in patients who presented with biochemical recurrence (BCR). STEAP1 overexpression was detected in PCa, and was significantly associated with high-grade Gleason scores, seminal vesicle invasion, BCR, and worse outcome (metastasis or PCa-specific death). STEAP1 overexpression was significantly associated with shorter BCR-free survival. Multivariate analysis revealed that STEAP1 is an independent marker for BCR. CONCLUSIONS: These findings provide evidence that STEAP1 is a biomarker of worse prognosis in PCa patients.

Dose-response of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in the urothelial mucosa of Wistar rats.

Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is a herbicide that induced urothelial tumors in the urinary bladder of Wistar rats fed 2500ppm during a long-term study. The currently suggested non-genotoxic mode of action (MOA) of diuron encompasses in succession urothelial necrosis induced by direct cytotoxicity, regenerative cell proliferation and sustained urothelial hyperplasia that increases the likelihood of neoplasia development. This study evaluated the dose-response profile of urothelial histological and ultrastructural lesions induced by diuron. Sixty male Wistar rats were fed ad libitum diuron mixed in the diet at 0, 60, 125, 500, 1250, or 2500ppm for 20 weeks. The incidences of urothelial simple hyperplasia and the cell proliferation index were significantly increased in the diuron-fed 1250 and 2500ppm groups. By scanning electron microscopy, the incidences and severity of lesions were significantly increased in the 500 and 1250ppm groups. The incidences of urothelial hyperplasia in the kidney pelvis were significantly increased in the 500, 1250 and 2500ppm groups. The present study documents the dose-response influence of diuron on the rat urothelium, with a no observed effect level (NOEL) at 125ppm; 1250ppm was as effective as 2500ppm at inducing urothelial lesions.