Resistance to Seven Site-Specific Fungicides in Botrytis cinerea from Greenhouse-Grown Ornamentals.

The fungal pathogen Botrytis cinerea is a notorious problem on many floriculture greenhouse hosts including petunia, geranium, and poinsettia; these key crops contribute to the $6.43 billion U.S. ornamental industry. While growers use cultural strategies to reduce relative humidity and free moisture to limit Botrytis blight, fungicides remain a primary component of control programs. Isolates (n = 386) of B. cinerea sampled from symptomatic petunia, geranium, and poinsettia in Michigan greenhouses from 2018 to 2021 were screened for resistance to eight fungicides belonging to seven Fungicide Resistance Action Committee (FRAC) groups. Single-spored isolates were subjected to a germination-based assay using previously defined discriminatory doses of each fungicide. Resistance was detected to thiophanate-methyl (FRAC 1; 94%), pyraclostrobin (FRAC 11; 80%), boscalid (FRAC 7; 67%), iprodione (FRAC 2; 65%), fenhexamid (FRAC 17; 38%), cyprodinil (FRAC 9; 38%), fludioxonil (FRAC 12; 21%), and fluopyram (FRAC 7; 13%). Most isolates (63.5%) were resistant to at least four FRAC groups, with 8.7% of all isolates demonstrating resistance to all seven FRAC groups tested. Resistance frequencies for each fungicide were similar among crops, production regions, and growing cycles but varied significantly for each greenhouse. Phenotypic diversity was high, as indicated by the 48 different fungicide resistance profiles observed. High frequencies of resistance to multiple fungicides in B. cinerea populations from floriculture hosts highlight the importance of sustainable and alternative disease management practices for greenhouse growers.

Advancing the science on chemical classes.

BACKGROUND: Hazard identification, risk assessment, regulatory, and policy activity are usually conducted on a chemical-by-chemical basis. Grouping chemicals into categories or classes is an underutilized approach that could make risk assessment and management of chemicals more efficient for regulators. OBJECTIVE AND METHODS: While there are some available methods and regulatory frameworks that include the grouping of chemicals (e.g.,same molecular mechanism or similar chemical structure) there has not been a comprehensive evaluation of these different approaches nor a recommended course of action to better consider chemical classes in decision-making. This manuscript: 1) reviews current national and international approaches to grouping; 2) describes how groups could be defined based on the decision context (e.g., hazard/risk assessment, restrictions, prioritization, product development) and scientific considerations (e.g., intrinsic physical-chemical properties); 3) discusses advantages of developing a decision tree approach for grouping; 4) uses ortho-phthalates as a case study to identify and organize frameworks that could be used across agencies; and 5) discusses opportunities to advance the class concept within various regulatory decision-making scenarios. RESULTS: Structural similarity was the most common grouping approach for risk assessment among regulatory agencies (national and state level) and non-regulatory organizations, albeit with some variations in its definition. Toxicity to the same target organ or to the same biological function was also used in a few cases. The phthalates case study showed that a decision tree approach for grouping should include questions about uses regulated by other agencies to encourage more efficient, coherent, and protective chemical risk management. DISCUSSION AND CONCLUSION: Our evaluation of how classes of chemicals are defined and used identified commonalities and differences based on regulatory frameworks, risk assessments, and business strategies. We also identified that using a class-based approach could result in a more efficient process to reduce exposures to multiple hazardous chemicals and, ultimately, reduce health risks. We concluded that, in the absence of a prescribed method, a decision tree approach could facilitate the selection of chemicals belonging to a pre-defined class (e.g., chemicals with endocrine-disrupting activity; organohalogen flame retardants [OFR]) based on the decision-making context (e.g., regulatory risk management).

Characterizing Extractables and Leachables Chemical Space to Support In Silico Toxicological Hazard Assessments.

This article describes the development of a representative dataset of extractables and leachables (E&L) from the combined Extractables and Leachables Safety Information Exchange (ELSIE) Consortium and the Product Quality Research Institute (PQRI) published datasets, representing a total of 783 chemicals. A chemical structure-based clustering of the combined dataset identified 142 distinct chemical classes with two or more chemicals across the combined dataset. The majority of these classes (105 chemical classes out of 142) contained chemicals from both datasets, whereas 8 classes contained only chemicals from the ELSIE dataset and 29 classes contain only chemicals from the PQRI dataset. This evaluation also identified classes containing chemicals that were flagged as potentially mutagenic as well as potent (strong or extreme) dermal sensitizers by in silico tools. The prevalence of alerting structures in the E&L datasets was approximately 9% (69 examples) for mutagens and 3% (25 examples) for potent sensitizers. This analysis showed that most (80%; 20 of 25) E&L predicted to be strong or extreme dermal sensitizers were also flagged as potential mutagens. Only two chemical classes, each containing three chemicals (alkyl bromides and isothiocyanates), were uniquely identified in the PQRI dataset and contained chemicals predicted to be potential mutagens and/or potent dermal sensitizers.

Systematic evidence mapping informs a class-based approach to assessing personal care products and pubertal timing.

BACKGROUND: Personal care products (PCPs) contain many different compounds and are a source of exposure to endocrine disrupting chemicals (EDCs), including phthalates and phenols. Early-life exposure to EDCs commonly found in PCPs has been linked to earlier onset of puberty. OBJECTIVE: To characterize the human and animal evidence on the association between puberty-related outcomes and exposure to PCPs and their chemical constituents and, if there is sufficient evidence, identify groups of chemicals and outcomes to support a systematic review for a class-based hazard or risk assessment. METHODS: We followed the OHAT systematic review framework to characterize the human and animal evidence on the association between puberty-related health outcomes and exposure to PCPs and their chemical constituents. RESULTS: Ninety-eight human and 299 animal studies that evaluated a total of 96 different chemicals were identified and mapped by key concepts including chemical class, data stream, and puberty-related health outcome. Among these studies, phthalates and phenols were the most well-studied chemical classes. Most of the phthalate and phenol studies examined secondary sex characteristics and changes in estradiol and testosterone levels. Studies evaluating PCP use and other chemical classes (e.g., parabens) had less data. CONCLUSIONS: This systematic evidence map identified and mapped the published research evaluating the association between exposure to PCPs and their chemical constituents and puberty-related health outcomes. The resulting interactive visualization allows researchers to make evidence-based decisions on the available research by enabling them to search, sort, and filter the literature base of puberty-related studies by key concepts. This map can be used by researchers and regulators to prioritize and target future research and funding to reduce uncertainties and address data gaps. It also provides information to inform a class-based hazard or risk assessment on the association between phthalate and phenol exposures and puberty-related health outcomes.