Journal of Toxicology and Environmental Health-Part B-Critical Reviews最新文献

To support regulatory risk assessment, standardized laboratory tests of toxicity to representative species including honeybees (Apis mellifera L.), orchard bees (Osmia spp.), and bumblebees (Bombus spp.) provide the benchmark toxicity values for use in preliminary Tier 1 assessments and more detailed and realistic higher-tier assessments. In this analysis, we summarize the results of studies of toxicity of SFX to pollinators conducted by the registrant as well as results published in the literature. The geometric mean of 48-hr adult acute oral LD₅₀ values for SFX for honeybees was 0.0740 μg SFX bee^-1 (n = 5). Toxicity values for technical grade SFX (SFX-T) and formulated products were not significantly different. The geometric mean 48 hr adult acute contact LD₅₀ values for SFX-T and several formulated products were 0.432 (n = 2) and 0.202 (n = 3) μg SFX bee^-1, respectively. Exposures sprayed foliage was not significant after the spray had dried did not cause significant toxicity. Transformation products were not significantly toxic to adult or larval honeybees or other representative bee species. Results showed that, to complete the risk assessment, higher-tier studies were required. Differences in results between standard test methods and the nonstandard methods used in published work affect the outcome of the risk assessment. An understanding of these differences reconciled the differences in the reported findings.

Atrazine is a chlorotriazine herbicide that is one of the most widely used herbicides in the USA and the world. For over 60 years atrazine has been used on major crops including corn, sorghum, and sugarcane to control broadleaf and grassy weed emergence and growth. Atrazine has exerted a major economic and environmental impact over that time, resulting in reduced production costs and increased conservation tillage practices. However, widespread use and a long half-life led to a high prevalence of atrazine in the environment. Indeed, atrazine is the most frequent herbicide contaminant detected in water sources in the USA. Due to its almost ubiquitous presence and questions regarding its safety, atrazine has been well-studied. First reported to affect reproduction with potential disruptive effects which were later linked to the immune system, cancer, stress response, neurological disorders, and cardiovascular ailments in experimental models. Atrazine impact on multiple interwoven systems broadens the significance of atrazine exposure. The endeavor to uncover the mechanisms underlying atrazine-induced dysfunction in mammals is ongoing, with new genetic and pharmacological targets being reported. This review aims to summarize the prominent effects of atrazine on mammalian physiology, primarily focusing on empirical studies conducted in lab animal models and establish correlations with epidemiological human studies when relevant. In addition, current common patterns of toxicity and potential underlying mechanisms of atrazine action will be examined.

In this paper, conceptual models of the exposure pathways outside the hive and the in-hive distribution of pesticide residues brought to the honeybee hive are presented. The conceptual model is based on the natural life history, behavior and diet of individual honeybees (Apis mellifera). Receptor groups of bees with similar diets and potential exposure are defined. From the conceptual model, a quantitative A. mellifera hazard and risk assessment model (AMHRA) is developed and illustrated using sulfoxaflor (SFX) as a case study. The model estimates the exposure of the receptor groups of honeybees within a colony via various routes of exposure. The user selects a deterministic mode to obtain hazard quotients (HQ) or a probabilistic mode to obtain risk quotients (RQ). The model was run in the deterministic mode using the pesticide concentrations in nectar and pollen from a field experiment in which SFX was applied to cotton crops at the highest permitted application rate of 101 g a.i. ha^-1. Acute and chronic exposure HQ values were calculated for the adult and larval receptor groups. The results showed that the SFX applied at the highest single application rate following the label directions was not hazardous to honeybees. The probabilistic mode was described but not run.

Sulfoxaflor (SFX) is a newly registered IRAC Group 4C nAChR-receptor-agonist systemic insecticide that is used to control sap-sucking insects in a variety of crops. SFX has a short half-life (< 2 days) in agricultural soil and is only used as a foliar-applied product. Pollinators such as honey bees could be exposed directly to spray if application occurs shortly before or during blooming of flowers, or, as SFX is systemic, via oral exposures to nectar and pollen collected by bees. Guided by a Weight-of-Evidence rubric, this paper critically assessed studies on the fate of SFX in bee-relevant matrices submitted by the registrant in several jurisdictions as well as a few studies published in the open scientific literature. These studies provided data for residues in pollen and/or nectar from 16 crops grown in several countries in both hemispheres. SFX and transformation products were detected in nectar and pollen. Transformation products have low hazard to honeybees, so the focus was on the parent material, SFX, which was observed to dissipate rapidly from pollen and nectar after application. Dietary No-Observed-Adverse-Effect-Concentrations (NOAEC) derived from results of 10-day continuous feeding studies of adult (0.50 mg kg^-1 diet d^-1) and larval honeybees (1.69 mg kg^-1 diet d^-1) were used as precautionary toxicity benchmarks to characterize hazards. In this paper, we used a tiered process. The initial screening tier was based on the greatest concentration measured in the matrix. For scenarios that did not pass Tier-1, a second tier based on the 10-day time-weighted average (area under the curve, AUC) concentration in the matrix was used as a more realistic measure of exposure. Of the 90 scenarios of use that were characterized, 36 did not pass the initial screening benchmark based on ≥1concentration of SFX exceeding the 10-day NOAEC. When the 10-day AUC of exposure was estimated for these scenarios, 3 of 90 did not pass the more realistic toxicity benchmark. These three scenarios were for residues in pollen or anthers for alfalfa grown in California, strawberries grown in France, peaches grown in Michigan. The two-tier screening procedure for hazard assessment lessened the need for further assessment for 97% of the exposure scenarios and reduced the need for characterizing hazards in field-level whole-hive tests conducted under controlled conditions of exposure.

Specific Target Organ Toxicity - Repeated Exposure (STOT-RE) is a hazard class in both Globally Harmonized System and Classification, Labelling and Packaging (CLP) Regulation in the European Union (EU) legislation on hazard classification labeling and packaging of substances and mixtures. This legislation, used for the chemical safety assessment under the EU Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), evaluates long-term exposure of chemicals on human or animals and designates three categories of classification - STOT RE 1 (potential to produce significant toxicity to humans); STOT RE 2 (presumed to be toxic to humans), or not classified. Human epidemiologic studies identified neurologic effects as the most sensitive adverse health effect following repeated manganese (Mn) exposure. However, there are inadequate human studies to assess the neurotoxicity and STOT-RE classification of the chloride, sulfate, and nitrate forms of Mn. This review summarizes peer-reviewed studies with original data identified from searches of PubMed and OECD studies submitted as part of the REACH information requirement. This review included peer-reviewed studies that exhibited a duration of ≥21 days, including oral or inhalation exposure, and reported neurobehavioral, neurochemical or neuropathologic outcomes. A total of 75, 6, and 0 investigations met the inclusion criteria for this review for the chloride, sulfate, and nitrate forms of Mn, respectively. Based upon retrieved data or read-across principles a proposed classification of these Mn salts, following repeated oral or inhaled exposure, is STOT RE 2, target organ, the brain.

Sulfoxaflor (SFX, CAS# 946578-00-3) is marketed by Corteva Agrisciences Inc. as Isoclast®. SFX is a Group 4C, nicotinic acetylcholine receptor agonist and is a systemic insecticide that is most active against sucking insects. This paper critically reviews and characterizes the physical and chemical properties of SFX to facilitate development of conceptual models that identify environmental compartments with the greatest potential concentrations and organisms most likely to be exposed. These conceptual models were assessed in a Weight of Evidence (WoE) framework to identify scenarios and organisms at greatest risk. The solubility of SFX in water is approximately 550 mg L^-1 and the P_OW of 0.8, so it will not bioconcentrate or undergo trophic transfer. It has the potential to move in soils, but this is unlikely because of the short half-life (hours to 2-5 days) in agricultural soils where bacteria mediate dissipation. Some of the transformation products of SFX have longer half-lives (months) in soil and are more mobile but are less toxic and not a concern for adverse effects. SFX does not undergo significant photolysis or hydrolysis in water, but this does not lead to a risk in aquatic systems because it is not approved for over-water use and the label recommends buffer zones to protect sensitive aquatic areas. Overall, use of SFX under good agricultural practices is unlikely to result in biologically relevant exposures in non-target species or areas in the environment.

Quaternary ammonium compounds (QACs) are widely used to kill pathogenic microbes (including COVID-19), providing a substantial public health benefit. This review is an update to our previous publications that summarized and interpreted the current knowledge of the safety of the two most widely used QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC). A literature search was conducted for studies published since 2000 that addressed possible toxicity of ADBAC and DDAC as well as investigations into human exposure. The current database of high-quality animal toxicology studies with ADBAC/DDAC showed that adverse cellular changes are limited to effects at the point of contact. (1) Non-guideline animal toxicology investigations, (2) studies of the effect of QACs on subcellular functions, and (3) the sole report of systemic effects in humans might not be informative for human health risk assessment. Because of their widespread use, human exposure to QACs is frequent. Various reports measured QACs in media in the home and workplaces. Risk calculations performed based upon these exposure estimates performed as part of this review demonstrated that none of the exposure scenarios examined are predicted to pose adverse health risks to exposed individuals.

The first paper in a series of seven serves as an overview of the initiation of the insecticide Sulfoxaflor Environmental Science review process and provides some regulatory background. The following papers are a series and describe a critical analysis of the data related to sulfoxaflor in terms of its uses, properties, environmental fate, and potential effects on aquatic organisms, and pollinators. The last paper describes a refined model for hazard and risk assessment of pesticides in pollinators.