Review of EPA's 2022 Draft Formaldehyde Assessment (2023) / Chapter Skim
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3 Toxicokinetics
3 Toxicokinetics
Pages 45-52
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From page 45... ...
DISTRIBUTION OF INHALED FORMALDEHYDE The 2022 Draft Assessment considers factors that influence the distribution of inhaled formaldehyde at the point of entry in the respiratory tract. EPA also reviewed available dosimetry models evaluating the initial delivery of formaldehyde to the upper respiratory tract (URT)
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From page 46... ...
Finding: EPA concluded that inhaled formaldehyde is not distributed to an appreciable extent beyond the respiratory tract to systemic sites; thus, inhaled formaldehyde is not directly in teracting with tissues distal to the portal of entry to elicit effects. EPA's conclusions regard ing systemic delivery of inhaled formaldehyde are based on its expert judgment, with the support of available scientific evidence.
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From page 47... ...
These models incorporate dosimetric and mechanistic data into a single computational model. They have two main subunits: species-specific CFD models to describe formaldehyde delivery in the respiratory tract, and a two-stage clonal growth model for formaldehyde carcinogenesis.
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to determine average flux values in the anterior region of the rat nasal cavity that corresponded to the rat benchmark concentration lower bound (BMCL) derived from the incidence of squamous metaplasia seen in a study.
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were used to predict formaldehyde flux and DPC concentrations in the rat and human nasal cavities. These alternative model estimates are provided in the Assessment Overview of the 2022 Draft Assessment (Table 2-22, "Benchmark Concentrations and Human Equivalents Using Formaldehyde Flux and DPC as Dose Metrics")
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2015. Comparative risks of alde hyde constituents in cigarette smoke using transient computational fluid dynamics/physio logically based pharmacokinetic models of the rat and human respiratory tracts.
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2001. Dosimetry modeling of highly soluble reactive gases in the respiratory tract.
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From page 52... ...
Toxicological Sciences 146(1)
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