Background: The RD(50) (exposure concentration producing a 50% respiratory rate decrease) test evaluates airborne chemicals for sensory irritation and has become an American Society for Testing and Materials (ASTM) standard method. Past studies reported good correlations (R(2)) between RD(50)s and the occupational exposure limits, particularly threshold limit values (TLVs).
Objective: The main purpose of this study was to examine the relationship between RD(50)s and human sensory irritation responses in a quantitative manner, particularly for chemicals that produce burning sensation of the eyes, nose, or throat, based on lowest observed adverse effect levels (LOAELs) reported for human subjects.
Methods: We compared RD(50)s with LOAELs and acute reference exposure levels (RELs). RELs, developed by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment, represent a level at which no adverse effects are anticipated after exposure. We collected RD(50)s from the published literature and evaluated them for consistency with ASTM procedures. We identified LOAELs for human irritation and found 25 chemicals with a corresponding RD(50) in mice.
Discussion: We found the relationship between RD(50)s and LOAELs as log RD(50) = 1.16 (log LOAEL) + 0.77 with an R(2) value of 0.80. This strong correlation supports the use of the RD(50) in establishing exposure limits for the public. We further identified 16 chemical irritants with both RD(50)s and corresponding acute RELs, and calculated the relationship as log RD(50) = 0.71 (log REL) + 2.55 with an R(2) value of 0.71. This relationship could be used to identify health protective values for the public to prevent respiratory or sensory irritation.
Conclusion: Consequently, we believe that the RD(50) has benefits for use in setting protective levels for the health of both workers and the general population.
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http://dx.doi.org/10.1289/ehp.9848 | DOI Listing |
Ecotoxicol Environ Saf
January 2025
Department of Stomatology, the Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, No. 242, Guangji Road, Suzhou, Jiangsu Province 215000, China. Electronic address:
Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in utero can result in osteogenic defect during palatogenesis, but the effects on other craniofacial bones and underlying mechanisms remain to be characterized. By treating pregnant mice with TCDD (40 μg/kg) at the vital craniofacial patterning stages (embryonic day 8.5, 10.
View Article and Find Full Text PDFEcotoxicol Environ Saf
January 2025
Chinese Medicine Guangdong Laboratory, Hengqin 519031, China; State Key Laboratory of Traditional Chinese Medicine Syndrome, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address:
Aging populations are susceptible to climate change due to physiological factors and comorbidities. Most relevant studies reported the effect of temperature on cardiovascular disease (CVD)-related mortality in aging populations. However, the combined effects of temperature and humidity on CVD-related mortality remain unclear.
View Article and Find Full Text PDFPLoS One
January 2025
Department of Pain Medicine, Aichi Medical University, Nagakute, Aichi, Japan.
Background: Lowering barometric pressure (LP) can exacerbate neuropathic pain. However, animal studies in this field are limited to a few conditions. Furthermore, although sympathetic involvement has been reported as a possible mechanism, whether the sympathetic nervous system is involved in the hypothalamic-pituitary-adrenal (HPA) axis remains unknown.
View Article and Find Full Text PDFMagnetic resonance imaging (MRI) is one of the most commonly used tools in neuroscience. However, it implies exposure to high noise levels. Exposure to noise can lead to temporary or permanent hearing loss, especially when the exposure is long and/or repeated.
View Article and Find Full Text PDFAm J Audiol
January 2025
Department of Communication Sciences and Disorders, University of Wisconsin-Madison.
Purpose: Prior work estimating sound exposure dose from earphone use has typically measured earphone use time with retrospective questionnaires or device-based tracking, both of which have limitations. This research note presents an exploratory analysis of sound exposure dose from earphone use among college-aged adults using real-ear measures to estimate exposure level and ecological momentary assessment (EMA) to estimate use time.
Method: Earphone levels were measured at the ear drum of 53 college students using their own devices, earphones, and preferred music and speech stimuli at their normal listening volume.
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