BackgroundThe RD50 (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 (R2) between RD50s and the occupational exposure limits, particularly threshold limit values (TLVs).ObjectiveThe main purpose of this study was to examine the relationship between RD50s 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.MethodsWe compared RD50s 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 RD50s 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 RD50 in mice.DiscussionWe found the relationship between RD50s and LOAELs as log RD50 = 1.16 (log LOAEL) + 0.77 with an R2 value of 0.80. This strong correlation supports the use of the RD50 in establishing exposure limits for the public. We further identified 16 chemical irritants with both RD50s and corresponding acute RELs, and calculated the relationship as log RD50 = 0.71 (log REL) + 2.55 with an R2 value of 0.71. This relationship could be used to identify health protective values for the public to prevent respiratory or sensory irritation.ConclusionConsequently, we believe that the RD50 has benefits for use in setting protective levels for the health of both workers and the general population.
We characterize cumulative intakes of organophosphorus (OP) pesticides in an agricultural region of California by drawing on human biomonitoring data, California pesticide use reporting (PUR) data, and limited environmental samples together with outputs from the CalTOX multimedia, multipathway, source-to-dose model. The study population is the CHAMACOS cohort of almost 600 pregnant Latina women in the Salinas Valley region. We use model estimates of OP intake and urinary dialkylphosphate (DAP) metabolite excretion to develop premises about relative contributions from different exposure sources and pathways. We evaluate these premises by comparing the magnitude and variation of DAPs in the CHAMACOS cohort with those of the whole U.S. population using data from the National Health and Nutrition Examination Survey (NHANES). This comparison supports the premise that diet is the common and dominant exposure pathway in both populations. Biomarker comparisons and model results support the observation that, relative to NHANES, the CHAMACOS population has a statistically significant (p < 0.001) added intake of OP pesticides with low inter-individual variability. We attribute the magnitude and small variance of this intake to residential nondietary exposures from local agricultural OP uses. These results show that mass-balance models can estimate exposures for OP pesticides within the range measured by biological monitoring.
BackgroundMultiple sensitizations in early age have been reported to be a risk for development of asthma. This study evaluates the emergence and evolution of IgE to aeroallergens among a cohort of children with physician-diagnosed atopic dermatitis and/or showing food allergy symptoms and to examine the relation to asthma development.MethodsThree-hundred and four children (median age 13.4 months at entry) with food allergy symptoms and/or atopic dermatitis without asthma at inclusion were analysed for IgE antibodies against food-, indoor- and outdoor-allergens and pet allergen components and correlated to the individuals’ outcome on asthma inception.ResultsAt 2 years of follow-up, physician-diagnosed asthma was 19.7% (n = 49) and asthma diagnosed any time was 24% (n = 67). History of persistent cough and asthma of father, combination of milk- and wheat-allergy symptoms and dual sensitization to house dust mite and Japanese cedar were independent risk factors for asthma. Sensitization to dog was the most prevalent inhalant allergen at entry. Asthma children had a higher proportion of sensitization to dog, cat and horse allergens at entry compared with non-asthma children. Being sensitized to both food, house dust mite and pet allergens was strongly associated with asthma (p = 0.0006). Component resolved diagnosis for dog and cat allergens showed that IgE antibodies to Can f 1 and Fel d 1 was common even at very young age.ConclusionsEarly sensitization to inhalant allergens increases the risk of developing asthma as well as having milk and wheat allergy symptoms. Sensitization to dog, was common at an early age despite dog ownership. Sensitization to secretoglobin and lipocalins and less to serum albumins explained the pet sensitization.
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