Estimating indoor galaxolide concentrations using predictive models based on objective assessments and data about dwelling characteristics.

BACKGROUND: Galaxolide (HHCB) is used for fragrance in many consumer products. The aim of the current study was to use objective assessments of HHCB to build a predictive model in order to estimate indoor-measured HHCB concentrations from questionnaire-based data on dwelling characteristics and occupants' habits and activities. METHODS: Environmental assessments of indoor HHCB, dwelling characteristics were carried out in 150 dwellings in Brittany (France). Among the various models that were tested, the best predictive model for the reduced set of characteristics was identified on the basis of the coefficient of determination (R2) criterion. RESULTS: Linear regression model showed among the best performances (R2 = 0.48), together with some more complex models. According to the estimated results, the main variables that significantly increased HHCB concentrations were: living in rural area, drying clothes inside dwellings, painted walls, chipboard furniture, double glazing, damaged floors and duration of bathroom door being kept open. Laminated floors and presence of indoor plants were found to significantly decrease HHCB concentrations. DISCUSSION: The linear model based on objective assessments and questionnaire-derived data about dwelling characteristics and occupants' activities constituted an easy method for predicting indoor air HHCB concentrations. For studies including a large number of dwellings, modeling of HHCB concentrations is cheaper than measuring it in every location. Our methodological procedure can be applied to other indoor air pollutants.

Reduced hypoxic ventilatory response in newborn mice knocked-out for the progesterone receptor.

Recent studies showed that progesterone stimulates the hypoxic ventilatory response and may reduce apnoea frequency in newborn rats, but so far we still do not know by what mechanisms and whether endogenous progesterone might contribute to respiratory control in neonates. We therefore determined the role of the nuclear progesterone receptor (PR; member of the steroid receptor superfamily) by using wild-type (WT) and PR knock-out (PRKO) mice at postnatal days (P) 1, 4 and 10. We measured the hypoxic ventilatory response (14 and 12% O2, 20 min each) and apnoea frequency in both male and female mice by using whole-body plethysmography. In response to hypoxia, WT male mice had a marked hypoxic ventilatory response at P1 and P10, but not at P4. At P1 and P10, PRKO male mice had a lower hypoxic ventilatory response than WT males. Wild-type female mice had a marked hypoxic ventilatory response at P10, but not at P1 and P4. At P1 and P10, PRKO female mice had a lower hypoxic ventilatory response than WT females. In basal conditions, apnoea frequency was similar in WT and PRKO mice at P1, P4 and P10. During hypoxia, apnoea frequency was higher in WT male mice compared with PRKO male mice and WT female mice at P1. We conclude that PR is a key contributor to the hypoxic ventilatory response in newborn mice, but PR deletion does not increase the frequency of apnoea during normoxia or hypoxia.

Concentration and determinants of molds and allergens in indoor air and house dust of French dwellings.

Molds and allergens are common indoor biocontaminants. The aims of this study were to assess the concentrations of common molds in indoor air and floor dust and the concentrations of house dust mite, cat and dog allergens in mattress dust in French dwellings, and to assess predictors of these concentrations. A sample of 150 houses in Brittany (western France) was investigated. Airborne Cladosporium and Penicillium were detected in more than 90% of the dwellings, Aspergillus in 46% and Alternaria in only 6% of the housings. Regarding floor dust samples, Cladosporium and Penicillium were detected in 92 and 80% of the housings respectively, Aspergillus in 49% and Alternaria in 14%. House dust mite allergens Der p1 and Der f1 were detected in 90% and 77% of the mattress dust samples respectively and Can f1 and Fel d1 in 37% and 89% of the homes. Airborne and dustborne mold concentrations, although not statistically correlated (except for Aspergillus) shared most of their predictors. Multivariate linear models for mold levels, explaining up to 62% of the variability, showed an influence of the season, of the age of the dwelling, of aeration habits, presence of pets, smoking, signals of dampness, temperature and relative humidity. Allergens in the dust of the mattress were strongly related to the presence of pets and cleaning practices of bedsheets, these factors accounting for 60% of the variability. This study highlights ubiquitous contamination by molds and underlines complex interaction between outdoor and indoor sources and factors.