Association of mechanical ventilation and flue use in heaters with asthma symptoms in Japanese schoolchildren: a cross-sectional study in Sapporo, Japan.

BACKGROUND: Use of fuel heaters is associated with childhood asthma. However, no studies have evaluated the associations of flue use and mechanical ventilation (ventilation) with asthma symptoms in schoolchildren. METHODS: This cross-sectional study investigated schoolchildren in grades 1 through 6 (age 6-12 years) in Sapporo, Japan. From November 2008 through January 2009, parents completed questionnaires regarding their home environment and their children's asthma symptoms. RESULTS: In total, 4445 (69.5%) parents of 6393 children returned the questionnaire. After excluding incomplete responses, data on 3874 children (60.6%) were analyzed. The prevalence of current asthma symptoms and ever asthma symptoms were 12.8% and 30.9%, respectively. As compared with electric heaters, current asthma symptoms was associated with use of flued heaters without ventilation (OR = 1.62; 95% CI, 1.03-2.64) and unflued heaters with ventilation (OR = 1.77; 95% CI, 1.09-2.95) or without ventilation (OR = 2.23; 95% CI, 1.31-3.85). Regardless of dampness, unflued heaters were significantly associated with current asthma symptoms in the presence and absence of ventilation. CONCLUSIONS: Use of unflued heaters was associated with current asthma symptoms, regardless of dampness. In particular, the prevalence of current asthma symptoms was higher in the absence of ventilation than in the presence of ventilation. Ever asthma symptoms was only associated with use of unflued heaters without ventilation. Consequently, use of fuel heaters, especially those that have no flue or ventilation, deserves attention, as their use might be associated with childhood asthma symptoms.

Detection and intake assessment of organophosphate flame retardants in house dust in Japanese dwellings.

The demand for phosphorus flame retardants (PFRs) has recently increased as an alternative to polybrominated diphenyl ether (PBDE). PFRs have been detected in house dust, but little is known about the concentrations of PFRs in private homes and the effects on human health. We measured the levels of 10 PFRs in indoor floor dust and upper surface dust from 128 Japanese dwellings of families with children in elementary school. The median (min-max) concentrations (µg/g) of PFRs were as follows: tris(2-butoxyethyl) phosphate (TBOEP), 30.88 (<0.61-936.65); tris(2-chloro-iso-propyl) phosphate (TCIPP), 0.74 (<0.56-392.52); and triphenyl phosphate (TPHP), 0.87 (<0.80-23.35). These values exceeded 50% detection rates, and the rates are median over the LOD in floor dust. The concentrations (µg/g) of TBOEP 26.55 (<0.61-1933.24), TCIPP 2.23 (<0.56-621.23), TPHP 3.13 (<0.80-27.47), tris(2-chloroethyl) phosphate (TCEP) 1.17 (<0.65-92.22), and tributyl phosphate (TNBP) 0.74 (<0.36-60.64) exceeded 50% detection rates in the upper surface dust. A significant positive correlation (P<0.05) between the concentrations of TCIPP and TBOEP was shown in floor dust and upper surface dust (n=48). Estimated median and 95th percentile daily intake was calculated for toddlers and elementary school children and was compared with reference dose values (RfD) from the literature. For TBOEP, the estimated 95th percentile intake from floor dust was 14% of RfD for toddlers and 4% for school children. The estimated intake from upper surface dust was somewhat lower. Estimated median intake of TBOEP and median intake for the other PFRs were less than 1% of the RfD. TBOEP, TCIPP and TPHP were the main PFRs in the dust. The median levels of PFRs are well below the RfD values.

Associations of phthalate concentrations in floor dust and multi-surface dust with the interior materials in Japanese dwellings.

Phthalates are widely used as plasticizers in numerous products. However, there has been some concern about the various effects they may have on human health. Thus, household phthalate levels are an important public health issue. While many studies have assessed phthalate levels in house dust, the association of these levels with building characteristics has scarcely been examined. The present study investigated phthalate levels in house dust samples collected from the living areas of homes, and examined associations between these phthalate levels and the interior materials. Dust was collected from two portions of the living area: floor dust from the entire floor surface, and multi-surface dust from objects more than 35 cm above the floor. The levels of seven phthalates were measured using gas chromatography/mass spectrometry in selective ion monitoring mode. Phthalate levels were higher in multi-surface dust than in floor dust. Among floor dust samples, those from dwellings with compressed wooden flooring had significantly higher levels of di-iso-butyl phthalate compared to those with other floor materials, while polyvinyl chloride (PVC) flooring was associated with higher di-2-ethylhexyl phthalate (DEHP) levels. Among multi-surface dust samples, higher levels of DEHP and di-iso-nonyl phthalate (DINP) were found in samples from homes with PVC wallpaper than without. The number of PVC interior materials was significantly positively correlated with the levels of DEHP and DINP in multi-surface dust. The phthalate levels in multi-surface dust were associated with the interior surface materials, and those in floor dust were directly related to the flooring materials. Our findings show that when using house dust as an exposure assessment, it is very important to note where the samples were collected from. The present report provides useful information about the association between phthalates and dust inside dwellings, which will assist with establishing public health provisions.