Indoor Residence Times of Semivolatile Organic Compounds: Model Estimation and Field Evaluation

Abstract

Indoor residence times of semivolatile organic compounds (SVOCs) are a major and mostly unavailable input for residential exposure assessment. We calculated residence times for a suite of SVOCs using a fugacity model applied to residential environments. Residence times depend on both the mass distribution of the compound between the "mobile phase" (air and dust particles settled on the carpet) and the "non-mobile phase" (carpet fibers and pad) and the removal rates resulting from air exchange and cleaning. We estimated dust removal rates from cleaning processes using an indoor-particle mass-balance model. Chemical properties determine both the mass distribution and relative importance of the two removal pathways, resulting in different residence times among compounds. We conducted a field study after chlorpyrifos was phased out for indoor use in the United States in 2001 to determine the decreases in chlorpyrifos air concentrations over a one-year period. A measured average decrease of 18% in chlorpyrifos air concentrations indicates the residence time of chlorpyrifos is expected to be 6.9 years and compares well with model predictions. The estimates from this study provide the opportunity to make more reliable estimates of SVOCs exposure in the indoor residential environment.

Distribution and determinants of urinary biomarkers of exposure to organophosphate insecticides in Puerto Rican pregnant women

“…We had questionnaire information on weekly chore frequency and duration, which may correlate with outdoor activities, but additional investigation of these variables with respect to employment status did not reveal any noteworthy relationships (data not shown). It is also possible that unemployed women spend more time inside the home where OP insecticides may persist due to protection from moisture, sunlight, and other conditions that lead to chemical degradation (Shin et al, 2013), or have differences in diet and sources of food relative to employed women, which influence exposure. Although Yolton et al (2013) reported a relationship that was opposite of our study findings (unemployed women had lower OP metabolite urinary concentrations than other women), which may reflect differences in occupational exposures between pregnant women living in Cincinnati versus Puerto Rico.…”

“…Direct use of pesticides by the participant creates opportunities for exposure. Because OP insecticides are fairly persistent indoors (Shin et al, 2013), there are also opportunities for exposure long after the product has been applied. The associations identified with being married and the other home pest-related issues are difficult to explain and are perhaps chance findings.…”

Polybrominated diphenyl ether (PBDE) concentrations and resulting exposure in homes in California: relationships among passive air, surface wipe and dust concentrations, and temporal variability

“…Detailed explanations of the extraction, cleanup, and analysis procedures for PBDE analysis are published elsewhere (Clifton et al, 2013; Shin et al, 2013). Briefly, dust samples were sieved to ≤150 µm and extracted using accelerated solvent extraction.…”

Measurement of Organophosphate Pesticides, Organochlorine Pesticides, and Polycyclic Aromatic Hydrocarbons in Household Dust from Two Rural Villages in Nepal

“…These levels are much higher than the levels seen on the compacted red clay floors in both Nepali villages in this study, where the maximum level of methyl parathion was 532 ng/m 2 . Carpet has been identified as a reservoir that can slow the removal of semivolatile organic compounds [58] such as methyl parathion, and as a source of increased particulate matter exposure when compared to bare floors [59]. In the rural Nepali homes in this study, the compacted red clay floors were cleaned with brooms, and floors were regularly re-mudded once per year during festival times.…”