Resuspension of house dust and allergens during walking and vacuum cleaning.

Conventional wisdom has been that hard, resilient surfaces resuspend fewer particles than carpeted surfaces, however, exceptions to this have been demonstrated and uncertainty remains about the factors that lead to this resuspension, notably, the effect of vacuum cleaning on either increasing or reducing resuspension from flooring. The purpose of this study was to determine how resuspension of house dust by aerodynamic size or particle type, including cat allergen and bacterial endotoxin, is affected by flooring, dust loading, embedding dust, and walking/cleaning activities. House dust was blown in and allowed to settle in a walk-in chamber after overnight deposition followed by walking or a vacuum cleaning procedure. Using an aerosol particle sizer and large-volume air samplers at different heights in the chamber, concentrations of airborne particles, resuspension rates, and fractions were computed for four types of flooring conditions during six walking activities. Carpeting resulted in significantly more airborne cat allergen and airborne endotoxin than a laminate floor. Height does have an effect on measured allergen over carpet and this is apparent with concentrations at the infant and adult air samplers. Walking on laminate flooring resuspends less house dust than walking on an equally dusty carpeted floor, where dust is entirely on the surface of the carpet. However, vacuum cleaning a laminate floor resuspended more dust than vacuum cleaning carpets, at large particle sizes of 5 µm and 10 µm. Activities following a deep cleaning of hard resilient or a carpeted surface is likely to leave no differences in resuspended particles between them.

The intersection of aggregate-level lead exposure and crime.

CONTEXT: Childhood lead exposure has been associated with criminal behavior later in life. The current study aimed to analyze the association between elevated blood lead levels (n=59,645) and crime occurrence (n=90,433) across census tracts within St. Louis, Missouri. DESIGN: Longitudinal ecological study. SETTING: Saint Louis, Missouri. EXPOSURE MEASURE: Blood lead levels. MAIN OUTCOME MEASURE: Violent, Non-violent, and total crime at the census tract level. RESULTS: Spatial statistical models were used to account for the spatial autocorrelation of the data. Greater lead exposure at the census-tract level was associated with increased violent, non-violent, and total crime. In addition, we examined whether non-additive effects existed in the data by testing for an interaction between lead exposure and concentrated disadvantage. Some evidence of a negative interaction emerged, however, it failed to reach traditional levels of statistical significance (supplementary models, however, revealed a similar negative interaction that was significant). CONCLUSIONS: More precise measurements of lead exposure in the aggregate, produced additional evidence that lead is a potent predictor of criminal outcomes.

Inactivation of Mold Spores from Moist Carpet Using Steam Vapor: Contact Time and Temperature.

Steam vapor has been shown to reduce viable mold spores in carpet, but the minimal effective temperature and contact time has not been established. This study evaluated the effectiveness of steam vapor in reducing the number of viable mold spores in carpet as a function of temperature and contact time. Seventy carpet samples were inoculated with a liquid suspension of Cladosporium sphaerospermum and incubated over a water-saturated foam carpet pad for 24 hr. Steam was applied to the samples as the temperature was measured from the carpet backing. Contact time was closely monitored over seven time intervals: 0, 2, 4, 8, 12, 16, and 20 sec. Following steam vapor treatment, mold spores were extracted from the carpet samples and the extract was plated on DG-18 plates at 1:1, 1:10, 1:100 dilutions followed by one week of incubation. Raw colony forming units were determined using an automated colony counter and adjusted based on dilution factor, extraction volume, and plated volume. Analysis of variance and linear regression were used to test for statistically significant relationships. Steam contact time exhibited a linear relationship to observed temperature of carpet backing (F = 90.176, R(2) = 0.609). Observed temperature of carpet backing had a positive relationship to percent reduction of mold (F = 76.605, R(2) = 0.569). Twelve seconds of steam vapor contact time was needed to achieve over 90% mold reduction on moist carpet.

Mold management of wetted carpet.

This study evaluated the growth and removal of fungi on wetted carpet using newly designed technologies that rely on physical principles of steam, heat, and fluid flow. Sixty samples of carpet were embedded with heat-treated house dust, followed by embedding, wearing with a hexapod, and wetting. Samples were inoculated using a liquid suspension of Cladosporium sphaerospermum prior to placement over a water-saturated foam pad. Incubation times were 24 hr, 7 days, and 30 days. Cleaning was performed using three methods; high-flow hot water extraction, hot water and detergent, and steam. Fungal loading increased from approximately 1500 colony forming units per area (CFU/cm(2)) in 24 hr to a maximum of approximately 10,200 CFU/cm(2) after 7 days with a slight decline to 9700 CFU/cm(2) after 30 days incubation. Statistically significant differences were found among all three methods for removal of fungi for all three time periods (p < 0.05). Steam-vapor was significantly better than the alternative methods (p <0.001) with over 99% efficiency in mold spore decline from wetted carpet after 24 hr and 30 days, and over 92% efficiency after 7 days. The alternative methods exhibited lower efficiencies with a decline over time, from a maximum of 82% and 81% at 24 hr down to 60% and 43% at 30 days for detergent-hot water and high-flow, hot water extraction, respectively. The net effect of the mold management study demonstrates that while steam has a consistent fungal removal rate, the detergent and high-flow, hot water methods decline in efficiency with increasing incubation time.

Do new wipe materials outperform traditional lead dust cleaning methods?

Government guidelines have traditionally recommended the use of wet mopping, sponging, or vacuuming for removal of lead-contaminated dust from hard surfaces in homes. The emergence of new technologies, such as the electrostatic dry cloth and wet disposable clothes used on mopheads, for removal of dust provides an opportunity to evaluate their ability to remove lead compared with more established methods. The purpose of this study was to determine if relative differences exist between two new and two older methods for removal of lead-contaminated dust (LCD) from three wood surfaces that were characterized by different roughness or texture. Standard leaded dust, <75 µm, was deposited by gravity onto the wood specimens. Specimens were cleaned using an automated device. Electrostatic dry cloths (dry Swiffer), wet Swiffer cloths, paper shop towels with non-ionic detergent, and vacuuming were used for cleaning LCD from the specimens. Lead analysis was by anodic stripping voltammetry. After the cleaning study was conducted, a study of the coefficient of friction was performed for each wipe material. Analysis of variance was used to evaluate the surface and cleaning methods. There were significant interactions between cleaning method and surface types, p = 0.007. Cleaning method was found be a significant factor in removal of lead, p <0.001, indicating that effectiveness of each cleaning methods is different. However, cleaning was not affected by types of surfaces. The coefficient of friction, significantly different among the three wipes, is likely to influence the cleaning action. Cleaning method appears to be more important than texture in LCD removal from hard surfaces. There are some small but important factors in cleaning LCD from hard surfaces, including the limits of a Swiffer mop to conform to curved surfaces and the efficiency of the wetted shop towel and vacuuming for cleaning all surface textures. The mean percentage reduction in lead dust achieved by the traditional methods (vacuuming and wet wiping) was greater and more consistent compared to the new methods (electrostatic dry cloth and wet Swiffer mop). Vacuuming and wet wiping achieved lead reductions of 92% ± 4% and 91%, ± 4%, respectively, while the electrostatic dry cloth and wet Swiffer mops achieved lead reductions of only 89 ± 8% and  81 ± 17%, respectively.

Validity and reliability of an occupational exposure questionnaire for parkinsonism in welders.

This study assessed the validity and test-retest reliability of a medical and occupational history questionnaire for workers performing welding in the shipyard industry. This self-report questionnaire was developed for an epidemiologic study of the risk of parkinsonism in welders. Validity participants recruited from three similar shipyards were asked to give consent for access to personnel files and complete the questionnaire. Responses on the questionnaire were compared with information extracted from personnel records. Reliability participants were recruited from the same shipyards and were asked to complete the questionnaire at two different times approximately 4 weeks apart. Percent agreement, kappa, intraclass correlation coefficient (ICC), and sensitivity and specificity were used as measures of validity and/or reliability. Personnel files were obtained for 101 of 143 participants (70%) in the validity study, and 56 of the 95 (58.9%) participants in the reliability study completed the retest of the questionnaire. Validity scores for items extracted from personnel files were high. Percent agreement for employment dates and job titles ranged from 83-100%, while ICC for start and stop dates ranged from 0.93-0.99. Sensitivity and specificity for current job title ranged from 0.5-1.0. Reliability scores for demographic, medical and health behavior items were mainly moderate or high, but ranged from 0.19 to 1.0. Most recent job/title items such as title, types of welding performed, and material used showed substantial to perfect agreement. Certain determinants of exposure such as days and hours per week exposed to welding fumes demonstrated mainly moderate agreement (kappa= 0.42-0.47, percent agreement 63-77%); however, mean days and hours reported did not differ between test and retest. The results of this study suggest that participants' self-report for job title and dates employed are valid compared with employer records. While kappa scores were low for some medical conditions and for caffeine consumption, high kappa scores for job title, dates worked, types of welding, and materials welded suggest participants generated reproducible answers important for occupational exposure assessment.

Positional accuracy and geographic bias of four methods of geocoding in epidemiologic research.

PURPOSE: We examined the geographic bias of four methods of geocoding addresses using ArcGIS, commercial firm, SAS/GIS, and aerial photography. We compared "point-in-polygon" (ArcGIS, commercial firm, and aerial photography) and the "look-up table" method (SAS/GIS) to allocate addresses to census geography, particularly as it relates to census-based poverty rates. METHODS: We randomly selected 299 addresses of children treated for asthma at an urban emergency department (1999-2001). The coordinates of the building address side door were obtained by constant offset based on ArcGIS and a commercial firm and true ground location based on aerial photography. RESULTS: Coordinates were available for 261 addresses across all methods. For 24% to 30% of geocoded road/door coordinates the positional error was 51 meters or greater, which was similar across geocoding methods. The mean bearing was -26.8 degrees for the vector of coordinates based on aerial photography and ArcGIS and 8.5 degrees for the vector based on aerial photography and the commercial firm (p < 0.0001). ArcGIS and the commercial firm performed very well relative to SAS/GIS in terms of allocation to census geography. For 20%, the door location based on aerial photography was assigned to a different block group compared to SAS/GIS. The block group poverty rate varied at least two standard deviations for 6% to 7% of addresses. CONCLUSION: We found important differences in distance and bearing between geocoding relative to aerial photography. Allocation of locations based on aerial photography to census-based geographic areas could lead to substantial errors.

Gender-specific differences of interaction between obesity and air pollution on stroke and cardiovascular diseases in Chinese adults from a high pollution range area: A large population based cross sectional study.

BACKGROUND: Little information exists regarding the interaction effects of obesity with long-term air pollution exposure on cardiovascular diseases (CVDs) and stroke in areas of high pollution. The aim of the present study is to examine whether obesity modifies CVD-related associations among people living in an industrial province of northeast China. METHODS: We studied 24,845 Chinese adults, aged 18 to 74 years old, from three Northeastern Chinese cities in 2009 utilizing a cross-sectional study design. Body weight and height were measured by trained observers. Overweight and obesity were defined as a body mass index (BMI) between 25-29.9 and ≥30 kg/m(2), respectively. Prevalence rate and related risk factors of cardiovascular and cerebrovascular diseases were investigated by a questionnaire. Three-year (2006-2008) average concentrations of particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxides (NO2), and ozone (O3) were measured by fixed monitoring stations. All the participants lived within 1 km of air monitoring sites. Two-level logistic regression (personal level and district-specific pollutant level) was used to examine these effects, controlling for covariates. RESULTS: We observed significant interactions between exposure and obesity on CVDs and stroke. The associations between annual pollutant concentrations and CVDs and stroke were strongest in obese subjects (OR 1.15-1.47 for stroke, 1.33-1.59 for CVDs), less strong in overweight subjects (OR 1.22-1.35 for stroke, 1.07-1.13 for CVDs), and weakest in normal weight subjects (OR ranged from 0.98-1.01 for stroke, 0.93-1.15 for CVDs). When stratified by gender, these interactions were significant only in women. CONCLUSIONS: Study findings indicate that being overweight and obese may enhance the effects of air pollution on the prevalence of CVDs and stroke in Northeastern metropolitan China. Further studies will be needed to investigate the temporality of BMI relative to exposure and onset of disease.

Association of polyfluoroalkyl chemical exposure with serum lipids in children.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs), as well as polymers of PFASs, have been widely used in commercial applications and have been detected in humans and the environment. Previous epidemiological studies have shown associations between particular PFAS chemicals and serum lipid concentrations in adults, particularly perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). There exists, however, limited information concerning the effect of PFASs have on serum lipids among children. In the present cross-sectional study, 225 Taiwanese children (12-15 years of age) were recruited to determine the relationship between serum level PFASs and lipid concentration. Results showed that eight out of ten particular PFASs were detected in the serum of >94% of the participants. Serum PFOS and perfluorotetradecanoic acid (PFTA) levels were at an order of magnitude higher than the other PFASs, with arithmetical means of 32.4 and 30.7 ng/ml in boys and 34.2 and 27.4 ng/ml in girls, respectively. However, the variation in serum PFTA concentration was quite large. Following covariate adjustment, linear regression models revealed that PFOS, PFOA, and perfluorononanoic acid (PFNA) were positively associated with total cholesterol (TC), low-density lipoprotein (LDL) and triglycerides (TG), particularly for PFOS and PFTA. Quartile analysis, with the lowest exposure quartile as a reference, yielded associations between serum PFTA and elevations in TC (p=0.002) and LDL (p=0.004). Though not statistically significant, high-density lipoprotein (HDL) appeared to decrease linearly across quartiles for PFOS and PFOA exposure. In conclusion, a significant association was observed between serum PFASs and lipid level in Taiwanese children. These findings for PFTA are novel, and emphasize the need to investigate the exposure route and toxicological evidence of PFASs beyond PFOS and PFOA.

Residential characteristics and household risk factors and respiratory diseases in Chinese women: the Seven Northeast Cities (SNEC) study.

BACKGROUND: Few studies have assessed the impact of residential home characteristics and home environmental risk factors on respiratory diseases in Chinese women. Therefore, this study sought to determine the association between residential home features, domestic pets, home renovation and other indoor environmental risk factors with respiratory health outcomes of Chinese women. METHODS: This cross-sectional study included a study sample of 30,780 Chinese women aged 23 to 49 from 25 districts of seven cities in Liaoning Province, Northeast China. Information on respiratory health, residential characteristics, and indoor air pollution sources was obtained by a standard questionnaire from the American Thoracic Society. Multivariable logistic regression was used to estimate prevalence odds ratios (POR) and 95% confidence interval (95%CI). RESULTS: The odds of respiratory diseases were higher for those who lived near the main road, or near ambient air pollution sources. Pet-keeping was associated with increased odds of chronic bronchitis (POR=1.40; 95%CI: 1.09-1.81) and doctor-diagnosed asthma (POR=2.07; 95%CI: 1.18-3.64). Additionally, humidifier use was associated with increased odds of chronic bronchitis (POR=1.44; 95%CI: 1.07-1.94). Home renovation in recent 2 years was associated with increased likelihood of allergic rhinitis (POR=1.39; 95%CI 1.17-1.64). CONCLUSION: Home renovation and residential home environmental risk factors were associated with an increased likelihood of respiratory morbidity among Chinese women.