Roger D. Lewis

Pollen and fungal spores indoor and outdoor of mobile homes

BACKGROUND Allergenic diseases triggered by aeroallergens extract a health cost in quality of life and in economic impact. People generally spend 90% to 95% of their time indoors, so understanding the environmental factors that affect the presence of aeroallergens indoors are important in understanding health impact and potential intervention methods. OBJECTIVE Describe the relationship of indoor airborne pollen and fungal spores in occupied mobile homes with outdoor concentrations and other environmental factors within geographically diverse areas of Texas. METHODS Airborne pollen and fungal spores were collected during the daytime with RotoRod samplers indoor and outdoor of mobile homes in Houston and El Paso, Texas. Samples were counted simultaneously with a dual eyepiece microscope and identified morphologically and through staining techniques. RESULTS Geometric mean concentrations (counts/m3) indoors and outdoors for pollen, respectively, were Houston 7.1 and 196.4; and El Paso 17.5 and 71.5. Geometric mean concentrations (counts/m3) indoors and outdoors for spore, respectively, were Houston 98.5 and 196.4; and El Paso 36.9 and 71.5. Indoor to outdoor ratios (I/O) for pollen and fungal spores were found to be higher on average than has been previously reported. Modeling of predictive factors in Houston demonstrate that 62% and 41% of indoor levels of pollen and fungal spores, respectively, can be explained by their corresponding outdoor levels. These data suggest that the many factors associated with individual exposure to airborne pollen and fungal spores indoors are under the control of the occupant, and may additionally be influenced by the physical characteristics of mobile homes, in particular the high surface area to volume ratio and restricted flow patterns.

Factors affecting the retention of dust mite allergen on carpet.

Carpeting is one of the most common and perhaps the most important reservoir of aeroallergens and other components of dust found in residential or commercial settings. This research evaluated factors that affect the retention of dust mite allergens on different types of tufted carpet commonly found in homes and offices. Twenty-six types of carpet were custom manufactured as part of a two-stage factorial experiment using 182 carpet samples. Carpets differed with respect to fiber denier, cross-sectional shape, presence of fluorocarbon treatment, carpet style, pile height, and pile density. The major hypothesis tested was that the amount of allergen-containing dust recovered from vacuum samples of tufted carpet sources was dependent on micro (fiber) or macro (construction) retention characteristics of the carpets. Carpet samples were doped in a uniform and reproducible manner using an allergen-containing reference dust. A standardized vacuum surface sampler was used to recover dust from samples. Allergen was assayed using a standard, monoclonal antibody ELISA. Carpet-surface area and presence of fluorocarbon were found to have the largest effects on retention and recovery of dust and allergen. Specifically, fluorocarbon treatment of fibers, square-hollow fiber shape, high-denier fiber, low-pile height in cut-pile carpets, and low-pile density in loop carpets were significantly associated with increased release and recovery of allergen. Results from this study suggest that carpet type be considered for both allergen avoidance and allergy and asthma risk assessment.

Influence of Wear, Pile Height, and Cleaning Method on Removal of Mite Allergen from Carpet

Carpet is a major sink for house dust mite allergen. Vacuum extraction methods have been shown to reduce concentrations of such allergen in dust, but the influence of carpet construction and cleaning parameters on the efficiency of extraction is poorly understood. The objective of this study was to determine the effect of construction, degree of wear, and cleaning method on ease of removal of the primary allergen (Der f I) derived from the North American house-dust mite, Dermatophagoides Farinae. Carpets of different pile heights were seeded with house dust, some were then subjected to artificial wear, and all were then either dry vacuumed or wet extracted. The Der f I content of carpet cores was measured at each stage. As a result, the degree of wear and pile height were shown to be the two most important factors determining ease of Der f I removal from carpet. For worn carpet, dry vacuuming of short pile constructions was shown to be significantly more effective (p ≤ 0.05) than for longer pile height constructions, while removal of Der f I using either wet or dry vacuum extraction techniques was shown to be more efficient (> 61%) for unworn carpet than for worn carpet (< 30%). Only minor differences between types of cleaning method (wet vs. dry) were found. This study suggests that carpets differ greatly in their propensity to retain allergens, and that a consideration of carpet age, construction, and cleaning regime is important when advising the merits of different floor covering types, and on allergen avoidance techniques.

Breastfeeding as a modifier of the respiratory effects of air pollution in children.

Background: Breastfeeding and air pollution are both important factors for respiratory symptoms and asthma in children. Few studies have examined possible interaction between them on respiratory outcomes. Methods: We studied 31,049 Chinese children, ages 2–14 years old, from 25 elementary schools and 50 kindergartens in the Seven Northeastern Cities during 2008–2009. Parents or guardians completed questionnaires about the children’s histories of respiratory conditions, risk factors, and feeding methods. Three-year average concentrations of particles with an aerodynamic diameter ⩽10 µm, sulfur dioxide, nitrogen dioxides, and ozone were calculated from monitoring stations in 25 study districts. We used two-level logistic regressions to examine the effects of exposure, controlling for covariates. Results: Association of air pollution with childhood respiratory conditions was modified by breastfeeding. Compared with children who had been breastfed, those who were not exhibited consistently stronger effects of air pollution. Among non-breastfed children, odds ratios (ORs) per 10 µg/m3 increase in nitrogen dioxide were 1.40 (95% confidence interval = 1.19–1.64) for cough, 1.41 (1.16–1.71) for phlegm, 1.17 (1.00–1.36) for current wheeze, and 1.25 (1.07–1.46) for doctor-diagnosed asthma. For breastfed children, the ORs were 1.25 (1.09–1.43) for cough, 1.15 (0.99–1.34) for phlegm, 0.97 (0.87–1.08) for current wheeze, and 1.17 (1.05–1.32) for doctor-diagnosed asthma. Breastfeeding was more protective among younger children. Breastfeeding was also associated with reduced effects of passive smoke exposure in children. Conclusion: Breastfeeding is associated with smaller associations between air pollution and respiratory conditions in children, suggesting that breastfeeding reduces susceptibility to the respiratory effects of pollutants.

Carpet properties that affect the retention of cat allergen

BACKGROUND Although the importance of carpeting on airborne levels of cat allergen (Fel d 1) has been demonstrated, no studies have been performed to determine specific properties of carpet that may affect its retention and removal. OBJECTIVES This study characterizes factors that affect the retention of cat allergen on tufted carpets. The experiments were designed to test the hypothesis that the amount of allergen-containing dust recovered from vacuum samples of tufted carpet sources was dependent on micro (fiber) or macro (construction) retention properties of carpets. METHODS Twenty-six types of custom manufactured carpet were spiked and embedded with reference dust containing Fel d 1. A standardized vacuum surface sampler was used to recover dust from the samples. Allergen was assayed using a standard, monoclonal antibody ELISA. RESULTS Carpet-surface area and fluorocarbon-fiber treatments were found to have the largest effects on retention and recovery of cat allergen. The style per se of a carpet, such as loop or cut pile, does not affect allergen retention. These results are generally in agreement with previous studies on dust mite allergen retention. CONCLUSIONS Carpets that are easiest to clean would have the following properties for release of cat allergen and in this order: low pile density and height, fluorocarbon coating of fibers, high denier per filament, and a fiber shape with a low surface area.

A Soiling System for Evaluation of House Dust, Allergens, and Lead Retention on Carpets and Other Surfaces

Artificial soiling of carpeted or other floor surfaces has several important applications in human exposure assessment and textile research including evaluation of textile properties, sampling devices, and cleaning regimens. A method was developed and validated to deposit uniform and reproducible known quantities of house dust, allergens, and leaded dust on carpets. The soiling apparatus consisted of a 100 cm x 60 cm inclined steel track and a plastic cylinder, with a series of staggered holes, that contains a known volume of reference house dust. After deposition, the dust is embedded by dragging a steel rod over the carpet surface. Deposition tests were performed with bulk house dust, sodium chloride, and house dust with reference quantities of dust mite allergen and lead. The apparatus deposited equivalent (arithmetic mean) amounts of dust, sodium chloride, and dust mite allergen on the front and back halves of test carpets. The introduction of inert fumed silica to the reference sample aided in dispersal of dust over test surfaces. Little to no variation in mean deposition was found within or between 4 days of testing. Using a grid containing weighing boats under the apparatus, spatial deposition was found to vary across a 92 x 46 cm surface by 13 percent. The apparatus deposited reproducible mean quantities of bulk dust on test surfaces from 7 g/m2 to 28 g/m2 with a coefficient of variation ranging from 4-6 percent. The apparatus could be altered to deliver smaller or larger amounts of dust.

A comparison of the sampling characteristics of two vacuum surface samplers for the collection of dust mite allergen

Abstract Hand-held vacuum cleaners are commonly adapted for collection of allergens in settled dust; however, the collection efficiencies for most of these devices have not been investigated. We evaluated and compared the collection characteristics of two vacuum surface samplers: the ReadiVac (6735), a hand-held vacuum cleaner with a cloth filter bonnet; and the high volume surface sampler (HVS3), a modified upright vacuum cleaner equipped with a cyclone for collecting small particles and a means for adjusting the air flow in the sampler. The efficiency and precision of the two vacuum samplers were evaluated by vacuum sampling 30 matched-pair carpet samples doped with house dust containing dust mite allergen. The HVS3 recovered twice as much bulk dust and four times as much allergen as the ReadiVac, although the intake velocities of the two samplers were practically equivalent. The correlation of bulk dust recovery with allergen recovery by the ReadiVac was r = 0.54 compared with the HVS3s of r = 0.90. T...

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.

Childhood lead exposure and sexually transmitted infections: New evidence.

INTRODUCTION The adverse health effects of lead exposure in children are well documented and include intellectual and behavioral maladies. Childhood lead exposure has also been linked to impulsive behaviors, which, in turn, are associated with a host of negative health outcomes including an increased risk for sexually transmitted infections (STI). The purpose of this study was to assess the association of lead exposure with STI rates across census tracts in St. Louis City, Missouri. METHODS Incident cases of gonorrhea and chlamydia (GC) during 2011 were identified from the Missouri Department of Health and Senior Services and aggregated by census tract. We also geocoded the home address of 59,645 children >72 months in age who had blood lead level tests performed in St. Louis City from 1996 to 2007. Traditional regression and Bayesian spatial models were used to determine the relationship between GC and lead exposure while accounting for confounders (condom and alcohol availability, crime, and an index of concentrated disadvantage). RESULTS Incident GC rates were found to cluster across census tracts (Morans I=0.13, p=0.006). After accounting for confounders and their spatial dependence, a linear relationship existed between lead exposure and GC incidence across census tracts, with higher GC rates occurring in the northern part of St. Louis City CONCLUSIONS At the census-tract level, higher lead exposure is associated with higher STI rates. Visualizing these patterns through maps may help deliver targeted interventions to reduce geographic disparities in GC rates.

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.