ChiroACCESS Article



Dust Bunnies Make Poor Pets



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October 11, 2011

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Dust bunnies have some positive attributes as low maintenance pets.  There is no need to walk them, no feeding and no vet bills.  Unfortunately they do pose a very serious health risk.  Residential dust is associated with exacerbating respiratory and dermatological conditions and as a risk factor for serious diseases including cancer.  Becoming aware of the sources of household dust is an important first step to prevention.   Many people believe the primary source is dead human skin cells.  Research conducted at the University of Arizona Tucson resulted in a method of modeling and quantifying household dust.  Their study suggests that 60% of dust inside a house actually comes from outside the home.  It is tracked into the home by humans and pets and large quantities often come from the air.  To the human eye the air appears clear - it is not.  

The many sources of dust generated from inside the home include cleaning agents, cooking, smoking, and fibers from clothing, drapes and furniture.  Carpets are a particularly problematic source both because of the contaminants harbored in the fibers which become repeatedly airborne from walking and also the breakdown over time of the fibers themselves.  Cleaning agents used in the home can also be a source of contamination.  Pet and human skin cells also represent about 40% of dust generated from inside the house.

Prevention can be addressed in many ways including using air filtering systems, changing filters often, controlling pests, removing shoes before entering the home, and good house cleaning procedures.  There are considerations when choosing where to live as each region has a different set of potential contaminants.  Irrespective of geographic location, living near heavily trafficked highways, radiofrequency electromagnetic fields or similar sources of manmade pollutants should be avoided. 

Free full text of the U. of Arizona Tucson can be found here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2782798/?tool=pubmed 

Note:  These mini-reviews are designed as updates and direct the reader to the full text of current research.  The abstracts presented here are no substitute for reading and critically reviewing the full text of the original research.  Where permitted we will direct the reader to that full text.

Migration of contaminated soil and airborne particulates to indoor dust.  [Link]

Environ Sci Technol. 2009 Nov 1;43(21):8199-205.

Layton DW, Beamer PI.
Community, Environment and Policy Division, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, Arizona, USA.

We have developed a modeling and measurement framework for assessing transport of contaminated soils and airborne particulates into a residence, their subsequent distribution indoors via resuspension and deposition processes, and removal by cleaning and building exhalation of suspended particles. The model explicitly accounts for the formation of house dust as a mixture of organic matter (OM) such as shed skin cells and organic fibers, soil tracked-in on footwear, and particulate matter (PM) derived from the infiltration of outdoor air. We derived formulas for use with measurements of inorganic contaminants, crustal tracers, OM, and PM to quantify selected transport parameters. Application of the model to residences in the U.S. Midwest indicates that As in ambient air can account for nearly 60% of the As input to floor dust, with soil track-in representing the remainder. Historic data on Pb contamination in Sacramento, CA, were used to reconstruct sources of Pb in indoor dust, showing that airborne Pb was likely the dominant source in the early 1980s. However, as airborne Pb levels declined due to the phase-out of leaded gasoline, soil resuspension and track-in eventually became the primary sources of Pb in house dust.


Allergens in household dust and serological indicators of atopy and sensitization in Detroit children with history-based evidence of asthma.  [Link]

J Asthma. 2011 Sep;48(7):674-84. Epub 2011 Aug 10.

Williams AH, Smith JT, Hudgens EE, Rhoney S, Ozkaynak H, Hamilton RG, Gallagher JE.
Epidemiology Branch, National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA. williams.annh@epa.gov

BACKGROUND: Home exposure to allergens is an important factor in the development of sensitization and subsequent exacerbations of allergic asthma. We investigated linkages among allergen exposure, immunological measurements, and asthma by examining (1) reservoir dust allergen levels in homes, (2) associations between presence of allergens in homes and sensitization status of resident children, and (3) associations between asthma status and total IgE, atopy (by Phadiatop), and positive allergen-specific tests.

METHODS: The study protocol was approved by Institutional Review Boards (IRBs) of the University of North Carolina Chapel Hill; Westat, Inc.; and the US Environmental Protection Agency Human Research Protocol Office. Data were collected from questionnaires, serum analyses, and household vacuum dust. Children (n = 205) were predominately African American (AA) (85.4%) and 51.6% were asthmatic. Sera from 185 children and home dust samples (n = 141) were analyzed for total and specific IgE antibodies to allergens from cat and dog dander, cockroach, dust mites, mice, rats, and molds.

RESULTS: Sixty percent of the homes had detectable levels of three or more dust allergens. The proportions of children with positive allergen-specific IgE tests were dust mite (32%), dog (28%), cat (23%), cockroach (18%), mouse (5%), rat (4%), and molds (24-36%). Children testing positive to a single allergen also had positive responses to other allergens. Those children with positive serum tests for cat, dog, and dust mite lived in homes with detectable levels of cat (51%), dog (90%), and dust mite (Der f 1) (92%) allergens. Correlations between children's specific IgE levels and dust levels were linearly related for dog (p < .04), but not for cat (p = .12) or dust mite (Der f 1) (p = .21). Odds ratios (95% CI) for the associations between asthma and serum-specific IgE were over 1.0 for cat, dog, dust mite (Der f 1), cockroach, and four types of molds. House dust allergen exposure levels, however, exhibited no differences between asthmatic and non-asthmatic homes.

CONCLUSIONS: Both the co-occurrence of multiple allergens in dust and the high frequency of multiple allergen sensitizations indicate that a broad-based intervention aimed at reducing multiple allergens (pets, pests, and molds) would be more successful than any approach that aimed at reducing one type of allergen.


Polycyclic aromatic hydrocarbons in household dust near diesel transport routes.  [Link]

Environ Geochem Health. 2011 May 21. [Epub ahead of print]

Kuo CY, Chen HC, Cheng FC, Huang LR, Chien PS, Wang JY.
Department of Public Health, College of Health Care and Management, Chung Shan Medical University, No. 110 Chien-Kuo N Rd., Sec. 1, Taichung, 40242, Taiwan, ROC, kcy@csmu.edu.tw.

A river-dredging project has been undertaken in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main roads. Ten stations along major thoroughfares were selected as the exposure sites for testing, while a small village located about 9 km from a main traffic route was selected as the control site. Levels of household dust loading at the exposure sites (60.3 mg/m(2)) were significantly higher than those at the control site (38.2 mg/m(2)). The loading (µg/m(2)) of t-PAHs (total polycyclic aromatic hydrocarbons) in the household dust at the exposure sites was significantly higher (P < 0.05) than was the case at the control site. The diagnostic ratios of PAHs showed that diesel emissions were the dominant source of PAHs at the exposure sites. The lack of a significant correlation between the concentrations of Fe and t-PAHs suggested that the t-PAHs in household dust might come from diverse sources. However, a significant correlation (P = 0.003) between the concentrations of Mo and t-PAHs implied that the most of the t-PAHs in the household dust might have resulted from diesel emissions. The lifetime cancer risks of BaP(eq) from household dust exposure were markedly higher than those resulting from inhalation exposure.


Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada.  [Link]

Chem Biol Interact. 2011 Apr 22. [Epub ahead of print]

Seiler R.
US Geological Survey, 2730 N. Deer Run Road, Carson City, NV 89701, USA.

In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and (210)Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and (210)Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous (210)Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia.


Estimating exposures to indoor contaminants using residential dust.  [Link]

J Expo Sci Environ Epidemiol. 2011 Apr 27. [Epub ahead of print]

Whitehead T, Metayer C, Buffler P, Rappaport SM.
School of Public Health, University of California, Berkeley, California, USA.

Residential dust has been used as a medium for assessing human exposures to a constellation of indoor contaminants including radionuclides, persistent organic pollutants, metals, allergens, and tobacco smoke. Here, we review and comment on investigations of household dust levels of particular analytes of health significance, namely polybrominated diphenyl ethers, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. In doing so, we not only describe methods for collecting and analyzing residential dust, but also describe global patterns in dust levels. Aside from geographic location, we discuss several potential determinants for dust levels of these contaminants. We also review previous estimates of the contribution of dust to overall intake of these three chemical classes and show how residential-dust measurements could be useful in either augmenting or replacing questionnaire-based assessment of human exposures in epidemiological studies. We conclude our review with a discussion of the current gaps in knowledge of worldwide dust levels and suggestions for how residential-dust measurements could be used to describe human exposures to chemicals in developing countries.


Predictors of airborne endotoxin concentrations in inner city homes.  [Link]

Environ Res. 2011 May;111(4):614-7. Epub 2011 Mar 22.

Mazique D, Diette GB, Breysse PN, Matsui EC, McCormack MC, Curtin-Brosnan J, Williams DL, Peng RD, Hansel NN.
Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.

Few studies have assessed in home factors which contribute to airborne endotoxin concentrations. In 85 inner city Baltimore homes, we found no significant correlation between settled dust and airborne endotoxin concentrations. Certain household activities and characteristics, including frequency of dusting, air conditioner use and type of flooring, explained 36-42% of the variability of airborne concentrations. Measurements of both airborne and settled dust endotoxin concentrations may be needed to fully characterize domestic exposure in epidemiologic investigations.


Sources of propylene glycol and glycol ethers in air at home.  [Link]

Int J Environ Res Public Health. 2010 Dec;7(12):4213-37. Epub 2010 Dec 15.

Choi H, Schmidbauer N, Spengler J, Bornehag CG
Department of Environmental Health, Harvard School of Public Health, USA. hchoi@hsph.harvard.edu

Propylene glycol and glycol ether (PGE) in indoor air have recently been associated with asthma and allergies as well as sensitization in children. In this follow-up report, sources of the PGEs in indoor air were investigated in 390 homes of pre-school age children in Sweden. Professional building inspectors examined each home for water damages, mold odour, building's structural characteristics, indoor temperature, absolute humidity and air exchange rate. They also collected air and dust samples. The samples were analyzed for four groups of volatile organic compounds (VOCs) and semi-VOCs (SVOCs), including summed concentrations of 16 PGEs, 8 terpene hydrocarbons, 2 Texanols, and the phthalates n-butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). Home cleaning with water and mop = once/month, repainting = one room prior to or following the child's birth, and "newest" surface material in the child's bedroom explained largest portion of total variability in PGE concentrations. High excess indoor humidity (g/m³) additionally contributed to a sustained PGE levels in indoor air far beyond several months following the paint application. No behavioral or building structural factors, except for water-based cleaning, predicted an elevated terpene level in air. No significant predictor of Texanols emerged from our analysis. Overall disparate sources and low correlations among the PGEs, terpenes, Texanols, and the phthalates further confirm the lack of confounding in the analysis reporting the associations of the PGE and the diagnoses of asthma, rhinitis, and eczema, respectively.


The epidemiology of ocular and nasal allergy in the United States, 1988-1994.  [Link]

J Allergy Clin Immunol. 2010 Oct;126(4):778-783.e6.

Singh K, Axelrod S, Bielory L.
Department of Medicine-Pediatrics, Cool Springs Internal Medicine & Pediatrics, Brentwood, TN, USA.

BACKGROUND: Allergies give rise to the fifth-leading group of chronic diseases. However, the specific prevalence of ocular allergy is poorly described.

OBJECTIVE: We sought to provide a more accurate representation of the epidemiology of ocular allergy in the United States.

METHODS: The National Health And Nutrition Examination Survey III performed in the United States from 1988-1994 was the source for the data collected. Items from the questionnaire regarding ocular and nasal allergy symptoms in relation to skin prick testing were stratified by age, race, region, and sex.

RESULTS: The sample size is 20,010: 1,285 (6.4%) reported ocular symptoms, 3,294 (16.5%) reported nasal symptoms, 5,944 (29.7%) reported both ocular and nasal symptoms, and 9.487 (47.4%) were asymptomatic. Forty percent of the population reported at least 1 occurrence of ocular symptoms in the past 12 months. Those 50 years and older have a higher frequency of isolated ocular symptoms (P < .001). There is an increase in the frequency of symptoms in those younger than 50 years in the populations of subjects with ocular and nasal symptoms combined and isolated nasal symptoms (P < .001). Ocular symptoms are more frequent than nasal symptoms in relation to animals (P < .001), household dust (P < .001), and pollen (P < .001).

CONCLUSION: This analysis provides the first representation of the epidemiology of ocular allergy in the United States. Up to 40% of the population, the highest reported to date, have experienced ocular symptoms at least once in their lifetime, with a peak of symptoms in the months of June and July.


Influence of indoor factors in dwellings on the development of childhood asthma.  [Link]

Int J Hyg Environ Health. 2011 Jan;214(1):1-25. Epub 2010 Sep 18.

Heinrich J.
Helmholtz Zentrum München, National Research Center for Environmental Health, Institute of Epidemiology, Munich, Germany. joachim.heinrich@helmholtz-muenchen.de

Asthma has become the most common, childhood chronic disease in the industrialized world, and it is also increasing in developing regions. There are huge differences in the prevalence of childhood asthma across countries and continents, and there is no doubt that the prevalence of asthma was strongly increasing during the past decades worldwide. Asthma, as a complex disease, has a broad spectrum of potential determinants ranging from genetics to life style and environmental factors. Environmental factors are likely to be important in explaining the regional differences and the overall increasing trend towards asthma's prevalence. Among the environmental conditions, indoor factors are of particular interest because people spend more than 80% of their time indoors globally. Increasing prices for oil, gas and other sources of primary energy will further lead to better insulation of homes, and ultimately to reduced energy costs. This will decrease air exchange rates and will lower the dilution of indoor air mass with ambient air. Indoor air quality and potential health effects will therefore be an area for future research and for gaining a better understanding of asthma epidemics. This strategic review will summarize the current knowledge of the effects of a broad spectrum of indoor factors on the development of asthma in childhood in Western countries based on epidemiological studies. In conclusion, several epidemiological studies point out, that indoor factors might cause asthma in childhood. Stronger and more consistent findings are seen when exposure to these indoor factors is assessed by surrogates for the source of the actual toxicants. Measurement-based exposure assessments for several indoor factors are less common than using surrogates of the exposure. These studies, however, mainly showed heterogeneous results. The most consistent finding for an induction of asthma in childhood is related to exposure to environmental tobacco smoke, to living in homes close to busy roads, and in damp homes where are visible moulds at home. The causing agents of the increased risk of living in damp homes remained uncertain and needs clarification. Exposure to pet-derived allergens and house dust mites are very commonly investigated and thought to be related to asthma onset. The epidemiological evidence is not sufficient to recommend avoidance measures against pet and dust mites as preventive activities against allergies. More research is also needed to clarify the potential risk for exposure to volatile and semi-volatile organic compounds due to renovation activities, phthalates and chlorine chemicals due to cleaning.


Simultaneous quantitation of parabens, triclosan, and methyl triclosan in indoor house dust using solid phase extraction and gas chromatography-mass spectrometry.  [Link]

J Environ Monit. 2010 Oct 6;12(10):1891-7. Epub 2010 Sep 6.

Fan X, Kubwabo C, Rasmussen P, Jones-Otazo H.
Health Canada, Healthy Environments and Consumer Safety Branch, Environmental Health Science and Research Bureau, Ottawa, Ontario, Canada.

An integrated analytical method for the simultaneous determination of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-), triclosan, and methyl triclosan in indoor house dust was developed based on gas chromatographic-mass spectrometric technique (GC/MS). Analytes were extracted from dust samples by sonication. After sample cleanup by solid-phase extraction (SPE), the extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and then analyzed by gas chromatography coupled with ion trap mass spectrometry operated in multiple reaction monitoring (MRM) mode. For quantitation, isotope-labelled internal standards were used for each corresponding target analyte. Only 0.05 g of dust sample was needed for the analysis. Method detection limits ranged from 6.5 to 10 ng/g, and absolute recoveries from 74% to 92%. The developed method demonstrated good repeatability and reproducibility, with relative standard deviations (RSDs) less than 16% for all the analytes. The analytes were determined in dust samples collected using two vacuum sampling methods from 63 Canadian homes: a sample of fresh or "active" dust (FD) collected using a Pullman-Holt vacuum sampler, and a composite sample taken from the household vacuum cleaner (HD). Methyl paraben, propyl paraben, and triclosan were detected in all HD and FD samples. HD samples yielded median values for methyl paraben, propyl paraben, and triclosan of 1080, 463, and 378 ng/g, respectively, which were comparable to the FD sample medians of 1120, 618 and 571 ng/g. Ethyl paraben was detected at frequencies of 89% in FD and 73% in HD samples, with median values of 52 and 25 ng/g, respectively. Butyl paraben was detected at frequencies of 44% in FD and 75% in HD samples, with median values of <10 and 59 ng/g, respectively. Benzyl paraben and methyl triclosan were not detected in any of the samples collected by either method. Samples collected according to the fresh dust protocol agreed with the household vacuum samples 90% of the time. Widely scattered concentration levels were observed for target analytes from this preliminary set of 63 Canadian samples, which suggests a wide variability in Canadian household exposures to these chemicals.


Dog characteristics and allergen levels in the home.  [Link]

Ann Allergy Asthma Immunol. 2010 Sep;105(3):228-33.

Nicholas C, Wegienka G, Havstad S, Zoratti E, Ownby D, Johnson CC.
Henry Ford Health System, Detroit, Michigan 48202, USA. cnichol4@hfhs.org

BACKGROUND: Comprehensive analyses on the effect of household dogs on dog allergen levels in the home are lacking.

OBJECTIVE: To identify environmental factors and dog-specific characteristics that influence the accumulation of Canis familiaris 1 (Can f 1) in homes.

METHODS: Dust samples were collected from the floor of infants' bedrooms at a Wayne County Health, Environment, Allergy, & Asthma Longitudinal Study birth cohort study home visit and processed for Can f 1 using a standardized protocol. Dog characteristics were based on maternal report. Homes with 1 dog were included in detailed analyses, including characterization of the dog based on coat type, dander level, and shedding.

RESULTS: Households with dogs had higher levels of dog allergen in the home than those without dogs; however, the number of dogs in the home was not related to dog allergen levels. Homes with exclusively outdoor dogs had significantly higher dog allergen levels than homes without any dogs but significantly lower levels of dog allergen than homes with indoor dogs. Homes where the dog was allowed in the infant's bedroom had significantly higher Can f 1 levels on the child's bedroom floor than homes where it was not. The homes of altered dogs had higher Can f 1 levels than did their unaltered counterparts.

CONCLUSIONS: Dogs in the home corresponded to dog allergen in the home. Time the dog was indoors and whether it was allowed on the vacuumed surface mattered. No dog characteristic, other than altered status, was associated with allergen levels in the home.


Childhood lead poisoning associated with lead dust contamination of family vehicles and child safety seats - Maine, 2008.  [Link]

MMWR Morb Mortal Wkly Rep. 2009 Aug 21;58(32):890-3.

Centers for Disease Control and Prevention (CDC).

Persons employed in high-risk lead-related occupations can transport lead dust home from a worksite through clothing, shoes, tools, or vehicles. During 2008, the Maine Childhood Lead Poisoning Prevention Program (MCLPPP) identified 55 new cases of elevated (>or=15 microg/dL) venous blood lead levels (BLLs) among children aged <6 years through mandated routine screening. Although 90% of childhood lead poisoning cases in Maine during 2003-2007 had been linked to lead hazards in the child's home, no lead-based paint or dust or water with elevated lead levels were found inside the homes associated with six of the 2008 cases (i.e., five families, including one family with two affected siblings). An expanded environmental investigation determined that these six children were exposed to lead dust in the family vehicles and in child safety seats. The sources of the lead dust were likely household contacts who worked in high-risk lead exposure occupations. Current recommendations for identifying and reducing risk from take-home lead poisoning include 1) ensuring that children with elevated BLLs are identified through targeted blood lead testing, 2) directing prevention activities to at-risk workers and employers, and 3) improving employer safety protocols. State and federal prevention programs also should consider, when appropriate, expanded environmental lead dust testing to include vehicles and child safety seats.


Predictors of endotoxin levels in U.S. housing.  [Link]

Environ Health Perspect. 2009 May;117(5):763-71. Epub 2008 Oct 16.

Thorne PS, Cohn RD, Mav D, Arbes SJ, Zeldin DC.
Environmental Health Sciences Research Center, College of Public Health, University of Iowa, Iowa City, Iowa 52242-5000, USA. peter-thorne@uiowa.edu

BACKGROUND: The relationship of domestic endotoxin exposure to allergy and asthma has been widely investigated. However, few studies have evaluated predictors of household endotoxin, and none have done so for multiple locations within homes and on a national scale.

OBJECTIVES: We assayed 2,552 house dust samples in a nationwide study to understand the predictors of household endotoxin in bedroom floors, family room floors, beds, kitchen floors, and family room sofas.

METHODS: Reservoir house dust from five locations within homes was assayed for endotoxin and demographic and housing information was assessed through questionnaire and onsite evaluation of 2,456 residents of 831 homes selected to represent national demographics. We performed repeated-measures analysis of variance (rANOVA) for 37 candidate variables to identify independent predictors of endotoxin. Meteorologic data were obtained for each primary sampling unit and tested as predictors of indoor endotoxin to determine if wetter or warmer microclimates were associated with higher endotoxin levels.

RESULTS: Weighted geometric mean endotoxin concentration ranged from 18.7 to 80.5 endotoxin units (EU)/mg for the five sampling locations, and endotoxin load ranged from 4,160 to 19,500 EU/m(2). Bivariate analyses and rANOVA demonstrated that major predictors of endotoxin concentration were sampling location in the home, census division, educational attainment, presence of children, current dog ownership, resident-described problems with cockroaches, food debris, cockroach stains, and evidence of smoking observed by field staff. Low household income entered the model if educational attainment was removed.

CONCLUSION: Increased endotoxin in household reservoir dust is principally associated with poverty, people, pets, household cleanliness, and geography.
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