House Dust Levels Research Articles

Prevalence of elevated blood lead levels and risk factors among children living in Patna, Bihar, India 2020.

Childhood lead exposure remains a key health concern for officials worldwide, contributing some 600,000 new cases of intellectually disabled children annually. Most children affected by high exposure to lead live in low- and middle-income countries. The leaded gasoline phase out in India was completed in 2000. Yet, in 2020, an estimated 275 million children aged 0 to 9 years had blood lead levels (BLLs) ≥ 5 μg/dL known to adversely affect intelligence and behavior. Lead sources reported in India include spices, cookware, paint, traditional medicines and cosmetics, and lead-acid battery recycling and repair. However, their relative contribution has not been characterized. More than 200 lead pollution sites related to battery recycling and repair activities were identified in Bihar and Jharkhand, India. Ninety percent of the recycling sites had soil lead concentrations exceeding the US Environmental Protection Agency's standards. We compared blood and environmental lead levels in two groups of children in Patna, Bihar. Households in proximity to battery recycling operations (Proximal n = 67) versus households distal to these operations (Distal n = 68). The average age of children was 40 months; 46% were female. Overall, the geometric mean (GM) BLL was 11.6 μg/dL. GM BLLs of children in Proximal and Distal households were not significantly different (10.2 μg/dL vs. 13.1 μg/dL respectively; p≤0.07). About 87% children, 56 Proximal and 62 Distal had BLLs ≥5 μg/dl. Lead concentrations in environmental samples were significantly higher in Proximal households (soil mean 9.8 vs. 1.6 μg/ft2; dust mean 52.9 vs. 29.9 μg/ft2 p<0.001; Proximal vs. Distal respectively) whereas concentrations in all spices were higher in Distal households (mean 46.8 vs 134.5 ppm p<0.001; Proximal vs. Distal respectively), and turmeric (mean 59.4 vs. 216.9 ppm Proximal vs. Distal respectively). In multivariate analyses for all children lead in spices and turmeric and number of rooms in the house were significant while for the Proximal group only lead in spices remained in the model. The predictive value of these models was poor. For the Distal group, a model with lead concentration in spices, turmeric and soil and number of rooms in the house was a much better fit. Of the 34 water samples collected, 7 were above the Indian standard of 10 ppb for lead in drinking water (2 in the Proximal area, 5 in the Distal area). Children in Patna, Bihar, India are exposed to multiple sources of lead, with lead levels in house dust and loose, locally sourced spices the most likely to increase blood lead levels. A holistic approach to blood lead testing and source identification and remediation are necessary to prevent lead exposure.

Diverging trends of plasticizers (phthalates and non-phthalates) in indoor and freshwater environments—why?

BackgroundEuropean chemicals management aims to protect human health and the environment from legacy and emerging contaminants. The plasticizer market changed in response to the restriction of low molecular weight (LMW) phthalate plasticizers such as Di (2-ethylhexyl) phthalate (DEHP) due to their hazardous properties. We investigated patterns and trends of 19 regulated and emerging plasticizers in house dust from German homes and in suspended particulate matter (SPM) from major German rivers. The samples were used from the mid-2000s and late 2010s from two governmental long-term monitoring programs in Germany.ResultsWhile the sum of the respective plasticizer levels hardly changed over the study period, we observed a significant decrease of LMW phthalates in both house dust (2003/06, 80% of the ∑plasticizer concentration; 2014/17, 31%) and SPM (2005, 48%; 2017, 28%). This was accompanied by their substitution with high molecular weight (HMW) phthalates and non-phthalates. HMW phthalates increased from 19% of the ∑plasticizer concentration to 46% between the mid-2000s and the late 2010s in house dust, and from 50% to 63% in SPM samples. Diisononyl phthalate (DINP) replaced DEHP as the dominant plasticizer in both compartments. A significant tenfold increase (p < 0.05) was observed in SPM samples for Di (2-propylheptyl) phthalate (DPHP) (1–13%), compared to low levels in house dust (2014/17, 1%). Non-phthalates increased to 23% of the ∑plasticizer concentration in house dust but only to 9% in SPM (mid-2000s: house dust, < 1%; SPM, 1.5%). In recent house dust samples, Di (2-ethylhexyl) terephthalate (DEHT) had the third highest concentration of all plasticizers and contributed 18% to the total load, whereas Tris (2-ethylhexyl) trimellitate (TOTM) was one of the major non-phthalates in SPM samples.ConclusionsUnlike in the indoor environment, the substitution of LMW phthalates in the aquatic environment was characterized by a significant shift towards plasticizers with potentially hazardous properties. DPHP and TOTM were identified by European chemical regulation as potentially endocrine disrupting compounds and persistent, bioaccumulative and toxic compounds. Our data document the need for integrated chemicals management to safeguard the transition to a non-toxic environment.

Initial assessment of imports of chlorinated paraffins into Nigeria and the need of improvement of the Stockholm and Rotterdam Conventions

Short-chain and medium-chain chlorinated paraffins (SCCPs/MCCPs) are of concern due to their persistence, bioaccumulation, and toxicity. SCCPs were listed in 2017 as persistent organic pollutants (POPs) in the Stockholm Convention and Rotterdam Convention for Prior Informed Consent (PIC) procedure. MCCPs are evaluated in the POPs Reviewing Committee for listing. Studies in Africa demonstrate high SCCP/MCCP levels in house dust and human milk. Therefore, this study undertook an initial assessment of the production and import situation in Nigeria. The Nigerian government has not assessed SCCPs yet and has no registered exemptions for SCCPs and therefore should not produce or use SCCPs. Also, Nigeria has not notified Rotterdam Convention of PIC procedure and, therefore, no SCCP should be imported into Nigeria. Since no local production of SCCPs/MCCPs was observed in Nigeria, this study therefore compiled data on importation of SCCPs/MCCPs and products which may likely contain these chemicals from the UN Comtrade Database for the period 1996 to 2018. Despite the listing of SCCPs in the Rotterdam Convention, there is still no specific Harmonized System (HS) codes for SCCPs/MCCPs. This study therefore used HS codes of product categories known to contain SCCPs/MCCPs. HS substance categories under which SCCP/MCCPs are usually imported include plasticisers and other product categories that amounted to 229,779 and 518,342 tonnes respectively but without specific information on the type of plasticiser. About 39% of PVC and rubber imports of 2,683,015 tonnes and 3,516,052 tonnes respectively contain plasticisers. Based on the SCCP and MCCP impact factors from literature for China, the highest amount of SCCP (33,712 tonnes) was imported in the different PVC products while rubber products accounted to 1386 tonnes and PUR foam to 2331 tonnes. The amount of imported MCCPs in PVC products (25,599 tonnes) and rubber products (32,317 tonnes) was in the same order of magnitude while MCCP imported in PUR foam was estimated to 2020 tonnes. At the end of life (EoL), these product categories most likely contain appreciable amount of SCCPs possibly above Basel Convention low POP limit. This will hamper recycling and circular economy for these waste categories and generate POPs stockpiles/wastes that are difficult to manage/destroy in Africa. Hence there is an urgent need for specific HS Codes for SCCPs and industrial POPs currently produced/used for better control. Presently, products containing SCCPs are not labelled and are imported in huge quantities into Nigeria, without monitoring. In its current form this rather conveys a pseudo-safety for industrial POPs that do not exist. The Rotterdam Convention needs to establish specific HS codes for POPs for an appropriate PIC procedure and effective control of industrial POPs still produced. Furthermore, products containing SCCPs (and other POPs) require labelling and should also be covered under the Rotterdam Convention. The study highlights that Nigeria should urgently update the NIP for chemicals listed from 2015 to 2019 with a detailed SCCP inventory and develop monitoring capacity for market surveys. The Rotterdam Convention does not function fully and need to significantly improve to assure PIC procedure.

In Utero and Lactational Exposure to Flame Retardants Disrupts Rat Ovarian Follicular Development and Advances Puberty.

Brominated flame retardants (BFRs), including polybrominated diphenyl ethers and hexabromocyclododecane, leach out from consumer products into the environment. Exposure to BFRs has been associated with effects on endocrine homeostasis. To test the hypothesis that in utero and lactational exposure to BFRs may affect the reproductive system of female offspring, adult female Sprague Dawley rats were fed diets formulated to deliver nominal doses (0, 0.06, 20, or 60 mg/kg/day) of a BFR dietary mixture mimicking the relative congener levels in house dust from prior to mating until weaning. Vaginal opening and the day of first estrus occurred at a significantly earlier age among offspring from the 20 mg/kg/day BFR group, indicating that the onset of puberty was advanced. Histological analysis of ovaries from postnatal day 46 offspring revealed an increase in the incidence of abnormal follicles. A toxicogenomic analysis of ovarian gene expression identified upstream regulators, including HIF1A, CREB1, EGF, the β-estradiol, and PPARA pathways, predicted to be downregulated in the 20 or 60 mg/kg/day group and to contribute to the gene expression patterns observed. Thus, perinatal exposure to BFRs dysregulated ovarian folliculogenesis and signaling pathways that are fundamental for ovarian function in the adult.

Endotoxin clustering with allergens in house dust and asthma outcomes in a U.S. national study

BackgroundEndotoxin is ubiquitous in the environment, but its clustering with indoor allergens is not well characterized. This study examined the clustering patterns of endotoxin with allergens in house dust and their association with asthma outcomes.MethodsWe analyzed data from 6963 participants of the 2005–2006 National Health and Nutrition Examination Survey. House dust sampled from bedroom floor and bedding was evaluated for endotoxin and allergens from fungi, cockroach, dog, cat, mites, and rodents. Two-step cluster analysis and logistic regressions were performed to identify the clustering patterns and their associations with current asthma and wheeze in the past 12 months, adjusting for covariates.ResultsOf the homes, 17.8% had low endotoxin and allergen levels in house dust (Cluster 1). High endotoxin level clustered with Alternaria and pet allergens in the homes of participants with a high socioeconomic status who own pets (Cluster 2) (48.9%). High endotoxin clustered with Aspergillus, dust mites, cockroach, and rodent allergens in the homes of participants with low socioeconomic status (Cluster 3) (33.3%). Compared to Cluster 1, Cluster 2 was associated with higher asthma prevalence (OR 1.42, 95% CI: 1.06–1.91) and wheeze (OR 1.32, 95% CI: 1.07–1.63). Cluster 3 was positively associated with wheeze only in participants sensitized to inhalant allergens (OR 1.42, 95% CI: 1.06–1.91) or exposed to tobacco smoke (OR 1.72, 95% CI: 1.15–2.60).ConclusionsThe clustering of endotoxin with allergens in dust from homes with pets or of people with low socioeconomic status is associated with asthma and wheeze.

Occurrence and human exposure assessment of perfluorinated substances in house dust from three European countries

65 house dust samples from three European countries (Belgium, Italy and Spain) were evaluated for the presence of 20 polyflouroalkyl substances (PFASs) including perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acid (PFCAs) and perfluoroalkane sulfonamides (PFOSAs). The three countries presented similar PFAS levels ranging from 3.13 to 155 ng/g (12.9 ng/g; median), but in all cases PFCAs concentrations (6.92, 15.2 and 8.68 ng/g; median for Belgium, Italy and Spain) were higher than those obtained for PFSAs (2.30, 1.76 and 2.68 ng/g). Interestingly, in comparison to previously published data exhibited an increase in perfluorobutanesulfonate (PFBS) concentrations in Belgian house dust. On the other hand, levels of perfluorooctanesulfonate (PFOS) decreased in Spanish case. Data were examined for relationships between PFAS house dust levels, building and outdoor surrounding characteristics and occupant habits. Main findings revealed a positive association between PFOS concentrations and the building edification age, which could highlight a decrease in the use of this chemical in Europe. Similarly, perfluorohexanesulfonate (PFHxS) levels correlated with the percentage of the floor covered by textiles. Homes located in industrial sites showed higher PFCA levels compared to urban or agricultural locations, revealing the industrial processes as a potential source of these chemicals in Europe. Data obtained were used to perform human exposure assessment for dust intake via oral ingestion. Estimated daily intakes, calculated for toddlers and adults at median and worst case scenarios, were below oral Reference Dose (RfD) and tolerable daily intakes (TDI). However, in perfluorooctanoic acid (PFOA) case, dust ingestion significance to total dietary exposure reached values of 51% for toddlers in the worst case scenario.

Phthalates and organophosphates in settled dust and HVAC filter dust of U.S. low-income homes: Association with season, building characteristics, and childhood asthma

Phthalates and organophosphates are ubiquitous indoor semi-volatile organic contaminants (SVOCs) that have been widely used as plasticizers and flame retardants in consumer products. Although many studies have assessed their levels in house dust, only a few used dust samples captured by filters of building heating, ventilation, and air conditioning (HVAC) systems. HVAC filters collect particles from large volumes of air over a long period of time (potentially known) and thus provide a spatially and temporally integrated concentration. This study measured concentrations of phthalates and organophosphates in HVAC filter dust and settled floor dust collected from low-income homes in Texas, United States, in both the summer and winter seasons. The most frequently detected compounds were benzyl butyl phthalate (BBzP), di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), tris (1-chloro-2-propyl) phosphate (TCIPP), triphenyl phosphate (TPHP), and tris (1,3-dichloroisopropyl) phosphate (TDCIPP). The median level of TCIPP in settled dust was 3- to 180-times higher than levels reported in other studies of residential homes. Significantly higher concentrations were observed in HVAC filter dust as compared to settled dust for most of the frequently detected compounds in both seasons, except for several phthalates in the winter. SVOC concentrations in settled dust in winter were generally higher than in summer, while different seasonality patterns were found for HVAC filter dust. Settled dust samples from homes with vinyl flooring contained significantly higher levels of BBzP and DEHP as compared to homes with other types of floor material. The concentration of DEHP and TDCIPP in settled dust also significantly associated with the presence of carpet in homes. Cleaning activities to remove dust from furniture actually increased the levels of certain compounds in HVAC filter dust, while frequent vacuuming of carpet helped to decrease the concentrations of some compounds in settled dust. Additionally, the size and age of a given house also correlated with the levels of some pollutants in dust. A statistically significant association between DEHP concentration in HVAC filter dust in summer and the severity of asthma in children was observed. These results suggest that HVAC filter dust represents a useful sampling medium to monitor indoor SVOC concentrations with high sensitivity; in contrast, when using settled dust, in addition to consideration of seasonal influences, it is critical to know the sampling location because the type and level of SVOCs may be related to local materials used there.

Electronics, interior decoration and cleaning patterns affect flame retardant levels in the dust from Dutch residences

Consumer products such as furniture foam and electronic device casings are treated with flame retardant chemicals (FRs) to prevent the spread of fire. Many FRs are able to leach out of a product and end up in house dust. FRs in house dust can be taken up by humans through inhalation, ingestion or dermal adsorption. This study aims to identify factors in the home environment that are associated with FR levels in house dust. House dust and a wide range of data on characteristics of electronics, including age and use, interior decoration, domestic house and cleaning patterns, were collected from 50 households in the Netherlands. Decabromodiphenyl ether (BDE209) and several organophosphate flame retardants were measured in dust at detection percentages ranging from 58 to 94%, with median concentrations ranging from 32 ng/g (resorcinol-bis(diphenyl)phosphate (PBDPP)) to 825 ng/g (tris(chloropropyl)phosphate (TCIPP)). For the first time, age, hours of operation and use of the standby function of electronic devices were found to affect FR levels in dust. We found that if the total number of electronic devices purchased before 2008 increased by 1 device, BDE209 levels in house dust significantly increased by 66%. In addition, house dust from homes with carpeted floors was significantly associated with a 70–80% lower concentration of several FRs compared to homes with smooth floors (e.g., laminate). Less frequent vacuum cleaning and dusting were significantly associated with 41 to 88% higher concentrations of several FRs in dust. These associations suggest that actions such as frequent vacuum cleaning and dusting as well as different FR regulations for electronic devices affect indoor exposure levels.

Can Increased Endotoxin Levels in House Dust be used as an Indicator of a Mould Problem?

Endotoxins are common indoor biocontaminants. Our purpose was to investigate the association of endotoxin content with mould problems in house dust in buildings, to determine whether endotoxins can be used as an indicator of the presence of moulds in buildings. The participants were selected from the Clinic for Indoor Air Health Problems on the basis of symptoms attributed to indoor air problems. We examined their health status. House dust was collected in new vacuum cleaner bags from surfaces in the rooms of their homes or workplaces. We measured the endotoxin concentrations in the house dust of 13 homes and 9 workplaces of the 19 participants, using a quantitative limulus test. The median endotoxin concentrations in the house dust of their homes was 9.9, and the range was 1.9–103 EU/mg; and in the house dust of workplaces it was 4.5, and the range 0.5–81 EU/mg. We found higher house dust endotoxin concentrations in rooms in which moisture problems had been identified or in dwellings in which pets were kept. Our pilot study suggests that endotoxins may be a useful additional tool for estimating possible mould contamination at homes or workplaces.

Occurrence of polybrominated diphenyl ethers in floor and elevated surface house dust from Shanghai, China

House dust is the main source of human exposure to flame retardants by ingestion. This study investigated the occurrence of polybrominated diphenyl ethers (PBDEs) in indoor dust from 22 houses in Shanghai, China. House dust was separately collected from the floor and elevated furnishings surface (mostly between 0.5 and 2 m height) for comparison. The concentrations of ∑22 PBDEs ranged from 19.4 to 3280 ng/g (with a geometric mean of 203 ng/g) and from 55.1 to 792 ng/g (with a geometric mean of 166 ng/g) in floor dust (FD) and elevated surface dust (ESD), respectively. BDE-209 was the predominant congener, accounting for about 73.1% of total PBDE burdens. In terms of congener profiles, the comparison of FD and ESD revealed no significant differences except for the ratio of BDE-47/BDE-99. ESD samples displayed a ratio of BDE-47/BDE-99 very similar to commercial penta-BDE products DE-71 while the ratio in FD was exceptionally higher. Significant correlation was found between concentrations of commercial penta-BDE compositions in FD and ESD (p < 0.05). Except for some occasional values, PBDE levels in house dust exhibited temporal stability. Human exposure to PBDEs via dust ingestion was estimated. The highest daily intake of PBDEs was for toddlers by using 95th percentile concentrations of PBDEs via high dust ingestion in FD (23.07 ng/kg bw/day). About 20-fold difference in exposure estimates between toddlers and adults supports that toddlers are facing greater risk from indoor floor dust. Expectedly, this study highlighted the point that residents in Shanghai were exposed to low doses of PBDEs in house dust.

The development of methods to measure exposure to a major rabbit allergen (Ory c 1).

Rabbits are used as laboratory animal models and are also popular domestic pets. Allergic responses to rabbit allergens have been documented in both settings, and several rabbit allergens identified. We have purified an 18 kD protein extracted from rabbit fur that was shown by N-terminal sequencing and mass spectrometry (MS) to be a lipocalin, identical to that identified as an odorant binding protein and an allergen with the formal nomenclature of Ory c 1. De novo sequencing of the MS peptide fragments gave additional primary sequence data of this protein. Polyclonal antisera were raised against the purified protein and used to develop two types of immunoassay. Ory c 1 content was measured in used rabbit bedding and household dust samples from homes keeping rabbits as pets. Atmospheric sampling was also undertaken in an animal facility undertaking rabbit experimental work. Ory c 1 levels in house dust where rabbits were kept as pets were between undetectable–41,290 ng·g−1, and in used bedding between 370–26,740 ng·g−1. Significantly higher house dust levels were found where rabbits spent large amounts, or all of, their time indoors. Personal air sampler levels within the animal facility were between 65–216 ng·m−3. Low levels (0.8–2 ng·m−3) were found in the facility's changing rooms, but undetected in the entrance lobby, office and laundry. We believe that these immunochemical assays may be used to identify activities in the occupational and domestic setting which produce higher levels of exposure to rabbit allergens, and where measures to control exposure may be warranted to reduce potential risk of allergic outcomes.

Associations between flame retardant applications in furniture foam, house dust levels, and residents' serum levels

Polyurethane foam (PUF) in upholstered furniture frequently is treated with flame retardant chemicals (FRs) to reduce its flammability and adhere to rigorous flammability standards. For decades, a commercial mixture of polybrominated diphenyl ethers (PBDEs) called PentaBDE was commonly applied to foam to fulfill these regulations; however, concerns over toxicity, bioaccumulation, and persistence led to a global phase-out in the mid-2000s. Although PentaBDE is still detected in older furniture, other FR compounds such as tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and Firemaster® 550 (FM550) have been increasingly used as replacements. While biomonitoring studies suggest exposure is widespread, the primary sources of exposure are not clearly known. Here, we investigated the relationships between specific FR applications in furniture foam and human exposure. Paired samples of furniture foam, house dust and serum samples were collected from a cohort in North Carolina, USA and analyzed for FRs typically used in PUF. In general, the presence of a specific FR in the sofa of a home was associated with an increase in the concentration of that FR in house dust. For example, the presence of PentaBDE in sofas was associated with significantly higher levels of BDE-47, a major component of PentaBDE, in house dust (10β=6.4, p<0.001). A similar association was observed with a component of FM550, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), with levels that were approximately 3 times higher in house dust when FM550 was identified in the sofa foam (p<0.01). These relationships were modified by dust loading rates in the living room and the ratio of sofa size to room size. Interestingly, levels of TDCIPP and tris(1-chloro-2-isopropyl) phosphate (TCIPP) were also higher in dust with detections in sofa foam; however, these associations were not statistically significant and may suggest there are other prominent sources of these compounds in the home. In addition, the presence of PentaBDE in sofa foam was associated with significantly higher levels of BDE-47 in serum (p<0.01). These results suggest that FR applications in sofas are likely major sources of exposure to these compounds in the home.

Ara h2 levels in dust from homes of individuals with peanut allergy and individuals with peanut tolerance.

Approximately 1% of the U.S. population has a peanut allergy. Previous studies that measured peanut protein in house dust support the hypothesis that household peanut consumption may lead to clinical sensitization through transdermal exposure. The aim of this pilot study was to characterize Ara h2 levels in house dust from homes with and without individuals with peanut allergy. Household dust was obtained from homes with an individual with peanut allergy and from homes with no individual with peanut allergy. Ara h2 levels were determined by using a monoclonal antibody-based immunoassay with a level of determination of 150 ng per gram of dust. Peanut consumption information was obtained by questionnaire. A total of 85 dust samples were collected: 38 from homes with a individual with peanut allergy and 47 from control homes. The median Ara h2 level in homes with an individual with peanut allergy was 1236 ng/g (interquartile range [IQR], 256-1342 ng/g), whereas the median Ara h2 level in homes without an individual with peanut allergy was 650 ng/g (IQR, 163-2201 ng/g). Ara h2 levels in dust from homes of individuals with peanut allergy were not significantly lower than in dust from control homes. Of the homes with an individual with peanut allergy, 15 reported complete avoidance of peanut in the home (39%). Ara h2 levels in homes that completely avoided peanuts were not significantly lower than Ara h2 levels in homes that did not restrict peanuts (p = 0.531). Although families may restrict peanuts and peanut products in the home, there was still detectable Ara h2 levels found in homes. Each subject's definition of restriction may vary, there seemed to be peanut protein entering the home, although the protein origin is not known. Possibilities include cross-reactivity with another antigen or transport into the home on some vector. Further investigation of hypotheses regarding cross-reactivity and environmental exposure to Ara h2 is necessary.

PBDEs Levels in House Dust and Human Exposure to PBDEs via Dust Ingestion in Hangzhou

In order to evaluate the pollution degree of the dust in Hangzhou City, the indoor dust samples of 19 offices, families and students' dormitories were collected from August to March in 2013 at Hangzhou for evaluating the pollution level of polybrominated diphenyl ethers (PBDEs), to analyze concentrations of 14 PBDEs congeners and congener distribution as well as the possible influencing factors, and to estimate the PBDEs exposure levels of adults and children through the dust intake. The results showed that the average ∑14PBDEs of office was 9.28×102 ng·g-1, and the median was 1.03×103 ng·g-1; the average ∑14PBDEs of family was 7.83×102 ng·g-1, and the median was 9.11×102 ng·g-1; the average ∑14PBDEs of student dormitory was 4.07×102 ng·g-1, and the median was 4.03×102 ng·g-1. The pollution level of the office was higher than that of the living environment. BDE-209 was the largest monomer, and its contribution was 75.48%, followed by BDE-190, BDE-154 and BDE-71.PBDEs exposure levels of adults and children by dust intake were 13.12-32.63 ng·d-1 and 32.40-54.54 ng·d-1, respectively. Children's PBDEs exposure in the dust was higher than that of the adults, mainly because the average dust intake of children was higher than that of adults. The analysis showed that the PBDEs from indoor dust intake was a potential health hazard, and the biggest potential harm to children.

Overview on relative importance of house dust ingestion in human exposure to polybrominated diphenyl ethers (PBDEs): International comparison and Korea as a case

Human exposure studies to polybrominated diphenyl ethers (PBDEs) have reached different results about the relative importance of diet intake and house dust ingestion. In the present study, concentrations of PBDEs in Korean house dust (n=15) from geographically different cities were measured, which were in agreement with a previous result, and compared with those for 22 countries of five continents collected from the most recent scientific literature. Compared with other exposure pathways, diet intake was the most important contributor to total PBDEs exposure of Korean adults (i.e., 71% of overall intake). On global comparison, total PBDE levels in house dust differed by two to three orders of magnitude among the countries investigated, with a significant relationship with gross domestic product (GDP). Whereas, dietary daily intakes exhibited a narrow difference within one order of magnitude worldwide and no relationship with GDP. Consequently, the relative importance of major two pathways depended on the contamination extent of PBDEs in house dust, which may be associated with the amount of PBDE products in use. In most countries except for UK and USA, the contribution of house dust ingestion was less important than diet intake in the current and are expected to much more mitigate in the future. However, how fast the effect of regulation will be reflected to house dust and human exposure is necessary to be monitored steadily.

Gestational and Early Postnatal Exposure to an Environmentally Relevant Mixture of Brominated Flame Retardants: General Toxicity and Skeletal Variations.

Brominated flame retardants (BFRs) are stable environmental contaminants known to exert endocrine-disrupting effects. Developmental exposure to polybrominated diphenyl ethers (PBDEs) is correlated with impaired thyroid hormone signaling, as well as estrogenic and anti-androgenic effects. As previous studies have focused on a single congener or technical mixture, the purpose of the current study was to examine the effects of gestational and early postnatal exposure to an environmentally relevant mixture of BFRs designed to reflect house dust levels of PBDEs and hexabromocyclododecane on postnatal developmental outcomes. Pregnant Sprague-Dawley rats were exposed to the PBDE mixture from preconception to weaning (PND 21) through the diet containing 0, 0.75, 250, and 750 mg mixture/kg diet. BFR exposure induced transient reductions in body weight at PND 35 in male and from PND 30-45 in female offspring (250 and 750 mg/kg). Liver weights (PND 21) and xenobiotic metabolizing enzyme activities (PND 21 and 46) were increased in both male and female offspring exposed to 250 and 750 mg/kg diets. Furthermore, serum T4 levels were reduced at PND 21 in both,male and female offspring (250 and 750 mg/kg). At PND 21, Serum alkaline phosphatase (ALP) was decreased in males exposed to 750 mg/kg dietat, and females exposed to 250 and 750 mg/kg diets. At PND 46 ALP was significantly elevated in males (250 and 750 mg/kg). Variations in the cervical vertebrae and phalanges were observed in pups at PND 4 (250 and 750 mg/kg). Therefore, BFR exposure during gestation through to weaning alters developmental programming in the offspring. The persistence of BFRs in the environment remains a cause for concern with regards to developmental toxicity.

A post-remediation assessment in Jersey City of the association of hexavalent chromium in house dust and urinary chromium in children.

Although all chromite ore processing residue (COPR) sites near residential neighborhoods in Jersey City, New Jersey have undergone remediation, recent studies found widespread, but low levels of hexavalent chromium (Cr(+6)) in house dust both in Jersey City and in communities with no known sources of Cr(+6). This study was designed as a follow-up to determine whether there is an association between current Cr(+6) levels in house dust and urinary chromium concentrations in young children. Dust samples (N=369) were collected from 123 homes. The median Cr(+6) concentration was 3.3 μg/g (mean±SD 5.2±7.5) and the median Cr(+6) loading was 1.1 μg/m(2) (1.9±3.1). These levels were not elevated compared with previously reported levels in background communities (median concentration=3.5 μg/g; median loading=2.8 μg/m(2)). Urinary chromium concentrations were measured in spot urine samples collected from 150 children, ages 3 months to 6 years. The median uncorrected urinary chromium concentration was 0.19 μg/l (0.22±0.16). Current urinary chromium concentrations were significantly lower than those previously reported before and during remediation (t-test; P<0.001). Urinary chromium concentrations were not significantly higher in homes with high (75th or 90th percentile) Cr(+6) dust levels (concentration or loading) compared with other homes. Multiple linear regression was used to examine the relationship between Cr(+6) levels (concentration and loading) in house dust and urinary chromium concentrations (uncorrected and specific gravity corrected). Contrary to pre-remediation studies, we did not find a positive association between Cr(+6) levels in house dust and urinary chromium concentrations. The findings indicate that current Cr(+6) levels in house dust are not positively associated with children's chromium exposure as measured by urinary chromium, and the children's exposure to Cr(+6) in house dust is below the level that could be identified by urine sampling.

Assessment of human hair as an indicator of exposure to organophosphate flame retardants. Case study on a Norwegian mother–child cohort

A major challenge of non-invasive human biomonitoring using hair is to assess whether it can be used as an indicator of exposure to Flame Retardants, such as Organophosphate Flame Retardants (PFRs), since the contribution of atmospheric deposition (air and/or dust) cannot be neglected. Therefore, the aim of this study was to evaluate the suitability of using human hair more thoroughly by comparison of (i) levels of PFRs in human hair (from 48 mothers and 54 children), with levels measured in dust and air in their respective households; and (ii) levels of selected PFRs in hair with the levels of corresponding PFR metabolites in matching urine samples collected simultaneously. Most PFRs (tri-n-butyl phosphate (TNBP), 2-ethyl-hexyldiphenyl phosphate (EHDPHP), tri-phenyl phosphate (TPHP), tri-iso-butyl phosphate (TIBP), and tris(2-butoxyethyl) phosphate (TBOEP)) were detected in all human hair samples, tris(2-ethylhexyl) phosphate (TEHP) and tris(1,3-dichloro-iso-propyl) phosphate (TDCIPP) in 93%, tri-cresyl-phosphate (TCP) in 69% and tris(2-chloroethyl) phosphate (TCEP) in 21% of the samples. Levels of individual PFRs ranged between <1 and 3744ng/g hair and were lower than in indoor dust from the participants' homes. Several statistically significant associations between PFR levels in human hair and PFR levels in house dust and/or air were found, e.g. Spearman correlation (rS=0.561, p<0.05) between TBOEP in children's hair and in indoor air. Also, associations were found between TDCIPP in hair and its metabolite bis(1,3-dichloro-iso-propyl) phosphate (BDCIPP) in urine; they were stronger for children (e.g. Pearson correlation rP=0.475; p=0.001) than for mothers (rP=0.395, p=0.01). Levels of diphenyl phosphate (DPHP) in mothers' and children's urine were slightly correlated (rS=0.409, p=0.008), suggesting similar sources of exposure. To the best of our knowledge, this is the first study with such design and our findings might help to understand human exposure to and body burdens of PFRs.

Organophosphorus flame retardants (PFRs) and plasticizers in house and car dust and the influence of electronic equipment

All nine PFRs studied were detected in house and car dust from the Netherlands with the exception of tris(butyl) phosphate (TNBP) and tris(isobutyl) phosphate (TIBP) in car dust. Tris(2-butoxyethyl) phosphate (TBOEP, median 22μgg−1) was dominant in house dust collected around and on electronics followed by tris(2-chloroisopropyl) phosphate (TCIPP, median 1.3μgg−1), tris(2-chloroethyl) phosphate (TCEP, median 1.3μgg−1) and tris(phenyl) phosphate (TPHP, median 0.8μgg−1). Levels of TPHP and tris(methylphenyl) phosphate (TMPP, also known as TCP) in house dust on electronics were significantly higher than in house dust collected around electronics, suggesting that electronic equipment has limited contribution to the PFR levels in house dust, with the exception of TPHP and TMPP.Car dust was dominated by tris(1,3-dichloroisopropyl) phosphate (TDCIPP) with the highest levels found in dust collected from the car seats (1100μgg−1). The mean TDCIPP and TCIPP levels observed in car dust were significantly higher than the levels observed in dust collected around electronics. Significantly higher mean TMPP levels in dust taken from car seats were found compared to dust collected around the equipment (p<0.05). This is probably influenced by the use of TDCIPP, TCIPP in polyurethane foam (car seats) and the use of TMPP as plasticizer in car interiors.Worldwide four PFR patterns were observed in house dust. The PFR pattern in the Netherlands of TDCIPP, TMPP, TCEP, TCIPP and TPHP in house dust is comparable to the pattern found in six other countries, which may point to identical sources of these PFRs in the indoor environment. However, the PFR levels between the countries and within countries showed high variation.

Exposure to an environmentally relevant mixture of brominated flame retardants affects fetal development in Sprague-Dawley rats

Brominated flame retardants are incorporated into a wide variety of consumer products and are known to enter into the surrounding environment, leading to human exposure. There is accumulating evidence that these compounds have adverse effects on reproduction and development in humans and animal models. Animal studies have generally characterized the outcome of exposure to a single technical mixture or congener. Here, we determined the impact of exposure of rats prior to mating and during gestation to a mixture representative of congener levels found in North American household dust. Adult female Sprague-Dawley rats were fed a diet containing 0, 0.75, 250 or 750mg/kg of a mixture of flame retardants (polybrominated diphenyl ethers, hexabromocyclododecane) from two weeks prior to mating to gestation day 20. This formulation delivered nominal doses of 0, 0.06, 20 and 60mg/kg body weight/day. The lowest dose approximates high human exposures based on house dust levels and the dust ingestion rates of toddlers. Litter size and resorption sites were counted and fetal development evaluated. No effects on maternal health, litter size, fetal viability, weights, crown rump lengths or sex ratios were detected. The proportion of litters with fetuses with anomalies of the digits (soft tissue syndactyly or malposition of the distal phalanges) was increased significantly in the low (0.06mg/kg/day) dose group. Skeletal analysis revealed a decreased ossification of the sixth sternebra at all exposure levels. Thus, exposure to an environmentally relevant mixture of brominated flame retardants results in developmental abnormalities in the absence of apparent maternal toxicity. The relevance of these findings for predicting human risk is yet to be determined.