Indoor phthalates from household dust in Qatar: implications for non-dietary human exposure

Mono-n-hexyl phthalate: exposure estimation and assessment of health risks based on levels found in human urine samples

Mono-n-hexyl phthalate (MnHexP) is a primary metabolite of di-n-hexyl phthalate (DnHexP) and other mixed side-chain phthalates that was recently detected in urine samples from adults and children in Germany. DnHexP is classified as toxic for reproduction category 1B in Annex VI of Regulation (EC) 1272/2008 and listed in Annex XIV of the European chemical legislation REACH; thereby, its use requires an authorisation. Health-based guidance values for DnHexP are lacking and a full-scale risk assessment has not been carried out under REACH. The detection of MnHexP in urine samples raises questions about the sources of exposure and concerns of consumer safety. Here, we propose the calculation of a provisional oral tolerable daily intake value (TDI) of 63 µg/kg body weight/day for DnHexP and compare it to intake levels corresponding to levels of MnHexP found in urine. The resulting mean intake levels correspond to less than 0.2% of the TDI, and maximum levels to less than 5%. The TDI was derived by means of an approximate probabilistic analysis using the credible interval from benchmark dose modelling of published ex vivo data on reduced foetal testosterone production in rats. Thus, for the dose associated to a 20% reduction in testosterone production, a lower and upper credible interval of 14.9 and 30.0 mg/kg bw/day, respectively, was used. This is considered a conservative approach, since apical developmental endpoints (e.g. changed anogenital distance) were only observed at higher doses. In addition, we modelled various scenarios of the exposure to the precursor substance DnHexP from different consumer products, taking measured contamination levels into account, and estimated systemic exposure doses. Of the modelled scenarios including the application of sunscreen (as a lotion or pump spray), the use of lip balm, and the wearing of plastic sandals, and considering conservative assumptions, the use of DnHexP-contaminated sunscreen was highlighted as a major contributing factor. A hypothetical calculation using conservative assumptions for the latter resulted in a margin of safety in relation to the lower credible interval of 3267 and 1007 for adults and young children, respectively. Most importantly, it was found that only a fraction of the TDI is reached in all studied exposure scenarios. Thus, with regard to the reported DnHexP exposure, a health risk can be considered very unlikely.

Phthalate Acid Esters (PAEs) in Indoor Dust from Decoration Material Stores: Occurrence, Sources, and Health Risks

Phthalate acid esters (PAEs) are one of the most widely used plasticizers globally, extensively employed in various decoration materials. However, studies on the impact of these materials on indoor environmental PAE pollution and their effects on human health are limited. In this study, forty dust samples were collected from four types of stores specializing in decoration materials (flooring, furniture boards, wall coverings, and household articles). The levels, sources, exposure doses, and potential health risks of PAEs in dust from decoration material stores were assessed. The total concentrations of Σ9PAE (the sum of nine PAEs) in dust from all decoration-material stores ranged from 46,100 ng/g to 695,000 ng/g, with a median concentration of 146,000 ng/g. DMP, DEP, DBP, and DEHP were identified as the predominant components. Among all stores, furniture board stores exhibited the highest Σ9PAE (159,000 ng/g, median value), while flooring stores exhibited the lowest (95,300 ng/g). Principal component analysis (PCA) showed that decoration materials are important sources of PAEs in the indoor environment. The estimated daily intakes of PAEs through non-dietary dust ingestion and dermal-absorption pathways among staff in various decoration-material stores were 60.0 and 0.470 ng/kg-bw/day (flooring stores), 113 and 0.780 ng/kg-bw/day (furniture board stores), 102 and 0.510 ng/kg-bw/day (wall covering stores), and 114 and 0.710 ng/kg-bw/day (household article stores). Particularly, staff in wall-covering and furniture-board stores exhibited relatively higher exposure doses of DEHP. Risk assessment indicated that although certain PAEs posed potential health risks, the exposure levels for staff in decoration material stores were within acceptable limits. However, staff in wall covering stores exhibited relatively higher risks, necessitating targeted risk-management strategies. This study provides new insights into understanding the risk associated with PAEs in indoor environments.

Neonatal di-(2-ethylhexyl)phthalate exposure induces permanent alterations in secretory CRH neuron characteristics in the hypothalamus paraventricular region of adult male rats

Corticotrophin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) play a critical role in the modulation of the hypothalamic-pituitary-adrenal (HPA) axis. Early-life exposure to di-(2-ethylhexyl) phthalate (DEHP) has been associated with an increased risk of developing psychiatric disorders in adulthood. The present work was designed to explore the impact of neonatal exposure to DEHP on adult PVN CRH neuronal activity. DEHP or vehicle was given to male rat pups from PND16 to PND22. Then, anxiety-like behaviors, serum corticosterone and testosterone, immunohistochemistry, western blotting, fluorescence in situ hybridization and acute ex vivo slice electrophysiological recordings were used to evaluate the influence of DEHP on adult PVN secretory CRH neurons. Neonatal DEHP-exposed rats exhibited enhanced anxiety-like behaviors in adults, with an increase in CORT. Secretory CRH neurons showed higher spontaneous firing activity but could be inhibited by GABAAR blockers. CRH neurons displayed fewer firing spikes, prolonged first-spike latency, depolarizing shifts in GABA reversal potential and strengthened GABAergic inputs, as indicated by increases in the frequency and amplitude of sIPSCs. Enhancement of GABAergic transmission was accompanied by upregulated expression of GAD67 and downregulated expression of GABABR1, KCC2 and GAT1. These findings suggest that neonatal exposure to DEHP permanently altered the characteristics of secretory CRH neurons in the PVN, which may contribute to the development of psychiatric disorders later in life.

Evaluating the risk of phthalate and non-phthalate plasticizers in dust samples from 100 Japanese houses

Phthalates are widely used as plasticizer and associated with various health issues. Recently, non-phthalate plasticizers are replacing phthalates; however, the exposure to these substances and the risk in Japan is unclear. In this study, we assessed the concentrations of phthalates, non-phthalate plasticizers, and phthalate degradation products in house dust and determined their respective exposure risks via oral and dermal routes. Twelve phthalates, seven non-phthalate plasticizers, and two degradation products were determined in the house dust obtained from 100 Japanese homes. The median concentration of di(2-ethylhexyl) phthalate (DEHP), accounting for 85 % of the total concentration of phthalates and non-phthalate plasticizers detected in this study, was 2.1 × 103 μg/g of dust. Apart from DEHP, diisononyl phthalate (DINP) and di(2-ethylhexyl) terephthalate (DEHT) were the most abundant in the house dust, accounting for 6.2 % (median: 1.7 × 102 μg/g of dust) and 6.1 % (median: 1.7 × 102 μg/g of dust) of the total concentrations, respectively. DEHP and DEHT concentrations in house dust were higher in apartment and small houses (floor area: ≤30 m2 or 31-60 m2 for DEHP and 31-60 m2 for DEHT) than in detached and large houses (floor area: ≥121 m2). Conversely, di-n-butyl phthalate (DnBP) concentrations were significantly higher in detached and large houses (floor area: ≥121 m2) than in apartment and small houses (floor area: ≤30 m2). The total hazard quotient (HQ), using the maximum concentration in house dust, revealed that oral and dermal exposure to house dust was 1.3 × 10-6-0.11 for adults (all substances) and 1.6 × 10-5-2.2 × 10-2 for preschool children (except for DnBP and DEHP), suggesting no risk. The HQs for DnBP and DEHP exposure via house dust for preschool children using the maximum values were 0.46 and 1.2, and 6.0 × 10-3 and 0.18 using the median values, indicating that risk of DEHP exposure should be exhaustively determined by considering other exposure routes that were not evaluated in this study, such as diet.

An overview of organic contaminants in indoor dust, their health impact, geographical distribution and recent extraction/analysis methods

People spend a substantial proportion of their time indoors; therefore, exposure to contaminants in indoor dust is persistent and profuse. According to the findings of recent studies, contaminants such as flame retardants (FRs), organochlorines (OCs), and phthalate esters (PAEs) are more prevalent in indoor dust. The discrepancy in the geographical distribution of these chemicals indicates country-specific applications. However, many studies have revealed that chlorophosphates, polychlorinated biphenyls (PCBs) and di-2-ethylhexyl phthalate are frequently detected in indoor dust throughout the world. Although some chemicals (e.g., OCs) were banned/severely restricted decades ago, they have still been detected in indoor dust. These organic contaminants have shown clear evidence of carcinogenic, neurotoxic, immunogenic, and estrogenic activities. Recent extraction methods have shown their advantages, such as high recoveries, less solvent consumption, less extraction time and simplicity of use. The latest separation techniques such as two-dimensional gas/liquid chromatography, latest ionization techniques (e.g., matrix-assisted laser desorption/ionization (MALDI)), and modern techniques of mass spectrometry (e.g., tandem mass spectrometry (MS/MS), time-of-flight (TOF) and high-resolution mass spectrometry (HRMS)) improve the detection limits, accuracy, reproducibility and simultaneous detection of organic contaminants. For future perspectives, it is suggested that the importance of the study of dust morphology for comprehensive risk analysis, introducing standard reference materials to strengthen the analytical methods, adopt common guidelines for comparison of research findings and the importance of dust analysis in the developing world since lack of records on the production and usage of hazardous substances. Such measures will help to evaluate the effectiveness of prevailing legislations and to set up new regulations.

Phthalic acid esters (PAEs) in workplace and house dust from Vietnam: concentrations, profiles, emission sources, and exposure risk

The occurrence of nine phthalic acid esters (PAEs) were determined in indoor dust samples collected from vehicle repair shops, waste processing workshops, and homes in Vietnam. Concentrations of total PAEs ranged from 585 to 153,000 (median 33,400 ng/g), which fall in the lower end of global range. The PAE levels in workplace dust (median 49,100; range 9210-153,000 ng/g) were significantly higher than those in house dust (median 23,700; range 585-83,700 ng/g), indicating waste processing activities as potential PAE sources. The most predominant compound was di-(2-ethyl)hexyl phthalate (DEHP), accounting for 62 ± 18% of total PAEs. Other major compounds were benzyl butyl phthalate (BzBP) (10 ± 12%), di-n-butyl phthalate (DnBP) (9.7 ± 7.7%), di-n-octyl phthalate (DnOP) (7.9 ± 8.1%), and diisobutyl phthalate (DiBP) (6.9 ± 5.0%). Proportions of BzBP and DnBP in some workplace dust samples were markedly greater than in common house dust, suggesting specific emission sources. Daily intake doses of selected PAEs (e.g., DnBP, DiBP, BzBP, and DEHP) through dust ingestion were much lower than reference doses, implying acceptable levels of risk.

Associations between phthalic acid esters in house dust and home characteristics/living habits in a rural region of Taiwan

Phthalic acid esters (PAEs) commonly used as plasticizers are distributed ubiquitously in the living environment. We conducted a field study to examine the associations between PAE residue in dust and home characteristics/living habits in 47 rural homes in Taiwan. A questionnaire regarding home characteristics/living habits and composite sampling of house dust were conducted in each participating home. Five PAEs were selected for analysis on gas chromatography-mass spectrometry with the limits of quantification being 0.5 ng/g or lower. Uni- and multivariate linear regression analyses were performed for examining the associations. The five PAEs were prevalently detected from the samples, and the concentrations were below 1000 ng/g; di(2-ethylhexyl) phthalate (DEHP) was the most frequently detected PAE (85%), whereas di-isobutyl phthalate (DiBP) appeared to the most abundant congener with the maximum concentration of 807.65 ng/g. Floor cleaning frequency and use of detergents for floor cleaning were significantly associated with DEHP in dust (P < 0.05), suggesting additives of plasticizers in detergent products. The factors of plastic wraps in storage and use of disposable cups were both significantly related to DiBP (P < 0.01), which could be extensively used in food packaging products. We confirmed that several home characteristics/living habits were related to certain PAE residue in dust.

Targeted and suspect screening of plasticizers in house dust to assess cumulative human exposure risk

Indoor dust is an important exposure route to anthropogenic chemicals used in consumer products. Plasticizers are common product additives and can easily leach out of the product and partition to dust. Investigations of plasticizers typically focus on a subset of phthalate esters (PEs), but there are many more PEs in use, and alternative plasticizers (APs) are seeing greater use after recognition of adverse health effects of PEs. In this study we use full scan high resolution mass spectrometry for targeted and suspect screening of PEs and APs in house dust and to assess the potential risk of human exposure. House dust samples from Eastern Slovakia were investigated and concentrations of ∑₁₂PEs and ∑₅APs ranged 12-2765 μg/g and 45-13,260 μg/g, respectively. APs were at similar levels to PEs, indicating common usage of these compounds in products in homes. Evaluation of individual compound toxicity combined with human intake via dust ingestion suggested PEs are of lower priority compared to semivolatile organic compounds such as polychlorinated biphenyls due to their lower toxicity. However, cumulative risk assessment (CRA) is a more appropriate evaluation of risk, considering the presences of many PEs in dust and their similar toxic mode of action. CRA based on median toxicity reference values (TRVs) suggested acceptable risks for dust ingestion, however, the wide range of literature-derived TRVs is a large uncertainty, especially for the APs. Use of newer TRVs suggest risk from dust ingestion alone, i.e. not even considering diet, inhalation, and dermal contact. Additionally, screening of full-scan instrumental spectra identified a further 40 suspect PE compounds, suggesting the CRA based on the 12 target PEs underestimates the risk.

Environmental Distribution of Personal Care Products and Their Effects on Human Health

Personal care products (PCPs) are generally used for personal hygiene, cleaning, grooming, and beautification. These include hair and skin care products, baby care products, UV blocking creams, facial cleansers, insect repellents, perfumes, fragrances, soap, detergents, shampoos, conditioners, toothpaste, etc., thus exposing humans easily. Personal preferences related to PCPs usage frequency are highly variable and depend on socioeconomic status and lifestyle factors. The increasing availability and diversity of PCPs from the retailer outlets consequently result in higher loading of PCPs into wastewater systems and, therefore, the environment. These compounds persistently and continuously release biologically active and inactive ingredients in the atmosphere, biosphere, geosphere, and demonstrating adverse effects on human, wild, and marine life. Advanced techniques such as granular activated carbon filtration and algae-based system may help biotransformation and remove PCP contaminants from water with improved efficiency. Additionally, harmony among PCPs related regulations of different countries may encourage standard checks to control their manufacturing, sale, and distribution across the borders to ensure consumers' safety. Furthermore, all intended ingredients, their concentrations, and instructions for frequency of use as per age groups may be clearly labeled on packages of PCPs. In conclusion, the emerging environmental contaminants of PCPs and their association with the growing risks of negative effects on human health and globally on the environment emphasize the chemical-free simple lifestyle.

Household Dust: Loadings and PM10-Bound Plasticizers and Polycyclic Aromatic Hydrocarbons

Residential dust is recognized as a major source of environmental contaminants, including polycyclic aromatic hydrocarbons (PAHs) and plasticizers, such as phthalic acid esters (PAEs). A sampling campaign was carried out to characterize the dust fraction of particulate matter with an aerodynamic diameter smaller than 10 µm (PM10), using an in situ resuspension chamber in three rooms (kitchen, living room, and bedroom) of four Spanish houses. Two samples per room were collected with, at least, a one-week interval. The PM10 samples were analyzed for their carbonaceous content by a thermo-optical technique and, after solvent extraction, for 20 PAHs, 8 PAEs and one non-phthalate plasticizer (DEHA) by gas chromatography-mass spectrometry. In general, higher dust loads were observed for parquet flooring as compared with tile. The highest dust loads were obtained for rugs. Total carbon accounted for 9.3 to 51 wt% of the PM10 mass. Plasticizer mass fractions varied from 5 µg g−1 to 17 mg g−1 PM10, whereas lower contributions were registered for PAHs (0.98 to 116 µg g−1). The plasticizer and PAH daily intakes for children and adults via dust ingestion were estimated to be three to four orders of magnitude higher than those via inhalation and dermal contact. The thoracic fraction of household dust was estimated to contribute to an excess of 7.2 to 14 per million people new cancer cases, which exceeds the acceptable risk of one per million.

Neural mechanisms underlying the deficit of learning and memory by exposure to Di(2-ethylhexyl) phthalate in rats

Di(2-ethylhexyl) phthalate (DEHP), as one of the most broadly representative phthalic acid esters, is used as a plasticizer in Polyvinyl chloride production. The exact neurotoxicologically effects of DEHP to human have not been adequately researched. In order to investigate the effects and mechanisms of DEHP exposure on neural circuit, the spatial learning and memory of Sprague Dawley (SD) rats was measured, and the cellular mechanisms underlying synaptic plasticity, cellular excitability and ion channels were detected. Our data showed that the spatial learning and memory was changed by DEHP (100 and 300 mg) treatment. Meanwhile, the frequency of mini Excitatory Postsynaptic Current (mEPSC) from CA3 pyramidal cells were significantly decreased by DEHP exposure (0.1 and 0.3 M); the firing threshold, membrane potential threshold, number, amplitude and latency of Action Potentials (Aps) of CA1 pyramidal cells were altered with the application of DEHP (0.1 and 0.3 M); furthermore, DEHP, both in 0.1 and 0.3 M could inhibit the voltage-gated potassium channel of CA1 pyramidal cells. Our results indicated that DEHP could impair the spatial learning and memory, and this impairment might due to the DEHP-induced suppression of the neuronal excitability and synaptic plasticity by inhibiting the voltage-gated potassium channel, supporting the hypothesis that DEHP could cause the disruption of neural function.