Intakes of phthalates by Japanese children and the contribution of indoor air quality in their residences

Exposure to organophosphorus compounds of Japanese children and the indoor air quality in their residences

Several organophosphorus compounds such as organophosphate pesticides (OPPs) and trialkylphosphates (TAPs) are suspected to inhibit cholinesterase activities, to affect endocrine systems or to possibly be carcinogenic. To evaluate their adverse effects on health with chronic exposure in the general population, especially in children, we measured the household exposure to OPPs and TAPs by Japanese children via all exposure pathways and the contribution of indoor air quality. First-morning void urine was collected from subjects aged 6 to 15 years (n = 132), and airborne organophosphorus compounds were sampled in the subject's bedroom for 24 h. Airborne levels of nine OPPs and three TAPs and their urinary metabolites were determined. No significant correlations were detected for any compounds between their airborne concentrations and the urinary excretion amounts of their corresponding metabolites. The estimated daily intakes were as follows (median, μg/kg b.w./d): chlorpyrifos, 0.042; diazinon, 0.067; tri-n-butylphosphate, 0.094. The 95th percentiles of the intakes for fenthion, fenitrothion and the above three compounds did not exceed their reference limit values, although one subject had a daily intake of tri-n-butylphosphate that was about twice its reference limit value. The concentration levels of the urinary metabolite of tri-n-butylphosphate in our subjects tended to be higher than those for children in many other countries. The fractions of the amounts absorbed by inhalation to the amounts absorbed via all of the exposure pathways was only 2.3 % (median) for tri-n-butylphosphate. Inhalation did not seem to contribute very much as an absorption pathway of the organophosphorus compounds in these Japanese children while they were at home. The exposure amounts of OPPs were not suggested to be high enough to adversely affect the health of these children at present on the basis of their daily intakes compared to their reference limit values.

Phthalates in the environment: characteristics, fate and transport, and advanced wastewater treatment technologies

Phthalates are well-known emerging contaminants that harm human health and the environment. Therefore, this review aims to discuss about the occurrence, fate, and phthalates concentration in the various environmental matrices (e.g., aquatic, sediment, soil, and sewage sludge). Hence, it is necessary to treat sources containing phthalates before discharging them to aqueous environment. Various advanced wastewater treatments including adsorption process (e.g., biochar, activated carbon), advanced oxidation processes (e.g., photo-fenton, ozonation, photocatalysis), and biological treatment (membrane bioreactor) have been successfully to address this issue with high removal efficiencies (70-95%). Also, the degradation mechanism was discussed to provide a comprehensive understanding of the phthalate removal for the reader. Additionally, key factors that influenced the phthalates removal efficiency of these technologies were identified and summarized with a view towards pilot-scale and industrial applications.

Exposure to phthalates and correlations with phthalates in dust and air in South China homes

We spend more than half of our daily time in indoor environments, and the contributions of phthalates present in it to total exposure are important. Here, we determined phthalate concentrations in paired indoor settled dust/air and their metabolites in human urine from 100 general families in south China to explore such kind of effect. The total concentrations of phthalates/metabolites were 48.7-2850 μg/g, 279-5080 ng/m³ and 10.7-2840 ng/mL in the indoor dust, air and urine samples, respectively. Among all targets, di-n-butyl phthalate, di-isobutyl phthalate and di-(2-ethylhexyl) phthalate and their metabolites were the predominant compounds. The daily intakes (DIs) of phthalates via dust or air decreased with age, except for infant, and the values of dust ingestion, air inhalation and air dermal uptake were 2720 ± 2460, 1300 ± 973 and 3590 ± 2890 ng/kg/day for toddlers and 236 ± 194, 360 ± 179 and 1120 ± 586 ng/kg/day for adults, respectively. The ratios of DIs from air to dust were greater than 1.0 for people in all age groups, and the ratio was the highest for adults. Furthermore, the contributions of phthalates from indoor dust and air to total DIs from all sources (estimated from urinary phthalate metabolites) were 0.60%-5.23% and 2.65%-12.2% for different ages, respectively. Our results indicated that indoor air was a quite important source for human exposure to phthalates in indoor environment in south China.

Secular trends of urinary phthalate metabolites in 7-year old children and association with building characteristics: Hokkaido study on environment and children's health

The widespread commercial production and use of phthalates as plasticizers in consumer products have led to significant human exposure. Some phthalates are known to disrupt the endocrine system and result in adverse health outcomes. As such, they have been regulated in materials used for children's items and food packages. In this study, we examined the secular trend of urinary phthalate metabolites in children and the association between metabolites and building characteristics. In total, 400 first-morning spot urine samples of 7 years old children collected from 2012 to 2017 from an ongoing birth cohort study were examined. Parents provided information on demographics and building questionnaires. We analyzed 10 urinary phthalate metabolites from five phthalate diesters using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS): MiBP, MnBP, MBzP, MEHP, MEOHP, MEHHP, MECPP, MiNP, OH-MiNP, and cx-MiNP. A multivariable regression model with creatinine-corrected metabolite levels was applied to assess secular trends during 2012-2017. The association between metabolite levels and building characteristics was investigated using a mutual-adjusted linear regression. The metabolites MnBP, MEHP, MEOHP, MEHHP, MECPP, and OH-MiNP were detected in all samples. The highest median concentration was for MECPP 37.4 ng/mL, followed by MnBP and MEHHP at concentrations of 36.8 and 25.8 ng/mL, respectively. Overall, DBP, BBzP, and DINP metabolite concentrations in this study were comparable to or lower than those in previous studies from Japan and other countries in a similar study period. Higher concentrations of DEHP metabolites were observed in this study than in children from the USA and Germany, as per previous reports. Despite updated phthalate regulations and reports of production volume change in Japan, all the measured metabolites showed a stable trend between 2012 and 2017. Higher phthalate metabolite levels were observed among children from households with low annual income, those who lived in old buildings, and those with window opening habits of ≥1 h than ≤1 h. In contrast, children in houses that vacuumed 4 or more days/week showed a lower level of MnBP than those in houses that vacuumed ≤3 days/week. This study demonstrates that the internal exposure level of phthalates in Japanese children was stable from 2012 to 2017. Our findings suggest that phthalate exposure in children is consistent. Thus, improvements in the indoor environment, such as frequent vacuuming, may reduce exposure. Biomonitoring of phthalates is critical for elucidating their possible health effects and developing mitigation strategies.

Air pollution caused by phthalates and cyclic siloxanes in Hanoi, Vietnam: Levels, distribution characteristics, and implications for inhalation exposure

Contamination status and distribution characteristics of ten phthalic acid esters (PAEs) and three cyclic volatile methyl siloxanes (CSs) were determined in the air (gas and particle) samples collected from indoor and outdoor spaces of several chemistry laboratories, offices, and homes from urban area of Hanoi, the capital city of Vietnam. Air concentrations of Σ10PAEs (median 688; range 142-2390 ng m^-3) and Σ3CSs (171; not detected-1100 ng m^-3) in the indoor air samples were significantly higher than those measured in the outdoor ones (Σ10PAEs: 161; 34.1-515 ng m^-3 and Σ3CSs: 43.2; not detected-258 ng m^-3), partly suggesting the predominance of indoor emission sources of these substances. There were significant positive correlations in total air concentrations of phthalates and siloxanes between the indoor and outdoor air samples. The most predominant phthalates were diethyl-, di-n-butyl-, diisobutyl-, and di(2-ethylhexyl) phthalate. For siloxanes, D5 and D6 were more abundant than D4 in most samples. Except for di(2-ethylhexyl)- and di-n-octyl phthalate in some locations, almost all the compounds were likely associated with gas phase than particle phase. Daily intake doses of airborne phthalates and siloxanes, and non-cancer and cancer risks of selected phthalates were estimated for different exposure groups such as adults, children, and university subjects (e.g., laboratory staff and students), indicating relatively low levels of risk.

Plasticizer contamination in the urine and hair of preschool children, airborne particles in kindergartens, and drinking water in Hong Kong

Common plasticizers and their alternatives are environmentally ubiquitous and have become a global problem. In this study, common plasticizers (phthalates and metabolites) and new alternatives [bisphenol analogs, t-butylphenyl diphenyl phosphate (BPDP), and bisphenol A bis(diphenyl phosphate) (BDP)] were quantified in urine and hair samples from children in Hong Kong, drinking water (tap water/bottled water) samples, and airborne particle samples from 17 kindergartens in Hong Kong. The results suggested that locally, children were exposed to various plasticizers and their alternatives. High concentrations of BPDP and BDP were present in urine, hair, tap water, bottled water, and air particulate samples. The geometric mean (GM) concentrations of phthalate metabolites in urine samples (126-2140 ng/L, detection frequencies < 81%) were lower than those detected in Japanese and German children in previous studies. However, a comparison of the estimated daily intake values for phthalates in tap water [median: 10.7-115 ng/kg body weight bw/day] and air particles (median: 1.23-7.39 ng/kg bw/day) with the corresponding reference doses indicated no risk. Bisphenol analogs were detected in 15-64% of urine samples at GM concentrations of 5.26-98.1 ng/L, in 7-74% of hair samples at GM concentrations of 57.5-2390 pg/g, in 59-100% of kindergarten air samples at GM concentrations of 43.1-222 pg/m³, and in 33-100% of tap water samples at GM concentrations of 0.90-3.70 ng/L. A significant correlation was detected between the concentrations of bisphenol F in hair and urine samples (r = 0.489, p < .05). The estimated daily urinary excretion values of bisphenol analogs suggest that exposure among children via tap water intake and airborne particle inhalation in kindergartens cannot be ignored in Hong Kong.