Ying Guo

Occurrence of Eight Bisphenol Analogues in Indoor Dust from the United States and Several Asian Countries: Implications for Human Exposure

Bisphenol A has been reported to be a ubiquitous contaminant in indoor dust, and human exposure to this compound is well documented. Information on the occurrence of and human exposure to other bisphenol analogues is limited. In this study, eight bisphenol analogues, namely 2,2-bis(4-hydroxyphenyl)propane (BPA), 4,4-(hexafluoroisopropylidene)diphenol (BPAF), 4,4-(1-phenylethylidene)bisphenol (BPAP), 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4-dihydroxydiphenylmethane (BPF), 4,4-(1,4-phenylenediisopropylidene)bisphenol (BPP), 4,4- sulfonyldiphenol (BPS), and 4,4-cyclohexylidenebisphenol (BPZ), were determined in indoor dust samples (n = 156) collected from the United States (U.S.), China, Japan, and Korea. Samples were extracted by solid-liquid extraction, purified by automated solid phase extraction methods, and determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The total concentrations of bisphenols (∑BPs; sum of eight bisphenols) in dust were in the range of 0.026-111 μg/g (geometric mean: 2.29 μg/g). BPA, BPS, and BPF were the three major bisphenols, accounting for >98% of the total concentrations. Other bisphenol analogues were rare or not detected, with the exception of BPAF, which was found in 76% of the 41 samples collected in Korea (geometric mean: 0.0039 μg/g). The indoor dust samples from Korea contained the highest concentrations of both individual and total bisphenols. BPA concentrations in dust were compared among three microenvironments (house, office, and laboratory). The estimated median daily intake (EDI) of ∑BPs through dust ingestion in the U.S., China, Japan, and Korea was 12.6, 4.61, 15.8, and 18.6 ng/kg body weight (bw)/day, respectively, for toddlers and 1.72, 0.78, 2.65, and 3.13 ng/kg bw/day, respectively, for adults. This is the first report on the occurrence of bisphenols, other than BPA, in indoor dust.

Comparative Assessment of Human Exposure to Phthalate Esters from House Dust in China and the United States

Because of volatilization and leaching from their application in consumer and personal care products, phthalate esters are ubiquitous contaminants in the indoor environment. In this study, we measured concentrations and profiles of 9 phthalate esters in indoor dust samples collected from six cities in China (n = 75). For comparison, we also analyzed samples collected from Albany, New York, USA (n = 33). The results indicated that concentrations, except for dicyclohexyl phthalate (DCHP) and bis(2-ethylhexyl) phthalate (DEHP), and profiles of phthalate esters varied significantly between the two countries. Concentrations of diethyl phthalate (DEP), di-n-hexyl phthalate (DNHP), and benzyl butyl phthalate (BzBP) were 5 to 10 times higher in dust samples collected from Albany than those from the Chinese cities. In contrast, concentrations of di-iso-butyl phthalate (DIBP) in dust samples from Albany were 5 times lower than those from the Chinese cities. We estimated the daily intake (DI) of phthalate esters through the routes of dust ingestion and dermal dust absorption. The extent of contribution of indoor dust to human exposures varied, depending on the type of phthalate esters. The contribution of dust to DEHP exposure was 2-5% and 10-58% of the estimated total DIs in China and the USA, respectively. On the basis of the estimates of total DIs of phthalates, extrapolated from urinary metabolite concentrations, the contributions of inhalation, dermal absorption, and dietary intake to total DIs were estimated. The results indicated that dietary intake is the main source of exposure to DEHP (especially in China), whereas dermal exposure was a major source for DEP. This is the first study to elucidate sources of human exposure to phthalates among the general population in China.

A Survey of Phthalates and Parabens in Personal Care Products from the United States and Its Implications for Human Exposure

Despite the widespread usage of phthalates and parabens in personal care products (PCPs), little is known about concentrations and profiles as well as human exposure to these compounds through the use of PCPs. In this study, nine phthalates and six parabens were determined in 170 PCPs (41 rinse-off and 109 leave-on), including 20 baby care products collected from Albany, New York. Phthalates were less frequently found in rinse-off PCPs but were more frequently found in perfumes (detection frequency of 100% for diethyl phthalate [DEP], 67% for dibutyl phthalate [DBP]), skin toners (90% for DEP), and nail polishes (90% for DBP). Parabens were found in ∼40% of rinse-off products and ∼60% of leave-on products. The highest concentrations of DEP, DBP, methyl- (MeP), ethyl- (EtP), propyl- (PrP), and butyl parabens (BuP) were on the order of 1000 μg per gram of the product. On the basis of amount and frequency of use of PCPs and the measured median concentrations of target analytes, the total dermal intake doses (sum of all phthalates or parabens) were calculated to be 0.37 and 31.0 μg/kg-bw/day for phthalates and parabens, respectively, for adult females. The calculated dermal intake of phthalates from PCPs was lower for infants and toddlers than for adult females. In contrast, dermal intake of parabens from PCPs by infants and toddlers was higher than that for adult females. The calculated maximum daily exposure dose of MeP, EtP, and PrP from PCPs ranged between 58.6 and 766 μg/kg-bw/day for infants and toddlers, which was 3 times higher than that calculated for adult females. PCPs are an important source of human exposure to parabens; the contribution of PCPs to phthalate exposure is low, except for DEP.

Occurrence and Profiles of Phthalates in Foodstuffs from China and Their Implications for Human Exposure

Phthalate esters are used in a wide variety of consumer products, and human exposure to this class of compounds is widespread. Nevertheless, studies on dietary exposure of humans to phthalates are limited. In this study, nine phthalate esters were analyzed in eight categories of foodstuffs (n = 78) collected from Harbin and Shanghai, China, in 2011. Dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), benzyl butyl phthalate (BzBP), and diethylhexyl phthalate (DEHP) were frequently detected in food samples. DEHP was the major compound found in most of the food samples, with concentrations that ranged from below the limit of quantification (LOQ) to 762 ng/g wet weight (wt). The concentrations of phthalates in food samples from China were comparable to concentrations reported for several other countries, but the profiles were different; DMP was found more frequently in Chinese foods than in foods from other countries. The estimated daily dietary intake of phthalates (EDIdiet) was calculated based on the concentrations measured and the daily ingestion rates of food items. The EDIdiet values for DMP, DEP, DIBP, DBP, BzBP, and DEHP (based on mean concentrations) were 0.092, 0.051, 0.505, 0.703, 0.022, and 1.60 μg/kg-bw/d, respectively, for Chinese adults. The EDIdiet values calculated for phthalates were below the reference doses suggested by the United States Environmental Protection Agency (EPA). Comparison of total daily intakes, reported previously based on a biomonitoring study, with the current dietary intake estimates suggests that diet is the main source of DEHP exposure in China. Nevertheless, diet accounted for only <10% of the total exposure to DMP, DEP, DBP, and DIBP, which suggested the existence of other sources of exposure to these phthalates.

Phthalates and Parabens in Personal Care Products From China: Concentrations and Human Exposure

Our previous studies showed that populations in China are widely exposed to phthalates and parabens. Nevertheless, sources of Chinese exposure to phthalates and parabens are not well understood. In this study, we measured concentrations of nine phthalates and six parabens in five categories of personal care products (PCPs, Nxa0=xa052) collected from Tianjin, China, and estimated human exposure doses to these compounds. The most frequently detected phthalates and parabens in PCPs were diethyl phthalate (DEP) (detection frequency 54xa0%), methyl paraben (MeP), and n-propyl paraben (PrP) (~75xa0%). The concentrations of DEP in PCPs ranged from not detected (ND; <0.1xa0μg/g) to 937xa0μg/g. The highest concentrations of MeP and PrP were 2,826 and 1,564xa0μg/g, respectively. Median exposure dose to parabens through dermal application of PCPs in China was estimated at 18,700xa0μg/d, which was two orders of magnitude greater than that calculated for phthalates (45.5xa0μg/d). Hand and body lotions were the major contributors to exposures, and the daily exposure doses for DEP, MeP, and PrP from these products were 38.4, 10,200 and 4,890xa0μg, respectively.

Challenges encountered in the analysis of phthalate esters in foodstuffs and other biological matrices

Phthalate esters are ubiquitous environmental pollutants and are recognized as environmental endocrine disruptors because of their potential to elicit reproductive and developmental toxicity. Several phthalate esters have been listed by the US Environmental Protection Agency (EPA) as chemicals of concern. Determination of concentrations of phthalate esters in foodstuffs, typically present at sub to low nanogram-per-gram concentrations (between 0.1 and 100xa0ngxa0g−1), is essential for assessment of human dietary exposure. However, phthalate esters are commonly present as contaminants in several laboratory products, including organic solvents, that are used in sample preparation and analysis. Therefore, accurate analysis of phthalates in food samples is a challenging task. In this review, we summarize the methods available for the determination of phthalate esters in foodstuffs and report on concentrations of phthalates in foodstuffs and potential sources of contamination by phthalates in the analysis of foodstuffs. We offer suggestions to eliminate and/or reduce background levels of contamination by phthalates in the analysis of food and other biological samples. We also introduce methods that are suitable for trace analysis of phthalates in a variety of liquid and solid food samples, in particular, a liquid–liquid extraction method for removal of lipids from food samples, because these can substantially reduce background levels of phthalates in the analytical procedure.

Occurrence and Human Exposure of p-Hydroxybenzoic Acid Esters (Parabens), Bisphenol A Diglycidyl Ether (BADGE), and Their Hydrolysis Products in Indoor Dust from the United States and Three East Asian Countries

p-Hydroxybenzoic acid esters (parabens) and bisphenol A diglycidyl ether (BADGE) are widely present in personal care products, food packages, and material coatings. Nevertheless, little is known about the occurrence of these compounds in indoor dust. In this study, we collected 158 indoor dust samples from the U.S., China, Korea, and Japan and determined the concentrations of 11 target chemicals, viz., six parabens and their common hydrolysis product, 4-hydroxybenzoic acid (4-HB), as well as BADGE and its three hydrolysis products (BADGE·H(2)O, BADGE·2H(2)O, and BADGE·HCl·H(2)O). All of the target compounds were found in dust samples from four countries. Concentrations of sum of six parabens in dust were on the order of several hundred to several thousands of nanogram per gram. Geometric mean concentrations of BADGEs in dust ranged from 1300 to 2890 ng/g among four countries. Methyl paraben (MeP), propyl paraben (PrP), BADGE·2H(2)O, and BADGE·HCl·H(2)O were the predominant compounds found in dust samples. This is the first report of BADGE and its hydrolysis products (BADGEs) in indoor dust samples and of parabens in indoor dust from Asian countries. On the basis of the measured concentrations of target chemicals, we estimated the daily intake (EDI) via dust ingestion. The EDIs of parabens via dust ingestion were 5-10 times higher in children than in adults. Among the four countries studied, the EDIs of parabens (5.4 ng/kg-bw/day) and BADGEs (6.5 ng/kg-bw/day) through dust ingestion were the highest for children in Korea and Japan.

Concentrations and Profiles of Urinary Polycyclic Aromatic Hydrocarbon Metabolites (OH-PAHs) in Several Asian Countries

Concentrations of 12 hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) were determined in 306 urine samples collected from seven Asian countries (China, India, Japan, Korea, Kuwait, Malaysia, and Vietnam) by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The total concentrations of OH-PAHs found in the seven Asian countries were in the following increasing order: Malaysia (median: 2260 pg/mL) < Japan (4030 pg/mL) < China (5770 pg/mL) < India (6750 pg/mL) < Vietnam (8560 pg/mL) < Korea (9340 pg/mL) < Kuwait (10170 pg/mL). The measured urinary concentrations of 1-hydroxypyrene (1-PYR) in samples from Malaysia, Korea, and Japan (∼ 100 pg/mL) were similar to those reported for North America and Western Europe. The concentrations of 1-PYR in urine samples from China, India, and Vietnam were 4-10 times higher than those reported for other countries, thus far. Among the 12 OH-PAH compounds analyzed, hydroxynaphthalene (NAP: sum of 1-hydroxynaphthalene and 2-hydroxynaphthalene) was the dominant compound (accounting for 60-90% of total OH-PAHs), followed by hydroxyphenanthrene (PHEN: sum of 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, 4-hydroxyphenanthrene, and 9-hydroxyphenanthrene [3-16%]), 2-hydroxyfluorene (3-20%), and 1-PYR (2-8%). The total daily intakes (DIs) of PAHs were estimated based on the urinary concentrations of their metabolites. The DIs of naphthalene were found to be higher for populations in Korea, Kuwait, and Vietnam (> 10 μg/day) than those of the other countries studied (∼ 5 μg/day). The DIs of phenanthrene and pyrene (> 10 μg/day) in the populations of China, India, and Vietnam were higher than those estimated for the populations in the other countries studied (∼ 5 μg/day).

Urinary Concentrations of Parabens in Chinese Young Adults: Implications for Human Exposure

Parabens are widely used as preservatives in foods, cosmetics, and pharmaceuticals. However, recent studies have indicated that high and systemic exposure to parabens can be harmful to human health. Although a few studies have reported urinary paraben levels in western countries, studies on paraben exposure in the Chinese population are limited. China is currently a major producer of parabens in the world. In this study, 109 urine samples collected from Chinese young adults (approximately 20xa0years old) were analyzed for five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-parabens) by high-performance liquid chromatography–tandem mass spectrometry. Methyl-, propyl-, and ethyl-parabens were the three major paraben analogues found in all (100xa0%) samples. The concentration of the sum of the five parabens ranged from 0.82 to 728xa0ng/mL with a geometric mean value of 17.4xa0ng/mL. Urinary concentration of parabens was 2-fold greater in females than in males. Based on the measured urinary concentrations, daily intake of parabens by the Chinese young adults was estimated and compared with those reported for United States adults. The estimated daily intakes (EDIurine) of parabens were 18.4 and 40.8xa0μg/kg bw/day for Chinese males and females, respectively, values that were lower than those reported for United States adults (74.7xa0μg/kg bw/day). Based on the reported concentrations of parabens in foods from China and the United States, the contribution of dietary intake to EDIurine was estimated to be 5.5, 2.6, and 0.42xa0% for Chinese males, Chinese females, and United States adults, respectively, which indicates the significance of nondietary sources of parabens to human exposures.

Urinary concentrations of phthalates in couples planning pregnancy and its association with 8-hydroxy-2'-deoxyguanosine, a biomarker of oxidative stress: longitudinal investigation of fertility and the environment study.

Oxidative stress has been recognized as one of the most important contributors to infertility in both males and females. Exposure to many environmental chemicals, such as phthalates, has been shown to induce oxidative stress. In a longitudinal study designed to assess exposure to environmental chemicals and fecundity in couples who were planning pregnancy, 894 urine samples were collected from 469 couples from Michigan and Texas during 2005–2009. The concentrations of 14 phthalate metabolites and a marker of oxidative stress, 8-hydroxy-2′-deoxyguanosine (8-OHdG), were determined in these samples. Concentrations, profiles, and estimated daily intakes (DIs) of phthalates were positively associated with 8-OHdG. The median concentrations of monomethyl phthalate (mMP), monoethyl phthalate (mEP), mono(3-carboxypropyl) phthalate (mCPP), mono-n-butyl phthalate (mBP), mono(2-isobutyl) phthalate (miBP), monobenzyl phthalate (mBzP), Σ5mEHP (sum of five metabolites of di(2-ethylhexyl) phthalate (DEHP)) and Σ14phthalates (sum of 14 urinary phthalate metabolites) were 0.48, 85.2, 4.50, 7.66, 4.36, 3.80, 54.8, and 249 μg/g creatinine, respectively. The estimated DI values for DEHP in 39 individuals were above the U.S. Environmental Protection Agency’s (EPA) reference dose (RfD) of 20 μg/kg-bw/day. The mean and median concentrations of 8-OHdG were 6.02 and 3.13 μg/g creatinine, respectively, which were significantly higher in females than in males. Statistically significant associations were found between 8-OHdG and urinary concentrations of mEP, and Σ5mEHP for females. Similarly, a significant association was found between 8-OHdG and DIs estimated for select phthalates. Our results suggested that phthalate exposure increases oxidative stress, which can be a mechanism for the diminished fertility observed in couples who were highly exposed to select phthalates.