Faculty Bibliography

Despite high production and usage of parabens and bisphenols, little is known about their spatiotemporal distribution in the marine environment. In this study, we determined the concentrations of several parabens and their metabolites as well as bisphenol analogues in sediment collected from coastal areas of northern China. All sediment samples, including surface sediment and sediment cores, contained at least one of the parabens analyzed, and the total concentrations of parabens (ΣPBs; sum of six parabens) ranged from 1.37 to 24.2 ng/g dw (geometric mean: 3.30-6.09 g/g dw), which was comparable to or slightly higher than those found for the total concentrations of five detectable bisphenols (ΣBPAs; geometric mean: 2.18-4.61 ng/g dw). 4-hydroxybenzoic acid, a common metabolite of parabens, was found in all samples at concentrations in the range of 6.85-437 ng/g dw, which was one order of magnitude lower than those found for benzoic acid. Methyl-, ethyl-, and propyl-parabens were the predominant paraben analogues, collectively accounting for >88% of ΣPBs. Bisphenol A and bisphenol F were the two major bisphenols, collectively accounting for >86% of ΣBPAs. We also examined vertical profiles in concentrations of target analytes in sediment cores. The sediment core from the Shandong Peninsula showed a gradual increase in the concentrations of several parent and metabolic parabens as well as bisphenols during the past decade. Relatively higher concentrations of parabens and bisphenols were found in sediment cores collected from industrialized areas. Significant positive correlations were found among the concentrations of parabens in sediment, which suggested the existence of similar sources for these compounds. Overall, our findings suggest that the Bohai Sea coast is moderately contaminated with parabens and bisphenols in comparison to other coastal areas in China or elsewhere.

Organophosphate esters (OPEs) are used in consumer products as flame retardants and plasticizers. Little is known, however, about the occurrence and profiles of OPEs in human milk. In this study, 14 OPEs were measured in 100 breast milk samples collected from the United States during the period of 2009-2012, using high-performance liquid chromatography and tandem mass spectrometry. The sum concentrations of 14 OPEs in human milk ranged from 0.670 to 7.83 ng/mL, with a mean value of 3.61 ng/mL. The highest mean concentration was found for tris-2-butoxyethyl phosphate (TBOEP, 1.44 ± 0.789 ng/mL), followed by tri-iso-butyl phosphate (TIBP, 0.569 ± 0.272 ng/mL) and tri-n-butyl phosphate (TNBP, 0.539 ± 0.265 ng/mL), which were the dominant OPEs found in breast milk at detection frequencies of >80%. No significant differences were observed between various maternal/infant characteristics and OPE concentrations (p > 0.05), except for TBOEP, for which the median concentrations in Hispanic mothers (0.765 ng/mL) were 2 times lower than those in non-Hispanic mothers (1.48 ng/mL) (p < 0.05). On the basis of the recommended daily milk ingestion rate, the average and the highest daily intakes of total OPEs were calculated to be in the range of 300-542 and 504-911 ng (kg of body weight)^-1 day^-1, respectively. The estimated daily intakes of OPEs did not exceed the current reference doses. Our study establishes baseline data for OPE exposure in breast-fed American children.

We determined the concentrations of melamine, ammeline, ammelide, and cyanuric acid in meat, fish and seafood, cereal products, beverages, cooking oil, and vegetables (n = 121) collected from Albany, New York, United States. In addition, food packaging (n = 24) and animal feed (n = 12) were analyzed to determine the sources of melamine and its derivatives in foods. Among the six categories of foods analyzed, median concentrations of ∑melamine (sum of melamine and its three derivatives) in meat (23.6 ng/g fresh weight; fw) and cereal products (20.9 ng/g fw) were significantly (p < 0.05) higher than those in other food categories (<5.03 ng/g fw). Cyanuric acid and melamine were the major compounds, accounting for 51% and 26% of the total ∑melamine concentrations, respectively. ∑melamine was found ubiquitously in food packaging (median: 36.2 ng/g fw) and animal feed (56.5 ng/g fw), which are two important sources of melamine found in foodstuffs. The median estimated daily dietary intakes (including concentrations reported for dairy products in our previous study) of melamine and cyanuric acid were in the ranges of 13.4-72.7 and 75.4-347 ng/kg body weight/day, respectively, for various age groups. Dairy products, cereal products, and meat were major sources of dietary melamine (~76%) and cyanuric acid (~95%) exposure. The calculated hazard quotients for dietary exposure to melamine and cyanuric acid were well below 1.0, which suggested minimal risk from current exposures.

Exposure of humans to pesticides is widespread. Measurement of urinary levels of pesticides and their metabolites is often used in the assessment of body burdens and exposure doses to these chemicals. An understanding of temporal variability in urinary levels of pesticides within individuals is critical for accurate exposure assessment. We examined within- and between-individual variability in concentrations of nine organophosphate and pyrethroid insecticides as well as two phenoxy herbicides in urine collected consecutively for up to 44 days from 19 individuals. Seven oxidative stress biomarkers also were measured in urine samples to elucidate their relationship with pesticide exposure. Intraclass correlation coefficients (ICCs) were calculated to assess reproducibility in urinary pesticide concentrations from repeated measures. Sensitivity and specificity analyses were performed to evaluate the suitability of spot urine to characterize average exposures. Data analysis was further limited to seven pesticides and their metabolites, which had a detection frequency of >60%. Poor reproducibility was found for the seven pesticides and their metabolites in both spot (ICCs ≤0.24) and first-morning-void (FMV) samples (ICCs <0.38) collected during the 44-day study period. Use of single-spot or FMV sample to classify high (top 33%) concentrations showed high specificities (0.73-0.85) but low sensitivities (0.45-0.70). The minimum number of samples (k) required per individual to estimate participant-specific mean value for pesticides (within 20% of the "true" values) were 28-140 and 18-119 for spot and FMV samples, respectively. Repeated longitudinal measurements of these pesticides and their metabolites in urine showed considerable within-individual variability in both spot and FMV samples. Urinary concentrations of seven pesticides and their metabolites were significantly correlated with oxidative damage to lipids, proteins, and DNA.

Bromate (BrO₃^-) is an anionic contaminant known possess carcinogenic potential. Although some studies have reported the occurrence of bromate in drinking water, very little is known about its presence in fruits and vegetables, especially in Chile. In this study, we quantified bromate in soils (n = 29), drinking water (n = 43), surface water (n = 6), groundwater (n = 6), fertilizers (n = 7), fruits (n = 12) and vegetables (n = 42) collected across Chile. The highest average concentrations of bromate in soils (11.7 ng g^-1) and drinking water (8.8 ng mL^-1) were found in northern Chile. Additionally, drinking water collected from four regions of Chile showed higher concentrations of bromate (median:18.5 ng mL^-1) than the maximum contaminant level (MCL, 10 ng mL^-1). Concentrations of bromate in nitrogenous and non-nitrogenous fertilizers were similar (median: 2.51 μg g^-1). Leafy vegetables (median: 9.52 ng g^-1) produced in the northern Chile contained higher bromate concentrations than those produced in other regions (median: 0.24 ng g^-1). The estimated daily intakes of bromate via drinking water in northern, central and southern were ranged between 58.6 and 447 ng/kg bw/d. Leafy vegetables were an important source of bromate for all age group. The EDI values were below the respective reference dose (RfD) of 4000 ng/kg-day.

Occurrence, spatial distribution, and temporal trends of melamine and its derivatives (ammeline, ammelide, and cyanuric acid) were investigated in surface sediment and two sediment cores collected from Lake Shihwa, South Korea. ∑Melamine (sum of melamine and its three derivatives) was found in all surface sediment samples at concentrations that ranged from 16.6 to 4390 ng/g dry weight (dw), with an average value of 202 ng/g dw. ∑Melamine concentrations exhibited a clear spatial gradient, in decreasing order, as: creeks (mean: 577 ng/g dw) > inshore locations (41.9 ng/g dw) > offshore locations (24.3 ng/g dw). ∑Melamine concentrations were notably high in sediment collected near wastewater treatment plant (WWTP) outfalls. Melamine was the most prevalent compound in sediment collected from creeks (87%) and WWTP outfall locations (48%), whereas cyanuric acid was the dominant compound in sediment from inshore (51%) and offshore (63%) locations. The historical profiles of ∑Melamine in sediment cores corresponded with coastal development and environmental changes in this region. This is the first study to document the occurrence and temporal distribution of melamine in sediment cores, and this information is useful in understanding the fate of these relatively less-studied chemicals in the environment.

Melamine received public and regulatory attention in 2008 following a scandal that involved the adulteration of milk and infant formula in China that affected tens of thousands of infants. Little is known about human exposure and the food chain transfer of melamine and its derivatives. In this study, melamine, cyanuric acid, ammeline, and ammelide were analyzed in 100 human milk samples collected from the United States during the period of 2009-2012. ∑Melamine (sum of melamine and its three derivatives) was found in breast milk at concentrations that ranged from 0.176 to 10.0 ng/mL (median: 1.40 ng/mL). Cyanuric acid was the major derivative, accounting for 73% of the total concentrations, followed by melamine (21%). No remarkable associations were noted between melamine and cyanuric acid concentrations and maternal/infant characteristics. The cumulative daily intakes of melamine (16.9-30.6 ng/kg bw/day) and cyanuric acid (88.8-161 ng/kg bw/day) were calculated for breast-fed infants and were found to be 1-2 orders of magnitude below the current tolerable daily intake. This is the first study to report the distribution of melamine and its derivatives in breast milk from the United States.

We determined the concentrations of 98 halogenated organic compounds and synthetic musks in breast fat tissues of 50 breast cancer patients (age range: 34-77 years) collected during 1996-1998 in Ulster County, New York, USA. Polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl 153 (PBB-153), polybrominated diphenyl ethers (PBDEs), and synthetic musk compounds (SMCs) were analyzed in breast fat tissues, and 46 analytes were found at a detection frequency of ≥ 65% and at concentrations in the decreasing order of OCPs > PCBs > SMCs > PBDEs > PBB-153. PCBs (median: 323 ng/g wet wt) and dichlorodiphenyltrichloroethanes (DDTs, median: 293 ng/g wet wt) were the major compounds found in breast fat tissues. Among PCB congeners, hexa- and hepta-chlorobiphenyls (60% of total PCBs) were the abundant ones. p,p'-DDE accounted for more than 99% of the total DDT concentrations. The concentrations of SMCs and PBDEs were 1-2 orders of magnitude lower than those of PCBs and DDTs. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-r-2-benzopyran (median: 33 ng/g wet wt) was the most abundant SMC, whereas BDE-47 (median: 4.5 ng/g wet wt) was the most dominant PBDE congener present in breast tissues. A significant correlation (p < 0.05) between women's age and concentrations of DDTs, chlordanes, hexachlorobenzene and PCBs in breast tissues was found. Concentrations of PCBs, PBDEs, OCPs, and SMCs were not significantly different between malignant and benign tumor cases. This study adds baseline information on target tissue burdens of persistent organic contaminants in breast cancer patients.

Synthetic phenolic antioxidants (SPAs) such as 2,6-di-tert-butyl-4-hydroxytoluene (butylated hydroxytoluene, BHT), are used in a wide variety of consumer products, including certain foodstuffs (e.g. fats and oils) and cosmetics. Although BHT is considered generally safe as a food preservative when used at approved concentrations, there is debate whether BHT exposure is linked to cancer, asthma, and behavioral issues in children. Little is known with regard to human exposure to SPAs and the methods to measure these chemicals in urine. In this study, six SPAs and the metabolites were analyzed in 145 urine samples collected from four Asian countries (China, India, Japan, and Saudi Arabia) and the United States. BHT was found in 88% of the urine samples at median and maximum concentrations of 1.26 and 15 ng/mL, respectively. BHT metabolites and butylated hydroxyanisole (BHA) were found in 39% to 89% of the urine samples at a concentration range of <LOQ-46 ng/mL. 3,5-Di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH), the major metabolite of BHT, is suggested as a potential urinary biomarker of exposure to BHT. The estimated median daily intakes (EDIs) of BHT, calculated from urinary concentrations, in children and adults were 0.38-56.6 and 0.21-31.3 μg/kg bw/day, respectively. BHT levels were high in urine samples from Japan, India, and the United States.

Organophosphate esters (OPEs) are ubiquitous in the environment, but little is known about their distribution in soils. In this study, we measured 19 OPEs in soil samples collected nationwide in China for the first time. Concentrations of 19 OPEs (∑OPEs) in soils ranged from 4.50 to 430 ng/g dry weight (dw), with a median value of 36.6 ng/g dw. ∑OPE concentrations in soils were significantly higher in Northeastern (90.6, 19.1-180 ng/g dw; median, range) and Eastern/Southern China (57.4, 7.23-430 ng/g dw), areas with high population density and economic development, than those in Central (35.8, 4.80-417 ng/g dw) and Western China (29.7, 4.50-228 ng/g dw). High concentrations of ∑OPEs were found in soils collected from sites located in the most urbanized areas of China including Beijing (126 ng/g dw), Shanghai (388 ng/g dw), and Guangzhou (430 ng/g dw). Chlorinated (Cl-) OPEs were the predominant compounds, accounting for over 74.0% of ∑OPE concentrations in soils from China. In soil samples from Northeastern and Eastern/Southern China, Cl-OPEs accounted for 84.3% and 92.1% of ∑OPE concentrations, respectively. Cresyl diphenyl phosphate (CDPP) and isodecyl diphenyl phosphate (IDDP), which have been less studied thus far, were also found at measurable concentrations (0.15-0.40 ng/g dw) in soils. The Spearman's rank correlations among major aryl-OPEs in soils were significant (Rho = 0.582-0.747, p < 0.01), which suggested similar sources of environmental release of these compounds. Total organic carbon (TOC) content was not correlated with the concentrations of ∑OPE in soils (Rho = 0.036, p > 0.05). A hazard assessment for ten OPEs in soils suggested a notable risk from tris(2-ethylhexyl) phosphate (TEHP) and trimethylphenyl phosphate (TMPP). Further studies are needed to elucidate the fate of TMPP in soils.