Faculty Bibliography

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.

Melamine and cyanuric acid have been reported to occur in animal products. Nevertheless, information that pertains to the occurrence of melamine and cyanuric acid in cattle feed and urine is lacking. In this study, the occurrence of melamine and its three derivatives (i.e., cyanuric acid, ammeline, and ammelide) was determined in 183 bovine urine and 29 matched feed samples collected from China, India, and the United States. ∑Melamine (sum of four target compounds) was found in all urine samples at concentrations that ranged from 4.2 to 5280 ng/mL (median: 370 ng/mL); cyanuric acid was the major derivative, accounting for 97% of the total concentrations, followed by melamine (2.2%). The ubiquitous occurrence of ∑Melamine in feed (21-6230 ng/g) suggests that it is the major source of melamine and its derivatives in bovines. Urinary concentrations of melamine and cyanuric acid varied significantly among the three countries, with samples from China as having the highest concentrations, followed by the United States and India. The calculated cumulative daily intakes of melamine and cyanuric acid were at least 10-fold below the current tolerable daily intake recommended for humans. Our study provides evidence-based data on exposure patterns and sources of melamine and cyanuric acid in cattle.

Human exposure to phthalates is ubiquitous and has received considerable attention due to their association with adverse health outcomes, including type 2 diabetes mellitus (T2DM). Nevertheless, earlier studies that link phthalate exposure to T2DM yielded ambiguous results. Furthermore, studies that associate phthalate exposure with oxidative stress and then with T2DM are scant. In this diabetic case-control study, urine samples collected from 101 individuals aged 28-68 years from Jeddah, Saudi Arabia, were analyzed to determine 20 phthalate metabolites (PhMs) and seven oxidative stress biomarkers (OSBs). Unconditional logistic regression was used to estimate odds ratios for the association between diabetes and urinary PhMs and OSBs in participants, stratified by age, gender, nationality, smoking status, occupation, and urinary creatinine. Twelve PhMs and five OSBs were found at detection rates above 50%, with geometric mean concentrations of 0.61-100 and 0.35-10.7 ng/mL (1.04-171 and 0.61-18.6 μg/g creatinine), respectively. Almost all exposures were significantly higher in diabetic cases than in controls. The 12 PhMs were positively associated with higher urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F_2α (8-PGF_2α). Individuals in the 3rd and/or 4th quartile(s) for urinary concentrations of PhMs and OSBs showed 3.7- and 7.3-fold increase, respectively, in the odds of having diabetes compared with those in the 1st quartile. The rank order of association of PhMs/OSBs with diabetes followed the order of: mEP ≈ mBP > mEHP > mCPP > mECPP ≈ mEOHP ≈ mEHHP ≈ mIBP ≈ mMP > mCMHP ≈ mBzP and 8-OHdG > 8-PGF_2α ≈ 15-PGF_2α. The relationship between phthalate exposure and risk of developing T2DM was mediated in part by phthalate-induced oxidative stress, especially 8-OHdG. Our study suggests that human exposure to phthalates is associated with increased oxidative stress which mediates the development of T2DM.

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

Glyphosate is one of the most widely used herbicides in the United States, which has led to its ubiquitous occurrence in food and water and regular detection in human urine at concentrations of 1-10 μg/L. Data pertaining to health risks arising from the ingestion of glyphosate are limited and are the subject of much debate, which demands the need for more exposure information for this herbicide. Very little is known about glyphosate exposure in pets. In this study, we determined concentrations of glyphosate (Glyp) and its derivatives, methyl glyphosate (Me-Glyp) and aminomethylphosphonic acid (AMPA), in urine collected from 30 dogs and 30 cats from New York State, USA. Glyp was the most predominant compound found in pet urine followed by AMPA and Me-Glyp. The mean urinary concentration of ∑Glyp (sum of Glyp + Me-Glyp + AMPA) in cats (mean: 33.8 ± 46.7 ng/mL) was 2-fold higher than that in dogs (mean: 16.8 ± 24.4 ng/mL). Cumulative daily intakes (CDI) of Glyp in dogs and cats estimated from the urinary concentrations were, on average, 0.57 and 1.37 μg/kg bw/d, respectively. The exposure doses were two to four orders of magnitude below the current acceptable daily intake (ADI) suggested by several international health organizations for humans.