Occurrence of phthalate esters in sediments in Qiantang River, China and inference with urbanization and river flow regime

Phthalate esters (PAEs), a group of emerging organic contaminants, have become a serious issue arousing much attention for their ubiquitous presence and hazardous impact on the environment. This study provides the first data on distribution of PAEs in the sediments in the Qiantang River, Zhejiang Province, China, and the inference with urbanization and river flow regime. PAEs were detected in all 23 sediment samples analyzed, and the total concentrations of their 16 congeners in sediments ranged from 0.59 to 6.74μg/g dry weight (dw), with the geometric mean value of 2.03μg/g dw. Of the 16 PAE congeners, di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and di(2-ethylhexyl) phthalate (DEHP) were present in all sediment samples. The PAEs concentrations in urban regions were higher than those in rural regions because of higher discharge of PAEs from plastic materials in urbanized areas. Concentrations of PAEs were positively correlated with sediment organic matter (fOM) and negatively correlated with logistic value of annual average flow volume at sample sites. River flow regime modified by man-made dams significantly affected the distribution of PAEs. Analysis of congener composition of PAEs indicated that the DEHP was predominant congener in the Qiantang River. The normalized concentration of DEHP exceeded recommended environmental risk limit (ERL).

Selecting adequate exposure biomarkers of diisononyl and diisodecyl phthalates: data from the 2005-2006 National Health and Nutrition Examination Survey

BACKGROUND

High-molecular-weight phthalates, such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), are used primarily as polyvinyl chloride plasticizers.

OBJECTIVES

We assessed exposure to DINP and DIDP in a representative sample of persons ≥ 6 years of age in the U.S. general population from the 2005-2006 National Health and Nutrition Examination Survey (NHANES).

METHODS

We analyzed 2,548 urine samples by using online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

We detected monocarboxyisooctyl phthalate (MCOP), a metabolite of DINP, and monocarboxyisononyl phthalate (MCNP), a metabolite of DIDP, in 95.2% and 89.9% of the samples, respectively. We detected monoisononyl phthalate (MNP), a minor metabolite of DINP, much less frequently (12.9%) and at concentration ranges (> 0.8 µg/L-148.1 µg/L) much lower than MCOP (> 0.7 µg/L- 4,961 µg/L). Adjusted geometric mean concentrations of MCOP and MCNP were significantly higher (p < 0.01) among children than among adolescents and adults.

CONCLUSIONS

The general U.S. population, including children, was exposed to DINP and DIDP. In previous NHANES cycles, the occurrence of human exposure to DINP by using MNP as the sole urinary biomarker has been underestimated, thus illustrating the importance of selecting the most adequate biomarkers for exposure assessment.

Human monitoring of phthalates and risk assessment

Some phthalates, such as di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP), and their metabolites are suspected of producing teratogenic and endocrino-disrupting effects. In this study, urinary levels of phthalates (DEHP, DBP, diethyl phthalate (DEP), butylbenzyl phthalate BBP), and monoethylhexyl phthalate (MEHP, a major metabolite of DEHP) were measured by high performance liquid chromatography (HPLC) in human populations (women [hospital visitors], n = 150, and children, n = 150). Daily exposure level of DEHP in children was estimated to be 12.4 microg/kg body weight/d (male 9.9 microg/kg body weight/d, female 17.8 microg/kg body weight/d), but, in women was estimated to be 41.7 microg/kg body weight/d, which exceeded the tolerable daily intake (TDI, 37 microg/kg body weight/day) level established by the European Union (EU) Scientific Committee for Toxicity, Ecotoxicity, and the Environment (SCTEE) based on reproductive toxicity. Based on these data, hazard indices (HIs) were calculated to be 1.12 (41.7/37 TDI) for women and 0.33 (12.4/37 TDI) for children, respectively. These data suggest that Koreans (women and children) were exposed to significant levels of phthalates, which should be reduced to as low a level as technologically feasible to protect Koreans from the exposure to toxic phthalates.

Determination of phthalate monoesters in human milk, consumer milk, and infant formula by tandem mass spectrometry (LC-MS-MS)

Daily exposure of humans to phthalates may be a health risk because animal experiments have shown these compounds can affect the differentiation and function of the reproductive system. Because milk is the main source of nutrition for infants, knowledge of phthalate levels is important for exposure and risk assessment. Here we describe the development and validation of a quantitative analytical procedure for determination of phthalate metabolites in human milk. The phthalate monoesters investigated were: monomethyl phthalate (mMP), monoethyl phthalate (mEP), mono-n-butyl phthalate (mBP), monobenzyl phthalate (mBzP), mono-(2-ethylhexyl) phthalate (mEHP), and monoisononyl phthalate (mNP). The method is based on liquid extraction with a mixture of ethyl acetate and cyclohexane (95:5) followed by two-step solid-phase extraction (SPE). Detection and quantification of the phthalate monoesters were accomplished by high-pressure liquid chromatography using a Betasil phenyl column (100 mmx2.1 mmx3 microm) and triple tandem mass spectrometry (LC-MS-MS). Detection limits were in the range 0.01 to 0.5 microg L(-1) and method variation was from 5 to 15%. Analysis of 36 milk samples showed that all these phthalates were present, albeit at different concentrations. Median values (microg L(-1)) obtained were 0.11 (mMP), 0.95 (mEP), 3.5 (mBP), 0.8 (mBzP), 9.5 (mEHP), and 101 (mNP). We also analysed seven samples of consumer milk and ten samples of infant formula. Only mBP and mEHP were detected in these samples, in the ranges 0.6-3.9 microg L(-1) (mBP) and 5.6-9.9 microg L(-1) (mEHP).

[Polyethylene terephthalate (PET)--health aspects and food packaging application]

Polyethylene terephthalate (PET) due to its physicochemical properties, especially regidity and glass-like transparency is widely used as food packaging material. The relevant legislation states that substances may not migrate from food contacting materials in quantities that may cause undesirable changes in organoleptic properties of food coming into contact with such material. The lists of substances authorized for food contact plastic materials and requirements for the final product were established. The requirements concern global migration limits (60 mg/kg or 10 mg/dm2) and specific migration limits (SML) set for substances which, when migrate into food in grater quantities may cause risk for human health. For the products manufactured from PET the specific migration limits were set for terephthalic acid (7.5 mg/kg), for isophthalic acid (5 mg/kg), for isophthalic acid dimethyl ester (0.05 mg/kg) and for ethylene and diethylene glycol (30 mg/kg). PET may undergo thermal degradation resulting in formation of acetaldehyde, which may influence organoleptic characteristics of packaged foods changing taste and smell.

Properties of reference Escherichia coli endotoxin and its phthalylated derivative in humans

The properties of a reference bacterial endotoxin prepared from Escherichia coli and its phthalylated derivative were studied in normal human volunteers infected intravenously with the compounds. The minimal pyrogenic dose of the reference endotoxin is about 0.1-0.5 ng/kg. The increase in white blood cell count, absolute granulocyte count, absolute immature granulocyte count, and concentrations of serum amyloid A, cortisol, and growth hormone was directly related to the concentration of reference endotoxin administered. Phthalylated reference endotoxin up to 1,000 ng/kg (at least 500 ng of the patent compound/kg) was administered to normal human volunteers without significant changes in temperature, white blood cell count, absolute granulocyte count, and concentrations of serum amyloid A, cortisol, and growth hormone. Thus, this study defines biologic properties of the new reference bacterial endotoxin in humans and demonstrates effective detoxification by phthalylation of the present compound.