ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS IN AMNIOTIC FLUID SAMPLES FROM SMOKERS AND NONSMOKERS

Effects of polycyclic aromatic hydrocarbons (PAHs) on pregnancy, placenta, and placental trophoblasts

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants that are carcinogenic, mutagenic, endocrine-toxic, and immunotoxic. PAHs can be found in maternal and fetal blood and in the placenta during pregnancy. They may thus affect placental and fetal development. Therefore, the exposure levels and toxic effects of PAHs in the placenta deserve further study and discussion. This review aims to summarize current knowledge on the effects of PAHs and their metabolites on pregnancy and birth outcomes and on placental trophoblast cells. A growing number of epidemiological studies detected PAH-DNA adducts as well as the 16 high-priority PAHs in the human placenta and showed that placental PAH exposure is associated with adverse fetal outcomes. Trophoblasts are important cells in the placenta and are involved in placental development and function. In vitro studies have shown that exposure to either PAH mixtures, benzo(a)pyrene (BaP) or BaP metabolite benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) affected trophoblast cell viability, differentiation, migration, and invasion through various signaling pathways. Furthermore, similar effects of BPDE on trophoblast cells could also be observed in BaP-treated mouse models and were related to miscarriage. Although the current data show that PAHs may affect placental trophoblast cells and pregnancy outcomes, further studies (population studies, in vitro studies, and animal studies) are necessary to show the specific effects of different PAHs on placental trophoblasts and pregnancy outcomes.

Identification of known and novel nonpolar endocrine disruptors in human amniotic fluid

BACKGROUND

Prenatal exposure to endocrine-disrupting compounds (EDCs) may contribute to endocrine-related diseases and disorders later in life. Nevertheless, data on in utero exposure to these compounds are still scarce.

OBJECTIVES

We investigated a wide range of known and novel nonpolar EDCs in full-term human amniotic fluid (AF), a representative matrix of direct fetal exposure.

METHODS

Gas chromatography high-resolution mass spectrometry (GC-HRMS) was used for the targeted and non-targeted analysis of chemicals present in nonpolar AF fractions with dioxin-like, (anti-)androgenic, and (anti-)estrogenic activity. The contribution of detected EDCs to the observed activity was determined based on their relative potencies. The multitude of features detected by non-targeted analysis was tentatively identified through spectra matching and data filtering, and further investigated using curated and freely available sources to predict endocrine activity. Prioritized suspects were purchased and their presence in AF was chemically and biologically confirmed with GC-HRMS and bioassay analysis.

RESULTS

Targeted analysis revealed 42 known EDCs in AF including dioxins and furans, polybrominated diphenyl ethers, pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Only 30% of dioxin activity and <1% estrogenic and (anti-)androgenic activity was explained by the detected compounds. Non-targeted analysis revealed 14,110 features of which 3,243 matched with library spectra. Our data filtering strategy tentatively identified 121 compounds. Further data mining and in silico predictions revealed in total 69 suspected EDCs. We selected 14 chemicals for confirmation, of which 12 were biologically active and 9 were chemically confirmed in AF, including the plasticizer diphenyl isophthalate and industrial chemical p,p'-ditolylamine.

CONCLUSIONS

This study reveals the presence of a wide variety of nonpolar EDCs in direct fetal environment and for the first time identifies novel EDCs in human AF. Further assessment of the source and extent of human fetal exposure to these compounds is warranted.

Urinary monohydroxylated polycyclic aromatic hydrocarbons in primiparas from Shenzhen, South China: Levels, risk factors, and oxidative stress

The main objectives of the present study were to investigate urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 77 primiparas who live in Shenzhen, Guangdong Province, China, and their association with 8-hydroxy-2'-deoxyguanosine (8-OHdG) and human health risks. High detection frequencies of OH-PAHs demonstrated the wide occurrence of chemicals in the human exposure to PAHs. The urinary concentrations of Σ₇OH-PAHs ranged from 1.37 to 45.5 ng/mL, and the median concentrations of 1-hydroxynaphthalene (1-OHN), 2-hydroxynaphthalene (2-OHN), 2-hydoxyfluorene (2-OHF), ΣOHPhe (the sum of 1-, 2+ 3-hydroxyphenanthrene), and 1-hydroxypyrene (1-OHP) were 3.00, 2.58, 0.31, 0.44, and 0.51 ng/mL, respectively. In the sum concentration of seven OH-PAHs, 1-OHN accounted for the largest proportion (43.7% of Σ₇OH-PAHs), followed by 2-OHN (37.1%), 2-OHF (4.94%), 1-OHP (8.01%), 1-OHPhe (4.79%), and 2+3-OHPhe (1.46%). The present results showed that vehicle exhaust and petrochemical emission are the main sources of PAHs in primiparas in Shenzhen, and inhalation is the most important exposure route. The living conditions have a significant influence on human exposure to PAHs. The concentrations of 8-OHdG were positively correlated with OH-PAH concentrations in urine because evidence suggested that urinary 8-OHdG levels can be considered as a biomarker of oxidative DNA damage. Hazard quotient was used to assess the human health risks from exposure to single compound, and hazard index was used to assess the cumulative risks of the compounds, which demonstrated that the exposure risks from PAHs in primiparas were relatively low.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and small for gestational age offspring

OBJECTIVES

While some of the highest maternal exposures to polycyclic aromatic hydrocarbons (PAHs) occur in the workplace, there is only one previous study of occupational PAH exposure and adverse pregnancy outcomes. We sought to extend this literature using interview data combined with detailed exposure assessment.

METHODS

Data for 1997-2002 were analysed from mothers of infants without major birth defects in the National Birth Defects Prevention Study, a large population-based case-control study in the USA. Maternal telephone interviews yielded information on jobs held in the month before conception through delivery. From 6252 eligible control mothers, 2803 completed the interview, had a job, met other selection criteria, and were included in the analysis. Two industrial hygienists independently assessed occupational exposure to PAHs from the interview and reviewed results with a third to reach consensus. Small for gestational age (SGA) was the only adverse pregnancy outcome with enough exposed cases to yield meaningful results. Logistic regression estimated crude and adjusted ORs.

RESULTS

Of the 2803 mothers, 221 (7.9%) had infants who were SGA. Occupational PAH exposure was found for 17 (7.7%) of the mothers with SGA offspring and 102 (4.0%) of the remaining mothers. Almost half the jobs with exposure were related to food preparation and serving. After adjustment for maternal age, there was a significant association of occupational exposure with SGA (OR=2.2, 95% CI 1.3 to 3.8).

CONCLUSIONS

Maternal occupational exposure to PAHs was found to be associated with increased risk of SGA offspring.

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).

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface water of the Raba River, Hungary

The objective of this study was to investigate the concentration level and distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water of the Raba River; the largest Danube tributary in Hungary. A total of 54 water samples were collected in the period of 2008-2011 and analysed for PAHs by gas chromatography-mass spectrometry (GC/MS) method. The total PAH concentrations (sum of the concentrations of 17 individual PAH compounds) ranged from 41 to 437 ng/L with the mean value of 111 ±  69.4 ng/L. Phenanthrene and naphthalene were the dominant species in the surface water. Using TEF approaches on the mean concentration PAH data, benzo[a]pyrene and dibenz[ah]anthracene contributed the highest carcinogenic exposure equivalent. A selected number of concentration ratios of specific PAH compounds were calculated to evaluate the possible sources of PAH contamination. The ratios reflected a pattern of pyrogenic input as a major source of PAHs. The comparison of the total PAH concentrations observed for Raba River with other surface waters of the world confirmed that the Raba River could not be regarded as a contaminated river according to the levels of PAHs.

Vibrational and electronic spectra of 9,10-dihydrobenzo(a)pyren-7(8H)-one and 7,8,9,10-tetrahydrobenzo(a)pyrene: an experimental and computational study

The molecular geometries, vibrational and UV-vis spectra of 9,10-dihydrobenzo(a)pyrene-7(8H)-one (9,10-H(2)BaP) and 7,8,9,10-tetrahydrobenzo(a)pyrene (7,8,9,10-H(4)BaP) were investigated using density functional theory (DFT-B3LYP), with the triple-ζ 6-311+G(d,p) and Dunning's cc-pVTZ basis sets. From the comparison of infrared experimental and calculated infrared, and Raman data comprehensive assignments are made. The calculated infrared frequencies below 1800 cm(-1) are in good agreement with experimental data, with an average deviation of <4 cm(-1). Using the B3LYP/6-311+G(d,p)//TD-B3LYP/6-311G(d,p) level of theory, transition energies, and oscillator strengths of the 30 lowest electronic absorption bands are assigned to π-π* transitions, with good qualitative agreement between experimental and simulated absorption data. In addition, the HOMO-LUMO gaps and their chemical hardness were analyzed.