Excretion characteristics of urinary 8-hydroxydeoxyguanosine after dietary exposure to polycyclic aromatic hydrocarbons

Diet, polycyclic aromatic hydrocarbons, and oxidative stress biomarkers in pregnancy: A Los Angeles pregnancy cohort

Polycyclic aromatic hydrocarbon (PAH) exposure during pregnancy has been associated with increased oxidative stress. Few studies have evaluated the relationship between diet, urinary PAHs, and oxidative stress biomarkers among pregnant women. We enrolled a prospective cohort of pregnant women who gave birth at UCLA between 2016 and 2019. Dietary intake over the past month was evaluated by a food frequency questionnaire during mid-pregnancy, and three diet index scores were calculated: Healthy Eating Index (HEI) 2015, Alternate Mediterranean Diet (aMED), and Alternate Healthy Eating Index for Pregnancy (AHEI-P). Urine samples were collected up to three times during pregnancy and analyzed for PAH biomarkers, including 2-hydroxyfluorene + 3-hydroxyfluorene (FLUO2FLUO3), 1-hydroxyphenanthrene (PHEN1), 2-hydroxyphenanthrene (PHEN2), 3-hydroxyphenanthrene (PHEN3), 4-hydroxyphenanthrene (PHEN4), 2-hydroxynaphthalene (NAP2), and 1-hydroxypyrene (PYR1), and two oxidative stress biomarkers, malondialdehyde (MDA) and 8-hydroxyguanosine (8-OHdG). We employed multiple linear regression models to estimate effects of diet on measures of urinary PAHs and oxidative stress biomarkers. A better diet quality, as indicated by three diet indices, was associated with lower urinary PAH metabolites and lower concentrations of oxidative stress biomarkers. This pattern appeared to be consistent across all three sampling periods (9-17 weeks, 18-29 weeks, and 30 weeks-delivery). Healthier diets may lower PAH exposure and oxidative stress in pregnancy.

Simultaneous HPLC-MS determination of 8-hydroxy-2'-deoxyguanosine, 3-hydroxyphenanthrene and 1-hydroxypyrene after online in-tube solid phase microextraction using a graphene oxide/poly(3,4-ethylenedioxythiophene)/polypyrrole composite

The exploration of monohydroxy polycyclic aromatic hydrocarbons and 8-hydroxy-2'-deoxyguanosine (8-OHdG) produced by oxidative stress and DNA damage is a powerful and non-invasive tool to study the health risk of exposure to polycyclic aromatic hydrocarbons (PAHs). A nanocomposite prepared from graphene oxide, poly(3,4-ethylenedioxythiophene) and polypyrrole was electrodeposited on the internal surface of a stainless-steel tube for online in-tube solid phase microextraction (IT-SPME) of 8-OHdG, 3-hydroxyphenanthrene and 1-hydroxypyrene from urine. The coating possesses excellent chemical and mechanical stability, high extraction efficiency, good resistance to matrix interference, and a long lifespan. An online IT-SPME-high performance liquid chromatography-mass spectrometry method was developed for the determination of these three metabolite biomarkers in human urine. Figures of merit include (a) enrichment factors of 30-48; (b) low limits of detection (4-41 pg·mL^-1 at S/N = 3); (c) wide linear ranges (0.05-50 ng·mL^-1); (d) good recoveries from spiked samples (71.6-109.5%); and (e) acceptable repeatability (2.3-14.6%). The method offers the advantages of low cost, simplicity, sensitivity, rapidity and automation. Graphical abstract Schematic illustration of online in-tube solid phase microextraction using graphene oxide/poly(3,4-ethylenedioxythiophene)/polypyrrole composites as adsorbent in a stainless-steel (SS) tube for the enrichment and simultaneous determination of 8-hydroxy-2'-deoxyguanosine, 3-hydroxyphenanthrene and 1-hydroxypyrene prior to HPLC-MS analysis.

Exposure to polycyclic aromatic hydrocarbons and volatile organic compounds among recently pregnant rural Guatemalan women cooking and heating with solid fuels

BACKGROUND

Household air pollution is a major contributor to death and disability worldwide. Over 95% of rural Guatemalan households use woodstoves for cooking or heating. Woodsmoke contains carcinogenic or fetotoxic polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Increased PAHs and VOCs have been shown to increase levels of oxidative stress.

OBJECTIVE

We examined PAH and VOC exposures among recently pregnant rural Guatemalan women exposed to woodsmoke and compared exposures to levels seen occupationally or among smokers.

METHODS

Urine was collected from 23 women who were 3 months post-partum three times over 72h: morning (fasting), after lunch, and following dinner or use of wood-fired traditional sauna baths (samples=68). Creatinine-adjusted urinary concentrations of metabolites of four PAHs and eight VOCs were analyzed by liquid chromatography-mass spectrometry. Creatinine-adjusted urinary biomarkers of oxidative stress, 8-isoprostane and 8-OHdG, were analyzed using enzyme-linked immunosorbent assays (ELISA). Long-term (pregnancy through 3 months prenatal) exposure to particulate matter and airborne PAHs were measured.

RESULTS

Women using wood-fueled chimney stoves are exposed to high levels of particulate matter (median 48h PM2.5 105.7μg/m3; inter-quartile range (IQR): 77.6-130.4). Urinary PAH and VOC metabolites were significantly associated with woodsmoke exposures: 2-naphthol (median (IQR) in ng/mg creatinine: 295.9 (74.4-430.9) after sauna versus 23.9 (17.1-49.5) fasting; and acrolein: 571.7 (429.3-1040.7) after sauna versus 268.0 (178.3-398.6) fasting. Urinary PAH (total PAH: ρ=0.89, p<0.001) and VOC metabolites of benzene (ρ=0.80, p<0.001) and acrylonitrile (ρ=0.59, p<0.05) were strongly correlated with long-term exposure to particulate matter. However urinary biomarkers of oxidative stress were not correlated with particulate matter (ρ=0.01 to 0.05, p>0.85) or PAH and VOC biomarkers (ρ=-0.20 to 0.38, p>0.07). Urinary metabolite concentrations were significantly greater than those of heavy smokers (mean cigarettes/day=18) across all PAHs. In 15 (65%) women, maximum 1-hydroxypyrene concentrations exceeded the occupational exposure limit of coke-oven workers.

CONCLUSIONS

The high concentrations of urinary PAH and VOC metabolites among recently pregnant women is alarming given the detrimental fetal and neonatal effects of prenatal PAH exposure. As most women used chimney woodstoves, cleaner fuels are critically needed to reduce smoke exposure.

Biomarkers of oxidative stress and its association with the urinary reducing capacity in bus maintenance workers

BACKGROUND

Exposure to particles (PM) induces adverse health effects (cancer, cardiovascular and pulmonary diseases). A key-role in these adverse effects seems to be played by oxidative stress, which is an excess of reactive oxygen species relative to the amount of reducing species (including antioxidants), the first line of defense against reactive oxygen species. The aim of this study was to document the oxidative stress caused by exposure to respirable particles in vivo, and to test whether exposed workers presented changes in their urinary levels for reducing species.

METHODS

Bus depot workers (n = 32) exposed to particles and pollutants (respirable PM4, organic and elemental carbon, particulate metal content, polycyclic aromatic hydrocarbons, NOx, O3) were surveyed over two consecutive days. We collected urine samples before and after each shift, and quantified an oxidative stress biomarker (8-hydroxy-2'-deoxyguanosine), the reducing capacity and a biomarker of PAH exposure (1-hydroxypyrene). We used a linear mixed model to test for associations between the oxidative stress status of the workers and their particle exposure as well as with their urinary level of reducing species.

RESULTS

Workers were exposed to low levels of respirable PM4 (range 25-71 μg/m3). However, urinary levels of 8-hydroxy-2'-deoxyguanosine increased significantly within each shift and between both days for non-smokers. The between-day increase was significantly correlated (p < 0.001) with the concentrations of organic carbon, NOx, and the particulate copper content. The within-shift increase in 8OHdG was highly correlated to an increase of the urinary reducing capacity (Spearman ρ = 0.59, p < 0.0001).

CONCLUSIONS

These findings confirm that exposure to components associated to respirable particulate matter causes a systemic oxidative stress, as measured with the urinary 8OHdG. The strong association observed between urinary 8OHdG with the reducing capacity is suggestive of protective or other mechanisms, including circadian effects. Additional investigations should be performed to understand these observations.