Concentrations and bioaccessibility of polycyclic aromatic hydrocarbons in wastewater-irrigated soil using in vitro gastrointestinal test

Abstract

Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. Materials and methods Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear regression model was used to assess the relationship between total PAH concentrations in soils and soil organic carbon (SOC). Results A wide range of total PAH concentrations ranging from 1,304 to 3,369 μg kg -1 in soils collected from different wastewater-irrigated sites in Tianjin, while ranging from 2,687 to 4,916 μg kg -1 in soils collected from different wastewater-irrigated sites in Beijing, was detected. In general, total PAH concentrations in soils from Beijing sites were significantly higher than those from Tianjin sites, indicating a dominant contribution from both pyrogenic and petrogenic sources. Results indicated that the oral bioaccessibility of PAHs in small intestinal was significantly higher (from P<0.05 to P<0.001) than gastric condition. Similarly, the oral bioaccessibility of PAHs in contaminated sites was significantly higher (from P≤0.05 to P<0.001) than in reference sites. Individual PAH ratios (three to six rings), a more accurate and reliable estimation about the emission sources, were used to distinguish the natural and anthropogenic PAH inputs in the soils. Results indicated that PAHs were both pyrogenic and petrogenic in nature. Discussion The identification of PAH sources and importance of in vitro test for PAH bioaccessibility were emphasized in this study. The oral bioaccessibility of individual PAHs in soils generally decreased with increasing ring numbers of PAHs in both the gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric conditions to that in the small intestinal condition generally increased with increasing ring number...

Identification of a new steroid degrading bacterial strain H5 from the Baltic Sea and isolation of two estradiol inducible genes

“…The same investigation detected testosterone in concentrations ranging from 200 to 1000 pM [11]. Furthermore, in China a wide range of total PAH concentrations was detected, ranging from 1304 to 3369 g/kg in soil collected from different wastewater-irrigated sites in Tianjing, and ranging from 2687 to 4916 g/kg in soil collected from different wastewater-irrigated sites in Beijing [16]. In addition, the total estrogen levels in the Xili and Shenzhen Reservoirs were in a range of with 3-11 ng/l with a mean value of 7 ng/l, where that in four rivers in Shenzhen were found to be 47-90 ng/l and 60.25 ng/l, respectively.…”

“…Endocrine disrupting activity has also been reported from a variety of polycyclic aromatic hydrocarbons (PAH) [16] which mimic the action of steroid hormones in the body and which have also been found in highly contaminated areas.…”

Human health risk due to consumption of vegetables contaminated with carcinogenic polycyclic aromatic hydrocarbons

“…All the data were statistically analyzed for mean of triplicates using Microsoft excel software (Microsoft 2007), while bioaccumulation factor, DI-PAH, and TEQ were calculated using different statistical equations. (Khan et al 2008a). A regression analysis was also performed to observe the relationship between SOC and total PAH in soil.…”

“…Polycyclic aromatic hydrocarbons (PAH) are recalcitrant, mutagenic, and carcinogenic pollutants, prevalent in the environment (air, water, and soil ecosystem) as a result of different anthropogenic activities (Meng et al 2011;Khan et al 2008a). This group consists of more than 100 compounds having aromatic rings ranging from two to six with high lipophilicy and low water solubility (Danyi et al 2009;Zhang et al 2011).…”

Steroid degradation and two steroid-inducible enzymes in the marine bacterium H5

“…Contaminated soil and water represent a potential health risk for all kinds of animals and humans because of the presence of hormonally active agents and a variety of polycyclic aromatic hydrocarbons (PAH) which mimic the action of steroid hormones [1,2]. Hormonally active agents interfere with sexual development, reproduction and abnormal feminizing responses, and may therefore cause adverse health effects to all kinds of life [1,[3][4][5][6][7][8][9][10].…”