| Traditional estimation methods of the hazards of pollutants are based on their total concentration,whereas only the bioavailable part of contaminants may be harmful for human.Therefore,determination of the bioaccessibility is vital for scientific evaluation of the influence of contaminants on human health.Besides,most studies on the bioaccessibility of pollutants mainly focused on the exposure pathway of oral ingestion while neglect the routes of inhalation and dermal contact.Therefore,a comprehensive study regarding the bioaccessibility considering multiple exposure routes is essential for achieving an accurate estimation of the toxicity and harms of pollutants.Herein,the studied samples were collected from the areas affected by vanadium（concentrate fines,soil,and dust）or fluorine（phosphate and compound fertilizers,and soil）.Objectives of this study are to measure the oral bioaccessibility of vanadium and fluorine in the whole digestive system,including mouth,gastric,small intestinal and large intestinal phases,and further in the plasma after the digestion in small intestine;estimate the influence of environmental matrix types,digestive enzymes,sweat and food on the oral bioaccessibility,respectively and comprehensively;further determine the inhalation and dermal bioaccessibility by in-vitro assays;comprehensive assess the health risk based on the bioaccessibility via oral,inhalation and dermal routes;and analyse the difference and correlation of the bioaccessibility determined in the simulated gastrointestinal tract of human with that of swine by an in-vitro swine digestibility prediction method developed previously.Results of the present study can help to scientific assess the health risk of vanadium and fluorine and is able to make a contribution for the related police establishment of pollution regulation.Oral bioaccessibility of vanadium and fluorine can be determined in each simulated phase,indicating the digestion occurred in the whole digestive system including mouth,stomach,small and large intestine,and plasma.In present study,vanadium is mainly digested in each digestive phase except for the mouth phase（2.90–9.59%）,and the oral bioaccessibility of vanadium（V）（0.56–8.05%）was higher than that of vanadium（IV）（0.11–1.54%）.Digestion of fluorine mainly occurred in the phases of upper digestive tract（4.35–56.33%）,the whole digestive tract（1.01–40.52%）,and the plasma（8.07–66.70%）.Decrease of the oral bioaccessibility of vanadium by digestive enzymes was observed in each simulated digestive phase apart from the large intestine which was significant in concentrate fines（p<0.05）.In addition,obvious increase and decrease of the oral bioaccessibility of fluorine have been observed with the lack of digestive enzymes in small and large intestines,respectively（p<0.05）.Generally,oral bioaccessibility increased by adding simulated sweat which however decreased after food addition,whereas comprehensive effects of sweat and food cannot be estimated by a simply direct superposition of the oral bioaccessibility determined with the separate addition of sweat and food.Different inhalation and dermal bioaccessibility of vanadium and fluorine has been determined in different environmental matrixes.After inhalation,higher bioaccessibility of vanadium was determined in concentrate fines（57.68–70.78%）than that in soil（39.78–53.11%）and dust（14.92–31.36%）.Similarly,inhalation bioaccessibility of fluorine was higher in compound fertilizers（15.01–106.28%）than that in soil（8.13–15.25%）and phosphate fertilizer（3.71–4.71%）.Present bioaccessibility of vanadium after dermal contact（<5%）was lower than that after inhalation,and the determination of vanadium（V）was about 2–7 times of that of vanadium（IV）.In accordance with the observation after inhalation,lower dermal bioaccessibility of fluorine has been determined in soil and phosphate fertilizer than that in compound fertilizers（<11.01%）.Overall,present health risk based on the bioaccessibility by the exposure of oral ingestion,inhalation,and dermal contact of both vanadium and fluorine was acceptable.Specifically,the exposure of fluorine which was below the daily intake limitation(5.3×10–2 mg/kg BW/d)did not lead to obviously potential non-carcinogenic risk（HQ<1）.Besides,though exposure of vanadium by oral ingestion in some digestive phases did exceed the limitation of daily intake(1.76×10–4 mg/kg BW/d),the ultimately potential non-carcinogenic risk was not obvious（HQ<1）.Additionally,health risk posed by oral ingestion was higher than that posed by inhalation and dermal contact,indicating the major contribution of oral ingestion for the health risk.Additionally,compared with general population,occupational population may suffer a relative high risk posed by the studied contaminants.For the simulation of the behaviour of vanadium and fluorine by oral ingestion of swine,similar to the result of the simulated oral ingestion of human,there existed a discrepancy of the bioaccessibility in different environmental matrixes.Specifically,oral bioaccessibility of vanadium to swine was also higher in concentrate fines,and the bioaccessibility of vanadium（V）was 2–10times of that of vanadium（IV）.Obviously higher oral bioaccessibility was also determined in compound fertilizers up to 88.14%than that in soil and phosphate fertilizer.Besides,notable correlation of the bioaccessibility of both vanadium and fluorine in in-vitro gastrointestinal tract of swine and human（0.741–0.92）indicated the potential of present swine in-vitro test for the contrast verification of the toxicity and risk obtained by the human in-vitro method.In summary,different bioaccessibility of vanadium and fluorine exposed by different pathways（oral ingestion,inhalation,and dermal contact）indicated the importance of incorporating the bioaccessibility into the health risk assessment.Estimation of the health risk corrected using the bioaccessibility suggested that oral ingestion was the mainly exposure route.Appropriately protective methods should be taken to avoid or decrease the unconsciously oral ingestion of concentrate fines or fertilizers in occupational exposure.Besides,comparability of the digestion of vanadium and fluorine between human and swine was observed by swine in-vitro test,indicating the potential of animal in-vitro model for contrasting verification of the results obtained by human in-vitro test. |
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