Co-Cytotoxicity And Genotoxicity Of Nano-Black Carbon And Arsenic

The chemical composition of atmospheric particulate pollutants is complex,in which carbon accounted for 40%-60%in PM2.5(fine particles),and 25%-35%in PM10(respirable particles)of the weight,respectively.Black carbon is an important component of urban particulate pollutants,and has been categorized as a class 2B carcinogen by International Agency for Research on Cancer(IARC).The level of black carbon in the air is associated with cardiovascular disease,respiratory disease,and has an adverse effect on the nervous system and the reproductive system.Black carbon particles have smaller particle size,but large specific surface area,enabling them to absorb other heavy metal elements and trace elements,and thus becoming a vital carrier of many organic pollutants and heavy metals.Arsenic,as an important component of air pollutants,has been classified as environmental carcinogen by US Environmental Protection Agency(USEPA)and the International Agency on Research on Cancer(IARC).However,the study of the combined toxic effects of black carbon and arsenic has rarely been reported.In this paper,on the one hand,we found that nano-black carbon has certain cytotoxicity through the study of the biological toxicity of nano-black carbon itself.Our results confirmed that nano-black carbon can induce cell viability decrease and upregulate the expression of caspase-3(a key protein in the signaling pathway related to cell apoptosis),and the elevated intracellular ROS levels may be one of the mechanisms behind nano-black carbon induced toxic effects.On the other hand,we study the complex effect of nano-black carbon and heavy metal arsenic on the basis of the gene mutation detection system of human mammalian cells.The results showed that the nano-black carbon and arsenic could induce severe decrease of AL cell survival rate,increase the mutation rate of CD59 gene significantly,and the toxicity effect was higher than that of nano-black carbon and arsenic alone.Further study on the mechanism showed that co-treatment of nano-black carbon and arsenic could induce intracellular ROS levels increase in a concentration-dependent manner,and higher than the exposure with either one alone,suggesting that ROS upregulation plays an important role in the toxicity induced by nano-black carbon and arsenic.This paper provides some experimental evidence for revealing the potential health hazards and risks of black carbon and heavy metal.