Research For The Stability Of Formaldehyde Concentration In Mouse Blood And Formaldehyde Distant-site Toxicity

For a long time, formaldehyde has been extensively used in industrial manufactures, laboratory technology, and cosmetics. Meanwhile, formaldehyde is a primary kind of air pollutant. So the research of its toxicity has been a hotspot. In June2004, scientists in the International Agency for Research on Cancer (IARC) of WHO classified formaldehyde as a "carcinogenic to humans" since it could cause human nasopharyngeal. In2009, many scientists in IARC judged that there was strong but not sefficient evidence in formaldehyde causing leukemia. Some researches showed that formaldehyde in some concentration exposure could not change the formaldehyde concentration in blood of rats, rhesus monkeys even human. This phenomenon is so interesting that we should think about some further problems.To demonstrate that formaldehyde exposure can or cannot change formaldehyde concentration in mouse blood, and whether glutathione-dependent formaldehyde dehydrogenase could keep formaldehyde concentration stable in mouse blood; To study whether formaldehyde toxicity comes from its chemical groups or not; And whether formaldehyde could induce distant-site toxicity but not by transporting itself into the distant-site organs directly. SPF-Kunming inbred male mice from the Experimental Animal Center of Hubei were randomly divided into thirteen sub-groups (n=5) and perfused with five substances containing10,20, and40mg/kg for one week. Mouse weight, blood formaldehyde concentration, the expression of glutathione-dependent formaldehyde dehydrogenase (FDH), complete blood cells count, ROS level and formaldehyde concentration in mouse bone marrow were determined.In all formaldehyde groups, the weight of mice decreased in the first one or two days and then increased in the following days while mice weight in formic acid, methanol, and acetaldehyde groups increased normally. With the increase of formaldehyde dose, blood formaldehyde concentration changed from0.3to0.348mg/L. In methanol and formic acid groups, there were significantL differences in20and40mg/kg groups compared with the control. By realtime qPCR, the relative value of FDH was10.20for formaldehyde group, while6.41,2.55, and1.81were for methanol, formic acid and acetadehyde groups, respectively. Complete blood cells count didn’t show significant difference in any exposed group compared with the control, however, all of other blood cells number reduced excepting neutrophile granulocytes just in formaldehyde group. The ROS levels in formaldehyde exposed groups were also much higher than those of the groups exposed to other chemical agents and the control group. For formaldehyde concentration in mouse bone marrow, no matter which exposed substance was perfused into mouse, formaldehyde concentration in bone marrow has not changed.Formaldehyde exposure can not change formaldehyde concentration in mouse blood and can increase the expression of glutathione-dependent formaldehyde dehydrogenase to keep formaldehyde concentration stable in mouse blood. But damage is still induced which may come from its metabolic regulation like a signal molecule. Formaldehyde could induce distant-site toxicity but not by transporting itself directly.