Preliminary Evaluation Of Acute Toxicity And Immunotoxicity Induced By Coal Flotation Reagent

1. BackgroundFlotation technology is the most effective way for fine slime selection, which is also one of the most important means among clean coal technologies. Coal flotation reagents have been widely used both in China and other countries all around the world. During the past 100 years, the theories and technologies of coal flotation have been developed by leaps and bounds. At the same time, new floating reagents have been invented one after another. However, many of the current flotation reagents testing focus only on the needs of flotation effect, without considering the health impact the coal flotation on occupational workers.The immune system plays an important role in the maintenance of individual health. Destruction of the immune system can lead to potentially far-reaching impact on health. The immune system may be more sensitive to xenobiotics, Indeed, in some instances, the immune system has been shown to be compromised in the absence of observed toxicity in other organ systems. Decreased immunocompetence (immunosuppression) may result in repeated, more severe, or prolonged infections as well as the development of cancer. Immunoenhancement may lead to immune-mediated diseases such as hypersensitivity responses or autoimmune disease. Therefore, it is very important to understand the impact of xenobiotics on the immune system.Due to the lack of scientific research evidence related to the relationship between occupational exposure to coal flotation and the impact of population health, the potential occupational hazards of coal flotation reagents have not aroused the attention to the relevant departments. Certainly, no occupational health standards have been formulated.2. ObjectivesThe present studies were carried out to explore the acute toxicity and immunotoxicity induced by coal flotation reagents, with a view to provide a basis for further study.3. Methods3.1 Acute Toxicity Testing Four batches of Kunming mice were obtained for four different samples of coal flotation reagents respectively, each batch of 40, a total of 160. Each batch of animals was randomly divided into five groups, solvent control group (negative control group) and four experiment groups (coal flotation reagent treated groups). Each group contained 8 animals. Mice were administrated by gavage at doses of 0 g / kg, 10.0 g / kg, 4.16 g / kg, 1.73 g / kg, 0.72 g / kg, 0.30 g / kg. Foods were given immediately after the exposure, and signs of poisoning and death were observed for a total of 14 days. LD50 were calculated in the end of experiment duration.3.2 Immunotoxicity Screening Balb/c mice were weighed, numbered, and then randomly divided into four groups which were solvent control group (negative control group) as well as low, medium and high dose group(coal flotation reagent treated groups). Each of the groups contained 12 animals. Mice were administrated by gavage at doses of 0 mg/kg, 100 mg/kg, 300 mg/kg, 1000 mg/kg for 28 days. In the 28th days, body weight and some organ like liver, kidney, thymus, spleen weight were measured and recorded. Half of each spleen was used for histopathological evaluation, another half was prepared as spleen single cell suspensions, which were utilized in T/B lymphocyte proliferation test and nature killer cell assay. The data statistical analysis was performed using SPSS 12.0 software.4. Results4.1 Acute Toxicity Testing LD50 of the four samples were calculated as 6.451341 g/kg,3.730032 g/kg,8.032024 g/kg,15.50065 g/kg。According to the Chinese hazard classification standards for occupational toxicants(GB 5044-85), sample #1,#3 and #4 should be classified intoⅣcategory(mild hazard),and sample #2 should be classified intoⅢcategory(moderate hazard)。4.2 Immunotoxicity Screening Compared to the solvent control group, thymus body weight ratio in high dose group decreased significantly (P<0.01), while no significant changes were observed in spleen body weight ratio among the groups. Spleen sinus congestion was observed in high dose group and medium group at histopathological level. T lymphocyte proliferation activity in high dose group and medium dose group decreased significantly (P<0.01), while B lymphocyte proliferation activity increased significantly (P<0.01). NK cell activity in high dose group and low dose group decreased significantly (P<0.01), while no such change was observed in medium dose group.5. Conclusions According to the acute toxicity tests, the coal flotation reagents can be considered as low toxicity, with mild or moderate hazard. However, coal flotation reagents could lead to immunotoxicity in Balb/c mice, which is worth attention.6. Innovations The present studies were the fist to explore acute toxicity and immunotoxicity induced by coal flotation reagents, which provide some basic data for further investigations.