Risk Assessment Of Health Hazards On Occupational Lead Exposure

Lead and its compounds were chemicals that were commonly used in industrial production and have multiple organ toxicity.Lead was widely used in the fields of metallurgy,chemical engineering,petroleum and electronics.Lead-acid battery manufacturing was the main consumption area of lead.Lead exposure workers were more likely to suffer occupational health injuries due to multiple exposure opportunities,large exposures,poor personal hygiene practices,and inadequate protective measures.Lead-acid battery companies in the production process,the main occupational hazards lead smoke,lead dust and sulfuric acid greater harm to human health.The newly revised Law of the People's Republic of China on Prevention and Control of Occupational Diseases proposes a risk assessment of key occupational diseases to protect the health of workers.At present,the research on the health hazards caused by occupational lead exposure in China mostly stays in the phase of investigation,diagnosis and treatment of lead hazards.There were not many quantitative evaluation studies conducted from the perspective of risk,which was not conducive to the effective control and prevention of occupational lead hazards.The current“Technical Guidelines for Occupational Health Risk Assessment of Chemical Harmful Factors in Industrial Sites”in the Technical Risk Assessment Method was to assess the risk from the perspective of occupational environment monitoring and cannot accurately reflect the total exposure and total load(intra-dose)of the organism to the chemical.Therefore,it was difficult to accurately conduct occupational health risk assessment.Biomonitoring can provide the actual exposure level (bio-eposure level),control more uncertainties,and establish a dose-response relationship between the exposure of hazards and biological effects using biological exposure levels,which was more advantageous.The physiologically based pharmacokinetic model(PBPK)was introduced into the health risk assessment with the concept of internal dose.The internal dose was a contact biomarker that could accurately reflect the absorption,distribution and metabolism of the chemical in the body.The dynamic process of excretion requires the use of mathematical models and calculation formulas to express the changes in the body of the chemical,and to reveal the relationship between the place,content and time of the chemical in the body.Therefore,it has been widely used in the health risk assessment of chemicals in Europe and the United States,but China did not incorporate it into the technical guidelines for occupational health risk assessment,which made the health risk assessment of lead lost a strong reference,and the health of the lead exposure industry could not It was fully guaranteed;furthermore,there were numerous methods for assessing occupational health risks,and each method has its applicable scope and advantages and disadvantages.Therefore,in order to better cope with the higher risks in this industry,research in this area was urgently needed. In this study,lead-acid batteries A and B of Jiangsu Province were selected as the research objects.The toxicological and metabolic kinetic model parameters of lead were collected from the literature,the PBPK model was constructed based on the mass conservation differential equations,and the Euler numerical method of the Excel table was used to solve the equations.In company B,the 11 workers who have been exposed to lead for three years at the three positions of casting, painting and grinding have been put into the PBPK model for their six years of occupational environmental monitoring.For workers'blood lead levels,the regression model was used to analyze the model to predict the fitting of the blood lead value and the measured blood lead value curve,and to verify the accuracy of the PBPK model in predicting the internal dose.Using the validated PBPK model to predict the internal doses of workers'organ tissues in a lead-acid battery company's A-grinding,casting,painting,grinding,brushing,and welding jobs at the corresponding occupational environment's lead exposure level,and evaluated by the total hazard index. Occupational health risks in key positions,and test the accuracy of the assessment results with the actual blood lead abnormality rate.According to the biological limits of occupational exposure to lead and its compounds in China,blood lead was 400?g/L,and blood lead?400?g/L was defined as abnormal.Harm to human health.Selection of International Council on Mining and Metals(ICMM),Control of Substances Hazardous to Health Essentials(COSHH Essentials)and Comprehensive Index Method The risk assessment method compares the advantages and disadvantages of the three methods and the scope of application of the research method to provide a basis for lead-acid battery companies to better conduct occupational health risk assessment.The results of the study were as follows:1.The time-weighted average concentration of lead-bearing smoke in lead-acid battery company A's cast-plate and welding posts was 0.013-0.058 and 0.041-0.100mg/m~3,respectively, and the time-weighted average concentration of lead dust in the grinding and separating brush posts was 0.060-0.207,0.055-0.105 mg/m~3,the time-weighted average concentrations of the above positions exceeded their occupational exposure limits;the time-weighted average concentrations of ball milling,coating,paste,and acid addition positions did not exceed their occupational exposure limits.The results suggest that the concentration of lead fumes in enterprise A cast plates and welding posts,and the concentration of lead dust in grinding discs and post brush positions exceed their occupational exposure limits,and effective measures must be taken to reduce the concentrations of lead and lead dust for the above positions.2.The PBPK model of lead-acid battery company predicts the fitting values of blood lead value and blood lead measured value curve were 0.928,0.901,0.942,respectively,suggesting that the PBPK model could be used to accurately predict the operation The internal dose of lead in various compartments after exposure to lead.According to the results of risk characterization,the total hazard index of health risks for ball milling and painting jobs of lead-acid battery enterprises was less than 1,within an acceptable range,and was consistent with the level of blood lead abnormalities;casting plates,grinding plates,and brushing machines The total hazard index of the welding posts was greater than 1,exceeding the acceptable range,and was consistent with the level of blood lead abnormalities.The results suggest that the risk of casting,grinding,brushing,and welding jobs was high.Companies need to take effective prevention and control measures.The relevant departments should also strengthen the occupational health supervision of enterprises to ensure the health of workers.3.The results of the ICMM method for the exposure of lead smoke to cast plates and welding posts,contact with lead dust,and the evaluation results of the brush positions were intolerable risks.The results of ball grinding and coating job evaluation of exposure to lead dust were tolerable risks.The results of the evaluation of exposure to sulfuric acid paste and acid post were all potential risks.The COSHH Essentials method was used to assess the risk of ball milling,coating,grinding and shredding of lead dust,cast sheet and welding post exposed to lead smoke.was 3,the risk rating for the exposure to sulphuric acid pastes and acid additions was 2;the risk rating for the cast plates and welding posts exposed to lead fumes and the exposure to lead dusts for the integrated index method were 3,and the evaluation results were both Medium risk.The risk of ball grinding and coating jobs on lead dust exposure,exposure to sulphuric acid paste,and post addition of acid was 2.The assessment results were all low risk.The PBPK model assessment results showed that the health risks of milling and painting jobs were less than 1 and the risk was relatively small and within an acceptable range.The health risks of cast,grinding,brushing,and welding posts were greater than 1,and the risk was greater than acceptable.range.When the site concentration was lower than 1/2 limit,the comprehensive index method was selected;when the site concentration was between 1/2limit and limit,ICMM method,COSHH Essentials method,and comprehensive index method can be selected;when the site concentration Above the limit,the COSHH Essentials method and the composite index method were selected.The results suggest that the comprehensive index method has the widest range of applications and was applicable to the occupational health risk assessment of on-site concentrations of any occupational hazards.The PBPK model was only applicable to the occupational health risk assessment at any on-site concentration of lead exposure.In terms of the accuracy of the assessment results,the PBPK model was based on the internal dose of biological monitoring indicators for occupational health risk assessment,the assessment results have a higher accuracy. In summary,the time-weighted average concentrations of lead-acid battery company A's exposure to lead smoke in the cast plate and welding positions,contact with lead dust,and abrasive brush positions exceeded occupational exposure limits.For the excessive lead and lead smoke concentration,the mechanical ventilation should be strengthened and the ventilation and dust removal facilities should be regularly cleaned and maintained to ensure the efficiency of ventilation and dust removal.The ventilation volume of the ventilation system should be sufficient to dilute lead smoke and lead dust.The PBPK model can be used for the occupational health risk assessment of lead-acid storage battery company A.The risk of ball milling and painting jobs was within an acceptable range,and the occupational health risks of cast plates,grinding plates,brush points,and welding jobs were relatively high.In the acceptable range,enterprises need to take effective prevention and control measures,and relevant departments should also strengthen the occupational health supervision of enterprises to ensure the health of workers.The comprehensive index method of the four occupational health risk assessment methods was the most widely used and was applicable to the occupational health risk assessment of on-site detection concentrations of any occupational hazards.The accuracy of the PBPK model assessment was higher.The model was based on the internal dose of this biological monitoring.The indicators used for occupational health risk assessment were more accurate than the composite index method.