This paper introduced concepts of occupational health risk grading and its development in China and abroad, reviewed the history of seeking occupational health classification supervision models, and explored the applicability and effectiveness of occupational health risk grading and assessment methods serving occupational health classified supervision on employers. These findings would provide a scientific basis for occupational health classification supervision and law enforcement.

In the face of a serious occupational disease prevention and control situation, the lack of efficient supervision and regulation methods has become a prominent contradiction. This paper reviewed the progress and application of occupational health grading and classification supervision methods for employers in China in recent years, and analyzed the characteristics and limitations of selected methods. The grading and classification supervision methods have gradually developed from considering only inherent health risk of occupational disease hazards, to considering both inherent attributes of occupational disease hazards and exposure duration. Some regional authorities introduced trial measures for grading and classification of occupational health supervision by embracing exposure level of an occupational disease hazard of interest, associated outcome severity, and occupational health management situation of targeted employers. In October 2022, the National Disease Control and Prevention Bureau issued the Notice on Carrying out Pilot Work of Occupational Health Classification Supervision and Law Enforcement, which further promoted the establishment of a differentiated occupational health supervision model. Grading and classification of occupational health supervision can improve the supervision efficiency of public health administration departments and promote employers to fulfill the main responsibility of occupational disease prevention and control.

The National Disease Control and Prevention Bureau and the National Health Commission jointly issued an announcement on Notice on Carrying out Pilot Work of Occupational Health Classification Supervision and Law Enforcement, which presented a method of comprehensive risk assessment method of occupational disease hazards of employers. This method embraces relevant factors at full scale and is simple in operation, but its applicability and accuracy of assessment results need further practical study. Based on the steps of occupational health risk assessment and proven occupational health risk assessment methods available at home and abroad, this paper proposed improvements and discussed the comprehensive risk assessment method of occupational disease hazards of employers, so as to provide a technical basis to implement the occupational disease hazard classification management of employers for relevant government supervision departments.

Background The complex and diverse occupational disease hazards in automobile manufacturing industry pose high occupational health risks to workers. Objective To explore the methods that can accurately reflect the workplace health risk grade of automobile manufacturing enterprises, and to guide enterprises to practice risk classification management. Methods Comprehensive index method, International Commission on Mining and Metals occupational health risk assessment method (ICMM method), and risk index method were used toassess health risks of occupational disease hazards in major workstations such as welding, polishing, and painting in three automobile manufacturing enterprises in Hunan Province. Kappa consistency test was used to test the grading results of the three assessment methods. The re-examine results and detection rate of contraindications of occupational health examinations in the past three years were used to verify the assessment results. Results The results of comprehensive index method showed that the hazards of each selected workstation in enterprises A and B were evaluated as grade 2-3, among which NO₂ in enterprise A was grade 3, and welding fume, NO₂, and formaldehyde in enterprise B were all grade 3. The hazards of each selected workstation in enterprise C were grade 3-4, among which NO₂ and benzene in were grade 4, and welding fume, manganese and its compounds, grinding wheel dust, and xylene were grade 3. The hazards evaluated by ICMM quantitative method were grade 2 and grade 5, among which manganese and its compounds in enterprise A and welding fume, grinding wheel dust, and benzene series in enterprise C were graded as grade 5. The hazards evaluated by risk index method were grade 1-4, among which manganese and its compounds in enterprises A and B were grade 3, and manganese and its compounds and benzene in enterprise C were grade 4. The Kappa value between comprehensive index method and ICMM method was 0.084 (P>0.05), that between comprehensive index method and risk index method was −0.046 (P>0.05), and that between ICMM method and risk index method was 0.014 (P>0.05), indicating poor consistency. By comparing the results of occupational health surveillance with the results of occupational health risk assessment, one worker was found to have occupational contraindication of manganese exposure and 1 worker was found to have excessive manganese in hair in enterprise A. However, the comprehensive index method graded low risk for manganese and its compounds in enterprise A and the result is conservative. The key workstations identified by ICMM method were consistent with the occupational health examination results, but the assessment grades were all extremely high risk, and the results were too strict. One worker was found to be contraindicated to welding fumes, and 2 polishers were found to have severe mixed pulmonary ventilation dysfunction in enterprise C. Mild and moderate pulmonary ventilation dysfunction was found to be common in welding and polishing workstations in each enterprise. The assessment results of welding fumes and grinding wheel dust by the risk index method were negligible risks, which were inconsistent with the occupational health examination results. Conclusion The comprehensive index method, ICMM method, and risk index method can basically identify workstations with serious occupational hazards, but they have certain limitations and applicability. In general, the evaluation results of the comprehensive index method were generates more consistent with the results with occupational health surveillance than the other two methods, is more comprehensive and objective in consideration, and is more suitable for health risk assessment of automobile manufacturing enterprises.

Background The contradiction between science and operability has always existed in the model of classified occupational health supervision and management. Comprehensive risk assessment method for occupational disease hazards of employers provides risk grading and classification for occupational health management, and it's a new attempt to explore classification supervision and law enforcement. Objective To apply a comprehensive risk assessment method for occupational disease hazards of employers to estimate health risk level of wood furniture enterprises, discuss its advantages and disadvantages, and provide a basis for improving the classified management of occupational health. Methods Seven typical factories were selected in counties with highly concentrated wooden furniture manufacturing. Occupational health field investigation and testing were carried out to estimate occupational disease hazard risk level (Ⅰ, Ⅱ, and Ⅲ). A self-rated checklist was applied to score occupational health management status by interviewing employers, one by one, and to determine occupational health management status grade (A, B, and C) by the score. Thus, a comprehensive risk level (Class A, Class B, and Class C) of a specific factory was obtained from a matrix of occupational disease hazard risk level and management status grade. Risk verification was carried out based on any abnormality reported by regular occupational physical examination in past 3 years. Results Defects in occupational health management were identified in all 7 factories, among which 6 were grade C with key nonconformities (poor), and 1 was grade B (medium). Disqualified occupational disease hazards were found in 6 of 7 factories, and the workstation-specific disqualified rates were 26.09% (12/46) for noise, 14.71% (5/34) for wood dust (hard), and 12.50% (1/8) for xylene. Level Ⅱ (medium) of occupational disease hazard risk was estimated in 5 of 7 factories, while level Ⅲ (high) in 2 factories. All 7 factories were class C (high risk) accessed by the comprehensive risk assessment method for occupational disease hazards. The occupational health surveillance documents showed 636 batches of regular occupational physical examination were ordered by the 7 employers, and a total of 37 workers from 5 factories reported abnormalities in physical examination, among which 3 workers reported dust exposure and 34 workers reported noise exposure. Conclusion The comprehensive risk assessment method for occupational disease hazards of employers is not able to perform with satisfaction in occupational health classification of wooden furniture manufacturing factories yet. It is necessary to expand the pilot to improve this assessment method and develop an efficient supervision mechanism to ensure the authenticity of the data before it is popularized and applied in classified occupational health management.

Background The mining of non-coal underground mines may come into contact with various types of dust, such as lead, zinc, copper, and non-metallic minerals. Dust of various kinds commonly exists in all aspects of mining and selection, and is one of the main occupational hazard groups in non-coal underground mines. Objective To compare the application of two risk assessment methods in the occupational health risk assessment of productive dust in non-coal underground mines, and to provide a reference for the selection of dust hazard health risk assessment methods and the management of dust hazards in non-coal mines. Methods A field investigation of the dust hazards of three typical non-coal underground mining enterprises (lead-zinc mines, copper mines, and fluorite mines) was carried out, and the comprehensive index method and the occupational health risk assessment method from the International Council on Mining and Metals (ICMM) were used to perform risk assessments. The comprehensiveindex method considers the following factors: dust monitoring data, the aerodynamic diameter of dust, hazard control measures, occupational health management, daily usage, and daily exposure time to determine exposure levels. The ICMM method determines the risk level based on the consequences caused by dust, exposure probability, exposure time, and uncertainty coefficient. Kendall consistency test was used to compare agreement between the results generated by the two methods. Results The results generated by the comprehensive index method were as follows: level 3 (medium risk) or level 4 (high risk) for silica dust or lead dust; level 1 (negligible risk) or level 2 (low risk) for other dust (dust with free SiO₂ content<10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The risk levels graded by the ICMM method were as follows: level 4 (very high risk) and level 3 (high risk) for exposure to silica dust and lead dust, respectively, and level 1 (tolerable risk) or level 2 (potential risk) for exposure to other dust (dust with free SiO₂ content <10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The consistency level between the results graded by the two methods was very high (Kendall W coefficient=0.974, P < 0.05). Conclusion For the occupational health risk assessment of productive dust in non-coal underground mines, the consistency level of risk assessment results between the ICMM method and the comprehensive index method is very high. The ICMM method is more convenient to operate and should be preferred in assessing health risks of dust hazard in non-coal underground mines.

Background Most of the studies on grading and classification of occupational health compre-hensive risks for specific employers still remain in the establishment and description of methodology, and practical application studies are rarely reported. Objective To explore the application of an occupational disease hazards comprehensive risk assessment method issued by the National Disease Control and Prevention Bureau in conjunction with the National Health Commission and a self-developed occupational health grading and classification method in petroleum refining enterprises, and to provide practical experience for the implementation of differentiated law enforcement by relevant regulatory authorities. Methods Two occupational health grading and classification methods were practiced in three petroleum refining enterprises in Guangdong Province. The occupational hazards comprehensive risk assessment method was provided by the Notice on Carrying out Pilot Work of Occupational Health Classification Supervision and Law Enforcement of the National Disease Control and Prevention Bureau and the National Health Commission. The principle was to derive the occupational health risk level according to nature of occupational hazards, exposure level, and number of workers exposed to them in an employer, and then to classify them into Class A, Class B, and Class C by combining with local occupational health management status level. The occupational health grading and classification method was self-developed according to available domestic and foreign occupational health risk assessment methods. Its principle was to calculate the risk level of each workstation in an employer based on published carcinogenicity classification or LD₅₀/LC₅₀ of chemical toxicants, level of noise, exposure parameters such as exposure level and exposure frequency, estimate the comprehensive risk R_o of the target employer by the Romanian comprehensive risk calculation method, and then calculate a comprehensive risk R_o' weighted by the occupational health management index of the target employer and classify it into class A, class B, and class C. Finally, assessment results, scope of application, inquired indicators, advantages,disadvantages and professional competence requirements of the two grading and classification methods were compared. Results The occupational hazards that were evaluated in three enterprises in this study were benzene, toluene, xylene, gasoline, hydrogen sulfide, and noise. The exposure levels of benzene, toluene, xylene, and gasoline were all below 10% OEL (occupational exposure limit), and hydrogen sulfide and noise were disqualified. Occupational hazards such as benzene and hydrogen sulfide were serious occupational hazards in the three enterprises, and the number of workers exposed was 461, 912, and 224, respectively; the HRs (hazard ratings) of benzene, toluene, xylene, gasoline, hydrogen sulfide, and noise were level 5, 3, 2, 3, 5, and 3 respectively. The occupational health management status of the three enterprises was graded as B, A, and B, respectively by the occupational disease hazards comprehensive risk assessment method. The occupational health management index of the three enterprises was graded as B, A, and A, respectively by the occupational health grading and classification method. The comprehensive risk assessment results showed that two enterprises classified into as the highest class C and one into class B by the occupational disease hazards comprehensive risk assessment method, while all three enterprises were classified into class B by the occupational health grading and classification method. Conclusion The two grading and classification methods are not consistent in the evaluation results of petroleum refining enterprises, and there are differences in the evaluation scope, indicators to be collected, and professionalism. It is recommended that occupational health regulators should fully consider the advantages and disadvantages of the two methods and choose the appropriate assessment method according to the actual regulatory purpose.

Background Neonicotinoid insecticides (NEOs) are emerging synthetic insecticides that have been used in various pest management regimens worldwide as alternatives to conventional insecticides. Recently, several studies have indicated that humans are widely exposed to NEOs, but limited is known about the levels and associated health risks of NEOs exposure among children. Objective To estimate exposure levels of four kinds of NEOs in urine samples among 5-year-old children from Laizhou Wan, Shandong Province, and to evaluate health risks of single and cumulative exposure to NEOs among children in this area. Methods A total of 205 children who participated in the 5-year-old follow-up in Laizhou Wan Birth Cohort (LWBC) were included. Urinary concentrations of four NEOs [imidacloprid (IMI), acetamiprid (ACE), clothianidin (CLO), and thiamethoxam (THM)] were measured by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Based on the detected NEOs concentrations, estimated daily intake (EDI) was calculated, and the health risk of exposure to single NEO was assessed using hazard quotient (HQ, risk threshold=1). A relative potency factor (RPF) approach was used to standardize the concentrations of the four NEOs by IMI to calculate their cumulative concentrations. Then, the health risk of cumulative exposure to the four NEOs was further evaluated based on the HQ method. Results The detection rates of the four NEOs in the 5-year-old children were all above 90%, and their median creatinine-adjusted urinary concentrations were in the order from high to low as follows: CLO (1.373 μg·g⁻¹) > THM (0.628 μg·g⁻¹) > IMI (0.310 μg·g⁻¹) > ACE (0.073 μg·g⁻¹). Of the four NEOs, the median EDI of IMI was 0.035 µg·kg⁻¹·d⁻¹, higher than those of CLO (0.032 µg·kg⁻¹·d⁻¹), THM (0.012 µg·kg⁻¹·d⁻¹), and ACE (0.002 µg·kg⁻¹·d⁻¹). The maximum HQ values of IMI, CLO, THM, and ACE were 0.168, 0.152, 0.055, and 0.022, respectively, which were all far lower than the risk threshold of 1. The median concentration of cumulative exposure to the four NEOs standardized by IMI was 21.241 μg·g⁻¹, and its median EDI was 2.370 µg·kg⁻¹·d⁻¹. The maximum HQ of cumulative exposure to the four NEOs was only 0.694, which also did not exceed the risk threshold of 1. Conclusion NEOs exposure is common among the 5-year-old children in Laizhou Wan, Shandong. Although there is no obvious health risk associated with single and cumulative exposure to NEOs in the children in this area, their exposure levels of NEOs are higher than those in some foreign areas. The adverse health effects of long-term exposure to low dose of NEOs deserve our extensive attention.

Background Exposure to perfluoroalkyl and polyfluoroalkyl substances (PFAS) during pregnancy might affect thyroid-related hormone levels in pregnant women. However, most previous studies focused on the effects of PFAS containing 8-10 carbon atoms, and few studies have estimated the associations between PFAS with longer carbon chain and thyroid-related hormone levels. Objective To examine the associations between PFAS exposure and thyroid-related hormones in pregnant women. Methods The present study was based on the Jiashan Birth Cohort from September 2016 to April 2018. We analyzed 13 PFAS in maternal blood samples (n=781) by high-performance liquid chromatography-tandem mass spectrometry, as well as total triiodothyronine (T3), total thyroxine (T4), free T3 (FT3), free T4 (FT4), thyroid stimulating hormone (TSH), thyroglobulin antibody (TG-Ab), and thyroid peroxidase antibody (TPOAb) by electrochemiluminescence immunoassay. PFAS were divided into three groups:low concentration, medium concentration and high concentration according to the tertile of their concentrations. We estimated the associations between PFAS concentrations and thyroid-related hormones in pregnant women by multiple linear regression. Results In the multiple linear regression models, a change in perfluorododecanoic acid (PFDoA) concentrations from the low concentration group to the high concentration group was associated with a −0.10 (95%CI: −0.20, 0) nmol·L⁻¹ change in T3, −0.15 (95%CI: −0.28, −0.02) pmol·L⁻¹ change in FT3, and −3.02 (95%CI: −5.66, −0.39) pmol·L⁻¹ change in FT4, respectively. A change in perfluorotridecanoic acid (PFTrDA) concentrations from the low concentration group to the high concentration group was associated with a −0.10 (95%CI: −0.20, 0) nmol·L⁻¹ change in T3. Compared with the low concentration group, the concentration of T4 in the medium concentration group of perfluorohexane sulfonate (PFHxS) increased by 6.10 (95%CI: 0.44, 11.75) nmol·L⁻¹. No statistically significant associations were found between PFAS and TSH concentration. The negative associations of PFAS with thyroid-related hormones were more pronounced in pregnant women with positive TG-Ab and/or TPOAb. Conclusion Exposure to PFAS during pregnancy may affect thyroid-related hormone homeostasis in pregnant women, and the effect is stronger in TG-Ab and/or TPOAb-positive pregnant women.

Background The correlation between noise exposure and negative emotions of noise-exposed workers has received increasing attention and related studies have been reported. However, there is a lack of research on the path and effect analysis of the relationship between noise exposure and negative emotions, which will contribute to a more comprehensive understanding of the health damage characteristics of noise in addition to hearing loss. Objective To explore the path and effects of cumulative noise exposure, tested hearing thresholds, and conscious hearing level of noise-exposed workers on negative emotions. Methods Using stratified random sampling, 312 noise-exposed workers from a machinery and equipment manufacturing enterprise were selected. Occupational history, negative emotions (including the feelings of stress, anxiety, and depression), and conscious hearing level of the workers were investigated using the Depression-Anxiety-Stress Scale (DASS-21) and a self-made questionnaire. The hearing threshold of the workers was measured by pure tone air conduction audiometry. Sound level meter was used to measure noise equivalent sound level at selected work sites. Individual cumulative noise exposure was estimated based on work site noise level and personal noise exposure history. Path analysis was used to analyze potential mediating effects of workers' hearing thresholds and conscious hearing levels on the relationship between noise exposure and negative emotions (including stress, anxiety, and depression). Results The positive rates of negative emotions among the 312 noise-exposed workers were 18.27% (57/312) for stress, 46.79% (146/312) for anxiety, and 28.53% (89/312) for depression; the cumulative noise exposure ranged from 101.0 to 136.1 dB(A)·d, with an average of 125.69 dB(A)·d. The distributions of tested hearing thresholds and conscious hearing levels among the workers exposed to noise were significantly inconsistent (P<0.001), with both unweighted and weighted Kappa values less than 0.4. The percentage of workers with conscious hearing levels higher than their hearing threshold levels was 16.0%, and the percentage of workers with conscious hearing levels lower than conscious hearing levels was 38.7%. The path analysis results showed that tested hearing thresholds had no mediating effect on the relationship between cumulative noise exposure and negative emotions. There was a partial mediating effect of conscious hearing level on the relationship between cumulative noise exposure and negative emotions, with a mediating effect value of 0.06 (95%CI: 0.03, 0.11) and a mediating effect ratio of 28.57%. Conclusion Conscious hearing plays a partial mediating role in the relationship between cumulative noise exposure and negative emotions of noise-exposed workers, while tested hearing thresholds do not.