[Influential factors on abnormal symptoms of respiratory and skin irritation towards workers in carbon raw anode plants].

OBJECTIVE

To evaluate potential hazardous factors towards abnormal symptoms on the respiratory system and skin irritation caused by coal tar pitch(CTP) fumes, petroleum asphalt(PA) fumes, coke oven emissions(COE) and coal dust incarbon anode manufacturing enterprises.

METHODS

August 2020, a cross-sectional study was conducted in 2 carbon anode manufacturing enterprises in Shandong Province, 349 workers were identified as objects and exposure assessment were accomplished through questionnaire inquiry, working daily records, self-monitoring exposure data and ambient concentration detection on PA, CTP, COE and coal dust. Hazardous factors towards respiratory abnormal symptoms and skin irritation symptoms would be conducted through logistical model of binary classification.

RESULTS

Among 349 participants, 27(7.74%) exhibited abnormal respiratory symptoms, 20(5.73%) reported skin irritation. Workers in roasting, ingredient mixing, molding and forming positions exposed to coal dust(SiO_2 constituent ratio: 4.48%-5.24%) and concentration-time weighted average(C_(TWA))(0.28-2.39 mg/m~3) complied with the OELs. C_(TWA )of CTP fume reached to 0.49-3.35 mg/m~3 exceeding OELs by 2.45-16.75 folds, COE reached to 1.65-3.04 mg/m~3, exceeding OELs by 16.5-30.4 folds. Workers in ingredient mixing(C_(TWA)=7.93 mg/m~3) and molding positions(5.38 mg/m~3) also exposed to PA fumes, C_(TWA )exceeding OELs by 1.59 and 1.08 folds respectively. PA fumes exposure concentration of short term(C_(STE))>7.82 mg/m~3, CTP fumes C_(STE)>0.65 mg/m~3and COE C_(STE)>3.18 mg/m~3, cumulative weekly exposure among 41-60 hours, Wearing cotton or surgical masks, suspended protective facilities were all hazardous factors to respiratory abnormal symptoms. Male, compromised protective facilities, PA fumes C_(STE)>5.68 mg/m~3, CTP fumes C_(STE)>1.33 mg/m~(3 )and COE C_(STE)>3.18 mg/m~(3 )were hazardous factors to skin irritation ve symptoms. Synergistic interactions of risk occurrence of respiratory abnormal symptoms and skin irritation symptoms were noted between CTP fumeand PA fumes(F=3.035, P=0.035). Interactions on risk occurrence of respiratory abnormal symptoms were noted among smoking habits and cumulative weekly exposure for 41-60 h(F=4.376, P=0.037), as well as male and mask replacement frequency<3 times/w(F=5.949, P=0.015).

CONCLUSION

Exposure to PA dust(C_(STE)>7.82 mg/m~3), CTP dust(C_(STE)>0.65 mg/m~3), COE(C_(STE)>3.18 mg/m~3), weekly exposure duration for 41-60 h; Usage of inadequate personal protective equipment as well as inoperative engineering controls were risk factors to develop abnormal respiratory symptoms Male ones, inoperative engineering controls, exposure to PA dust(C_(STE)>5.68 mg/m~3), CTP dust(C_(STE)>1.33 mg/m~3) and COE(C_(STE )>3.18 mg/m~3) were ones to contribute to skin irritation symptoms. Interaction effects between exposure to CTP dust and PA dust were noted on both respiratory and skin symptoms. Risk of respiratory symptoms is affected by interactions among smoking habits and weekly exposure duration for 41-60 h, as well as male and the frequency of mask replacement<3 times/w.