1, welding hazards and influencing factors
There are many hazards of electric welding to health, which can be generally divided into physical factors and chemical factors. The former includes ultraviolet and infrared rays generated by high temperature arc light. The latter is various components of welding aerosol, including solid metals such as iron, manganese, aluminum, chromium, lead, nickel and radioactive elements, and gaseous gases such as manganese oxide, hydrogen fluoride and nitrogen oxides. High temperature, vibration and noise are not obvious.
Welding aerosol has high dispersibility and its biological activity is obviously higher than other dusts. The composition of welding aerosol varies greatly with different covered electrode and welding methods, and its biological activity is also different. Biological activity is also related to the solubility and freshness of welding fume.
2. Damage of welding operation to workers' health
2. 1 Effect of welder's pneumoconiosis on lung function
During arc welding, the core, coating and base metal in covered electrode are melted, evaporated, oxidized and agglomerated at high arc temperature, which produces a lot of dust of metal oxides and other substances, which can cause welder's pneumoconiosis if inhaled for a long time. Welder's pneumoconiosis usually occurs in a closed and poorly ventilated working environment, and the average length of service is about 18 years. The measurement of pulmonary ventilation function shows that exposure to welding dust can damage pulmonary ventilation function to a certain extent, and the indexes of pulmonary ventilation function, such as FVC, FEV 1.0, FEV 1.0%, MMF, V50, V25 and PEFR, decrease obviously. Smoking and dust exposure may have a synergistic effect on the pulmonary ventilation function of welders. The damage of welder's lung ventilation function tends to increase with the extension of dust exposure time.
2.2 manganese poisoning
All kinds of weldments and covered electrode contain different amounts of manganese. Generally, the manganese content in the core is very low, only about 0.3~0.6%. In order to improve the mechanical strength, wear resistance, corrosion resistance and other properties, when covered electrode containing manganese is used, the manganese content can be as high as 23%. Welding in places with poor ventilation, such as cabins, boilers or closed containers, can cause manganese poisoning by inhaling manganese-containing smoke for a long time, and can detect manganese bleeding, increased urine manganese and changes in neurobehavioral functions. The determination of hair manganese can also be used as an early screening index for manganese poisoning.
2.3 welding smoke heat
Welding fume heat, also known as welder heat, is a kind of metal fume heat. It is a systemic disease, which is mainly manifested by the sudden increase of body temperature and the increase of peripheral white blood cell count caused by inhalation of metal oxides. It often occurs 6- 12 hours after exposure to metal oxide smoke, and dizziness, fatigue, chest tightness, shortness of breath, muscle and joint pain, followed by fever, leukocytosis and severe chills occur.
2.4 Effects on nervous system
A large number of studies show that there is nervous system damage related to occupational exposure in welding operation, which mainly involves information processing functions such as memory, analysis and location, showing abnormal neurophysiology, neuropsychology and neurobehavior, which is closely related to manganese, aluminum and lead in welding dust. Use who. NCTB test showed that the total score of behavioral function was negatively correlated with urinary manganese, suggesting that the change of neurobehavioral function can be used as one of the early indicators to prevent manganese poisoning. Foreign studies have reported that the total score of behavioral function of electric welding workers is higher than that of the control group. The author analyzes that it may be caused by the health effect of workers and the training effect of work-related skills. The influence of electric welding on the investigation function of workers' parasympathetic nerve has also been reported. It has been reported abroad that the onset age of welder's Parkinson's syndrome is obviously earlier (the average age is 46 years old, and the average age of control group is 63 years old), suggesting that welding work is one of the risk factors of Parkinson's syndrome.
2.5 Effects on eyes and skin
The harm of ultraviolet rays (UVR) and infrared rays (IFR) to eyes and skin is an important aspect of occupational injuries in electric welding. It is often reported that the eye symptoms of welders are obviously increased, such as electro-optic ophthalmia, chronic blepharitis, conjunctivitis and lens opacity. The prevalence of chronic blepharitis and conjunctivitis tends to increase with the length of service. The main damage caused by UVR overexposure is photosensitive keratitis, and the welder's cataract is related to infrared exposure. Recent studies abroad show that workers exposed to excessive UVR are at risk of non-melanoma skin cancer and other chronic diseases (such as malignant melanoma of the eye).
2.6 Effects on reproductive system
The outcome of reproductive toxicity is of great significance, so in recent 10 years, some studies on reproductive toxicity of electric welding have been carried out at home and abroad, mainly involving the semen quality of male workers, reproductive outcome of female workers and injury mechanism. The research shows that the menstrual amount, shortened cycle, prolonged menstrual period, increased leucorrhea, spontaneous abortion, premature delivery and dysmenorrhea of female welding workers are higher than those of the control group. . The semen appearance of male workers with manganese poisoning is even grayish white, and the PH value is normal. The average liquefaction time was longer than that of the control group. The test results show that the average ejaculation volume, total sperm count, sperm survival rate and activity rate of male workers with manganese poisoning are lower than those of the control group, and the sperm abnormality rate of male workers with manganese poisoning is significantly higher than that of the control group [19 > . It is considered that manganese metal can affect the spermatogenic system of male workers, have a direct toxic effect on sperm development, and can kill sperm, thus causing changes in male semen quality. It has also been reported abroad that the sex hormone secretion of welders has changed and the sperm quality has decreased, but it has no effect on the sex ratio of offspring.
2.7 Effects on the levels of enzymes and antibodies in vivo
In recent years, there are many reports about the influence of electric welding on enzymes and antibodies in workers. The results showed that the total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) in welders' serum were significantly decreased, and the level of malondialdehyde (MDA) was significantly increased, but there was no dose-effect relationship between welders and oxidative stress, and the antioxidant capacity was weakened, suggesting that biofilm was damaged.