Heavy metals are playing a vital role in modern society as we use them to obtain socio-economic as well as health benefits. However, if they are not properly managed, they can be extremely harmful and their extended exposure can exacerbate serious health issues.
It has been reported that the world-wide production of heavy metals has been increased by 10-fold in recent years and it is still dramatically increasing day by day.
In a recent analysis, scientists of WHO (World Health Organization) have estimated that 4.9 million casualties (8.3 percent of total mortality worldwide) are caused due to inappropriate management of heavy metals.
Among all heavy metals, the most toxic ones include mercury (Hg), lead (Pb), arsenic (As), nickel (Ni) and cadmium (Cd). According to WHO (World Health Organization), these heavy metals are listed among the top ten chemicals of major public concern due to their potential of causing cancer and organ damage.
Through anthropogenic activities like mining, smelting, automobile exhaust, fertilization, pesticides and application of organic livestock manure, heavy metals are now part of our soil, atmosphere and hydrosphere, therefore posing potential threat to our environment and damaging human health as well.
We are indirectly ingesting heavy metals by processes described above whereas the labor staff working in industries is directly susceptible to heavy meals.
In developing countries, most of the people engage themselves with industries to earn their livelihood. There are thousands of workers in chemical industries which work at least eight hours a day in front of chemicals.
Health risk for the employees of chemical industries is due to emission of harmful gases (carbon mono-oxide, carbon dioxide and ozone) and heavy metals in the workplace.
According to OSHA (Occupational Safety and health Administration), workplace fatalities have increased by 26% in mining and oil and gas extraction industries in 2017.
Adverse effects of heavy metals are posing serious challenges in different industries. Beryllium (Be) occurs in industries where processing and extraction of alloy metal is done.
Workers exposed to beryllium are prone to skin and lung diseases. Industrial workplaces where ores are being processed or smelted are a common source of Be. It is extremely toxic.
Several deaths occur among welders who weld on cadmium-containing alloys. In industries where chromate (Cr) and pigments containing chromate are produced, there is an increased risk of lung cancer among workers.
Calcium chromate and chromium trioxide are well-known human carcinogens. Lead (Pb) is involved in construction work and smelting operations. Exposure to manganese (Mn) is associated with nervous system disorders.
Arsenic (As) induces kidney and brain diseases, cancer and genotoxicity as well. In the United States Department of Labor, an agency named Occupational Safety and Health Administration (OSHA), works for the welfare,
safety and health protection of workers has estimated in 2015 that the number of workers exposed to Cd is 300,000, 558,000 are exposed to Cr and about 838,000 workers involved in construction face Pb exposures. Around 35,000 workers are covered by Be and 804,000 workers in general industry annually.
In industries where welding, cutting and heating of material is performed, workers are prone to noxious fumes and gases frequently emitted during this work. Immediate symptoms are not caused therefore workers are unaware of their over-exposure to such infectious gases and fumes until they get checked by some physician.
In 2011, it was reported that Workers in iron and steel industries were highly affected by skin problems (31%), respiratory disorders (66%) and noise-related hearing impairments. When workers perform welding, burning or brazing work with heavy metals, it results in repeated trauma injuries and some other neurovascular disorders.
Workers dismiss them as normal aches and pains, however when it is lately diagnosed, it leads to severe condition and require extensive treatment of injury leading to permanent disability.
They also cause chronic toxicities and other disorders such as kidney diseases, breathing problem, nervous disorders, viral infections, malfunctioning of immune system, loss of memory, lack of sleep and cancer.
During their routine work in chemical industries, workers experience different kind of musculoskeletal disorders (MSDs) that need to be addressed instantly. The best treatment of disorders or poisoning caused by heavy metal is complete termination of exposure to the metal.
Various chelating agents can also be used in form of drugs for treatment purpose as they bind with the toxic element and excreted in the urine.
Calcium EDTA, Pencillin and Dimercapol are three common drugs used for treatment of metal poisoning. Some ingested metals can be removed by pumping of the stomach via process called gastric lavage.
In case of inhaling poisonous substance, the affected individual must be removed from contaminated site immediately and provided with respiratory support.
If kidney failure occurs in any patient, hemodialysis should be done. Diseases related to nervous system or brain (e.g. cerebral edema) are treated with corticosteroid drugs or diuretics (e.g. Mannitol).
Apart from medical treatments, awareness programs must be conducted to make workers familiar with intensity of hazard; they face during their work in chemical industry and how they could prevent themselves from its hazardous effects.
It is very important for any chemical organization to ensure that his employees are safe from the devastating effect of toxic chemicals and heavy metals.
New approaches should be proposed for awareness of possible health effects and employees willingness to enhance working conditions. Employees must use respiratory protection.
Lead (Pb) aerosols can cause eye or skin irritation therefore full-piece face respirators should be used instead of half-mask respirators. Employees should be provided with HEPA (High efficiency particulate absorber) filters for powered and non-powered air-purifying respirators.
A powered air-purifying respirator (PAPR) must be provided instead of a negative-pressure respirator as PAPR provides adequate protection.If there is possibility of skin or eye irritation, employers should provide the employees with appropriate Personal Protection Equipments (PPE).
A medical surveillance program must be arranged for the employees exposed to toxic heavy metals as it actively monitors employee health over time. This tracking system is very useful to access the health record and can also determine if any changes have occurred to employee’s health.
Co Authored by:
Maira Naveed, Aisha A Waris, Muhammad Zia ur Rehman