11. HEAVY METAL POISONING DUE TO LEATHER TANNING - cadmium, lead, mercury and chromium (VI).
Tanning Factories are so toxic they had to be outsourced. The following chemicals are often used in the tanning process.
Main article: Cadmium poisoning
Cadmium is an extremely toxic metal commonly found in industrial workplaces. Due to its low permissible exposure limit, overexposures may occur even in situations where trace quantities of cadmium are found. Cadmium is used extensively in electroplating, although the nature of the operation does not generally lead to overexposures. Cadmium is also found in some industrial paints and may represent a hazard when sprayed. Operations involving removal of cadmium paints by scraping or blasting may pose a significant hazard. Cadmium is also present in the manufacturing of some types of batteries. Exposures to cadmium are addressed in specific standards for the general industry, shipyard employment, construction industry, and the agricultural industry.
Main article: Mercury poisoning
Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury (chemical symbol Hg) is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses. Its zero oxidation state Hg0 exists as vapor or as liquid metal, its mercurous state Hg22+ exists as inorganic salts, and its mercuric state Hg2+ may form either inorganic salts or organomercury compounds; the three groups vary in effects. Toxic effects include damage to the brain, kidney, and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease.
Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure.
Adverse health effects associated with Cr(VI) exposure include occupational asthma, eye irritation and damage, perforated eardrums, respiratory irritation, kidney damage, liver damage, pulmonary congestion and edema, upper abdominal pain, nose irritation and damage, respiratory cancer, skin irritation, and erosion and discoloration of the teeth. Some workers can also develop an allergic skin reaction, called allergic contact dermatitis. This occurs from handling liquids or solids containing Cr(VI) such as portland cement. Allergic contact dermatitis is long-lasting and more severe with repeated skin exposure. Furthermore, contact with non-intact skin can lead to ulceration of the skin sometimes referred to as chrome ulcers. Chrome ulcers are crusted, painless lesions showing a pitted ulcer covered with fluid.
Workers today are still being exposed to lead that result in adverse health effects. Recent studies have provided evidence that lead can cause health effects at blood lead levels lower than those established by OSHA’s 1978 Lead standard.
Epidemiological and experimental studies indicate that chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Pregnant women need to be especially concerned with reducing BLL since this can have serious impact on the developing fetus.
Chronic exposures leading to BLLs above 20 µg/dL can cause subclinical effects on cognitive functions as well as adverse effects on sperm/semen quality and delayed conception. BLLs between 20 to 40 µg/dL are associated with effects such as cognitive aging as well as deficits in visuomotor dexterity, lower reaction times and attention deficit. At BBLs above 40 µg/dL, workers begin to experience symptoms such as headache, fatigue, sleep disturbance, joint pain, myalgia, anorexia, and constipation.
While much less common today, workers can be exposed to high lead levels resulting in BLL over 60 µg/dL. Health effects at these very high BLLs can range from acute effects such as convulsions, coma, and in some cases, death, to more chronic conditions such as anemia, peripheral neuropathy, interstitial kidney fibrosis, and severe abdominal cramping.
OSHA’s general industry and construction lead standards include a medical removal protection provision for workers whose blood lead levels reach or exceed 50 µg/dL (construction) or 60 µg/dL (general industry) Recently, medical management guidelines for adult lead exposure has been developed by a national expert panel coordinated by the Association of Occupational and Environmental Clinics (AOEC), in collaboration with the NIOSH Adult Blood Lead Epidemiology and Surveillance (ABLES) program. The panel recommends that maintaining BLLs below 20 µg/dL over a twenty-year period, or below 10 µg/dL over a forty-year period, would be sufficient to prevent chronic effects associated with cumulative exposures.
Based on limited evidence of human carcinogenic effects, workers may develop stomach cancer and lung cancer following inhalation exposure to lead, but more studies are needed to demonstrate the cancer risks compared to the levels and durations of lead exposure, and possibly confounding factors such as smoking, diet, and other carcinogens in the workplace. Experimental research indicates that rats and mice develop renal tumors following exposure to lead.
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