Transcript Slide 1
Heavy Metals “The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.” Mercury (Hg) Arsenic (As) Chromium (Cr) Thallium (Tl) Lead (Pb) Cadmium (Cd) Characteristics Natural components of the Earth's crust Can’t be degraded or destroyed Essential to maintain the metabolism of the human body Higher concentrations lead to poisoning Heavy metals are dangerous because they tend to bioaccumulate. Effect of Lead on the Environment Lead is a naturally occurring bluish-gray metal found in small amounts in the earth's crust. Lead is a chemical element with the atomic number 82 Extremely poisonous to humans!! SOURCES Natural • • • • • Weathering and erosion Volcanic eruption Sea spray Plants Forest fires Man-made • • • • • • • • • • Lead piping system Leaded gasoline lead acid batteries Municipal and Industrial solid waste and waste water Cosmetics Lead based paints Tanneries Lead particles from vehicular emission Jewelry Lead-glazed pottery Lead Exposure in the environment 220 million pounds car exhaust 3 billion pounds smoking chimneys of manufacturing plants 4 million tons earth’s crust each year In air Industrial emissions, smelters and refineries, weathering and erosion, volcanic eruption, forest fires etc. Atmospheric concentration had been known to range between 0.3-1.1 ug/m3 in urban areas 0.5-0.3 ug/m3 in rural areas In Food Airborne lead falls onto crops or soil and is absorbed by plants. Lead solder used in making cans can also contaminate food. Infants can also absorb lead from their mothers' bodies through breast milk. Gardens grown in lead-contaminated soils may contain lead root vegetables. In Dust and soil Lead in soil can come from the air or from erosion of lead-bearing rocks, and may be carried indoors as dust. Lead dust can also come from within the home, especially older homes that used lead-based paints or lead solder. In Drinking Water Lead can enter the water supply from lead solder in plumbing, lead service connections or lead pipes in your home. Lead levels in tap water increase as water stands in pipes. Drinking fountains may have higher levels of lead than water from nearby taps, because the water usually sits for a longer time. How does lead get in your body? Breathing (inhalation) Eating/drinking (ingestion) Skin contact (dermal contact) Effects of Lead Pollution to Human Health Dioscorides, a Greek physician who lived in the first century A.D., wrote that lead makes the mind "give way". Lead poisoning was among the first known and most widely studied work and environmental hazards Lead was used extensively in Roman aqueducts from about 500 B.C. to 300 A.D. Ancient Roman society was degenerated due to lead poisoning from plumbing, which induces schizophrenia, Short-term lead poisoning affects • • • • • • • Nausea Abdominal pain Insomnia Lethargy Hyperactivity Headache Seizures Long term effects of lead poisoning Small increases in blood pressure Anemia Liver Damage Kidney Damage Gastritis Mental retardation Learning disabilities Decreased growth Cause osteoporosis Severe damage to the brain Reduced IQ level Effect of lead on children Lead poisoning is now recognized internationally, as one of the greatest environmental health risks facing children today. Since their brain and nervous system are still developing they are more easily damaged by lead. Children’s bodies will absorb 50% of lead while adults will only absorb 10% In other animals Sources of lead exposure in pets can be the same as those that present health threats to humans sharing the environment, such as paint and blinds, and there is sometimes lead in toys made for pets. Farm animals such as cows and horses as well as pet animals are also susceptible to the effects of lead toxicity. Animals experience many of the same effects of lead exposure as humans do, such as abdominal pain, peripheral neuropathy, and behavioral changes such as increased aggression How to reduce lead exposure Wash all food before cooking Make sure all paint is in good condition. Wet-clean all surfaces, especially window sills, at least every week. Wash children’s hands frequently. Renovate house to get rid of old lead pipes and paint Plant grass on exposed areas of soil Run hot water 3-5 seconds to clear the lead out of older pipes Dispose of lead-glazed pots correctly Effect of Cadmium on the Environment Cadmium is a naturally occurring minor element, Metallic components in the earth’s crust and oceans First discovered in Germany in 1817 as a by-product of the zinc refining process Sources of cadmium Natural • Erosion • Abrasion of rocks and soils • Forest fires • Volcanic eruptions Man-made • Nickel-Cadmium Batteries • Phosphorous fertilizers containing cadmium • Cadmium pigments • Burning of fossil fuel • Cement industry • Release during combustion • Smelter or power plant Cadmium in the environment Cadmium levels in the environment reached a peak in the 1960's. Since then, these levels have been constantly decreasing due to improved technology for the production, use and disposal of cadmium and cadmium-containing products Cadmium in Air Cadmium in ambient air Cadmium air levels in occupational exposure situations Cadmium in air from the smoking of tobacco Whereas cadmium from occupational environments and cadmium from cigarette smoke are transferred directly to humans. Cadmium in ambient air is generally deposited waters or soils plants and animals human body through the food chain. Cadmium Levels in Soils Earth's crust Igneous and metamorphic rocks Sedimentary rocks Fossil fuels contain Phosphate fertilizers contain 0.1-0.5 ppm 0.02-0.2 ppm 0.1-25 ppm 0.5-1.5 ppm 10-200 ppm In food Leafy vegetables such as lettuce and spinach and certain staples such as potatoes and grain foods ppb Meat and fish normally contain lower ppb Animal offal such as kidney and liver ppb 30-150 5-40 1,000 In water Any cadmium in sewage is there because it has somehow entered the sewerage system via drains in homes, or business premises, or from drains in the streets and roads. How does Cadmium get in your body? Food you eat Water you drink Particles you breathe in. Very little cadmium enters through your skin. If you do not eat foods that contain enough iron or other nutrients, you are likely to take up more cadmium from your food than usual. Effects of Cadmium Pollution to Human Health Flu like symptoms including chills, fever, and muscle ache Tracheo-bronchitis pulmonary edema. Osteomalacia Bones become soft Osteoporosis Lose bone mineral density Anosmia lose their sense of smell The kidneys lose their function to remove acids from the blood in proximal renal tubular dysfunction. Hypophosphatemia Low phosphate levels in the blood (causing muscle weakness and sometimes coma) Hyperchloremia Increased levels of chloride in the blood (The kidneys can also shrink up to 30%.) In other organisms Soils that are acidified enhance the cadmium uptake by plants. This is a potential danger to the animals that are dependent upon the plants for survival. Cadmium can accumulate in their bodies, especially when they eat multiple plants. Cows may have large amounts of cadmium in their kidneys due to this. Earthworms and other essential soil organisms are extremely susceptive to cadmium poisoning. In aquatic ecosystems cadmium can bio accumulate in mussels, oysters, shrimps, lobsters and fish. Animals eating or drinking cadmium sometimes get high blood-pressures, liver disease and nerve or brain damage. How to reduce Cadmium exposure Lucky people who are blessed with abundant minerals. Although cadmium alters the function of zinc, zinc can also neutralize or antidote it. High levels of calcium can also partially protect against cadmium uptake, and accumulation in the liver and kidney. Taking supplemental doses of copper, iron, zinc, and selenium can also lessen its effect. A high protein diet reduces the retention of cadmium. As vitamin C is a natural chelator, it also helps curb its adverse effects. Situation in Pakistan In the formal sector of Pakistan, the leather industry plays an important role in the economy of a country. More than 750 tanneries are unevenly distributed among the four provinces. The effluents from the tanning unit are discharged indiscriminately into natural water bodies or open land, resulting in contamination of the surface and ground waters as well as the soil flora and fauna. Most adverse of all, the tannery effluents are polluting the Kabul River to which they are directly or indirectly discharge thus rendering its water unfit for irrigation. Current actions and strategies and future plans for preventing and controlling releases and limiting use and exposures, including waste management practices Pakistan Environmental Protection agency (PEPA) at federal level and provincial EPAs level are enforcing the following acts and rules the matters relating to collection, transportation, storage, handling, treatment disposal of hazardous waste including lead and cadmium and their compounds: Pakistan Environmental Protection Act, 1997 National Environmental Quality standard (Self-Monitoring and Reporting by Industries) Rules, 2001 Environmental Tribunal rules, 1999 Hazardous Substances Rules, 2003 In future we shall work on: Exact National inventory of Lead and Cadmium uses and release Documentation of realistic statistic about Lead and Cadmium Identification of the areas severely affected by Lead and Cadmium pollution Designing of safe Lead and Cadmium disposal protocol and methodologies Public awareness programmes of lead and cadmium exposure Enforce the local industries to adopt Lead and Cadmium free alternative chemical processes