Page 7/31 Date 04.05.2017 Size 238.52 Kb.
Lead Affects brain development ; associated with lower IQ, ADHD, hearing loss, depression, panic disorder, early menopause No safe level for neurological development Lead Levels between 4 and 10 significantly increase risk of cardio- and cerebrovascular disease Elevated levels associated with depression, anxiety, schizophrenia, Alzheimer’s disease, crime, and violent behavior , obesity in children MRI changes in gray matter areas responsible for attention, regulation of emotions, and impulse control; disruption of white matter Lead Childhood exposure linked to violent crime, impulsiveness/aggressiveness, and teen pregnancy in later life Exposure leads to permanent loss of gray matter in prefrontal cortex Rates of consumption of leaded gasoline correlate with violent crime 20 yrs later Lead 535,000 US children age 1-5 (1/38) have levels exceeding 5 mcg/dL Poor, African-Americans , and Hispanics more commonly exposed Levels declining in US, however Lead paint still widespread in older buildings (built before 1978) 35% of homes with some lead paint; 22% with significant lead paint Lead 83,000 tons of lead shot into environment annually in U.S. (bullets) Gun shop/range owners/patrons heavily exposed, as are those who consume shot wild game California bans (2013); Obama’s Interior Department bans on federal lands (2017); Trump administration overturns ban (2017) U.S. military increasing use of “green bullets” (containing copper/copper alloys) Lead Developing world at risk Due to increased environmental exposure and, possibly , early umbilical cord clamping 12 million people worldwide lead poisoned Economic loss to developing nations estimated at close to $1 trillion (over 1% of worldwide GDP) Lead Leaded gasoline banned in Canada in 1990, US in 1996 (after 25-year phase-out period), EU in 2002, Africa in 2006 Still used in piston-engine aircraft (the chief source of U.S. lead emissions) Ban fought by industry for decades Lead paint banned in U.S. in 1978 after decades of industry push-back Still widely used in developing world Lead banned from plumbing in U.S> in 1986 Leaded Gasoline 6 countries still sell small amounts of leaded gasoline: North Korea, Iraq, Afghanistan, Algeria, Myanmar/Burma, and Yemen (all to phase out by 2013 Until recently, used in tire vulcanization Still used in airplanes (mostly U.S.) Lead Cleanup Lead costs US economy $50 billion/yr Cleanup cost: $20 billion/yr for 20 yrs Benefits: $200 billion dollars annually (cognitive and health benefits and decreased crime) 10:1 return on investment (some estimates as high as 200:1) Mercury Syphilis Treatment - 15th Century onward - abandoned 1940 for penicillin Recognized as cause of disease in 19th Century (Hunter-Russell Syndrome) - chemists, hatters Mercury Added by US government to industrial during Prohibition to make it more lethal and discourage moonshine production (1926-1933) Led to more than 10,000 deaths Mercury: S/S, Dx, and Rx S/S: neuropsychiatric symptoms, excessive salivation/inflammation of gums, rash, nephropathy Dx: mercury levels in air, blood, urine (>100 mcg/l in blood and/or urine = toxic) Rx: chelation with BAL, penicillamine, DMPS, DMSA Acute / Chronic Poisoning: numbness, slurred speech, ataxia, unsteady gait, deafness, poor vision, dysphagia, hypersalivation, confusion, drowsiness/stupor to irritability/restlessness; chronic liver disease, liver cancer, hypertension , autoimmune disorders death within a few months if severe Rx EDTA – only partially effective Minamata Disease: Signs and Symptoms Congenital: high dose → infertility; medium dose → spontaneous abortions; low dose → congenital disease (including anencephaly and spina bifida) S/S: poor physical growth, developmental delay, ADHD, impaired speech/chewing/swallowing, muscle tone abnormalities, involuntary movements , constricted visual fields, hearing loss - EDTA not effective Mercury Released into air by coal combustion, industrial processes, mining, waste disposal, and volcanoes; concentrated (along with lead, arsenic, and other heavy metals) in coal ash Mercury Travels throughout atmosphere and settles in oceans and waterways Bacteria convert it to toxic methyl-mercury Travels up food chain via fish Avoid top predators (tuna, shark, swordfish) 1/3 of US exposure to methylmercury from canned tuna Gold Mining Gold = Cyanide + Mercury Mercury used to capture gold particles as an amalgam Gold leached from ore using cyanide Cyanide paralyzes cellular respiration At least 18 tons of mine waste created to obtain the gold for a single 3 oz., 18k ring Gold Mining and Mercury Contaminated groundwater often sits in large toxic lakes held in place by tenuous dams Release of cyanide and mercury into local waterways kills fish, harms fish-eating animals , and poisons drinking water Share with your friends:
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