2 Objectives Discuss the different types of heavy metals. Explain how selected metals enter the body.Describe the health implications of certain heavy metals.
3 Toxic MetalsInclude:Heavy metals (e.g., lead, mercury, nickel)Other metallic compounds (e.g., aluminum, iron, tin)Featured in the CERCLA Priority List of Hazardous SubstancesComprehensive Environmental Response, Compensation, and Liability Act (CERLA)
4 CERCLA Priority List of Hazardous Substances The Agency for Toxic Substances and Disease Registry (ATSDR - CDC) has identified the top 20 hazardous substances.This list is revised every two years.
5 Hazardous SubstancesPose the most significant potential threat to human health because they:Have known or suspected toxicity andHave potential for human exposureA substance can be on the NPL (National Priority List) if:there is a high frequency of occurrenceand potential for human exposure even if it is not among the most toxic substances.
6 National Priorities List (NPL) “EPA’s list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund.”Sites are scored based on the Hazard Ranking System and updated annually.
7 Definition: Heavy Metals A heavy metal has a high atomic weight with a specific gravity that exceeds the specific gravity of water by five or more times at 4° C.
8 Classification of Metals Major toxic metals with multiple effectsEssential metals with potential for toxicityMetals related to medical therapyMinor toxic metals
9 BioaccumulationToxic substances such as heavy metals become more concentrated and potentially more harmful as they move up the food chain.- example (tuna fish and mercury)
10 Modes of ExposureLungs (through inhalation of dusts, metal fumes, and vapors)Skin (through contact with dusts)Mouth (by ingestion)
11 High and Low Level Contacts Contact with high concentrations of toxic metals in an occupational settingFor example, persons who work with metalsLower-level exposures may result from contact with the ambient environment.Children may ingest lead present in paint.
12 Acute Toxic Metal Poisoning The symptoms of acute poisoning from exposure to metals generally have rapid onset—from a few minutes to approximately one hour.
13 Symptoms of Acute Poisoning Depends upon entry route into the bodySymptoms may consist of:gastrointestinal effects (vomiting and stomach pain) andneurological effects (headaches, suppression of normal breathing, and convulsions).
16 Gender Differences and Exposure The health effects of exposure to heavy metals (nickel, cadmium, lead, and mercury) are different for women than men.These differences have been attributed to:hormonal and metabolic processes related to menstruation, pregnancy, and menopause.smaller size of women.
17 Children’s Exposure to Heavy Metals For fetuses, infants, and children (especially young children), heavy metals are known to present serious hazards such as:impairment of physical and mental developmentdamage to internal organs and the nervous systemsome forms of cancermortality
18 Children and Exposure Nervous system damage Memory impairment Difficulty in learningRange of behavioral problems, such as hyperactivity syndrome and overt aggressiveness
19 Heavy Metal Exposure - Children Children consume more food in proportion to their body weight and thus receive higher doses of heavy metals.They absorb 30 times more than adults and their immune systems are less developed to handle heavy metals.
20 Fetal Exposure Effects Lead and mercury have the capacity to cross the placental barrier, causing potential fetal brain damage.
21 Major Toxic Metals - Multiple Effects ArsenicBerylliumCadmiumChromiumMercuryLeadNickel
22 Arsenic Varies in toxicity depending upon its chemical form By product of refining gold and other metalsUsed in pesticides, wood preservatives, and in manufacturing processesExposure from ingestion and inhalation.
23 Standards for ArsenicIn 2001, the EPA announced the standard of 10 µg of arsenic per liter of drinking water with the year 2006 set as the compliance date for this standard.This standard has been lowered from µg of arsenic per liter of water.
24 Arsenic - Health Effects Skin, bladder, kidney, and liver cancer when ingestedLung cancer when inhaledPeripheral vascular diseaseCerebrovascular diseaseCardiovascular diseaseDiabetes (long-term exposure)Adverse pregnancy outcomes--spontaneous abortions, stillbirths, and preterm births
25 BerylliumUsed widely in industry because of its special properties (lighter than aluminum and stronger than steel)Employees in the metal processing industry most likely to be exposedInhalation is most common method of exposureClass A carcinogen
26 Occupational Cadmium Exposures Occupational exposure to cadmium comes from:production of nickel cadmium batteries,zinc smelting,manufacture of paint pigments,soldering,employment in metal factories.
27 Cadmium and All Individuals Primary sources of cadmium exposure:cigarette smokedietary cadmiumCadmium bioaccumulates in shellfish and is found in some species of mushrooms.
28 Effects of Cadmium Exposure Osteoporosis in womenHeight loss in menKidney damageElevated blood pressureCardiovascular diseases“Itai-Itai” disease (Jinzu River, Japan)
29 ChromiumNaturally occurring element in the earth’s crust (rocks, soils, and volcanic materials)Most common forms are:chromium(0)chromium(III): an essential nutrientchromium(VI): classified as a carcinogen by EPA and WHO
30 Erin BrockovichAdvocated for residents of Hinkley, California, against an electric power company accused of contaminating the town’s water with chromium VI.
31 Hexavalent Chromium(VI) Effects Digestive problemsDamage to organs such as the kidney and liver when ingested.Skin ulcers when applied to the skin.Respiratory problems, nose bleeds, perforation of the nasal septum, and runny nose, when inhaled
32 Mercury Naturally occurring metal that is highly toxic Released into the environment as a by-product of industrial processes
33 Exposure to MercuryEven at low levels, mercury represents a hazard to human health.It becomes deposited in lakes, rivers, and other bodies of water.Microorganisms ingest small amounts of mercury.Bioaccumulation causes the mercury to become more concentrated in aquatic invertebrates (i.e. tuna fish)
34 Legacy of Mercury Contamination Minamata diseaseJapan in 1956From a plastics factory into Minamata BayResulted in disease with end result being deathWater contamination around the New Almaden mine in California until 1976Contamination of San Francisco Bay due to mercury mining
35 Lead Sources of environmental lead: leaded gasoline tap water from soldered pipespainted surfaces in older buildingsimported pottery used in food service
36 Lead ExposureSerious central nervous system (CNS) effects and adverse health effects even when ingested at low levels.Lead poisoning is one of the most common environmental pediatric health problems in the United States (>10mg/dL).
37 Nickel One of the constituents of the earth’s crust. Human exposure to low levels of nickel is universal and unavoidable.Employed in the production of many of the appliances and tools used in everyday life (nickel cadmium batteries).
38 Effects of Nickel Exposure One of the most common reactions to skin contact is nickel allergy,contact dermatitis.Cardiovascular-related and renal diseases as well as fibrosis of the lungsPotential carcinogenic action
39 Essential Metals - Toxicity Copper, zinc, and iron are essential for human nutrition and to maintain health.These can be toxic if ingested in excessive amounts.
40 Copper and the Environment Appears in electrical wires, pipes, in combination with other metals to form alloys, as a mildew inhibitor, and as a wood and leather preservative.In 2000 alone, approximately 1.4 billion pounds were released into the environment during industrial processing.
41 Exposure to CopperOccurs by inhalation, ingestion of copper-containing foods and water, and direct contact with the skin.Small amounts may dissolve into tap water from copper piping.Copper levels become more concentrated when the water remains in the pipes overnight.Run your tap for 10 seconds before using it.
42 Effects of Copper Exposure Concentrated amounts (far above trace levels) can produce respiratory and gastrointestinal disturbances.Respiratory effects from dust include irritation of the respiratory tract (nose and mouth).Very high levels are known to cause liver damage, renal damage, and death.
43 Zinc Frequently occurring element found in the earth’s crust Permeates air, soil, water and, to some degree, all foods.Used as a coating for rust inhibition, as a component of batteries, and in combination with other metalsA nutritional element that is important for maintaining health
44 Effects of Excessive Zinc Consumption of large quantities is associated with gastrointestinal problems (stomach cramps, nausea, and vomiting).Can cause anemia and damage to the pancreas.Breathing high concentrations of zinc causes metal fume fever, an immune-mediated response that starts in the lungs.
45 Iron One of the most ubiquitous metals in the earth’s crust Vital to human health:important to the growth of cellsthe transport of oxygen within the circulatory system
46 Iron Toxicilty Acute iron intoxication (accidental iron poisoning): Is the most common childhood poisonings.Occurs among men and postmenopausal women.Effects:Vomiting, diarrhea and intestinal damageLow BP and fatigueSeizuresLiver damage
47 Metals Used in Medicine AluminumBismuthGalliumGoldLithiumPlatinum
48 AluminumUsed in food and beverage containers, pots and pans, and construction sites.Found in medicines and cosmetics (buffered aspirin and antiperspirants)Powerful neurotoxicant; possibly associated with Alzheimer’s diseaseAssociated with asthma, rashes and skeletal problems