Small Dose of Mercury A Small Dose of Toxicology A Small Dose of Hg An Introduction To The Health Effects & Risk of Mercury Exposure ENV H 472 A - ENVIRONMENTAL RISK AND SOCIETY Class 4

A Small Dose of ToxicologySmall Dose of Mercury Child Health

A Small Dose of ToxicologySmall Dose of Mercury Key Words of Toxicology Hazard + Exposure = Risk Individual Susceptibility Dose / Response

A Small Dose of ToxicologySmall Dose of Mercury Mercury the Metal

A Small Dose of ToxicologySmall Dose of Mercury Methyl Mercury (MeHg) Hg CH 3

A Small Dose of ToxicologySmall Dose of Mercury Hg - Inorganic & Organic Hg CH 3 Inorganic – Quick Silver Hg Organic – Methyl Mercury

A Small Dose of ToxicologySmall Dose of Mercury Hg Facts & Uses Quicksilver 13.6 times the weight of water Evaporates at room temperature Bacteria change to Methylmercury Amalgam Many Industrial uses (thermometers, chemical reactions, gold mining)

A Small Dose of ToxicologySmall Dose of Mercury Hg – Like Water

A Small Dose of ToxicologySmall Dose of Mercury Hg – Solid Enough to Sit On

A Small Dose of ToxicologySmall Dose of Mercury Alchemy Medicine - cure syphilis? Egyptian tomb BC Ancient Awareness

A Small Dose of ToxicologySmall Dose of Mercury Greek God Mercury “For then she bare a son, of many shifts, blandly cunning, a robber, a cattle driver, a bringer of dreams, a watcher by night, a thief at the gates, one who was soon to show forth wonderful deeds among the deathless gods...” Description of the birth of the Greek God Mercury

A Small Dose of ToxicologySmall Dose of Mercury Occupational Exposure Gold mining. Hatters in the felt industry. Historical Events

A Small Dose of ToxicologySmall Dose of Mercury Historical Awareness

A Small Dose of ToxicologySmall Dose of Mercury Polluting with HG Discharge in Minamata Bay

A Small Dose of ToxicologySmall Dose of Mercury Fetal Effects of MeHg

A Small Dose of ToxicologySmall Dose of Mercury Life-Long Effects of MeHg

A Small Dose of ToxicologySmall Dose of Mercury Planting Seed with Mercury

A Small Dose of ToxicologySmall Dose of Mercury Iraq Mothers with Bread

A Small Dose of ToxicologySmall Dose of Mercury Iraq Infant - Effects of Mercury

A Small Dose of ToxicologySmall Dose of Mercury Coal Fired Plants – Hg Emissions

A Small Dose of ToxicologySmall Dose of Mercury Outbreaks of MeHg Poisoning PlaceYearCases Minamata Nigata Guatemala Ghana Pakistan Iraq Iraq19601,002 Iraq197140,000 On-going2001???

A Small Dose of ToxicologySmall Dose of Mercury Inorganic - elemental mercury vapor Hg 0 Biotransformation Organic - Methylmercury - CH 3 Hg + Bioaccumulatio n Mercury to Methyl Mercury

A Small Dose of ToxicologySmall Dose of Mercury Mercury Release 50-75% mercury of released in the environment related to human activities

A Small Dose of ToxicologySmall Dose of Mercury Atmospheric Hg

A Small Dose of ToxicologySmall Dose of Mercury Ambient Water Sediments Edible Fish Inorganic Mercury Methyl- Mercury In Humans Biomethylation Bioaccumulation Exposure Discharge Biotransformation of Mercury

A Small Dose of ToxicologySmall Dose of Mercury Natural Degassing of the earth Combustion of fossil fuel Industrial Discharges and Wastes Incineration & Crematories Dental amalgams Hg 0 Hg 2+ CH 3 Hg + Environmental Sources of Mercury

A Small Dose of ToxicologySmall Dose of Mercury The Mercury Cycle

A Small Dose of ToxicologySmall Dose of Mercury Blindness - Deafness Cerebral Palsy - Seizures Abnormal reflexes & muscle tone Retarded motor development Visual and Auditory Deficits Delayed motor development Altered DRH performance Neurobehavioral Effects

A Small Dose of ToxicologySmall Dose of Mercury Decrease in Brain Size Cell loss Disorganization of cells Cell migration failures Effects On The Brain

A Small Dose of ToxicologySmall Dose of Mercury How do you know? How good is the data? Uncertainty

A Small Dose of ToxicologySmall Dose of Mercury Use of Uncertainty Factors Divide Dose by Power of 10 Human variability Interspecies extrapolation Children Subchronic to chronic extrapolation Absence of a NOAEL Database uncertainty

A Small Dose of ToxicologySmall Dose of Mercury Use of Uncertainty Factors Animal Dose Response Data NOAEL (No Observed Adverse Effect Level) Divide by 10 (Account for inadequate animal data) Divide by 10 (Animal to Human Extrapolation) Divide by 10 (Human Variability or Individual Sensitivity) Reference Dose (RfD) Or Acceptable Daily Intake (ADI)

A Small Dose of ToxicologySmall Dose of Mercury Reducing Uncertainty Upstanding mechanism of action Physiologically based pharmacokinetic models (distribution and metabolism) Sample size

A Small Dose of ToxicologySmall Dose of Mercury  MONKEY - 25 µg/kg - LOAEL  RAT - 10 µg/kg - LOAEL  RAT - 50 µg/kg - replicated Animal - Risk Assessment

A Small Dose of ToxicologySmall Dose of Mercury  2.5 µg/kg - NOAEL (animals)  0.25 µg/kg - Human  µg/kg - Sensitive populations Animal - Risk Assessment (the rule of dividing by 10)

A Small Dose of ToxicologySmall Dose of Mercury ppm hair - LOAEL ppb blood - LOAEL µg/kg 0.06 µg/kg - RfD Human - Risk Assessment

A Small Dose of ToxicologySmall Dose of Mercury Mercury Fishing Advisories  In 2000, 41 States have over 2000 fish consumption advisories  An increase form 27 in 1993  Pregnant women, nursing mothers, women who intend to have children, and children under 15

A Small Dose of ToxicologySmall Dose of Mercury Reduce environmental release Restrict global production and sale Advise women of child bearing age Research mechanisms of action Assess neurodegenerative effects Recommendations

A Small Dose of ToxicologySmall Dose of Mercury MeHg Consumption Limits US EPA – 0.1 ug/kg-day US FDA – 1 ppm (mg/kg) in tuna

A Small Dose of ToxicologySmall Dose of Mercury Limit the amount of canned tuna you eat, based on your bodyweight. Guidelines are: Women of childbearing age should limit the amount of canned tuna they eat to about one can per week (six ounces.) A woman who weighs less than 135 pounds should eat less than one can of tuna per week. Children under six should eat less than one half a can of tuna (three ounces) per week. Specific weekly limits for children under six range from one ounce for a twenty pound child, to three ounces for a child weighing about sixty pounds. WA State Advisory

A Small Dose of ToxicologySmall Dose of Mercury WA State Mercury Chemical Action Plan Reduce Hg in fish Reduce Hg release into the environment 4-5 tons of Hg released in WA Educating consumers about Hg in home WA State Hg CAP

A Small Dose of ToxicologySmall Dose of Mercury U.S. EPA Produced “First-Ever Rule to Reduce Mercury Emissions from Power Plants” Last 15 years no drop in Hg emissions from power plants Is Cap and Trade appropriate for a demonstrated neurotoxic compound? Hg CAP and Trade

A Small Dose of ToxicologySmall Dose of Mercury Mercury A Global Issue Mercury distribution and exposure is a global problem

A Small Dose of ToxicologySmall Dose of Mercury Precautionary Principle "When an activity raises threats of harm to the environment or human health, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically." - Wingspread Statement on the Precautionary Principle, Jan. 1998

A Small Dose of ToxicologySmall Dose of Mercury Alice’s Adventures “Everything’s got a moral, if you can only find it” Lewis Carroll in Alice’s Adventures in Wonderland

A Small Dose of ToxicologySmall Dose of Mercury Children have a right to a safe, fair and healthy environment Ethical Responsibility to share and use of knowledge Duty to promote health and well being of children Thoughtful public health advocate Knowledge - Responsibility

Small Dose of Mercury A Small Dose of Toxicology Mercury or Lead Questions or Comments?

Small Dose of Mercury A Small Dose of Toxicology Additional Information - Hg  Web Sites  World Health Organization - global prospective on mercury health effects. GDWQ/Chemicals/mercuryfull.htm  US EPA - Main site on Mercury.  The Mercury Policy Project (MPP). - works to raise awareness about the threat of mercury contamination - 

A Small Dose of ToxicologySmall Dose of Mercury Authorship Information For Additional Information Contact Steven G. Gilbert, PhD, DABT Web: This presentation is supplement to “A Small Dose of Toxicology”