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Human Health Risk Assessment Process. Michael A. Jayjock, Ph.D CIH Jayjock Associates, LLC www.jayjock-associates.com http://jayjock-associates.blogspot.com/. Risk Assessment: Risk of What?. Being Poor? Being Ugly? Being Unhappy? Having “Bad Hair”? Being Sick? Being Killed ?.
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Human Health Risk Assessment Process Michael A. Jayjock, Ph.D CIH Jayjock Associates, LLC www.jayjock-associates.com http://jayjock-associates.blogspot.com/
Risk Assessment: Risk of What? • Being Poor? • Being Ugly? • Being Unhappy? • Having “Bad Hair”? • Being Sick? • Being Killed?
RISK ASSESSMENT RISK= f (Bad Effects/Exposure)(Exposure)
Today we are going to look at: • Probability Statistics for Some Rare Events or Exposures (Putative vs Actuarial Risk) • Overview of Risk Assessment and Risk Management for Human Health • Basic Concepts of the Paradigm • Technical Models • Scientific Uncertainty as a Process Driver • Our Responsibility and Opportunities in all this as Professionals and Citizens.
Risk of Death Due to Injury, United States, for a person born in 2003 Re: http://www.nsc.org/lrs/statinfo/odds.htm
RISK IS UNAVOIDABLE IN OUR EVERYDAY LIVES Number of Deaths per Million Persons Annual Risk of Death in the US. Hazard All Causes 9,000.0 Motor Vehicle Accidents 210.0 Work Accidents 150.0 Homicides 93.0 Drowning37.0 Poisonings 17.0 Boating 0.6 Tornadoes 0.4 Bites and Stings 0.2 Source: Wilson, R. and Crouch, E., Risk/Benefit Analysis. Cambridge: Baltimore, 1982
RISK COMPARISONS FOR INVOLUNTARY RISKS Risk of Death / Person / Year Risk Influenza 1 in 5000 Leukemia 1 in 12,500 Struck by Automobile 1 in 20,000 Floods 1 in 455,000 Tornadoes (Midwest) 1 in 455,000 Earthquakes (California) 1 in 588,000 Nuclear Power Plant 1 in 10 million Meteorite ????? Source: Dinman, B.D., “The Reality and Acceptance of Risk,” Journal of the American Medical Association, Vol. 244 (11): 1126-1128, 1980.
“The Sky is Falling! The Sky is Falling!”Chicken Little (Early Risk Assessor)
Chicken Little was quite correctThe Sky IS FALLING:METEORS are Indeed Significant AGENTS of RISK forYou and I
There are 140 major craters on the face of the Earth, the vast majority of which are from 1-10 kilometer asteroids traveling at 11-74 km/s. Deadly, no? We expect three of these every million years, but there is, of course, no promise that a major NEO impact won't happen in our lifetime. Furthermore, a minor asteroid could cause large tsunamis about every century. Lastly, a 500 meter could devastate an area the size of Ontario and Quebec. Meteorites and Impacts Advisory Committee to the Canadian Space Agency http://miac.uqac.ca/MIAC/impactearth.htm
DEATH BY METEORWhat is the risk?While rocks raining from space are scary and there is no way to completely eliminate their threat, they are also thankfully sporadic. Your odds of getting killed by a meteorite are roughly 1 in 250,000. You are far more likely to die in an earthquake, tornado, flood, airplane crash, or car crash (but less likely to be killed by lightning). Most asteroids burn up in the atmosphere long before they hit the ground and the few that do will probably hit open ocean or a remote part of the Earth rather than your head.Ref: http://www.wired.com/2013/02/asteroid-odds/
Tunguska (Siberia) Meteor Explosion June 30, 1908 at 7:17am • 60 meter (200ft) diameter Asteroid 30 degrees to the Horizon • 3-5 Megaton TNT Equivalent (~150 Hiroshima bombs -no radiation) • Detonated ~5 Miles Up • Hundreds of Square Miles of Devastation. • Herds of Incinerated Reindeer • Unknown number of persons killed
Chelyabinsk Meteor Explosion February 15, 2013 • Delivered the biggest astronomical “punch” felt on Earth in a century, • 0.5 Megaton TNT Equivalent • 15-20 meters wide; detonated 17 miles high • Injured 1500 people. • Came from direction of sun • Example of a “city buster”.
A Less Dramatic and More Detailed and Realistic Discussion On-Line • It’s 1000 ft in Diameter (5x Tunguska) • Will just miss Earth in 2029 • But could be perturbed enough to hit earth on it’s return pass on Friday, April 13, 2036. First estimate 2.7% - the latest estimate is a risk of less than 1 in 1,000,000. http://www.space.com/19221-asteroid-apophis-earth-safe-2036.html
It is almost impossible to Effectively Manage Any Risk which has not been Reasonably Assessed. Rule #1:
DEATH BY METEOR What can we do about it?“…of all the ways we can die from astronomical events, asteroid impacts are both the highest probability event and the only ones we can prevent. We can’t stop the Sun from blasting out flares which take down our power grids, or a nearby star from exploding. But we do in fact have the technology (or will in literally ten years) to detect incoming asteroids and then move them out of the way.” (emphasis added)Discover Magazine Blog: http://blogs.discovermagazine.com/badastronomy/2008/10/13/death-by-meteorite/#.VIYSpTHF98E
CONCEPTOF DE MINIMIS RISK • De minimis risks are those risks judged to be too small to be of social concern, or too small to justify the use of risk management resources for control. • The De minimis risk level frequently used by government agencies (EPA, FDA) is 1 in 1,000,000 or “1 in a million” increased risk of an adverse effect occurring over a 70 year lifetime in a large population.
“There is no point in getting into a panic about the risks of life until you have compared the risks which worry you with those that don’t, but perhaps should.” (Lord Rothschild, The Wall Street Journal, 1979). The 1 in a million risk level used to regulate some chemicals and other hazards is many times below risks which people face every day.
RISKS THAT INCREASE PROBABILITYOF DEATH BY ONE IN A MILLION Cause of Death Activity Smoking 1.4 Cigarettes Cancer, Heart Disease Traveling 10 miles by Bicycle Accident Traveling 300 miles by Car Accident Flying 1000 miles by JetAccident One Chest X-Ray Cancer from Radiation Source: Wilson, R., “Analyzing the Risks of Daily Life,” Technology Review, 81, (1979).
Actuarial Risk of the Space Shuttle • 1981 – predicted to be 1 in 78 • 1986 – Challenger lost on the 25th flight 1 in 25 • 1986+ NASA set goal 1 in 1000 • Later 40% budget cuts caused the predicted/goal risk to slip to 1 in 250 • 2003 – Columbia lost on 113th flight: 1 in 56.5 Ref: Discovery, v25, n1, p.30
Our Lifetime Risk of Dying in an Automobile Accident is 1 in 88 !!!
Small Risks of Being Killed SHARK!! 1 in 3,943,110 Fireworks 1 in 386,766 Flood: 1 in 175,803 Earthquake: 1 in 148,756 Dog Attack: 1 in 120,864 Legal Execution: 1 in 96,691 Insect Sting: 1 in 71,632 Storm: 1 in 46,044 Heat Exposure: 1 in 12,517 Air Transport: 1 in 7,032 Firearm 1 in 6,309 National Safety Council, Injury Factors 2011
Principal Elements of Risk Assessment • Anticipation • Recognition • Evaluation Effect/Dose = Dose-Response Dose = Exposure Control is NOT an element
Anticipation, Recognition and Evaluation are Risk AssessmentControl is Risk Management
Rule #1 (again): It is highly problematic to rationally MANAGE any risk which has not been reasonably assessed. or “Doing Risk Management without Risk Assessment (i.e., DATA) is Tough”
Risk is an EQUAL Functionof Toxicity and Exposure • Risk = Toxicity X Dose • Exposure Dose • Risk Toxicity X Dose Paracelsus Understood Risk Assessment
Operationally: Dose = Exposure Toxicity and Exposure are Equal Partners in Risk Assessment
Rule #2: The Precautionary Principle • Axiom of Conservatism • Err on the Side of Safety • Trade Conservatism for DATA
Putative versus Actuarial Risk • The Estimated Quantitative Risk at the Low Dose of an OEL are essentially PUTATIVE (i.e., ascribed based on testable but untested assumptions). • High Consequence - Low Probability (e.g., lotteries, accidents) events occur with historically validated consistency - ACTUARIAL.
Dose Typical rodent data Response
Dose How do you get there from here? Response ?
Dose How do you get there from here? Response
Dose How do you get there from here? Response
Dose How do you get there from here? Response
Dose How do you get there from here? Response
The only time a quantitative level of risk is estimated at an exposure limit is in the case of cancer risk. (10-5 or 10-6 for non-workers, ca. 10-3 for workers).It is assumed that there is an acceptably “low” but essentially indeterminate level of adverse risk for other health effects at the exposure limits.
Cancer Risk x -0 10 X x X LINEARIZED DOSE-RESPONSE MODEL -1 10 x X -2 10 x = DATA -3 10 Predicted Incidence of Liver Tumors -4 10 -5 10 -6 10 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 Dose in mg/kg