Flashcards in Q 2 Risk Assessment Deck (18)
Objectives of Risk Assessment? 4
Evaluate the risks
-Environmental contaminant, drugs, pesticides, industrial chemical
Evaluate uncertainty of data
Set target levels of exposure
-Food, air, water, work place
Provide information to agencies
.Regulatory agencies, Manufacturers, Environmental/Consumer Agencies
NOAEL stands for
No Observable Adverse Effect Level
HQ < 1 suggests ______ level of risk
HQ > 1 suggests _______ level of risk
(HQ) evaluate the observed exposure to some form of reference dose that is assumed to be just below the threshold for effects, the NOAEL, usually called a Reference Dose (RfD)
HQ= Actual exposure/ RfD
HQ<1 suggests acceptable level of risk
HQ>1 suggests unacceptable
Measurements error in experiments
Errors in chemical measurement
Extrapolation of animal studies to humans
Sample sizes for animal & human studies
Selection of endpoint
Intra and inter subject variability
Human subject variability
Lifestyle – risk of exposure to ….
Occupation – risk of exposure to ….
Breathing & digestion – uptake of chemicals
Metabolism & kidney function – elimination
Age, gender & disease – susceptibility to toxicity
Use of uncertainty factors(UF)
Divide Dose by Power of 10
Exposure of Children
Subchronic to chronic extrapolation
Absence of a NOAEL
Etc, etc …..
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)
There is no scientific reasoning behind the selection of a factor of 10
It is simply easy and understandable
Evaluation of UFs on a case by case basis would be extremely time consuming
The excessive use of UFs can result in high degree of ‘overprotection’
Overprotection can be costly and counter productive – scare the hell out of people !
Worst case scenario
Assume all variables are at their most ‘conservative’
-Most sensitive species
-Most contaminated food
If risk is negligible in this scenario then all other scenarios must be of lower risk
Risk is said to be ‘de minimis’
De Minimis refers to a level of risk that is too small to be concerned with. Some refer it as a "virtually safe" level
Caution: Worse case scenarios are a double edged sword, they can be very misleading if risk is not de minimis
Worst-Case exposure scenario:
Smallest mink eats the largest amount of the most contaminated fish every day for life.
Rocky Mountain Arsenal(RMA) History
The Rocky Mountain Arsenal (RMA) is located in Commerce City, Colorado, approximately 10 miles northeast of downtown Denver.
In 1942, during World War II, the U.S. Army purchased 17,000 acres for chemical weapons manufacture: mustard gas, white phosphorus, napalm.
To foster economic growth, offset operational costs and maintain facilities for national security, RMA facilities were leased to industry for pesticide production after the war.
Chemicals or weapons are no longer produced or stored at RMA. The site’s only mission is the safe, timely and cost-effective cleanup and transition to one of the largest, urban national wildlife refuges.
Rocky Mountain Arsenal National Wildlife Refuge
US-FWS involvement at RMA began in 1986 when a winter communal roost of bald eagles, then an endangered species, was found on site
US-FWS soon realized that more than 330 wildlife species inhabit RMA including deer, coyotes, white pelicans and owls.
1992: Congress passed the Rocky Mountain Arsenal National Wildlife Refuge Act, making RMA part of the national wildlife refuge system after cleanup
RMA Dioxin Issue
RMA was already being remediated due to organochlorine pesticide contamination – several billion dollars
During the clean-up the analysis of some samples indicated the presence of dioxins – not previously discovered or investigated on site
Should Dioxins be a CoC ? Should RD/RA be stopped until extent is known ?
Reason Prevailed and RA continued while dioxin issues were addressed with a risk assessment
The Dioxin Assessment provides a mini example of how the larger process was undertaken.
BAS stands for?
Biological Advisory Subcommittee
TRV'S stands for
Toxicity Reference Values
"We should remember that risk assessment data can be like the captured spy: If you torture it long enough, it will tell you anything you want to know.“
First administrator of US EPA