Q 2 Risk Assessment Flashcards Preview

Y2 T1 Toxicology 200 > Q 2 Risk Assessment > Flashcards

Flashcards in Q 2 Risk Assessment Deck (18)
Loading flashcards...

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


Risk= ____X_____

hazard, risk


NOAEL stands for

No Observable Adverse Effect Level


Hazard Quotients?

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


Uncertainty= 7

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

Contaminant mixtures


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
Human variability
Interspecies extrapolation
Exposure of Children
Subchronic to chronic extrapolation
Absence of a NOAEL
Database uncertainty
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


Kalamazoo River

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.“
Quote by?

William Ruckelshaus,

First administrator of US EPA


Consequences of Wind Turbines

The U.S. Fish and Wildlife Service estimates that wind turbines kill 440,000 birds including bald and golden eagles, hawks, falcons, owls, cranes, egrets, geese, and other birds every year in the U.S., along with countless insect-eating bats

Under both the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act, the death of a single bird without a permit is illegal.