Transcript Science Update

Residential Radon Exposure – A Leading Environmental
Health Risk:
Why we need to take action in (insert your region)?
R. William Field, Ph.D., M.S.
Associate Professor
Department of Occupational
and Environmental Health
Department of Epidemiology
College of Public Health
104 IREH
University of Iowa
Iowa City, IA 52242
[email protected]
Why is the evidence ignored
or not accepted ??
 Invisible, odorless, colorless
 Naturally occurring (no villains)
 Can not link deaths to radon exposure
 Long latency period
 Not a dread hazard
 Cancers occur one at a time
 Voluntary risk
 Lack of press – no sensational story
 No sensory reminders to repetitively stimulate

us to think about it
Lung cancer does not occur in children
Radon
Mines
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #1
There is widespread potential
for radon exposure in homes
coast to coast as well as
workplaces!
U.S. Radon Potential
Many parts of
the country
have elevated
radon
concentrations.
Map developed
as basis for
radon control
techniques in
new
construction.
Insert slide here describing radon
occurrence in year area of interest
Radon maps can be found here:
http://www.epa.gov/radon/zonemap.html
What Is Radon –222
(radon)? • Radon is a gas
• It is naturally
occurring
Radon
CERTI©
3.8 days
Radium
1,600 years
Uranium
4.5 billion years
• You can not see or
smell it
• It enters buildings
from the soil beneath
them
Average Contributions From
Radon Sources In U.S. Homes

Water
< 1%
Emanation
2 - 5%
Soil Gas
85 - 90%
Diffusion
1 - 4%
Radium Containing Soil

The movement of
soil gas into a home
is the predominant
entry route.
These are averages a particular home
can be different!
Radon Gas Spatial Distribution
<5
• Radon enters from beneath
foundation and travels
upward.
5-6
– Diluted with outdoor air
infiltrating building
10
CERTI©
• If radon is less than 4 pCi/L
in lower level, one can say
with reasonable confidence
that upper floors are also
less than 4 pCi/L.
Occupational Exposure to Radon –
Very Common
• Mine workers, including uranium, hard rock, and
vanadium
• Workers remediating radioactive contaminated sites,
including uranium mill sites and mill tailings
• Workers at underground nuclear waste repositories
• Radon mitigation contractors and testers
• Employees of natural caves
• Phosphate fertilizer plant workers
• Oil refinery workers
• Utility tunnel workers
• Subway tunnel workers
• Construction excavators
• Power plant workers, including geothermal power
and coal
• Employees of radon health mines
• Employees of radon balneotherapy spas
(waterborne 222Rn source)
• Water plant operators (waterborne 222Rn source)
• Fish hatchery attendants (waterborne 222Rn
source)
• Employees who come in contact with
technologically enhanced sources of naturally
occurring radioactive materials
• Incidental exposure in almost any occupation from
local geologic 222Rn sources
• Plowing?
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #2
Outdoor radon exposure can
be significant!
Outdoor 222Rn Concentrations
18
16
14
222
Rn (pCi/L)
12
10
8
6
4
2
0
13
14
15
16
17
JUNE
18
19
20
Outdoor Radon in Iowa
1.5pCi /L
1.3pCi /L
1.1pCi /L
0.9pCi /L
0.7pCi /L
0.5pCi /L
0.3pCi /L
National INDOOR Average 1.4 pCi/L
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #3
Alpha particles are very
effective at causing DNA
damage!
Why Is Radon A Concern?
Radon Decay Products
Radon
Radon
CERTI©
• Radon decays into
radioactive particles
known as radon decay
products.
• These particles are
easily inhaled and
deposited in the lungs
where they can damage
sensitive lung tissue.
What Happens When Radon-222
Enters a House?
RDPs
RDPs
Radon
Radon
CERTI©
• Radon enters home.
• Radon radioactively
decays into RDPs in
the air.
• Some RDPs remain
in the air.
• Some RDPs plate out
on surfaces.
Radon-222
4 day
a,g
Polonium-218
3 min
a,g
Lead-214
27 min
b,g
Bismuth-214
20 min
b,g
Polonium-214
0.2 ms
a,g
Lead-210
218Po
and 214Po
deliver the
radiologically
significant dose to
the respiratory
epithelium.
22 yrs
b,g
Bismuth-210
b,g
5 day
Polonium-210 138 day
a,g
Lead-206
Stable
Radon
Progeny
Alpha a
Decay
4He
+
+
Nucleus Ejected from
222Rn Nucleus
+
+
+
+
+2
+
+
+
Radon - 222
4He
+ 218Po
What Happens When Radon
Decay Products Are Inhaled?


Double Strand Breaks
CERTI©
Highly radioactive
particles adhere to
lung tissue, where
they can irradiate
sensitive cells.
Radiation can alter
the cells, increasing
the potential for
cancer.
Ionizing radiation can directly and
indirectly damage DNA
Alpha
Particle
Defects in tumor
suppressor genes – p53
At risk individuals–GSTM1
(glutathione S-transferase M1)
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #4
For the average individual in the United
States – Radon decay products (radon)
deliver over 50% of our average radiation
dose! For the average, Iowan it
represents well over 75%!!
Annual Effective Dose Equivalent to
Member of the U.S. Population
NCRP 93 (1987)
Consumer
Products
Artificial 18% Nuclear 3% Other
< 1%
Medicine
4%
Medical X-rays
11%
Cosmic
(Outer Space)
8%
Terrrestrial
(Rocks & Soil)
8%
Internal
(Inside Human
Body)
11%
Other Includes:
Occupational 0.3%
Fallout
< 0.3%
Nuclear Pow er 0.1%
Miscellaneous 0.1%
Natural
(mrem)
Radon
Cosmic
200
27
Terrestrial:
-external
-internal
Radon
55%
Natural 82%
28
39
Artificial (mrem)
-Diag. X-rays
39
-Nuc. Med.
14
-Consumer Pro. 10
-Other
~1
TOTAL
~360
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #5
Waterborne radon also contributes
to our overall radon exposure!
Waterborne Radon
Primarily from groundwater sources
(wells) rather than rivers
Waterborne radon to air ratio
10,000 : 1
Proposed Waterborne
Radon Standard
• EPA proposed new regulations November
2, 1999 (64 FR 59246).
• 300 pCi/L standard for public water
supplies
• Multimedia Mitigation (MMM) programs - while individual water systems reduce
radon levels in drinking water to 4,000
pCi/L or lower
Pipe scale
Highest waterborne
radon concentrations
(> 10,000 pCi/L) in
Iowa have been
attributed to radium
adsorbed pipe scale.
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #6
National and International Public Health
Agencies support the contention that
radon is a leading environmental
health risk!
EPA & Surgeon General Recommend
Take action if a home is at or
above 4.0 pCi/L
(year long average)
4.0 pCi/L EPA ACTION LEVEL
Average indoor: 1.3 – 1.4 pCi/L
Average outdoor: 0.4 pCi/L
How Does Radon Rank As A
Cancer Causing Agent?
• Radon is ranked as a Group A
carcinogen
– Highest ranking for cancer potential
– Known to cause cancer in humans
– Tobacco smoke and tobacco
products in same category
International Agency for Research on Cancer
“Radon Is A Serious
National Health Problem”
•
•
•
•
•
American Lung Association
American Medical Association
Environmental Protection Agency
National Academy of Sciences
National Council on Radiation
Protection and Measurement
• U.S. Surgeon General
• World Health Organization, and
others…..
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #7
Laboratory studies using different
species of radon-exposed animals
clearly show a linear doseresponse relationship between
radon and lung cancer.
Animal Studies
• Confirm carcinogenicity of radon.
• Exposure to ore dusts and diesel
fumes, simultaneously with radon, did
not increase incidence of lung cancer
above that produced by radon progeny
exposures alone. (DOE/OER 1988)
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #8
Studies of occupationally-exposed
miners clearly show a linear
relationship between radon
exposure and lung cancer!
Early Radon Related
Epidemiology
1556 Agricola - Miners in Europe
1879 Harting & Hesse - Lung Cancer in Miners
1921 Uhlig - Radium Emanations & Lung Cancer
1950s Peller - First Review of Mining Related
Cancers
1970s (ongoing) – Studies of Underground Miners
Original Scientific Basis For
Radon Risk Estimates
• Studies on miners.
–Uranium miners in U.S. and other
countries
EPIDEMIOLOGIC MINER STUDIES
China (Tin Miners)
Czechoslovakia (Uranium)
Colorado (Uranium)
Ontario (Uranium)
Newfoundland (Florspar)
Sweden (Iron)
New Mexico (Uranium)
Beaverlodge (Uranium)
Port Radium (Uranium)
Radium Hill (Uranium)
France (Uranium)
Dose Response Model
Adverse Health Effects
Linear Non-Threshold Theory
Atomic
Bomb
Survivors
Observed Effects
Underground Miners
Medical Patients
Dose (rem)
Occupational Miner Studies
• Linear dose response relationship was found for all
the occupational studies.
• A 1994 NCI pooled analyses of 68,000 miners
concluded that about 39% of the lung cancer deaths
among smokers and 73% of the lung cancer deaths
among never-smokers may have been due to their
occupational radon progeny exposure.
• Projecting risks to the residential setting they
concluded that radon progeny may be
responsible for 10 – 12% of lung cancers in
smokers and 28 -31% in never-smokers.
National Academy of Sciences
BEIR VI 1999
 Risk estimates based
primarily on radonexposed miners
 Estimated 18,600 lung
cancer deaths each year in
the U.S. from residential
radon exposure
EPA Estimates 21,000
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #9
Case-control studies of individuals
exposed to radon in their homes
show an increased lung cancer risk
even at or below the EPA’s action
level of 4 pCi/L (150 Bq/m3).
N.
American
Pooling
___________________________________________________________
Study
Cases
Controls
___________________________________________________________
New Jersey
480
442
Winnipeg
738
738
Missouri - I
618
1,402
Missouri – II
697
700
Iowa
413
614
Connecticut
963
949
Utah/S. Idaho
511
862
_______________________________________
Total
4,420
5,707
Basement and Living Area Radon Concentrations
for U.S. Residential Radon Studies.
Study
Location
New Jersey
Missouri-I
Missouri-II
Iowa
Connecticut,
Utah Southern
Idaho2
1Summary
Geometric Mean (GSD) in pCi/L
Basement
2.4
2.4
4.6
1.5
1.8
Level 1
0.5
1.2
Level 2
0.7
1.2
1.2
2.5
1.2
2.0
0.5
1.2
0.4
1.0
data represent those homes that were measured with no imputed
(values added to replace missing values) values.
International Pooling of Residential
Radon Case-Control Studies
New Jersey, Missouri I, Canada, Iowa, Missouri
II, a combined study from Connecticut, Utah
and S. Idaho
Shenyang, China, Stockholm, Sweden, Swedish
nationwide, Winnipeg, Canada, S. Finland,
Finnish nationwide, SW England, W.
Germany, Sweden, Czech Republic, ItalyTrento, Spain, Austria, France, China - Gansu
Province, E. Germany
Risk Estimates for Alternative Models
(live cases and controls)
2.2
Complete
exposure
Odds Ratio
2.0
1.8
Other location
radon
concentrations
only
WLM20
1.6
1.4
1st Story
BR
BR/LR
LR
Basement
1.2
1.0
0.8
20-39%
40-59%
60-79%
JEAEE 12(3): 197-203, 2002
80+%
Iowa Study Summary
• The findings suggest that prolonged
exposure to radon, even at 4 pCi/L,
increases lung cancer risk.
• These findings indicate that radon is a major
environmental carcinogen.
Residential Radon Exposure – A Leading
Environmental Health Risk:
What is the Evidence?
WHAT IS THE EVIDENCE #10
Radon exposure represents a major
source of cancer mortality in the
United States!
LUNG CANCER DEATHS
Per Year
Estimated 163,510 Lung Cancer
Deaths in 2005*
*CA: A Journal for Clinicians - 2005
Attributed to Radon
Approximately 21,000 EPA 2003
Should we be concerned
about radon-induced lung
cancer given that the risk
pales in comparison to the
risk posed by smoking?
Comparing Radon Related
Cancer to Other Cancer Types
Annual U.S. Cancer Deaths
Lung Cancer (radon)
20000
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
Liver Cancer
Brain Cancer
Stomach Cancer
Melanoma
Oral Cancer
Gallbladder Cancer
Bone Cancer
Radon Induced Lung Cancer
Non-Hodgkin Lymphoma
Ovary
Liver
Esophagus
Bladder
Brain
Kidney
Stomach
Multiple Myeloma
Acute Myeloid Leukemia
Melanoma
Oral Cavity and Pharynx
Uterine Corpus
Chronic Lymphocytic Leukemia
Larynx
Uterine Cervix
Soft tissue
Gall Bladder
Thyroid
Acute Lymphocytic Leukemia
Hodgkin Disease
Bone and Joint
Small Intestine
Chronic Myeloid Leukemia
Ureter
Testis
Eye
5000
10000
15000
20000
Cancer Mortality per Year - United States
Is Radon a Leading
Environmental Health Risk ?
Radon Decay Products
Radon
Radon
CERTI©
Further Information on Radon
EPA 1-800-SOS-RADON
http://www.epa.gov/radon/
Bill Field 319-335-4413
[email protected]