September
22, 2000
Ms. Elsie
Mae Begay
Dear Ms.
Begay,
I am writing
to you in response to your concerns about having lived in your
hogan that was constructed with uranium containing rock. Specifically
I will comment on my interpretation of the US EPA environmental
monitoring and the information that you provided to me about
living in the hogan. The focus of what I write will be on potential
health concerns for you and your family.
The US EPA
measured levels of gamma radiation at 800-1,000 uR per hour
(micro roentgens per hour) at one meter above the floor of the
hogan. Gamma radiation is one of three types of radiation, the
others being alpha and beta radiation. Uranium ore gives off
all three types of radiation. Gamma is able to pass into the
body from outside, as is some beta radiation. Alpha and most
beta radiation is of concern primarily when the source is ingested
or inhaled and alpha radiation cannot hurt a person while the
source is outside the body. I say this to clarify what the US
EPA measurements do and do not tell us. They do not tell us
how much internal exposure you and your family might have had
from inhalation of radon or dust or ingestion of dust. In a
sense they represent a minimum exposure estimate.
Nevertheless,
based solely on the gamma radiation readings in your hogan,
I would concur with Sean P. HoganŐs letter to you that there
should be no further habitation of the Hogan and that the structure
should be removed or otherwise safeguarded from entry. The Uranium
Mill Tailings Remediation Act requires that uranium mill sites
have no more than 20 uR per hour one meter above the ground
at the end of the clean-up. Further, exposure to 1,000 uR per
hour for one year (assuming, conservatively, 12 hours per day
spent in the house) would result in a personal dose of 4,380
mREM (one mREM is essentially 1,000 uR). The standard for environmental
exposure for one year from radiation is 100 mREM. Thus, living
in the house would result in an exposure that is about 44 times
larger than is considered acceptable by US EPA or US NRC.
However,
occupants did not, according to the information you provided
about living in the hogan, remain standing or sitting on chairs,
nor did they always sleep on full beds (which would have lifted
them off the floor). In fact, children played on the floor and
occupants slept either on mattresses directly on the floor or
on carpets. All these scenarios mean that heads, bodies and,
reproductive organs, rested for lengthy periods directly on
the source of radiation. While a very large flat surface, such
as the ground or a floor, should have little change in gamma
radiation levels as distance increases, at least relatively
close to the source, gamma radiation may have been somewhat
higher close to the floor. More importantly, we do not know
what the beta radiation levels were close to the floor as these
may have been significantly attenuated by air at a meter above
the floor. It would be appropriate to test radiation levels
at the floor surface and at successive distances above the floor.
Furthermore,
as stated above, gamma exposure may not have been the only source
of radiation. Internal alpha and beta radiation exposure are
as yet undetermined. The potential for internal exposure exists
both through inhalation and ingestion. Uranium ore produces
radon gas, which is invisible and odorless and is the main source
of lung cancer among uranium miners. Radon may have been present
in the hogan, could have been inhaled and may have been higher
close to the floor or during the winter when the hogan was closed
up to keep heat in. It is possible to measure radon levels,
and it might be worth doing so to assess what they may have
been when you and your family lived in the hogan. Radon will
build up more when there is little fresh air getting in. The
more natural ventilation (open doors and windows, cracks etc.)
the less the radon. Ingestion or inhalation of dust from the
rocks that made up the floor is also a possible route of exposure.
The likelihood of ingestion and/or inhalation depends on several
factors. First we would need to know more about how easily the
rock floor could be abraded to generate sand or dust. Second
we would need to know something about activities that might
have abraded the rock flooring. You responded to my questions
by pointing out some possibilities, including rain water entering
the hogan, sweeping, walking and playing on the floor. Third
we would want to know whether the dust was ingested or breathed
in. For example, a child might get the dust on his or her hands
and then put them in their mouth, a common behavior in babies
and younger children. The food storage and eating habits that
you describe appear, on the surface, to suggest little potential
for food contamination.
Alpha radiation,
when present inside the body becomes much more harmful. While
it will not present a risk if outside the body, once it is inside,
an amount of alpha equal to gamma radiation will cause up to
20 times as much harm. In addition, the alpha radiation may
end up concentrated in the bones and could lead to health problems
that are different or less likely compared to whole body gamma
exposure. Since uranium ore gives off considerable amounts of
alpha radiation, we need to be concerned that in addition to
the gamma radiation there could have been internal exposure
to alpha radiation resulting from living in the hogan.
Dose reconstruction
is a method of estimating, after the fact, the amount of exposure
that an individual or population was likely to have experienced.
You might want to consider a dose reconstruction that accounts
for all of the exposures that you received. While a dose reconstruction
is possible, it would require more information of the sort discussed
above and would take time to complete. The benefit would be
a more precise accounting of the exposures that you and your
family received and an improved ability to estimate the probability
that any illness you have today was caused by radiation exposures
in the hogan. I turn now to diseases known to be caused by radiation
and, in particular radiation from uranium ore.
Uranium
ore consists of more than just uranium, sand and rock. It also
contains radium, thorium, radon (which because it is a gas leaves
the rock and enters the air) and other radioactive species.
Uranium ore can also contain various toxic heavy metals, such
as lead, arsenic, vanadium, magnesium and beryllium. For many
of the constituents of uranium ore there is evidence, more convincing
in some cases less convincing in others, that these substances
can cause illness. Attached is a table that I have constructed
that lists the key associations between uranium ore constituents
and disease. Also, appended are more detailed reviews of the
toxicity of uranium ore constituents.
Some of
the associations in the table are poorly documented (those cancers
in parentheses, for example). We must not assume that they are
real. Nevertheless, it should be apparent from this table that
there are many diseases associated with exposure to uranium
ore constituents. Because of the limits of our knowledge it
is important to understand that there may also be diseases not
in the table that have yet to be documented. There have been
very few studies of persons such as yourself and your family
that have lived near uranium ore. I will briefly discuss what
is known in this context next.
It is studies
of persons exposed to the entire mix of contaminants in uranium
ore that would be most relevant to your situation. I will briefly
describe the few studies of this sort that I know about. Only
one involved Navajos. This study conducted in the Shiprock area
looked at birth defects and found a statistically significant
association between mothers living near uranium mines and unfavorable
birth outcomes. A more recent study compared residents living
near uranium mill or mine sites with those living at a distance
in Texas. They found genetic changes (chromosomal aberrations)
associated with living near uranium waste. A third study, this
time from Canada, found that persons drinking water contaminated
with relatively small amounts of uranium had altered kidney
function.
I am not
a physician and therefore can make only general suggestions
about medical evaluation/screening that would be appropriate
for your and/or your family. First, I would suggest that you
show this letter to your physician since he/she may be unaware
of some of the environmental information that I have discussed
above. Second I would suggest that the diseases listed in the
table would be a starting place for screening. Third the findings
of the studies listed above suggests that chromosomal aberrations
and/or kidney function might be indicators of the level of exposure
to uranium. Forth you might want to seek someone who can measure,
directly or indirectly, the amount of uranium in your body.
This last recommendation may be problematic, however, because
there are very few facilities that can provide such a service.
In conclusion
let me state my personal opinion about your experience. The
exposures to community members living near uranium mine sites
both on and off the Navajo Nation has not been investigated
nearly as thoroughly as has exposures to the miners and mill
workers. I believe that there is a need to evaluate community
exposures and to assess the health effects that they may be
causing. Until that has been done, it will be difficult to adequately
address the needs of community members, either in terms of medical
care or in terms of just compensation. I hope that your case
can help prompt the authorities to take action. I will be more
than willing to continue to consult with you and to do what
I can to see that this issue gets the attention that it deserves.
I want to
extend my best wishes to you and your family. Please feel free
to contact me with any questions or further concerns that you
might have.
Sincerely,
Doug Brugge,
PhD, MS Assistant Professor
Director,
Navajo Uranium Miner Oral History and Photography Project
