Investigation of Thyroid Cancer Rates in Utah
During the 1950's and the 1960's the Nevada
Testing Site detonated more than 100 above ground nuclear weapons. Approximately half of
the nuclear weapons that were detonated deposited radioactive fallout in Utah. The most
significant of these radioisotopes that entered the food chain, primarily through milk,
was Iodine-131 (I-131). Exposure to I-131 is the most significant risk factor associated
with the development of thyroid cancer.
Through Congressional legislation in 1982, the Department of Health and
Human Services developed methods to assess the amount of I-131 exposure nationally and to
assess the risks associated with the development of thyroid cancer from these exposures.
In August of 1997 the National Cancer Institute released a report indicating that every
person living in the Continental United States, during the 1950's and 1960's, was exposed
to some level of I-131. The average national dose was approximately two rads. A rad is
defined as a unit of measure that stands for radiation absorbed dose (rad), which
is the amount of radiation that is absorbed by human tissue.
The per capita dose of I-131 exposure considered high by the National
Cancer Institute was nine rads or greater. The per capita dose of I-131 exposure in Utah
counties, as estimated by the National Cancer Institute, ranged from 1.6 in Iron County to
11.3 in Washington County. The National Cancer Institute identified Kane County and
Washington County as the two Utah counties which received I-131 exposures of nine rads or
The Environmental Epidemiology Program examined the incidence of
thyroid cancer in all 29 Utah counties covering the years 1966 through 1995 to assess if
any statistically significant increases of thyroid cancer existed in contrast to the state
of Utah (comparison population). The analysis for each county and the state of Utah was
assessed in six year intervals: 1966-1971, 1972-1977, 1978-1983, 1984-1989 and 1990-1995.
Thyroid cancer data was obtained from the Utah Cancer Registry from 1966 through 1995 for
each county and the state of Utah. The data obtained provided age-adjusted thyroid
incidence rates and counts for both sexes for each interval.
The results of this investigation found significant elevated thyroid
cancer rates in Salt Lake County during time periods 1984-1989 and 1990-1995 and in Tooele
County during time period 1971-1977 as compared to the state of Utah rates. These
significant elevated rates were found for females only. The two Utah counties with high
I-131 exposure, Kane County and Washington County, did not demonstrate significant
elevated rates in the occurrence of thyroid cancer for any time period analyzed. Garfield
County (8.9 rads) and Millard County (8.7 rads) also received high levels of I-131
exposures but neither county demonstrated significant elevated rates of thyroid cancer in
any time period. No other evidence was found in any other time periods that demonstrated
statistically significant increases in the incidence of thyroid cancer for either males or
females in each of the remaining Utah counties.
There were several factors that made it difficult to draw a conclusion
from the results of this investigation. These factors included migration into and out of
counties with high I-131 exposure which presented a problematic issue relative to
assessing the long term impact of I-131 exposure levels, latency or induction period (10
to 30 years), personal habits, and familial history. Furthermore, I-131 exposure is not
the only environmental risk factor associated in the development of thyroid cancer.
External beam radiation treatment for medical therapy, acute gamma ray exposure from
environmental sources (nuclear weapons, nuclear power plant accidents) and estrogen
receptor immunoreactivity have been etiologically associated in the development of thyroid
cancer. Prescription drugs such as pentobarbital, meclizine, diphenoxylate, dicyclomine,
griseofulvin, bisacodly and senna have also been etiologically associated with thyroid
cancer. This investigation was unable to assess the contributions that each of these risk
factors had on the thyroid cancer rates in Utah.
Thyroid cancer is uncommon, accounting for only 1 percent of all
cancers in the United States. This type of cancer occurs more frequently in women than in
men, primarily the result of hormonal influences. The risk for developing thyroid cancer
in women is greater during the reproductive years then decreases to the same rate as men.
Data from the Utah Cancer Registry indicates that the incidence rates of Utah females (not
males) have been slightly higher than the national rates in recent years.
The complete National Cancer Institute report can be found on the
National Cancer Institutes INTERNETs home page http//rex.nci.nih.gov or
you can call the toll-free number, 1-800-4CANCER.
For more information contact John Contreras, Epidemiologist,
Environmental Epidemiology Program at 801-538-6191.
Estimated per capita
average individual thyroid dose of I-131 for populations in each Utah County resulting
from the Nevada Testing Site tests (1950's to 1960's).
|Box Elder 1
Box Elder 2
|* A unit of measure that stands for radiation
absorbed dose, the amount of radiation absorbed by the tissues in the body.
** Identified by the National Cancer Institute as receiving I-131 rad exposures of nine or
Data Source: National Cancer Institute, 1997.
Meningitis in Ski School
The Communicable Disease Control Program
recently received a telephone call from Mississippi reporting a case of meningococcal
meningitis in a child who had been vacationing in Park City the previous week. While
attending a ski school/day care, the child may have had contact with more than 70 children
from areas outside of Utah. Staff from the Communicable Disease Control Program were able
to contact the childrens families to provide information on signs and symptoms of
meningococcal disease. One child from New Jersey and another childs father from
Bermuda reported illnesses resembling meningitis, however cultures from both were negative
for N. meningitidis. Summit County Health Department followed up on employees at
the hotel. No other cases were identified.
Later that week, the Communicable Disease Control Program received a
telephone call from the Arizona Department of Health reporting a case of meningococcal
meningitis in a woman who had attended a religious gathering in Southern Utah the previous
weekend. Little information was available, so the San Juan County health office was
contacted for assistance. With the help of the Indian Health Service and their Community
Health Representatives, the site of the meeting, the organizer (an Arizona resident), and
the minister (a New Mexico resident) were all identified. Contacts to the patient were
found and Rifampin prophylaxis was provided. Arizona telephoned later to report that the
original case was indeed a resident of Utah.
These cases are two good examples of how cooperation and rapid
communication among several different groups is essential to public health. In both cases,
everyone that needed to be contacted was identified and located in a timely manner. Thank
you to all who were involved.
Summer Food Hazards
Summer is a time of picnics, barbecues,
family reunions, weddings, and vacations. During this time of year people take advantage
of the nice weather and plan large gatherings which are often held outdoors. Usually, the
most serious hazards faced by attendees at these get-togethers are ants in the salad and
sand in the sandwiches. However, improper food-handling can ruin the most carefully
planned get-together and can quickly turn it into a nightmare (particularly if bathroom
facilities are scanty). Fortunately, by following a few simple precautions, summer cooks
can avoid inflicting their friends and family with an unwelcome case of food poisoning!
Select menu items
Select food items based on available facilities. For
example, if you will be spending a day in the sun at the beach with no place to keep food
refrigerated, peanut butter and jelly would be a much better choice than chicken salad for
sandwiches. If there are no hand washing facilities, don't plan to handle raw ground beef
Always wash hands thoroughly before handling food. Prepare
as much food as possible before leaving home where facilities are the most adequate.
Clean cutting boards and utensils used for raw meats with hot
soapy water before using them for ready to eat foods.
Wash hands frequently during food preparation to avoid
Always use clean, treated water for washing.
When eating in the mountains, never wash hands or dishes in
lakes, rivers or streams.
Cook meats thoroughly. Cook raw hamburger and chicken until the
meat is no longer pink in the middle and the juices run clear.
Keep foods in coolers, on ice, or in warming pans until ready to
eat. Keep hot foods hot and cold foods cold.
Keep hot foods on the grill, fire, coals, or warming pan until
serving time and keep cold foods in the shade, in a cooler, or sitting on ice.
Never store uncooked meats with ready-to-eat foods.
Protect food from insects such as flies which can spread
bacteria and store food so that it is not accessible to rodents.
Eat food as soon as it is served. Do not allow it to sit for
long periods of time.
Do not eat food you would normally refrigerate if it has been
sitting at room temperature for more than 2 hours, less time if it is hotter than room
temperature (such as sitting out on a picnic table on a hot summer day).
Put food away as soon as possible after eating.
Have a great summer!!
Morbidity Summary - April 1998 - Provisional Data Utah Department
of Health, Bureau of Epidemiology
The Epidemiology Newsletter is published monthly by the
Utah Department of Health, Division of Epidemiology and Laboratory Services, Bureau of
Epidemiology, to disseminate epidemiologic information to the health care professional and
the general public.
Send comments to:
The Bureau of Epidemiology
PO Box 142104
Salt Lake City, UT 84114-2104
or call (801) 538-6191
Approval 8000008:Appropriation 3705
Rod Betit, Executive Director Utah Department of Health
Charles Brokopp, Dr.P.H. Division of Epidemiology and Laboratory Services
Craig R Nichols, MPA, Editor, State Epidemiologist, Director Bureau of Epidemiology
Cristie Chesler, BA Managing Editor