My name is Kimberley Marie Crehan and I am an undergraduate student at Pima Community College. This summer I have been lucky to be involved in the Pima Community College/University of Arizona Summer Bridge Program. I have been working in the Physics and Atmospheric Sciences building under Brian Barbaris. Researchers have been studying air, water, and tree-core samples in southern Arizona as a preliminary investigation into the possibility of environmental causes for a leukemia cluster identified in Sierra Vista, AZ. I have been studing the aerosols in the air from filters that were left in Sierra Vista, the cluster area, and Cochise College, a remote site, in order to investigate what and how much material is in the air. I have been using a Dionex DX-100 Ion Chromatograph to investigate what is on the filters and in the air.Kimberley Marie Crehan
Abstract: Atmospheric aerosols were collected on glass-fiber filters in southern Arizona from May 28, 2003 to June 4, 2003 as a preliminary investigation into the possibility of environmental causes for a leukemia cluster identified in Sierra Vista, AZ. The filters were analyzed for total particulate mass and the major ionic species chloride, nitrate, sulfate, sodium, potassium, calcium, magnesium, and ammonium. Preliminary results indicate that Sierra Vista aerosols differ dramatically from Cochise College, a remote site 40 miles to the east on the US-Mexico border, indicating a local source of aerosols in Sierra Vista. Cochise College data indicates that Mexico is most likely not a contributor to aerosols in Sierra Vista.
Sierra Vista Cochise College
Here is a graph of the major ions (chloride, nitrate, sulfate, calcium, magnesium, sodium, ammonium, and potassium) found in the filters from Sierra Vista, where the leukemia clusters are located, from Cochise College, a remote site, and a field blank, the filter before it was used at the test sites.
Total Mass Loading
For one week in 2002, aerosols were collected in Sierra Vista and for
one week in 2003 aerosols were collected in Sierra Vista, the leukemia
cluster site, and in Cochise College, a remote site about 40 miles away.
In 2002 a background site was not analyzed. Field Blanks were used
to make sure the filters were not originally contaminated or contaminated
in transport. The blanks are put through the same process as the
other filters but no air is pumped through them. We use the data
from the field blanks to subtract from the filters of the sites of interest
so this way we don’t take into account something that was on the filter
before the data was actually taken. We used the data from both of
these years to compare with each other and be sure we had consistent data
from one year to the next for two different weeks out of the year.
Both weeks there were over 300 milligrams per filter. Sierra Vista
has twice as much material on the filter than our remote site, Cochise
College.
Tungsten has a detection limit of about 50-100 parts per trillion. Here is a graph that shows how much tungsten was on filters for two consecutive years. The amount of tungsten in the air is rising as we can see. Amazingly there were traces of tungsten on the field blanks. We need to subtract the field blank value from what we saw in the field sample to get the actual amount of tungsten on the filter. (6.12-1.44= 4.68 micrograms per filter). From this analysis we have decided to change the type of filters used to collect data so this way the filters won’t originally have so much tungsten on them.
Jessica Durkit is three years old and lives in Sierra Vista. When she was two years old she became anemic, withdrawn, and bruised easily. She had a poor appetite and even looked sickly. No one could figure out what was wrong with her, some even saying she’d grow out of it. While receiving treatment for a spider bite on her foot, the doctor determined she had the adult form of leukemia, the most serious type. She was rushed to University Medical Center where she quickly had to receive a blood transfusion. The doctors told her parents in six months she’d either be in remission or be dead. After a couple of days doctors couldn’t find a trace of leukemia but still recommended seven rounds of chemotherapy and biopsies of bone marrow, which she went through rarely crying said her parents. Luckily Jessica didn’t end up needing to receive the bone marrow transplant. In March she celebrated her first anniversary of being in remission.
“10th child in Sierra Vista gets Leukemia" February 25, 2003 Arizona Daily Star
“Nev. Cancer study to aid Ariz. Officials” December 27, 2002 The Arizona Republic
“Family fears leukemia, Sierra Vista linked” January 9, 2003 The Arizona Republic
“Kolbe asks for cancer probe: Seeks CDC aid for Sierra Vista leukemia cases” September 24, 2002 Arizona Daily Star
“Arizona leukemia cluster to be studied: Small military town has seen increase in number of cases” January 28, 2002 Las Vegas Review Journal
Conclusion: In general, the aerosol loading was quite low for the week on both filters. The Sierra Vista filter (339 mg per filter) is about twice as dirty as the Cochise College filter (161 mg per filter). There is much more nitrate and sulfate in the air in Sierra Vista and slightly more chloride in the air at Cochise College. There is about three times the amount of ammonium in Sierra Vista than in Cochise College. There is about two times the amount of magnesium and potassium on the Sierra Vista filters than on the Cochise College filters. There is more sodium and calcium on the Sierra Vista filter. Contamination could also be a factor but further investigations are being done to show repeatable results and rule this situation out.
In conclusion from our major ion analysis we have learned that nitrate compounds make up a large part of the air in Sierra Vista, almost twice as much as Cochise College. Our mass loadings in Sierra Vista were double Cochise College but still less than Tucson’s. Tungsten amounts are rising since last year. I have only done a small portion of a big project. Now that we know what and how much material is in the air, we can identify why its there and find out if anything in it is contributing to the leukemia clusters in Sierra Vista.