San Francisco's Cancer Necklace
“A conundrum is a riddle — a confusing or difficult problem or question. Breast cancer disparities by race and geographic location have been a conundrum in the San Francisco Bay Area for decades, flared by public health researchers in 1995 after a statistically significant excess in invasive breast cancer cases were detected among women in Bayview Hunters Point. Additionally, the Northern California Cancer Registry determined white women have the highest reported breast cancer rates in the world!”
Dr. Ahimsa Porter Sumchai - Westside Observer, October 23, 2021
Frances Taylor M.D., MPH is an unsung hero who served as a preventive medicine specialist in San Francisco following completion of a residency at Johns Hopkins and board certification in public health.
As Director of the Bureau of Epidemiology & Disease Control for the Department of Public Health in 1995, Taylor conducted pioneering research that detected a cluster of cases of a water borne parasite called cryptosporidium in the cities Castro district.
Dr. Taylor believed it was being spread through sexual activity - not by unfiltered drinking water from the Hetch Hetchy reservoir as many health officials argued.
She proved to be right and in standing up for her beliefs saved an inestimable number of lives during the peak years of the AIDS epidemic.
Retired from practice, I was delighted to reach her by phone from her home in Cow Hollow. Frances Taylor is a very common name and a ‘graveyard” of obituaries popped up in my search to locate a woman I believed was in her nineties!
Dr. Taylor Opens the Breast “Can” of Worms!
“Lead investigator Frances Taylor, Director of the Bureau of Epidemiology and Disease Control, said the reason for the high breast cancer rates “remain a puzzle.”

Taylor minced no words in admitting the results of her 1995 investigation displeased health officials and influenced her decision not to publish findings she believed were significant.“I was convinced there was something there!”
“The risk of radiogenic breast cancer appears to decrease with increasing age at exposure. These results suggest exposure of female breast tissue to ionizing radiation during the first four decades of life can induce breast cancer.”
“The risk of radiogenic breast cancer appears to decrease with increasing age at exposure. These results suggest exposure of female breast tissue to ionizing radiation during the first four decades of life can induce breast cancer.”
Incidence of female breast cancer among atomic bomb survivors, Hiroshima and Nagasaki 1950-1980
Breast cancer incidence rates in San Francisco surpassed those in Japan and China in 1982 and were detected at a younger age. Breast cancer cases were observed in women as young as 20 by Taylor in 1995. The National Cancer Institute analyzed new breast cancer cases by age and found across all races the average age at diagnosis was 62. In women aged 20-34 the percent of new cases in women was 1.9%.https://emedicine.medscape.com/article/1697353
By 1980 a link between radiation exposure and breast cancer had been established in women under the age of 20 when the bombs were dropped on Hiroshima and Nagasaki in 1945.
Dr. Taylor conducted the most cited investigation of her career in 1995. The findings were reported by Chronicle Environmental writer Jane Kay.
Based on an analysis of data from seven census tracts in the 94124 zip code, Taylor found between the years of 1988–1992 “women under the age of 50 contributed to a breast cancer incidence rate double that of San Francisco as a whole. A total of 107 cases were detected compared to an expected 83 cases. Among African American women under 50 the number of cases detected was 28 - 13 were expected. The finding that Bayview women under the age of 50 contributed to a breast cancer incidence rate double that of San Francisco as a whole was unexplainable.”
Taylor minced no words in admitting the results of her 1995 investigation displeased health officials and influenced her decision not to publish findings she believed were significant.“I was convinced there was something there!”
That year, Debbie Gillis, MD - an African American public health researcher - compared cancer incidences in the Bay Area with San Francisco and Bayview Hunters Point using data derived from the Bureau of Epidemiology, Disease Control and AIDS. It confirmed Dr. Taylors findings.
The Gillis investigation is referenced in Introduction to Bayview/Hunters Point.
students at a UC Berkeley summer camp.
Raymond Tompkins is an air monitoring expert and lead researcher for the BAAQMD funded project Hidden Hazards in Bayview Hunters Point. Tompkins participated in community forums with Dr. Gillis in 1995 and recalls the data she presented included breast cancer cases in women as young as 20.
The Gillis investigation cannot be located on advanced search, the Bureau of Epidemiology no longer exists and DPH no longer publishes cancer incidence by zip code in the city of San Francisco.
The Greater Bay Area Cancer Registry collects data on all cancers diagnosed in the five Bay Area counties. In a 1998 report Glaser et. al. compared the number of observed cancers in BVHP residents for the three-year period 1993-1995 to the number of cancers expected if residents had the same cancer rates as the Bay Area.
Unlike the Taylor and Gillis investigations, expected cases in the 1998 Glaser report were not projected from US Census data. Instead, mid-year census tract population estimates for BVHP were calculated using “econometric models” and data stored by the California Department of Finance Demographic Research Unit. According to Oxford Scholarship a key property of econometric models is falsifiability!
Additionally, the Glaser report used cancer rates in the Bay Area as the reference population instead of cancer rates for the city of San Francisco as a whole, with the justification that:
“In 1990 approximately 22% of the African American population of San Francisco lived in Bayview Hunters Point, so cancer rates for the African American population of San Francisco are heavily influenced by cancer rates in Bayview Hunters Point. For this reason, we used the entire Bay Area rather than San Francisco alone as the reference population. In general cancer rates are lower in the Bay Area as a whole than in San Francisco; consequently, expected numbers based on Bay Area rates would be lower than expected numbers based on San Francisco rates and the ratio of observed to expected numbers would be higher.”
Eva Glaser, MD, MPH - Cancer Surveillance Section Department of Health Services - January 1998
Reliance on census tract data and econometric models to estimate expected cancer cases in BVHP is undercut by U.S. Census Bureau data showing population undercounts as high as 5%! African Americans, American Indians, Asians, Pacific Islanders and Hispanics have been historically undercounted by the census. The majority of BVHP residents fall into racial/ethnic categories census data may not accurately reflect in determining neighborhood compositions of densely populated public housing.
It’s like Deja Vu…all over again!
Tables 4 & 5 from the 1998 Glaser review.
Numbers and stage at diagnosis of breast cancers diagnosed from 1985 to 1995 in BVHP showed an increase in the percentage of early stage in situ or localized lesions detected from 1988 onward.
Panel A is a model based estimate for mammography use among women aged 50 to 74.
Panel B is a geospatial mapping of observed breast cancer cases diagnosed at Stage llB in 2016.
Over 30% of Stage llB breast cancers with tumors as large as a lime with possible spread to lymph nodes were detected in southeast San Francisco and the 94124 census tracts.
A total of 5,595 invasive primary breast cancers were diagnosed in San Francisco between January 1, 2006 and December 31, 2015. Guan et al found neighborhood and racial/ethnic differences in stage at diagnosis, pathology and mortality. Patients in Bayview Hunters Point were more likely to have Stage llB breast cancer at diagnosis and more likely to be diagnosed with triple-negative breast cancers. African Americans continued to experience the greatest disparities in breast cancer outcomes across the cities geographic areas.
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In State of the Evidence 2017, Gray et al reviewed the “continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the high incidence of breast cancer.” In an eight-year review, the authors identified six classes of chemical toxicants linked to high incidences of breast cancer -radiation, endocrine disruptive compounds, industrial chemicals, tobacco smoke, food additives and hormones in pharmaceuticals and cosmetics.
“We will never know the composition of that cloud, because the wind carried it away, but people were breathing and eating it…What we do know is that it had all kinds of god-awful things in it. Burning jet fuel. Plastics, metal, fiberglass, asbestos. It was thick, terrible stuff. A witch’s brew.”
Dr. Michael Crane -World Trade Center Health Program
According to the World Trade Center Health Program, a higher than expected incidence of cancer has been documented in residents and rescue workers exposed to toxic dust debris in the aftermath of the collapse of the Twin Towers on September 11, 2001. A study published in JAMA found an association between exposure to World Trade Center debris and excess prostate and thyroid cancer and multiple myeloma by 2008.
According to UC Davis Professor Emeritus air toxics expert Thomas Cahill, tons of debris from the Twin Towers collapse was composed of pulverized concrete, 50% non-fibrous material and construction debris, 40% glass, 9.2% cellulose and 0.8% asbestos.
pDetectable levels of lead, mercury, cadmium, silica, dioxins, PAHs, were known to be present by the EPA following the collapse.
On September 11, 2019, 17 years after the Twin Towers Collapse, a New York City law firm reported 15 men exposed to toxic dust had been diagnosed with breast cancer according to the World Trade Center Health Program.
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Biomonitoring is the measurement of the body burden of toxic chemical compounds, elements or their metabolites in blood, urine and tissue. Biomonitoring is an advanced biotechnology used in public health and occupational safety to monitor toxic exposures and workplace surveillance. In 2001 the U.S Centers for Disease Control and Prevention launched the National Report on Human Exposure to Environmental Chemicals.
One of the most conclusive biomonitoring studies conducted in women diagnosed with breast cancer detected high concentrations of iron, nickel, chromium, zinc, cadmium, mercury and lead in cancerous breast biopsies. The metals were found in higher concentrations in blood and urine obtained from women diagnosed with breast cancer than in healthy women. The authors conclude that epidemiological data strongly support a link between an increased risk of breast cancer and exposure to ionizing radiation, DES and DDT. [Biol Trace Elem Res.2006,113:9-18]
Multiple Proposition 65 listed carcinogenic heavy metals and radioactive biomarkers are detected in concentrations exceeding maximum allowable levels for the reference population including cesium, gadolinium, nickel, rubidium, thallium, copper, manganese, strontium, vanadium, and zinc. All are documented by the Navy and US EPA to be chemicals of concern at HPNS.
Spot maps are used for clusters with a limited number of cases. A dot or X is placed on the location relevant to the disease investigation- most often the address where the subject lives or works. The mapping of small case numbers can be useful in detecting clusters of emerging and rare diseases. The visual display of small cases can prove to be powerful in identifying sources of exposure to hazardous materials.
John Snow, MD created a spot map of the Broad Street region in London’s Soho neighborhood in 1854 where people and animals lived in proximity in dirty crowded conditions. Doctors and scientists of the time blamed the outbreak of a new disease that caused severe diarrhea, dehydration and death on “miasma”- bad air. By mapping cases in the outbreak, Snow discovered everyone affected had one thing in common…their water source was the Broad Street pump.
On September 18, 1854 Snow removed the pumps handle, ended the outbreak and proved his theory that cholera was a waterborne disease.
“John Snow’s accomplishments in medicine, anesthesia, and epidemiology constituted an achievement that changed the face of medical practice.“
John Snow, MD: anesthetist to the Queen of England and pioneer epidemiologist.
Geographic information systems contain data projected as visual displays. Geospatial mapping is an analytical tool capable of generating maps with spatially distributed data. Google maps is a geospatial mapping tool in common use that assigns a single indicator pin to a location on a standard map entered into the location bar of the software program by users.
HP Biomonitoring has relied on manual mappings to create visual displays of chemical and disease clusters detected using urinary screenings, field surveillance and family referrals since it’s launch in 2019.
Overlapping geographic information systems with cancer and chemical cluster mappings can create easily understandable visual displays of disease distributions in time and space.
GIS mappings are a powerful tool in determining the source of a disease outbreak or chemical exposure.
The Hunters Point Biomonitoring Foundation was awarded a $50,000 grant by CalEPA to create Community Window on Exposure in BVHP. The virtual window will build an integrated website with major environmental geographic information systems (GIS) on the homepage, including the EPA EJScreen, CalEPA EnviroScreen, BVHP IVAN Network and BAAQMD Interactive Maps and live stream data from the AB617 funded Marie Harrison Bayview Air Monitoring network of ten stationary fine particulate sensing Dylos monitors.
Geographic information systems allow investigators to store, analyze, model and display all relevant data. GIS visual displays can easily understood by non-English speaking residents and students seeking proficiency in environmental science.
Community Window on Exposure will incorporate a digital mapping tool capable of assigning multiple colored indicator pins corresponding to specific chemicals, cancers or diseases to an address or work location. At build out, Community Window on Exposure will support electronic health and laboratory records as a critical first step in establishment of the Hunters Point Community Toxic Registry.
Cluster mapping tools have been developed that visualize and analyze where and why health events occur. CLUSTER is an IBM compatible software program offering researchers a choice of statistical methods to use when investigating clusters. Maptitude software can be used to detect clusters of health events requiring further investigation and analysis. ArcGIS Pro is a tool that performs cluster analysis to identify the location of “hot spots” in an epidemic.
SaTScan is a free (I like free) software program that analyzes spatial, temporal and space-time data to perform geographic surveillance of disease clusters, test whether a disease is randomly distributed over space and time or perform repeated surveillance for early detection of emerging clusters.
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According to CDC Guidelines a cluster is a greater than expected number of observed cases for a population similar in age, race or gender in a geographic area. Equally important, the detection of anomalous patterns of disease distribution within the cluster may aide in identifying the source of an epidemic or exposure.
“The Breast Cancer Necklace” is the eponym HP Biomonitoring assigned to the pattern of breast cancer cases mapped in women living within the six block perimeter of the federal Superfund system. The cases encircle the perimeter of the base, northeast to southwest, like a loose string of red pearls - unlike the concentration of radiation induced cancers mapped around the main entry corridor and western fence line of the naval base.
It is one of the most subtle and intriguing findings HP Biomonitoring has uncovered in mapping the pattern and distribution of radiation induced cancers within the one mile perimeter of the federal Superfund system at the Hunters Point Naval Shipyard.
In verifying a cancer clusters all cases must involve the same type of cancer or types of cancer scientifically proven to have the same cause. HP Biomonitoring’s geospatial mapping of radiation induced cancers offers an undeniably significant visual image of radiosensitive cancers of the brain, breast, thyroid, lung and leukemia clustered around the corridor of entry to the US Naval Radiological Defense Laboratories, its radiation contaminated Parcel E-2 shoreline and industrial landfill - a federal Superfund site.
One of every four deaths in the United States is due to some form of cancer making it inherently challenging to identify and interpret cancer clusters. State and local health departments are tasked with responding to a suspected cancer cluster.
Meg McKinley of the California Cancer Registry has agreed to verify the growing cluster of cancers linked to radiation, carcinogenic heavy metals and other Proposition 65 listed chemicals known to be present in the estimated 800 acre system of federal Superfund sites at the Hunters Point Naval Shipyard.
A conundrum is a riddle and the detection of a small strand of pearls in a “Breast Cancer Necklace” encircling the western perimeter of a system of three federal Superfund sites raises questions.
- Is the ring like pattern of breast cancer cases encircling the perimeter of a radiation contaminated naval base evidence of exposure to cancer causing chemicals documented to be present there?
- Is the ring like pattern of breast cancer cases encircling the perimeter of the southern shoreline possible evidence of airborne transmission of carcinogenic heavy metals and volatile organic compounds?
- Or is the ring like pattern simply an artifact created by the distribution of breast cancer cases in a densely populated neighborhood encircling a largely uninhabited naval base?
Ahimsa Sumchai Porter, MD, West Portal, Medical Director Golden State MD Health & Wellness is a longtime neighborhood and environmental activist
APRIL 2022


































































































































































































































