Serpentinites & the High Incidence of Breast Cancer in Marin

Institution: Marin Breast Cancer Watch
Investigator(s): Janice Barlow, BSN, NP - Scott Fendorf, Ph.D. -
Award Cycle: 2004 (Cycle 10) Grant #: 10AB-1200 Award: $10,000
Award Type: CRC Pilot Award
Research Priorities
Etiology and Prevention>Etiology: the role of environment and lifestyle



Initial Award Abstract (2005)
[This abstract describes an intended research project. Beginning, July 1, 2004, the team will utilize a small planning grant to gather necessary preliminary data, and strengthen the research plan and the scientific and community collaborations, in order to submit a CRC Pilot application in early Spring, 2005. Funding for this research depends on the success of that competitive application.]

Research on the incidence of breast cancer in Marin has primarily focused on traditional risk factors and lifestyle behaviors. Relatively little research has examined the role environmental factors may play in Marin’s high breast cancer rates. MBCW has sponsored several town hall discussions and completed three research studies. Community members were given opportunities to share local knowledge about potential environmental factors. One frequently mentioned factor was the high prevalence of serpentinite in the county. (Serpentine is a group of common rock-forming hydrous magnesium iron silicate minerals. Rock composed primarily of these minerals is called serpentinite.) Bringing together community members, geologic experts, epidemiologists and risk communication specialists, this pilot study addresses the community’s concern whether the increased incidence of breast cancer is due in part to exposure to areas with serpentine rocks, soils formed from these rocks and related water sources.

In this study, we hypothesize that the increased incidence of breast cancer in Marin County is due in part to exposures to certain cancer causing trace elements (nickel, chromium, iron, magnesium, manganese, cobalt, cadmium, mercury and vanadium) found in serpentinites, soils formed from these rocks, and in related water sources. The goal of this pilot project is not to determine whether serpentinites cause the high incidence of breast cancer in Marin County, but to determine whether certain cancer causing elements from these rocks and soils are potential environmental factors that should be considered in future ecologic and/or epidemiology studies of breast cancer in Marin.

Field and laboratory studies facilitated by community involvement provide the foundation for evaluating cancer-causing elements from serpentinites and their potential association with breast cancer in Marin County. Academic and community investigators will 1) collect rock, soil, water and household dust samples for mineral/chemical analysis; 2) map geological and chemical data into geographical information system (GIS) database to identify potential pathways for exposure; 3) complete literature review; 4) obtain databases with Marin -specific, individual level breast cancer risk factor data and residency information; 5) collaborate with an epidemiologist experienced in research on environmental risk factors and breast cancer: 6) collaborate with an environmental risk communication specialist on how the results of the pilot study can best be communicated; and 7) prepare a comprehensive CRC Research Award proposal. A

This project encompasses a multi-disciplinary approach bringing together the broad range of fields in geology, animal and human health, epidemiology and advocacy, to address an unexplored area of study in breast cancer and the environment. While a great deal is known about the natural environment, it’s elements and chemistry, an understanding of the geographic distribution and the impact of these elements on human health is needed. This emerging field of medical geology explores the “geo-environment” and brings attention to geologic factors and the health and well being of women at risk for breast cancer. This study will identify new pathways of exposure for these natural components and develop strategies to intervene in these pathways. It addresses the goals of identifying new or not yet established environmental risk factors for breast cancer.


Final Report (2005)
This award was a research assistance grant to Marin Breast Cancer Watch to further develop the Community Research Collaboration (CRC) application submitted for CBCRP's funding cycle X: “Serpentinites & the High Incidence of Breast Cancer in Marin”. The expected outcome was a revised grant application submission for CBCRP’s Cycle XI.

The hypothesis proposed that, at least in part, the risk of breast cancer in Marin County was elevated due to exposure by air, soil or water to the county's serpentine rocky outcrops, which contain concentrations of trace/heavy metals such as Cr, Ni, Fe, Mg, Mn, Co, Cd, V, and Hg, several of which are known carcinogens.

The chief tasks concluded during this research assistance project included the following:

1.A comparison of breast cancer incidence rates among counties with high concentrations of serpentinites.

In addition to Marin County, the following California counties have a high concentration of serpentinite: El Dorado, Yolo, San Francisco and Trinity. Age adjusted incidence data of female invasive breast cancer (1998-2002) indicates that the rates of both Marin and the other combined four high serpentine areas are indeed significantly higher for White Non-Hispanic women, particularly upper class as compared to California. Given the geographic and demographic variances of the five counties, further investigation is underway to control for traditional risk factors. Also of interest is the elevated rate of Ductal Carcinoma in Situ in counties with high levels of serpentinite outcrops.

2.An examination of the evidence as to whether livestock or other animals show the expected health effects of exposure to the soil types of interest as further evidence that the soil types contain substances that are relevant to health outcomes. After a comprehensive review, several articles were found addressing heavy/trace metal toxicity in livestock resulting in negative health outcomes. Of particular interest within this area of study is the accumulation and effect of cadmium. The following excerpt is an example of this concern One article (“The Accumulation of Potentially-toxic Metals by Grazing Ruminants” J. M. Wilkinson, J. Hilland and J. C. Phillips) concluded, in the specific instance of cadmium, that animals that graze in areas of high concentration for more than one grazing season should not be used for food as there is a risk of intake of toxic metals (cadmium in this case) by humans.

3.Other activities undertaken include: a justification of the mineralogical data to be used in the study should it be funded; determining the nature and completeness of the Marin-specific, individual-level breast cancer risk factor and residency data.

Finally, in response to reviewer concerns about the “ecologic fallacy” (the "ecologic fallacy' occurs when the assumption is made that an exposure-disease relationship exists at the individual level when it exists at the group level) the aims of the original application were significantly modified. The new hypothesis is that residents living in predicted high-exposure areas in Marin County will have increased exposure opportunities to serpentinite derived trace/heavy metals. The modified application resulting from this grant will not seek to generate a hypothesis between exposure and disease; rather, it intends to take the first step toward defining the exposure, that is, developing pathway of exposure profiles for future human health studies assessing environmental factors potentially related to disease, including breast cancer.

A revised application “Exposure to Serpentinites: An Environmental Risk Factor?” was submitted for review for CBCRP’s Cycle 11.


Symposium Abstract (2005)
This pilot proposal responds to the concerns of women living in Marin County that exposure to serpentinites and their related soils, water, and airborne elements may be an environmental risk factor contributing to the county’s incidence of breast cancer. Certain chemical breakdowns of serpentinites are associated with cancer, and may play a role in the development of breast cancer.

This pilot study will bring together breast cancer advocates, community members, geologists, and health specialists to study whether exposures related to serpentinites in Marin County should be considered as an environmental risk factor for breast cancer.

This project will test the scientific idea that residents living in certain areas of Marin County termed as “high exposure” areas will have increased opportunities to be exposed to serpentinite elements known as “trace” or “heavy” metals. These serpentine trace/heavy metals may affect human health through airborne particles, or they can enter the body through soil and water exposure. Support for these hypotheses has been established through an extensive evaluation of a Marin-specific Geographic Information System (GIS) database that includes where serpentinites are present, serpentine geology, wind patterns and location according to maps of land and waterways, and where Marin populations are concentrated.

Based on the GIS database developed for this project, the research team has identified a “risk assessment map” of serpentine locations and Marin residents’ estimated exposure levels (high, possible, low). The county will be divided into five major areas for collecting a total of 125 physical specimens of serpentinite samples. Seventy-five households will be recruited for a survey of exposures found in indoor dust and water. Samples will be analyzed in the lab; and all new information will be entered into a special GIS format for future breast cancer studies. Volunteers will participate in specific project activities. All data will be coded to protect privacy and confidentiality. Results will be shared in summary form.

This ground breaking pilot study will introduce the specialized field of geology to measurement of exposures that may be a contributing environmental risk factor for breast cancer. Stanford University geologists will work with MBCW, the Serpentine Community Advisory Board, and interested community members to: (a) conduct measurements of indoor (dust and water) and outdoor (soil and air) exposures associated with trace/heavy metals present in serpentinites, (b) produce pathways of exposure data that can be used for future studies, and (c) involve interested community members.

This pilot project will lay the foundation for future breast cancer studies in Marin County by creating an environmental model to research breast cancer risk.

Residents of Marin County, including women and families affected by breast cancer, are known for environmental consciousness and a consistent community interest in exploring the role of environmental factors that may be related to breast cancer. A Serpentine Community Advisory Board has been formed to include women living with breast cancer, environmental health advocates, and breast cancer researchers, geologists and academics. This board will meet quarterly, and will assist with recruitment of volunteers and households representing the diverse Marin community who will participate in the pilot project research. The Community Advisory Board will identify long-term objectives for further study.