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Silent Spring Institute researchers have created the Cape Cod Public Water Supply Data Resource to provide online, public access to water quality data gathered during the Cape Cod Breast Cancer and Environment Study. The dataset includes information about individual wells operating on Cape Cod from 1972 to 1995.
Note that not all wells were continuously operating during this period. Nitrate data for individual wells have been collated and graphed against the average for the water district. Some wells include interpolated nitrate values, which are clearly marked.
To access the data in the Cape Cod Public Water Supply Data Resource, you may click on a town on the map; you can then click on an individual well to view the data. The entire Microsoft Access database is available for download; simply click on the zip icon. Note that the database is compressed and you will need a decompressor such as WinZip or Stuffit to open it.
Historical reconstruction of wastewater and land use impacts to groundwater used for public drinking water on Cape Cod, MA.
This work has been published in the Journal of Exposure Analysis and Environmental Epidemiology.
Source: Swartz, C.H., R.A. Rudel, J.R. Kachajian, J.G. Brody. (2002). Indicators of wastewater and land use impacts on public drinking water: Historical reconstruction of exposure on Cape Cod. Newton, MA: Silent Spring Institute Report.
This documents methodologies and data developed in the Cape Cod Breast Cancer and Environment Study to estimate historical wastewater and land use impacts to drinking water distributed by public water supplies on Cape Cod, Massachusetts. Data tables and graphs are available on-line for each town, water supply district, and well operating during the period 1972 - 1995, and accessed via a Town Index map. Data for individual wells is obtained by clicking on the well location. Precise geographic coordinates of public water wells are not available on this website.
This work is one component of a multifaceted exposure assessment for a case-control epidemiological study of 2100 women that was designed to investigate the role that exposures to environmental pollutants, including hormonally active chemicals and mammary carcinogens, may have in explaining elevated breast cancer incidence on Cape Cod. Previous research has shown that breast cancer incidence on Cape Cod has been elevated in comparison with other areas of Massachusetts, even after controlling for established risk factors (Silent Spring Institute 1997). The Cape Study also incorporates assessment of historical exposures to wide-area spraying of pesticides on the Cape for agriculture and insect control (Brody et al. 2002) and personal use of pesticides (Brody et al. manuscript in preparation) in this investigation of the role of environmental factors in breast cancer incidence.
Reconstruction of historical water quality for each of the eighteen public water supply systems serving 150,000 year-round Cape residents is a critical component of the Cape study, as these systems have historically supplied, and continue to serve, approximately 80 % of Cape residents. The water distributed by these systems is drawn almost entirely from a shallow, water table aquifer underlying the land surface of Cape Cod, and the vulnerability of this aquifer to contamination from land use activity is well documented (LeBlanc et al. 1986; Janik 1987; Barber et al. 1988; Barlow 1994; Rudel et al. 1998b). Specifically, on-site sewage disposal in septic tanks and cesspools has been identified as one of the most serious non-point sources affecting water quality on the Cape (Belfit 1984), as greater than 90 % of Cape residents dispose of domestic sewage in cesspools or septic systems. More generally, sewage disposal and its impact on ground water quality is a critical issue in residential areas throughout the U.S. (Grady 1993), supporting the need for methods to study potential health effects of exposure to land use-impacted drinking water and planning tools that can aid in mitigating future impacts.
The metrics developed in this study to estimate wastewater and other land use impacts to public water distribution systems incorporate historically measured chemical parameters for public water supply wells on Cape Cod and analysis of land use surrounding these wells. The chemical parameters serve as proxy indicators for the presence of a suite of co-contaminants associated with wastewater and other land use impacts, a methodology that has been suggested for estimating historical exposures to disinfection by-products (Arbuckle et al. 2002). In addition, geographic information system technology was used to estimate impact to wells through analysis of historical land use within geographic areas delineated as recharge areas (zones of contribution, or ZOCs) for each of the groundwater wells supplying the public water distribution systems. Historical land use within recharge areas to public supply wells was chosen as an indicator of impact because numerous studies have shown an association between land use and groundwater contamination and aerial photographs for Cape Cod are available that indicate land use as early as 1951. These land use-based indicators provide exposure estimates for time periods prior to the existence of recorded chemical parameters, and they also supplement information about water quality impact based on chemical parameters.
The 18 public water supply districts on Cape Cod, which are supplied by approximately 145 wells and one surface water source, are included in the analysis. The period of analysis is bounded by the earliest year (1972) for which measured water quality parameters were available and the latest year included in the case-control portion of the Cape Study (1995).
Source Water Quality Characterization
Nitrate impact for each well was calculated as the annual nitrate concentration (in mg/L) measured in that well after subtracting 0.2 mg/L, the maximum nitrate concentration typically observed in unimpacted groundwater on the Cape (Silent Spring Institute 1997). One study of nitrogen loading to the Cape aquifer found a median background level of nitrate to be 0.07 mg/L, and water with levels greater than 0.5 mg/L were characterized as impacted from an anthropogenic source (DeSimone et al. 1995). Because nitrate is naturally occurring, subtracting the maximum background concentration from a nitrate measurement produces a final nitrate level that represents anthropogenic nitrate typically associated with wastewater and agriculture impacts.
Land use impacts were assessed by characterizing the amounts and types of land use that occurred in recharge areas, or zones of contribution (ZOCs), for each public supply well or group of public supply wells. Land use pertaining to (1) residential development, (2) routine pesticide applications such as cranberry bog cultivation, other agricultural applications, golf courses, and railroad and power line rights of way, and (3) industrial, commercial, waste disposal, military activities, cemeteries, and transportation features such as major roads and airports were considered in calculating three different land use impact values for each ZOC. These impact values were calculated as the percent land area within each ZOC devoted to each of the three land use groups listed above. These three fractions are referred to as the ZOC-residential, ZOC-pesticide, and ZOC-commercial fractions, respectively. These fractions were derived using standard GIS techniques to overlay ZOC boundaries and land use maps representing four different time points (1951, 1971, 1984, and 1991) incorporated in the Silent Spring Institute GIS. To determine ZOC land use fractions for each of the three land use categories for each of the years falling between the time points for which land use maps were available, linear interpolation was performed using the fractions derived for these four time points.
District-wide Water Quality Characterization
Yearly district-wide nitrate concentrations were obtained by weighting the annual nitrate concentrations for each well by the ratio of the volume contribution of that well to the district’s total pumping volume for that year. Note that the district-NO3 concentrations retain units of concentration after this weighting procedure. This method of estimating a district impact value from the nitrate concentrations for wells within each district assumes the water is homogeneously mixed prior to distribution at the tap. This assumption was necessary, as information on system hydraulics required to model intra-district mixing was not available from Cape water suppliers.
Land use-based scores
Unlike the nitrate measurements made at a well, land use surrounding a particular well in a given year does not reflect concurrent impact to that well, but rather, represents potential impact to that well at some future point in time. To take into account the travel time required for land use impacts to affect a neighboring well, an average time required for contaminants to reach a well from sources within its zone of contribution was first estimated. This travel time represents the time between when a contaminant is introduced into an aquifer from a particular land use and its expected appearance at the neighboring well. This travel time was then considered in determining which historical year of land use to use in estimating impact to a well at time points considered for the case-control study. District-wide impact values for each of the three land use categories were then calculated by multiplying the particular land use fractional area for a ZOC for that historical year by the ratio of the cumulative volume contribution of all wells within that ZOC to the district’s total pumping volume for the year in which impact was being determined. Again, the assumption of homogeneous mixing with a district is assumed with this impact estimation method.
The travel time is dependent on three primary variables: (1) the distance between the well and the contaminant source, (2) the groundwater flow velocity, and (3) the behavior of the contaminant in the aquifer. The distance between the contaminant's point of entry into the aquifer and a well is, of course, case specific. The groundwater flow velocity is dependent on the natural gradient and any additional gradient that is superimposed on it by the pressure induced by the pumping well. The behavior of organic contaminants that are the primary targets in this study depends in large part on their tendency to associate with, or partition into, natural organic matter distributed among the sediments composing the aquifer. Significant slowing, or retardation, of organic contaminants relative to inorganic contaminants such as nitrate can result owing to this partitioning process.
To derive a travel time for EDCs and mammary carcinogens in the Cape aquifer, we used nonylphenol as a representative contaminant. Nonylphenol has been documented as estrogenic and is present in Cape groundwater impacted by wastewater (Barber et al. 1988; Rudel et al. 1998b). To represent the distance between contaminant source and a well, we used a constant value equal to half of the average length (1585 m) of all ZOCs for the Cape. The average distance between a well and the furthest lateral extent of its ZOC was 3170 ± 1950 m. We used a retardation factor (Rf) measured for nonylphenol traveling in a secondary sewage effluent plume on the Cape (Barber et al. 1988) to estimate travel time for this class of representative compounds. Barber et al. (1988) presents retardation factors measured for nonylphenol considering both the maximum distance of measurable concentrations of nonylphenol from the contaminant source (Rf = 2.4) and the distance to the leading edge of the zone of maximum concentration of nonylphenol (Rf = 3.3). Assuming a groundwater flow velocity twice (0.6 m day-1) that of typical natural conditions (0.3 m day-1) (LeBlanc et al. 1986; Barber et al. 1988; DeSimone and Barlow 1995) to account for pumping-induced stress on the aquifer, it would take approximately 18 to 24 years for nonylphenol to travel half the average length (1585 m) of ZOCs on the Cape, depending on the retardation factor used. Note that contaminants such as the volatile organics trichloroethene (TCE) and tetrachloroethene (PCE) would take approximately 7 to 18 years to travel this distance based on the range of retardation factors (1.0 and 2.4) measured in the same study (Barber et al. 1988).
Based upon these calculations, a value of twenty years was used as the travel time for our target class of compounds across a typical ZOC on the Cape. Thus, for example, a land use impact value for a well in 1991 would be calculated using 1971 land use map data within the ZOC for that well; calculation of an impact value for a well in 1980 would require use of land use data interpolated for 1960 from the 1951 and 1971 land use maps.
Well Operation Data
Years in which each of the 132 wells found to be operating on the Cape at some time during the period studied (1972-1995) were deduced from well operation data documented by two USGS studies of southeastern Massachusetts water supplies (LeBlanc et al. 1986; Bratton 1991), well data from Massachusetts Department of Environmental Protection (MA DEP) (1997) and information provided directly by water suppliers.
Pumping volumes for wells, used to determine the percent contribution of each well to its respective district, were obtained from three different sources. LeBlanc et al. (1986) documents pumping volumes for wells operating on the Cape for the period 1975-76 and Bratton (1991) provides pumping volumes for wells operating in 1986. Pumping volumes for wells operating in 1996 were obtained from MA DEP (1997). Because pumping volume data are readily available for only the three discrete time points mentioned above, the pumping data for each of these three time points was assumed to apply throughout the decade in which the respective data point was documented. These data were augmented by pumping volume information supplied by district representatives.
Water quality data
Annual nitrate concentrations were obtained electronically from the Cape Cod Commission (formerly the Cape Cod Planning and Economic Development Commission), which has collected these measurements for virtually all public supply wells on the Cape since 1972. Nitrate concentrations for wells through 1986 are also presented in the State of the Aquifer Report (Janik 1987). Additional nitrate concentrations were obtained from the MA DEP and directly from water district representatives. After combining the data from all of these sources, gaps in nitrate concentrations were still present for some wells, typically spanning one to several years. For 132 wells over 23 years, there were 17 instances of a data gap spanning two years, 17 instances of a three to four year gap, 12 instances of a data gap spanning five to nine years, and three instances of a data gap spanning 10 or more years (14 years was the maximum). Missing values were interpolated by linear regression of existing data points. Additionally, a value for the year prior to the first available nitrate measurement (for years after 1972) was extrapolated by linear regression to reflect the observation made by district representatives that wells generally began operation the year prior to the first available nitrate measurement. Nitrate values for each district were sent to district officials for confirmation.
Land use data
Land use data that identify 26 types of land use including locations of residential, commercial, industrial, golf course, and agricultural land were developed from the MacConnell series of land use coverages, which are based on aerial photographs by the Resource Mapping Project at the University of Massachusetts-Amherst (MacConnell 1975; MacConnell et al. 1984). Land use coverages were developed for four years: 1951, 1971, 1984, and 1990. Resolution is three acres for the 1951 coverage and one acre for later years. These four land use maps were also used in conjunction with town parcel maps and orthophotos to identify the location and area of airports operating during those time points. Cemetery locations were obtained from a 1999 land use coverage obtained from MassGIS, a state office within the Massachusetts Executive Office of Environmental Affairs, because the maps from earlier time points did not distinguish cemetery locations uniquely.
Polygon coverages of major roads and highways were created from vector-based files downloaded from MassGIS. Lines representing roads in these vector-based files were buffered to the appropriate width (to create polygons) using information contained in supplementary databases containing road right-of-way width. Road information was assumed to apply back to the earliest land use coverage time point (1951).
Power line and railroad rights of way coverages were obtained from MassGIS. The railroad coverage was augmented with information from historical paper maps and a coverage obtained from the Cape Cod Commission documenting bike paths developed on former railroad rights of way. Paper maps with parcel and street information obtained from public utilities were used to augment the power line rights-of-way coverage.
Public water supply data
Datasets locating all public supply wells and ZOCs operating in Massachusetts were obtained from MassGIS. The ZOCs were approved by MA DEP and defined for state regulatory purposes as “that area of an aquifer which contributes water to a well under the most severe pumping and recharge conditions that can be realistically anticipated (180 days of pumping at safe yield, with no recharge from precipitation)” (310 CMR 22.02). The datasets comprise ZOCs, referred to in regulatory context as Zone IIs, delineated through 1996. These Zone IIs are linked to the public water supply wells used to delineate the Zone IIs through a unique identification number. A dataset containing additional ZOCs was obtained from the Cape Cod Commission and combined with the MassGIS data. A new unique identification number was given to each ZOC in this combined ZOC dataset. To ensure that all wells were linked to appropriate ZOCs, the positions of all wells with respect to ZOCs were verified using GIS.
Tabulations of annual chemical measurements for individual wells, derived from the Cape Cod Commission and MA DEP databases, were sent to the respective district representatives so that these data could be checked and verified with district records. The values for fractional volume contributions of each well to its respective district, calculated based on literature values as discussed, were also reviewed by district representatives for accuracy.
Nitrate concentrations in wells range from values of zero (representing undetectable levels) to the highest recorded concentration of 6.0 mg/L measured in one public supply well in 1979. Nitrate levels in wells never surpass the maximum contaminant level (MCL) of 10 mg/L set by the Environmental Protection Agency in any wells during the period documented. Nitrate concentrations in a number of wells do approach 5.0 mg/L, a level set as a regional planning guideline for the Cape (Cape Cod Commission 1993). Approximately 60 % of the operating wells (81 out of 132) have had nitrate concentrations greater than or equal to twice the maximum background level of 0.2 mg/L (i.e., original concentrations of 0.4 mg/L or greater) for two years or more. Approximately 20 % of the source-IDs (30 out of 132) have had nitrate greater than or equal to ten times the maximum background level (i.e., original concentrations of 2.0 mg/L or greater) for two or more years.
Variations in well nitrate concentrations over time can be characterized generally as (1) having an upward trend with time, (2) being elevated, but with no apparent trend, and (3) falling near or within maximum background levels (0.2 mg/L) for the Cape. Trends in nitrate concentration with time are generally distinct. In contrast, nitrate concentrations in a number of wells remain elevated within a certain range (typically 1 to 3 mg/L) throughout the study period. Finally, other wells show little, if any, excess nitrate above background levels.
Statistics (i.e., mean, median, 75th and 90th percentiles) generated for annual excess nitrate concentrations, considering all wells operating in a given year, indicate a generally increasing trend in nitrate impact to Cape wells for the study period. The median excess nitrate concentration rises from 0.00 mg/L (no impact) in 1972 to 0.31 mg/L in 1995, while the mean concentration increases from 0.26 mg/L to 0.72 mg/L during this period. Approximately 10% of wells had excess nitrate concentrations greater than or equal to 1.0 mg/L in 1972, while more than 25% of wells had 1.0 mg/L or greater nitrate in 1995.
Land Use in ZOCs
While well chemistry data for nitrate indicate impact at the well contemporaneous with measurement, land use analysis within well ZOCs provides information on future impact to wells. The fraction of total ZOC area designated for each of three categories of land use was calculated for this analysis. Residential land use constitutes the largest fraction of ZOC areas (ZOC-residential fraction) on Cape Cod for all four time periods analyzed, and the median fraction of land in ZOCs that is residential rises over the forty year time span from a value of 2% in 1951 to 23% in 1990. The maximum ZOC-residential fraction observed over this time period ranges from 33% in 1951 (SSI ZOC ID 28) up to 80% in 1984 and 1991 (SSI ZOC ID 50).
The fraction of ZOC land use area on which pesticide application occurs (ZOC-pesticide fraction) remains relatively constant during the forty year period. Median values of the ZOC-pesticide fraction range from 5% to 6%. Maximum ZOC-pesticide fraction values fall also in a narrow range from 24% in 1951 to 21% in 1971 through 1991.
Land use area within ZOCs used for commercial, industrial, waste disposal, transportation (major roads, highways, and airports), and military purposes (ZOC-commercial fraction) is generally much smaller than that used for either residential development or pesticide application, although the mean and median values for the ZOC-commercial fraction do increase over the time period. Median values for ZOC-commercial fraction rise from 1.0% in 1951 to 4.0% in 1990, mean values increase in a similar fashion from 5.0% to 9%. Maximum values for the ZOC-commercial fraction range from 69% in 1951 to 82% in 1984 and 1990 (all values for SSI ZOC ID 43, Barnstable Water Company district). The intersection of airport land use with this ZOC causes the ZOC-commercial fraction for SSI ZOC ID 43 to be so elevated. Several other ZOCs have considerable commercial fractions, including SSI ZOC IDs 39 (29% to 58%), 42 (32% to 58%), and 44 (25% to 44%) (all in Barnstable Water Company district) and SSI ZOC IDs 28 (29% to 61%) and 39 (29% to 58%) in Barnstable Fire district.
District Scores based on Well Chemistry
Concentrations were calculated using the volume fractional contributions of each well to its respective district for the periods 1972-79, 1980-89, and 1990-95, the annual well nitrate concentrations for the period 1972-95. Note that district concentrations typically fall when impacted wells were taken out of operation. The Cotuit district appears to have the highest nitrate concentrations consistently across the study period, with most values between 1.0 and 2.0.
The Brewster district appears to have the least historical and current impact from nitrate contamination. District-nitrate concentrations for the Brewster district are consistently below 0.1.
To facilitate comparison of district-nitrate concentrations among districts located in proximity to each other, district concentrations are presented in groups based on geographic location on the Cape. Districts were divided into the following town groups, in a direction moving from the Upper Cape to the Lower Cape: (1) the town of Bourne, comprising the North Sagamore, South Sagamore, Bourne and Buzzards Bay districts, (2) the towns of Sandwich, Falmouth and Mashpee and their respective districts, (3) the town of Barnstable, comprising the Barnstable Fire district, Barnstable Water Company district, the Cotuit district, and the Centerville-Osterville-Marstons Mills district, (4) the towns of Yarmouth and Dennis and their respective districts, and (5) the towns of Brewster, Orleans, Harwich, and Chatham, and their respective districts. The Provincetown district is geographically isolated at the lower Cape from the other districts.
When the districts are grouped geographically in this manner, some intra-group similarities can be observed, for the most part for district nitrate concentrations with time. For the Bourne town group, district nitrate concentrations for both the North Sagamore and South Sagamore districts are relatively high early in the 1970s before falling to the range of values (0.0 to 0.5) observed for the Bourne and Buzzards Bay districts throughout the study period. The Sandwich, Mashpee and Falmouth districts all have district nitrate concentrations varying similarly within the range of 0.0 to 0.5. The districts in the town of Barnstable all appear to exhibit a slight increase in district nitrate concentrations through the study period, although the ranges over which these increases occur are variable. Districts for the towns of Yarmouth and Dennis also exhibit an increase in district nitrate concentrations over the study period, with generally less inter-annual variability than is observed for the four districts in the town of Barnstable. The Harwich district, whose wells and zones of contribution lie near the town boundary with Dennis, exhibits an increase in district nitrate concentrations very similar in range to that of the Dennis district. Districts for the towns of Brewster and Orleans both are virtually unimpacted by nitrate contamination, as indicated by their mutual lack of district nitrate concentrations greater than 0.1 for the entire study period. The similarity between these two districts may be due in part to the fact that zones of contribution for Orleans district wells extend over into the town of Brewster, near the zones of contribution for Brewster district wells. Nitrate concentrations for the Chatham district show a smaller increase than those for the neighboring Harwich district.
Aravena, R., M. L. Evans and J. A. Cherry (1993). Stable isotopes of oxygen and nitrogen in source identification of nitrate from septic systems. Ground Water 31(2): 180-186.
Arbuckle, T., S. Hrudey, W. Krasner, J. Nuckols and et al (2002). Assessing exposure in epidemiologic studies to disinfection by-products in drinking water: Report from an international workshop. Environmental Health Perspectives 110(1): 53-60.
Barber, L. B., E. M. Thurman, M. P. Schroeder and D. R. LeBlanc (1988). Long-term fate of organic micropollutants in sewage-contaminated groundwater. Environmental Science & Technology 22(2): 205-211.
Barlow, P. M. (1994). Particle-tracking analysis of contributing areas of public- supply wells in simple and complex flow systems, Cape Cod, Massachusetts. Marlborough, Massachusetts, U. S. Geological Survey.
Bean, J. A., P. Isacson, J. W.J. Hausler and J. Kohler (1982). Drinking water and cancer incidence in Iowa: I. Trends and incidence by source of drinking water and size of municipality. American Journal of Epidemiology 116(6): 912-923.
Belfit, G. C. (1984). Septage/Sewage Disposal Practices on Cape Cod. Barnstable, MA, Cape Cod Planning and Economic Development Commission.
Belfit, G. C., T. Cambareri, D. McCaffery, G. Prahm and B. Smith (1993). Monomoy Lens Groundwater Protection Project. Barnstable, MA, Cape Cod Commission Water Resources Office.
Bernstein, L. (2002). Epidemiology of endocrine-related risk factors for breast cancer. Journal of Mammary Gland Biology and Neoplasia 7(1): 3-15.
Bove, F., Y. Shim and P. Zeitz (2002). Drinking water contaminants and adverse pregnancy outcomes: A review. Environmental Health Perspectives 110(1): 61-74.
Bratton, L. (1991). Public Water-Supply In Massachusetts, 1986. Boston, MA, US Geological Survey and Massachusetts Department of Environmental Management Office of Water Resources.
Brody, J. G., A. Aschengrau, R. A. Rudel, C. H. Swartz and N. I. Maxwell (manuscript in preparation). Breast cancer risk and historical exposure to pesticides: Home use, occupational, and farm residence. Newton, MA, Silent Spring Institute.
Brody, J. G., R. A. Rudel, S. J. Melly and N. I. Maxwell (1998). Endocrine Disruptors and Breast Cancer. Forum for Applied Research and Public Policy 13(3): 24-31.
Brody, J. G., D. J. Vorhees, S. J. Melly, S. R. Swedis, P. J. Drivas and R. A. Rudel (2002). Using GIS and historical records to reconstruct residential exposure to large-scale pesticide application. Journal of Exposure Analysis and Environmental Epidemiology 12: 64-80.
Buxton, H. National Reconnaissance of Emerging Contaminants in the Nation's Stream Waters. 2000, U. S. Geological Survey.
Cambareri, T. C. (1997). personal communication. Barnstable, MA
Cantor, K. P. (1997). Drinking water and cancer. Cancer Causes and Control 8: 292-308.
Cape Cod Commission (1993). Monomoy Lens Groundwater Protection Project. Barnstable, MA, Water Resources Office.
Corwin, D. L., P. J. Vaughan and K. Loague (1997). Modeling nonpoint source pollutants in the vadose zone with GIS. Environmental Science & Technology 31: 2157-2175.
Daughton, C. G. and T. A. Ternes (1999). Pharmaceuticals and personal care products in the environment: Agents of subtle change. Environmental Health Perspectives 107(suppl 6): 907-937.
Davis, D. L., H. L. Bradlow, M. Wolff, T. Woodruff, D. G. Howl and H. Anton-Culver (1993). Medical hypothesis: xenoestrogens as preventable causes of breast cancer. Environmental Health Perspectives 101(5): 372-377.
Deane, M., S.H. Swan, J.A. Harris, D.M. Epstein and R.R. Neutra (1989). Adverse pregnancy outcomes in relation to water contamination, Santa Clara County study, California, 1980-1981. American Journal of Epidemiology 129: 894-904.
Desbrow, C., E. J. Routledge, G. C. Brighty, J. P. Sumpter and M. Waldock (1998). Identification of Estrogenic Chemicals in STW Effluent. 1. Chemical Fractionation and in Vitro Biological Screening. Environmental Science & Technology 32(11): 1549-1558.
Desbrow, C., M. Waldock, D. Sheahan, M. Blackburn, E. Routledge, J. Sumpter and G. Brighty (1996). The Identification of Compounds Causing Endocrine Disruption in Fish in UK Rivers. Society of Environmental Toxicology and Chemistry 17th Annual Meeting, Washington DC.
DeSimone, L. A. and P. M. Barlow (1995). A Nitrogen-Rich Septage-Effluent Plume in a Glacial Aquifer, Cape Cod, Massachusetts, February 1990 through December 1992. Marlborough, MA, Massachusetts Department of Environmental Protection, Office of Watershed Management.
DeSimone, L. A. and B. L. Howes (1998). Nitrogen transport and transformation in a shallow aquifer receiving wastewater discharge: A mass balance approach. Water Resources Research 34(2): 271-285.
Doyle, T., W. Zheng, J. Cerhan, C. Hong, T. Sellers, L. Kushi and et. al. (1997). The association of drinking water source and chlorination by-products with cancer incidence among postmenopausal women in Iowa: a prospective cohort study. American Journal of Public Health 87(7): 1168-1176.
Dunnick, J. K., M. R. Elwell, J. Huff and J. C. Barrett (1995). Chemically induced mammary gland cancer in the National Toxicology Program's carcinogenesis bioassay. Carcinogenesis 16(2): 173-179.
Eckhardt, D. A. V. and P. E. Stackelberg (1995). Relation of ground-water quality to land use on Long Island, New York. Ground Water 33(6): 1019-1033.
Erickson, B. E. (2002). Analyzing the ignored environmental contaminants. Environmental Science & Technology 36(7): 140A-145A.
Folmar, L. C., N. D. Denslow, V. Rao, M. Chow, D. A. Crain, J. Enblom, J. Marcino and L. J. Guilette (1996). Vitellogenin induction and reduced serum testosterone concentrations in feral male carp (Cyprinus carpio) captured near a major metropolitan sewage treatment plant. Environmental Health Perspectives 104(10): 1096-1101.
Gallagher, M. D., J.R. Nuckols, L. Stallones and D.A. Savitz (1998). Exposure to trihalomethanes and adverse pregnancy outcomes. Epidemiology 9: 484-489.
Goldberg, S. J., M.D. Lebowitz, E.J. Graver and S. Hicks (1990). An association of human congenital cardiac malformations and drinking water contaminants. Journal of the American College of Cardiology 16: 155-164.
Gottlieb, M. S., J. K. Carr and J. R. Clarkson (1982). Drinking water and cancer in Louisiana: A retrospective mortality study. American Journal of Epidemiology 116: 652-67.
Grady, S. J. (1993). Effects of Land Use on Quality of Water in Stratified-Drift Aquifers In Connecticut. Hartford, CT, US Geological Survey.
Harman, W. A., C. J. Allan and R. D. Forsythe (2001). Assessment of potential groundwater contamination sources in a wellhead protection area. Journal of Environmental Management 62: 271-282.
Heaton, T. H. E. (1986). Isotopic studies of nitrogen pollution in the hydrosphere and atmosphere: A review. Chemical Geology 59: 87-102.
Janik, D. S. (1987). State of the Aquifer Report. Barnstable, MA, Cape Cod Planning and Economic Development Commission.
Jobling, S., M. Nolan, C. R. Tyler, G. Brighty and J. P. Sumpter (1998). Widespread Sexual Disruption in Wild Fish. Environmental Science and Technology 32: 2498-2506.
Jobling, S., T. Reynolds, R. White, M. G. Parker and J. P. Sumpter (1995). A variety of environmentally persistent chemicals, including some phthalate plasticizers, are weakly estrogenic. Environmental Health Perspectives 103: 582-587.
Kaplan, N. and M. Margaritz (1986). A nitrogen-isotope study of the sources of nitrate contamination in groundwater of the pleistocene coastal plain aquifer, Israel. Water Resources 20(2): 131-135.
Kelsey, J. L. and M. D. Gammon (1991). The epidemiology of breast cancer. CA-A Cancer Journal for Clinicians 41(3): 146-165.
Kolpin, D. W., J. E. Barbash and R. J. Gilliom (1998). Occurrence of pesticides in shallow groundwater of the United States: Initial results from the National Water-Quality Assessment Program. Environmental Science & Technology 32: 558-566.
Kolpin, D. W., E. T. Furlong, M. T. Meyer, E. M. Thurman, S. D. Zaugg, L. B. Barber and H. T. Buxton (2002). Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance. Environmental Science and Technology 36(6): 1202-1211.
Komor, S. C. and H. W. Anderson (1993). Nitrogen isotopes as indicators of nitrate sources in Minnesota sand-plain aquifers. Ground Water 31(2): 260-270.
Larkowski, D. (2001). personal communication. Dennis Water District, Dennis, MA
LeBlanc, D. R., J. H. Guswa, M. H. Frimpter and C. J. Londquist (1986). Ground-Water Resources of Cape Cod, Massachusetts (map), U.S. Geological Survey, Massachusetts Water Resources Commission, Barnstable County, and National Park Service.
Levin, R. B., P.R. Epstein, T.E. Ford and e. al. (2002). U.S. drinking water challengers in the twenty-first century. Environmental Health Perspectives 110(suppl 1): 43-53.
Loague, K. (1994). Regional scale gound-water vulnerability estimates: impact of reducing data uncertainties for assessments in Hawaii. Ground Water 32(4): 605-616.
Loague, K., D. L. Corwin and T. R. Ellsworth (1998). The challenge of predicting nonpoint source pollution. Environmental Science & Technology 32: 130A-133A.
MacConnell, W., D. Swartout and J. Stone (1984). Land Use Update for Cape Cod and the Islands with Area Statistics for 1951, 1971, and 1980. Amherst, MA, University of Massachusetts at Amherst, College of Food and Natural Resources, Massachusetts Agricultural Experiment Station.
MacConnell, W. P. (1975). Remote sensing 20 years of change in Massachusetts 1952-1972: Classification manual, land use and vegetative cover mapping. Amherst, MA, University of Massachusetts at Amherst, Massachusetts Agricultural Experiment Station.
Massachusetts Department of Environmental Protection (1997). Monitoring data for Cape Cod public water supplies, 1988 - 1995. Boston, MA.
McLay, C. D. A., R. Dragten, G. Sparling and N. Selvarajah (2001). Predicting groundwater nitrate concentrations in a region of mixed agricultural land use: a comparison of three approaches. Environmental Pollution 115: 191-204.
Mueller, B., K. Newton, E. Holly and S. Preston-Martin (2001). Residential water source and the risk of childhood brain tumors. Environmental Health Perspectives 109(6): 551-556.
Persky, J. H. (1986). The Relation of Ground-Water Quality to Housing Density, Cape Cod, Massachusetts. Boston, MA, US Geological Survey and Cape Cod Planning and Economic Development Commission.
Purdom, C. E., P. A. Hardiman, V. J. Bye, N. C. Eno, C. R. Tyler and J. P. Sumpter (1994). Estrogenic effects of effluents from sewage treatment works. Chemical Ecology 8: 275-285.
Quadri, C. G. (1984). The Relationship Between Nitrate-Nitrogen Levels in Groundwater and Land Use on Cape Cod. Barnstable MA, Cape Cod Planning and Economic Development Commission.
Raloff, J. (1998). Drugged Waters. Science News 153: 187-189.
Reif, J. S., M. C. Hatch, M. Bracken, L. B. Holmes, B. A. Schwetz and P. C. Singer (1996).
Reproductive and developmental effects of disinfection by-products in drinking water. Environmental Health Perspectives 104(10): 1056-1061.
Richards, R. P. (1997). Cultural and hydrogeological factors that influence well water quality. Environmental Science & Technology 31(3): 632-638.
Robertson, W. D., J. A. Cherry and E. A. Sudicky (1990). Ground-water contamination from two small septic systems on sand aquifers. Ground Water: 82-92.
Rodenback, S. E., L.M. Sanderson and A. Rene (2000). Maternal exposure to trichloroethylene in drinking water and birth-weight outcomes. Archives of Environmental Health 55(3): 188-194.
Routledge, E. J., D. Sheahan, C. Desbrow, G. C. Brighty, M. Waldock and J. P. Sumpter (1998). Identification of Estrogenic Chemicals in STW Effluent. 2. In Vivo Responses in Trout and Roach. Environmental Science & Technology 32(11): 1559-1565.
Rudel, R. A., David Camann, John D Spangler, Dana B. Barr and Julia G. Brody (manuscript in preparation). Household exposure to phthalates, pesticides, alkylphenols, PBDEs, and other hormonally active agents and animal mammary carcinogens in indoor air, dust, and residents' urine on Cape Cod, MA. Newton, MA, Silent Spring Institute.
Rudel, R. A., P. Geno, S. J. Melly, G. Sun and J. G. Brody (1998b). Identification of alkylphenols and other estrogenic phenolic compounds in wastewater, septage, and groundwater on Cape Cod, Massachusetts. Environmental Science and Technology 32(7): 861-869.
Rudel, R. A., P. W. Geno, G.Sun, A. Yau, J. D. Spengler, J. Vallarino and J. G. Brody (2001). Indentification of selected hormonally active agents in animal and mammary carcinogens in commercial and residential air and dust samples. Journal of Air and Waste Management Association 51: 499-513.
Rudel, R. A., A. M. Soto, C. Sonnenschein, M. Luizzi, B. Weill, S. J. Melly, P. W. Geno and J. G. Brody (1998a). Estrogenic components in wastewater, septage, and groundwater: A comparison between chemical analysis and results from and MCF-7 cell proliferation bioassay. NIEHS/USEPA Endocrine Disruptors Investigators Meeting, Research Traiangle Park NC.
Silent Spring Institute (1997). Cape Cod Breast Cancer and Environment Study: Final report, December 8, 1997. Newton, MA.
Silent Spring Institute (2000). Exposure assessment in the Cape Cod Breast Cancer and Environment Study [draft]. Newton, MA, Silent Spring Institute.
Silva, E., N. Rajapakse and A. Kortenkamp (2002). Something from "nothing" -- Eight weak estrogenic chemicals combined at concentrations below NOECs produce significant mixture effects. Environmental Science and Technology 36(8): 1751-1756.
Silva, L. and D. D. Williams (2001). Buffer zone versus whole catchment approaches to studying land use impact on river water quality. Water Resources 35(14): 3462-3472.
Snyder, S. A., T. L. Keith, D. A. Verbrugge, E. M. Snyder, T. S. Gross, K. Kannan and J. P. Giesy (1999). Analytical methods for detection of selected estrogenic compounds in aqueous mixtures. Environmental Science and Technology 33: 2814-2820.
Soto, A. M., H. Justicia, J. W. Wray and C. Sonnenschein (1991). P-Nonyl-phenol: an estrogenic xenobiotic released from "modified" polystyrene. Environmental Health Perspectives 92: 167-173.
Soto, A. M., C. Sonnenschein, K. L. Chung, M. F. Fernandez, N. Olea and F. O. Serrano (1995). The E-SCREEN assay as a tool to identify estrogens: An update on estrogenic environmental pollutants. Environmental Health Perspectives 103(Suppl 7): 113-122.
Squillace, P. J., J. C. Scott, J. M. Michael, B. T. Nolan and D. W. Kolpin (2002). VOCs, pesticides, nitrate, and their mixtures in groundwater used for drinking water in the United States. Environmental Science and Technology 36(9): 1923-1930.
Sumpter, J. P. and S. Jobling (1995). Vitellogenesis as a biomarker for estrogenic contamination of the aquatic environment. Environmental Health Perspectives 103(Supplement 7): 173-178.
Swan, S. H., G. Shaw, J. A. Harris and R. R. Neutra (1989). Congenital cardiac anomalies in relation to water contamination, Santa Clara County, California, 1981-1983. American Journal of Epidemiology 129: 885-863.
US Geological Survey (1985). National Water Summary 1984: Hydrologic Events, Selected Water Quality Trends, and Ground-Water Resources. United States Geological Survey Water-Supply Paper 2275. Washington DC, US Geological Survey.
Ward, M. H., S. Mark, K. Cantor, D. Weisenburger, A. Correa-Villasenor and S. Zahm (1996). Drinking water nitrate and the risk of non-Hodgkin’s lymphoma. Epidemiology 7(5): 465-471.
White, R., S. Jobling, S. A. Hoare, J. P. Sumpter and M. G. Parker (1994). Environmentally persistent alkylphenolic compounds are estrogenic. Endocrinology 135(1): 175-182.
Wilkins, J. R. and G. W. Comstock (1981). Source of drinking water at home and site-specific cancer incidence in Washington County, Maryland. American Journal of Epidemiology 114(2): 178-190.
Wilkins, J. R., N. A. Reiches and C. W. Kruse (1979). Organic chemical contaminants in drinking water and cancer. American Journal of Epidemiology 110(4): 420-448.
Wolff, M. S., G. W. Collman, J. C. Barrett and J. Huff (1996). Breast cancer and environmental risk factors: epidemiological and experimental findings. Annual Review of Pharmacology and Toxicology 36: 573-596.