Wisconsin's environmental public health tracking network: information systems design for childhood cancer surveillance.

In this article we describe the development of an information system for environmental childhood cancer surveillance. The Wisconsin Cancer Registry annually receives more than 25,000 incident case reports. Approximately 269 cases per year involve children. Over time, there has been considerable community interest in understanding the role the environment plays as a cause of these cancer cases. Wisconsin's Public Health Information Network (WI-PHIN) is a robust web portal integrating both Health Alert Network and National Electronic Disease Surveillance System components. WI-PHIN is the information technology platform for all public health surveillance programs. Functions include the secure, automated exchange of cancer case data between public health-based and hospital-based cancer registrars; web-based supplemental data entry for environmental exposure confirmation and hypothesis testing; automated data analysis, visualization, and exposure-outcome record linkage; directories of public health and clinical personnel for role-based access control of sensitive surveillance information; public health information dissemination and alerting; and information technology security and critical infrastructure protection. For hypothesis generation, cancer case data are sent electronically to WI-PHIN and populate the integrated data repository. Environmental data are linked and the exposure-disease relationships are explored using statistical tools for ecologic exposure risk assessment. For hypothesis testing, case-control interviews collect exposure histories, including parental employment and residential histories. This information technology approach can thus serve as the basis for building a comprehensive system to assess environmental cancer etiology. Key words: childhood cancer, environment, exposures, informatics, information systems, public health, surveillance, tracking. Environ Health Perspect 112:1434-1439 (2004). doi:10.1289/ehp.7150 available via http://dx.doi.org/[Online 3 August 2004]

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Even though the environment is known to play an important role in human health, no comprehensive, integrated, state or national system exists to track the countless hazards, exposures, and ensuing health effects that could be due to environmental factors [Environmental Public Health Tracking Network (EPHTN) 2004]. For example, when environment is broadly defined to include occupational exposures, environmental pollution, and ionizing and ultraviolet radiation, 9% of cancer deaths have been attributed to known environmental causes (Harvard Report on Cancer Prevention 1996). And yet, what ultimately is known may be extremely limited precisely because a comprehensive, ongoing environmental health tracking system linking hazards and exposures to health effects does

not exist.

In response to this challenge, the EPHTN program was established to develop a comprehensive environmental public health surveillance system. The program involves

   the ongoing collection, integration, analysis,
   interpretation, and dissemination of data on
   environmental hazards; exposures to those hazards; and
   related health effects. The goal of tracking is to
   provide information that can be used to plan,
   apply, and evaluate actions to prevent and control
   environmentally related diseases. (EPHTN 2004)

Public health depends heavily upon information science. Increasingly, modern public health practice requires advanced, networked, computer-assisted technology to process a wide variety of information assets that monitor disease, analyze and detect risks, provide decision support, alert and communicate with those who need to know, continuously educate and train, support and manage public health response, and measure effectiveness. This recognition has brought about the specification and development of the Public Health Information Network (PHIN) by the Centers for Disease Control and Prevention (CDC) and its public health partners (e.g., state and local public health agencies and professional associations, for example, the Association of State and Territorial Health Officials, Council of State and Territorial Epidemiologists, Association of Public Health Laboratories, National Association of County and City Health Officials).

It has been estimated that environmental pollutants are responsible for a substantial attributable fraction of certain childhood diseases and their associated health care costs (Landrigan et al. 2002). The attendant environmental causes for childhood lead poisoning, asthma, cancer, and developmental disabilities alone may account for as much as $64.8 billion or 2.8% of total U.S. health care costs annually (Landrigan et al. 2002). The environmental attributable fraction for childhood cancer is estimated at 5% (range, 2-10%), and annual health care costs are estimated at $333 million (Landrigan et al. 2002).

Indeed, studies of childhood cancer have discovered a number of biologically plausible environmental associations (Zahm and Devesa 1995), including hazardous air pollutants and leukemia (Reynolds et al. 2003), leukemia and pesticide use (Reynolds et al. 2002), leukemia and electric and magnetic fields (Brain et al. 2003), leukemia and ionizing radiation (Axelson et al. 2002), nervous system cancers and parental pesticide exposures (Feychting et al. 2001), and road traffic (benzene exposures) and leukemia (Crosignani et al. 2004).

In Wisconsin an estimated 25,800 new cases of cancer are expected to have occurred in 2003 (American Cancer Society 2004). Approximately 269 will occur in children. Presently, the environmental contribution and etiology of these cases are unknown. Over the years, many of these childhood cancer cases have been the source of numerous requests for labor-intensive, systematic environmental cancer cluster investigations and assessments (Fiore et al. 1990). However, because of the many intrinsic limitations of the "self-selected" cluster analytic approach (Rothman 1990), our experience has resulted in little, if any, insight into the potential causes, environmental or otherwise.

The maturation of networked information systems holds the promise of automating much of public health practice (Yasnoff 2001). By automating practice with advanced information technology, comprehensive surveillance and tracking systems may be created that have the statistical power and considerable information depth needed to understand the operation of complex disease causal factors. To this end, an information technology platform is described that is in development to support environmental public health tracking in Wisconsin. One application of effort is illustrated using cancer registry data.

Materials and Methods

Information technology development. A number of stakeholder committees were established to guide Wisconsin's PHIN (WI-PHIN) development and establish functional system requirements. Members included public health staff from the Wisconsin Department of Health and Family Services, the University of Wisconsin [university information technology staff (UW-DoIT)], WiscNet (networking provider), University of Wisconsin Medical School, and Wisconsin State Laboratory of Hygiene); other state agencies; local public health services; hospitals, the health insurance industry; and the Wisconsin business community.

The "Wisconsin Idea," used to develop the state's PHIN, involves rapid, state-of-the-art technology transfer from the university to government, businesses, and all citizens of the state and nation (Stark 1995). The WI-PHIN program is a 21st century embodiment of the idea, providing cutting-edge information technology services through research and development. UW-DoIT provides the information systems research, development, technical support, and hosting for WI-PHIN.

Wisconsin has combined its financial support from several categorical funding sources to develop a secure, web-based WI-PHIN portal to respond to bioterrorism and all other public health threats. Funding resources have included bioterrorism public health preparedness funding, National Electronic Disease Surveillance System (NEDSS)-NEDSS Base System (NBS) deployment, Wisconsin Maternal and Child Health Program, audiometric newborn screening, environmental public health tracking, among others.

Nationally, the PHIN has nine architectural functional specifications to guide development. NEDSS (2001) also specifies standards for database structure and electronic surveillance systems. Using the PHIN specifications as a guide (CDC 2002), EPHTN program area module (PAM) architectural requirements were developed for the childhood cancer tracking system. Together, the following attributes were applied to the design of the WI-PHIN portal: The EPHTN PAM must include the secure, automated exchange of cancer case data between public health-based and hospital-based cancer registrars; web-based supplemental data entry for environmental exposure confirmation and hypothesis testing; automated data analysis, visualization, and exposure-outcome record linkage; directories of public health and clinical personnel for role-based access control (RBAC) to sensitive surveillance information; public health information dissemination and alerting; and information technology security.

Surveillance example: hypothesis generation. Available data systems were inventoried and included systems describing hazards, exposures, health outcomes, and populations at risk. Sources of data included statewide health and environmental monitoring information and nationally available environmental and demographic data sets. Each system was qualitatively evaluated for its ability to be linked with other systems and for its coverage (years, geographic completeness, etc.). These systems would be contained in an integrated data repository (IDR) and linked through common attributes such as time and geographic location. System specifications required the support of two surveillance tracks hypothesis generation and hypothesis testing--to provide a more complete view of environmental, disease risk. Under the first track (hypothesis generation), cancer case data are sent electronically to WI-PHIN to populate the IDR, and basic surveillance/descriptive analyses are performed. Environmental data are then linked, and exposure-disease relationships are modeled using statistical and geographic information system (GIS) tools for ecologic exposure risk assessment. In the second track (hypothesis testing), case follow-back interviews are conducted using secure web-based data entry forms to obtain person-level exposure histories, including parental employment and residential histories, on cases and controls.

Childhood cancer data were obtained from the Wisconsin Cancer Registry for 1990 through 2000 (the most recent available year) (Wisconsin Department of Health and Family Services 2004). Cases were selected where individuals were younger than 20 years of age at diagnosis. Case frequencies were arrayed by cause, and age-adjusted rates were plotted by county for the most frequent cancer types.

Known exposure-disease relationships were ascertained by performing searches of the National Library of Medicine's PubMed (2004) database along with Internet searches. A work group was established to review findings and determine the web-based interview structure that would obtain risk-confirming and hypothesis-testing person-level exposure data on cases and controls.

To begin work on hypothesis generation, initial ecologic risk assessments were performed by correlating county air pollution exposure estimates (Technology Transfer Network 2002) with county age-adjusted cancer rates. Age-adjusted rates were constructed using the direct method and the 2000 census standard million population (U.S. Census Bureau 2004). A nonparametric correlation was then calculated between the ranks of county air pollutants and the rank of age-adjusted cancer rate.

Results

Information technology. Substantial progress has been made on the secure WI-PHIN portal since its start in 1999. Since its inception, > $7 million has been expended by combining public health information technology funding sources. Table 1 illustrates the information technology function requirements and Wisconsin's progress toward achieving them. Figure 1 provides a conceptual diagram of portal information flows and services.

[FIGURE 1 OMITTED]

The WI-PHIN has the capability to perform automated data exchange, use electronic clinical data for event detection, and use the web for secure data entry for case follow-up. An online survey capability was created that can support web-based manual entry for case reporting. Storage capacity for laboratory results is established, as is case management capability. Specific case management rules continue to be refined with the integration of PAM business requirements. SAS (version 8.2; SAS, Inc., Cary, NC) has been integrated into the portal for automating statistical analyses and visualization, and GIS services (using Environmental Systems Research Institute, Inc., Redlands, CA, products) continue to be developed. A directory of personnel has been established containing more than 2,400 registered WI-PHIN users from more than 900 agencies (state and local public health agencies, hospitals, local emergency response agencies, clinics, etc.). The directory contains user contact information (e.g., E-mail, phone, fax, pager, cell phone) along with other attributes (public health role, occupation, agency affiliation, professional skills/competencies/certifications, volunteer for emergency response, etc.). Users can create personal groups from the directory and synchronize entries to their personal digital assistants (PDAs).

A considerable alerting and information dissemination capability has been developed. A commercial call-tree service (simultaneous phone, fax, pager, E-mail for public health emergencies and other alerts) has been integrated into the portal. Scenarios are being developed that contact appropriate responders to specific public health emergencies. In addition, the web portal has public and private topic areas and threaded discussion forums that are associated with public health programs such as environmental tracking. Users may bookmark topic areas and receive E-mail updates (digests) when new content is added to their subscribed content areas. All users can easily add content to the portal (text, web links, upload documents, streaming media) and add events to the calendar. Calendar entries can be synchronized to a PDA. Distance training and streaming media services are available within the portal. These features have been used to create on-line courses to train public health staff throughout the state on public health topics (e.g., bioterrorism) and on portal features and use techniques.

Advanced security controls are a part of the portal design. Users must register with the State of Wisconsin Web Access Management System and obtain a login ID and password to access the system. Users then reach the web site with an encrypted secure socket layer (SSL) connection. RBAC determines enduser access to surveillance programs such as the NBS (infectious disease reporting), SPHERE (Secure Public Health Electronic Record of the Wisconsin Maternal and Child Health Program), WE-TRAC (Wisconsin Early Hearing Detection and Intervention Referral and Coordination System), and the EPHTN childhood cancer pilot.

Hardware is also protected. Servers have redundant firewalls, virus scanning, continuous external port scanning and probing, and intrusion detection appliances. The system is continually backed up, and continuity of operations is assured through site mirroring planning and procedural implementation. Administrative security policies cover appropriate conduct and use documents, access auditing and logging, and on-line training.

Hypothesis generation example: benzene and leukemia. Table 2 displays the environmental, population, and health outcome data systems that are under evaluation for inclusion and linkage in the EPHTN IDR. Wisconsin childhood cancer cases are displayed in Table 3. A total of 2,960 cases were selected. Leukemia, lymphatic, and brain cancers accounted for 51% of the cases. These were selected for rate analysis, plotting, literature review, and follow-back to assess environmental contributions. More than 1,000 articles/sources were obtained, and environmental exposure history development continues (Agency for Toxic Substances and Disease Registry 2004) for web-based data entry.

A preliminary hypothesis-generating assessment was made with some of the currently available data. These data consisted of the Wisconsin Cancer Registry (Wisconsin Department of Health and Family Services 2004), National Air Toxics Assessment data for 1996 (Technology Transfer Network 2002), and census county population estimates. Age-adjusted county cancer rates were correlated to each of the pollutants. Estimated inhalation concentrations for benzene are depicted by county in Figure 2. Figure 3 plots the age-adjusted leukemia incidence by county. Correlating the two revealed a significant rank correlation between exposure and disease (R = 0.31, p < 0.01). Indeed, benzene appears repeatedly in the literature as a potential cause of leukemia.

[FIGURES 2-3 OMITTED]

Discussion

The PHIN information technology functions provide a clear implementation plan to automate public health practice. Automation will be a tremendous benefit to the public health system, improving efficiency, coordination, assurance, response, and evaluation. However, substantial resources are necessary to accomplish this. An EPHTN program meeting the PHIN requirements is only possible by combining multiple funding sources that support public health information technology. Wisconsin has done this and has made substantial progress in its development of WI-PHIN and EPHTN, but much work remains. Continued federal funding and support from other sources will be necessary if the many ambitious PHIN goals are to be achieved.

Wisconsin's EPHTN childhood cancer pilot PAM has established a PHIN-compatible framework to track the environmental causes of disease. Two mechanisms are specified--hypothesis generating and hypothesis testing. Hypothesis generation occurs through the linking of environmental exposure databases (by time and place) with health outcome and population data. Ecologic risks can be generated that suggest avenues for further investigation. When a subset of the available data was used, a population-level rank correlation was found between estimated human inhalation benzene exposures and childhood leukemia risk, corroborating previous findings. However, the "ecologic fallacy" is the chief limitation of this approach: There can be underlying heterogeneity of exposure levels and covariates within the group or area assigned its population-level fixed value (Rothman and Greenland 1998). Hypothesis testing provides a solution to this by creating a web-based follow-back form to capture individual, person-level exposure histories on cases and controls. Known risks can be assessed on the questionnaire, and hypothesized causes can be tested in the case-control framework. These results can then be used to construct environmental attributable fractions for case incidence.

But both of these approaches are limited in that neither obtains biologic or environmental markers of actual exposures or individual susceptibility. In addition, pre-existing exposure monitoring data may be further limited because much of the available information is collected for regulatory purposes. These environmental monitoring systems have not been designed to substantially support environmental health tracking systems. Reliable and valid laboratory measures of environmental exposures, cancer risk, and individual susceptibility (i.e., gene-environment interactions) are needed, and they would considerably increase our understanding of the environment's contribution to childhood cancer (Grufferman 1998). Although this detailed environmental monitoring activity is outside of the project scope largely because of funding, the EPHTN PAM is positioned to integrate these kinds of measures because it can accept laboratory result messaging.

Through the Wisconsin Idea, the WI-PHIN program has developed innovative information technology solutions that can serve as an implementation model for others. Best practices and lessons learned are emerging as the WI-PHIN develops its pilot program for environmental childhood cancer tracking. This experience will be shared with other states seeking to better understand the relationship between childhood cancer and the environment using advanced information technology. This approach can then serve as the foundation building toward a comprehensive system to assess environmental cancer etiology while extending the method to tracking other environmental exposure and disease relationships.

Table 1. PHIN information technology functional standards and
Wisconsin implementation status.

PHIN IT function
specification                 PHIN standard implementation (a)

1. Automated data    Establish ebXML-compliant SOAP web service via an
   exchange          HTTPS connection after appropriate authentication;
                     encrypted messages use industry standard ebXML
                     format and include standardized HL7, version 2.3;
                     HL7, version 3.0; X12; and LDIF message content.

2. Electronic        Data received via ebXML messaging identified in
   clinical data:    function 1 above stored using NEDSS logical data
   event detection   model specification of the HL7 Reference
                     Information Model and extensions. This allows
                     standards-based interaction with commercial
                     products for reporting, statistical analysis,
                     geographic mapping, and automated outbreak
                     detection algorithms, as well as the processing of
                     queued data from and for electronic messages; the
                     data repository should implement common database
                     technology (e.g., Sybase, Oracle, or SOL Server)
                     running on servers using Windows NT/2000/XP,
                     LINUX, or UNIX and supporting ODBC, ANSI standard
                     SOL, and JDBC access.

3. Web: manual       Secure browser-based data entry for data input and
   data entry        results other reporting from and to primary care
                     clinical care sites and sources; develop web
                     browser-based data systems using open-platform
                     web servers supporting generic web browsers (HTML
                     3.0+/Java)

4. Laboratory        Data stored in HI-7-compatible data formats;
   result            coding of request and results messages with the
   information       LOINC and SNOMED vocabularies, information
                     messaging using function 1.

5. Case management   Using functions 1-4 above, cases should be
                     "linked" and traceable from detection via
                     electronic sources of clinical data or manual
                     entry of case data, and through confirmation
                     via laboratory result reporting.

6. Analysis and      Commercial reporting systems integrated using ODBC
   visualization     and JDBC data access; security and access control
                     applied for remote access using SSL and
                     certificate- or token-based authentication with
                     appropriate authentication and authorization.

7. Personnel         Directories present an LDAP version 3.0 standard-
   directories       based service allowing data access and sharing
                     across multiple computer systems and appropriate
                     organizational boundaries; directory information
                     transfer and sharing supports standard message
                     format (LDIF); data fields use X.500 standards for
                     field type and length.

8. Information       Receive, manage, and disseminate alerts,
   dissemination     protocols, procedures, and other information for
   and alerting      dissemination to public health workers, primary
                     care physicians, public health laboratories, and
                     other partners; ability to "push" information via
                     messages and allow participants to "pull"
                     information  via the browsing of secure web sites,
                     support of interactive communication sites for
                     threaded discussion capabilities.

9. IT Security       Meet/exceed HIPAA requirements; client and server
                     X.509 digital certificates or comparable strong
                     authentication methodology for access, establish
                     RBAC protocols and effective administrative
                     policies; employ desktop/server virus scanning,
                     intrusion detection, network vulnerability
                     analysis, security policy monitoring, regular
                     penetration testing, and active threat
                     intelligence; ensure continuity of operations
                     through planning and procedure implementation.

PHIN IT function
specification                         WI-PHIN status

1. Automated data    Web service capability established; test
   exchange          deployment with several laboratories.

2. Electronic        Data repository established using Oracle 9i;
   clinical data:    messaging of laboratory data in pilot/
   event detection   production, hospital tumor registries
                     contacted for case messaging, pilot
                     volunteers identified.

3. Web: manual       Function established; system operates on
   data entry        Sun Solaris using Weblogic application server;
                     capability will be used to obtain supplemental
                     risk and exposure history data.

4. Laboratory        Storage capability established; vocabulary
   result            capability in development.
   information

5. Case management   Capability established; PAM-specific
                     business rules in development for linkage
                     and tracking.

6. Analysis and      SAS product integrated, ESRI GIS capability
   visualization     in development; SSL and RBAC established.

7. Personnel         Capability established, directory contains
   directories       contact information and roles of > 2,400
                     registered PHIN users from > 900
                     organizations.

8. Information       Capability established; call-tree alerting
   dissemination     system integrated (voice technologies), public
   and alerting      and private topic areas, threaded discussion
                     forums established; push digest subscriptions
                     available from bookmarked topic areas,
                     directing appropriate content to audience.

9. IT Security       Capability established, including RBAC,
                     administrative policies, auditing, and training,
                     ongoing virus scanning, intrusion detection,
                     threat intelligence, continuity of operations;
                     independent validation and verification in
                     development, client digital certificates in
                     exploratory phase.

Abbreviations: ANSI, American National Standards Institute, ebXML,
Electronic Business using eXtensible Markup Language; ESRI,
Environmental Systems Research Institute; HIPAA, Health Insurance
Portability and Accountability Act (1996); HL7, Health Level 7; HTTP,
Hypertext Transfer Protocol; IT, information technology; JDBC, JAVA
Database Connectivity; LDAP, Lightweight Directory Access Protocol;
LDIF, Lightweight Data Interchange Format; LOINC, Logical Observation
Identifiers; ODBC, Open Database Connectivity; SNOMED, Systemized
Nomenclature of Medicine; SOAP, Simple Object Access Protocol; SOL,
Structured Query Language.

(a) From CDC (2002).

Table 2. Wisconsin EPHTN data inventory.

Abbreviation                       Data set                    Scope

AEI               Air Emissions Inventory                      State

BRRTS             Bureau of Remediation and Redevelopment      State
                  Tracking System

Census            Census                                       National

DWS               Drinking Water System                        State

GEMS              Groundwater Environmental Monitoring         State
                  System

GLAT              Great Lakes Air Toxic Emissions Inventory    Regional

GEN               Groundwater Retrieval Network                State

NATA              National Air Toxics Assessment               National

NEI               National Emissions Inventory                 National

PEI               Periodic Emissions Inventory                 State

RR GIS Registry   Remediation and Redevelopment GIS Registry   State

SHWIMS            Solid and Hazardous Waste Information        State
                  Management System

SWAP              Source Water Assessment Plan Database        State

TRI               Toxics Release Inventory                     National

WCR               Wisconsin Cancer Registry                    State

WI Hosp           Wisconsin Hospital Discharge                 State

WMOR              Wisconsin Mortality                          State

Abbreviation                          Description

AEI               Emissions from mobile sources

BRRTS             Database of environmental contamination sites
                  including spills, leaking underground storage
                  tanks, state-response sites, and federal Superfund
                  sites

Census            Decennial population counts, age, gender, race,
                  census tract, county, ZIP code

DWS               Drinking-water quality in Wisconsin public wells

GEMS              Environmental monitoring data for Wisconsin
                  landfills, including landfill gas, groundwater, and
                  other sample types

GLAT              Airborne toxic pollutant emissions affecting air and
                  water quality in eight Great Lakes states

GEN               Groundwater quality in Wisconsin private, public,
                  and monitoring wells

NATA              Estimates of 33 air toxics (a subset of 32 air
                  toxics on the Clean Air Act's list of 188 air
                  toxics, plus diesel particulate matter) (U.S. EPA
                  1993)

NEI               Hazardous and criteria air pollutants

PEI               Annual emissions of criterion air pollutants and
                  some noncriterion pollutants

RR GIS Registry   Sites closed with residual water or soil
                  contamination

SHWIMS            Sitings for waste management facilities

SWAP              Assessment of possible contamination sources within
                  a specified distance from a drinking water well

TRI               Toxic chemical releases and other waste management
                  activities for specific industry groups and federal
                  facilities

WCR               Cancer incidence by age, gender, race, county, ZIP
                  code, histology, cytology, staging

WI Hosp           Hospitalizations by age, gender, race, county, ZIP
                  code, cause

WMOR              Mortality by age, gender, race, county, cause

Table 3. Wisconsin Cancer Registry 1990-2000: childhood cancer cases
frequency by cause (chil-dren < 20 years of age).

Cause                               Frequency (%)

Leukemia                             672 (22.7)
Lymphatic cancers                    428 (14.5)
Brain cancer                         413 (14.0)
Cervical cancer                      283 (9.6)
Bone cancer                          174 (5.9)
Soft tissue cancer                   151 (5.1)
Kidney and other urinary cancer      126 (4.3)
Thyroid cancer                        91 (3.1)
Skin cancer/melanoma and              88 (3.0)
  other reportable
Other endocrine gland cancer          74 (2.5)
Testicular cancer                     66 (2.2)
Eye cancer                            59 (2.0)
Ovarian cancer                        58 (2.0)
Other central nervous system          47 (1.6)
  cancer
All other cancers/unknown cancers     42 (l.4)
Oral cancer                           33 (1.1)
Peritoneal cancer                     27 (0.9)
Liver cancer                          24 (0.8)
Nasalcancer                           15 (0.5)
Colorectal cancer                     14 (0.5)
Other respiratory/thoracic cancer     14 (0.5)
Bladder cancer                        13 (0.4)
Bronchus and lung cancer              11 (0.4)
Other female genital cancer           11 (0.4)
Prostate cancer                        7 (0.2)
Small intestine cancer                 3 (0.1)
Breast cancer                          3 (0.1)
Uterine cancer                         3 (0.1)
Other leukemias                        3 (0.1)
Stomach cancer                         2 (0.1)
Pancreatic cancer                      2 (0.1)
Laryngeal cancer                       1 (0.0)
Pleural cancer                         1 (0.0)
Other male genital cancer              1 (0.0)

Total                               2,960 (100.0)

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Lawrence P. Hanrahan, (1) Henry A. Anderson, (1) Brian Busby, (2) Marni Bekkedal, (1) Thomas Sieger, (1) Laura Stephenson, (1) Lynda Knobeloch, (1) Mark Werner, (1) Pamela Imm, (1) and Joseph Olson (1)

(1) Division of Public Health, Wisconsin Department of Health and Family Services, Madison, Wisconsin, USA; (2) E-Commerce, University of Wisconsin Division of Information Technology, Madison, Wisconsin, USA

This article is part of the mini-monograph "National Environmental Public Health Tracking," which is sponsored by the Centers for Disease Control and Prevention (CDC).

Address correspondence to L.P. Hanrahan, Bureau of Health Information and Policy, Division of Public Health, Wisconsin Department of Health and Family Services, Room 372, 1 West Wilson St., Madison, WI 53702 USA. Telephone: [phone]. Fax: [phone]. E-mail: [e-mail]

This work was funded by CDC through the Wisconsin Environmental Public Health Tracking Program (grant U50/CCU522439-01).

This article was supported by an environmental public health tracking cooperative agreement from CDC. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of CDC.

The authors declare they have no competing financial interests.

Received 1 April 2004; accepted 3 August 2004.