August, 12, 2005 - ASM Comments to the National Institute of Environmental Health Sciences

[Docket No. 05-12129]

August 12, 2005

National Institute of Environmental Health Sciences
National Institutes of Health
Department of Health and Human Services
The Office of Science Policy and Planning
P.O. Box 12233
Research Triangle Park, NC 27709

The American Society for Microbiology (ASM) is submitting comments in response to the National Institute of Environmental Health Sciences (NIEHS) notice requesting comments, on the NIEHS 2006 strategic plan, in the Federal Register, Vol. 709, No. 118 on June 21, 2005, Docket No. 05-12129. The following comments were developed by ASM’s Committee on Environmental Microbiology of the Public and Scientific Affairs Board.

The ASM is the largest single life science society with more than 42,000 members, including scientists in academic, industrial, clinical, and government institutions, working in areas related to basic and applied research, the prevention and treatment of infectious diseases, laboratory and diagnostic medicine, the environment, and water and food safety. The ASM applauds NIEHS’s efforts to reduce the burden of human illness and dysfunction from environmental causes and appreciates the opportunity to provide input on the NIEHS 2006 strategic plan.

Widespread exposure to low levels of biologically significant and persistent pathogens associated with acute and chronic diseases occurs through the environment. The detection, transport, exposure and risk of diseases associated with microbial agents in waters, soil and air have been largely neglected in the past. Indeed, the environmental background and ecology of many pathogens is unknown or poorly characterized. Furthermore, inadequate attention has been devoted to understanding the occurrence, distribution and health consequences of infectious, pathogenic microbes in the environment, even though they represent a major source of serious human health problems both nationally and globally.

The ten-year anniversary of the largest and most important waterborne disease outbreak in the U.S. has recently refocused attention on environmental exposure to pathogens. The Cryptosporidium outbreak in Milwaukee, Wisconsin alerted the Great Lakes region to the importance of water quality, and the significant and immediate impacts that contamination can have on a community, its sensitive populations and on the water industry. However, this outbreak and the attention it brought to microbial water quality have not prevented increases in both drinking water and recreational waterborne disease outbreaks in the U.S. according to statistics from the Centers for Disease Control (2002).

In addition to water, there are other routes of exposure from the environment. The soil contains microbial pathogens harmful to human health, and disruption of the environment can lead to airborne dissemination of these pathogens. For example, the 1994 earthquake in Ventura Country led to increases in a serious fungal infectious disease, coccidiodomycosis, also known as Valley Fever. Excavation of land during construction and other projects has also led to increases in this disease in some areas of the Southwestern United States. Suburban development has increased the risk of tick-borne diseases such as Lyme disease and ehrlichiosis. Agricultural and aquacultural practices are also affecting the threat of the emergence of infectious diseases.

While the EPA is charged with research on environmental contamination, its research efforts are designed to help the Agency fulfill its regulatory role. This has created a void in addressing microbial low-dose environmental exposures via soil, bioaerosols and water, and left the risks of these exposures largely unknown. For example, the environmental risks of human pathogen discharges from Concentrated Animal Feeding Operations have not been adequately identified.

Chronic exposure to environmental sources that contain a pathogen at low levels of contamination may result in infection. For many pathogens, it is unknown if there is a safe level of contamination. Assessing whether a given level of contamination may be considered "safe" is also more difficult given the large numbers of persons who are immunocompromised as a result of age, chronic disease (e.g., diabetes, AIDS), or immunosuppression (e.g., transplant patients).

In addition to the acute illness caused by many infectious agents, microbial pathogens can also result in other conditions and chronic illnesses. For example, Campylobacter infections can cause both an acute diarrheal illness but also may cause Guillain Barre Syndrome and reactive arthritis; Helicobacter pylori can result in stomach ulcers and cancer. Following disease outcomes of infected individuals could provide valuable insights.

The NIEHS mission is highly appropriate for supporting a new generation of research on microbial pathogens as contaminants in the environment, and for developing a strategic plan to fill voids in this area.

• What are the disease processes and public health concerns that are relevant to environmental health sciences?

Mechanisms of exposure to infections caused by microbes in the environment are poorly understood, as is the relationship between exposure and disease incidence. It is clear, however, that a wide variety of pathogenic microorganisms occur in the natural and anthropogenic environment and that contamination can be localized or widespread. Human dose-response studies along with limited monitoring studies also show that infectious microbes do occur in the environment at concentrations that represent potential human health risks.

Increased numbers of sensitive or susceptible individuals in the U.S. population means that widespread contamination of the environment (e.g., water) will result in increased exposure to infectious agents. The growing susceptible population groups include elderly and immunocompromised (transplant patients, AIDS patients) individuals, in addition to diabetics, infants, and pregnant women, all of whom can experience severe health outcomes as a result of infections.

Thus, it is essential to understand the factors that determine the sources and levels of exposure and the impacts of infectious agent concentration, persistence, and modes of transmission on the development of disease in susceptible individuals.

• How can environmental health sciences be used to understand how biological systems work, why some individuals are more susceptible to disease, or why individuals with the same disease may have very different clinical outcomes?

NIEHS has developed considerable expertise in understanding how various abiological agents (e.g., anthropogenic chemicals in the environment) cause disease. The models and expertise developed by NIEHS can be used to further understand impacts of infectious microbes. Developing risk assessment models for infectious microbes based on exposure, level of contamination, and relevant environmental variables is of particular importance, and would help meet needs of health-related agencies from local to federal levels. Waterborne outbreaks (about 10 in drinking water and 12-20 per year in recreational settings), foodborne outbreaks (dozens documented per year), and airborne microbial exposures (such as Legionellosis outbreaks and other occupational diseases in “sick” buildings) are opportunities to examine an array of populations and their susceptibilities from various pathogen exposures.

• What are the major opportunities and challenges in global environmental health?

Changes in the global biosphere are enormous and these have had a major impact on the emergence of infectious diseases, from malaria resurgence to avian influenza. Environmental factors are often part of a complex web of factors resulting in emergence of disease, often a zoonotic disease with transmission of infection directly from wildlife to humans or indirectly from wildlife to humans through a domestic animal. The cascade of Nipah virus infection from bats to pigs to humans in Malaysia in the past decade was largely a result of environmental changes including forest destruction and new agricultural practices. The relationships between environmental changes and microbial pathogens need to be better understood to prevent conditions likely to spawn emergence or re-emergence of infectious disease from avian influenza to vector-borne diseases. Infectious organisms that are transmitted by environmental exposure may also be transmitted by secondary factors (fomites, aerosols, etc.). Our ability to model the population level dynamics of the transmission of such infections is only at a very early stage, and the coupling of molecular epidemiological methods with sophisticated mathematical epidemiology and risk assessment may allow our knowledge to dramatically advance.

It is essential to understand the dynamics and impacts of environmental pathogens sufficiently well to design systems that decrease the risks of exposure.

• What are the environmental exposures that need further consideration?

A complete and predictive understanding of the impact of infectious microbes in the environment requires analysis of the effects of simultaneous exposure to complex mixtures of hazardous chemicals and microbes. Likewise, it is important to identify factors that pre-condition certain individuals or groups, and lead to adverse outcomes upon exposure. Relationships between levels of contamination and health outcomes also need significant attention, particularly since the health effects of low but persistent levels of contamination are poorly understood. The circumstances in which minority communities or socio-economically disadvantaged communities may be at greater risk of environmental contamination need to be better defined and addressed.

In addition, increased animal populations and changes in agricultural and aquacultural practices may lead to greater transmission of infectious microbes from animals to humans; zoonotic pathogens currently comprise 75% of emerging infectious diseases. Avian flu represents just one current, highly relevant example of the complex relationship that exists between infectious disease and human use of animals that are a growing concern worldwide.

• What are the critical needs for training the next generation of scientists in environmental health?

A full understanding of the behavior and dynamics associated with infectious microbes and the diseases they cause, particularly those with a significant environmental reservoir, can no longer depend on educational programs limited to traditional health science disciplines. Interdisciplinary training that integrates microbiology, the environmental sciences, risk analysis and health sciences is essential. The National Science Foundation’s Integrated Graduate Education, Research and Training program offers a model that can be adapted to train a new generation of environmental health scientists who are knowledgeable about pathogens and infectious diseases from environmental exposures.

The “pipeline” for environmental health scientists does not begin with graduate students, however. It includes undergraduates, secondary students and reaches even further to basic science education for children. Thus, NIEHS should develop and support a broad range of educational programs that can be delivered to and motivate students prior to the point at which career decisions are made. Educational programs should also stimulate greater participation by minorities in the environmental health sciences profession.

• What technology and infrastructural changes are needed to fundamentally advance environmental health science?

Development of a new, focused, robust and sustained science-based research program is essential for understanding the natural and anthropogenic processes that affect microbial contamination of the environment, and subsequent impacts on human health. Such a program should emphasize linkages of cellular and molecular-level processes with the classical risk assessment paradigm and traditional health science approaches. Attempts to address measures of exposure will need to include the development of new monitoring technologies and an improved understanding of the physical, chemical and biological processes that control the occurrence, evolution, fate and transport of microbial pathogenic contaminants from point of release to point of exposure. Key areas of interest should include, among others, antibiotics and antibiotic resistance, sewage-borne viral pathogens associated with cancer and other chronic diseases, cyanobacterial toxins, bioaerosols, pathogen health effects from land application of biosolids and manure, and the potential human health risks associated with zoonotic pathogens such as Mycobacterium paratuberculosis, avian influenza viruses, or the occurrence of Helicobacter in groundwater.

NIEHS should also leverage existing and developing technologies supported by the Department of Homeland Security, the National Science Foundation and others. For instance, systems for monitoring airborne biothreat agents as a part of the “Biowatch” program (now managed by the Centers for Disease Control) could provide highly valuable information on the incidence and transport of infectious microbes in urban environments. NSF’s proposed “National Ecological Observatory Network” (NEON) could likewise provide extremely important detailed, synoptic and long-term information on a wide range of environmental variables that are critical for understanding the distribution and behavior of infectious microbes in the environment. NOAA’s Oceans and Human Health program and the multi-agency “Ecology of Infectious Disease” programs are other examples of opportunities for NIEHS to link to national and global initiatives that focus on pathogenic microbes, the environment and human health risks.

In conclusion, a significant need exists for greater environmental health research that focuses on the issues of infectious microbes in the environment as noted above, and on related issues, which are currently under-represented in the federal research portfolio. The NIEHS has a strong role to play in the development of a research agenda that addresses environmentally-transmitted infectious diseases. The ASM urges the NIEHS to address the occurrence, level, fate, exposures and health outcomes associated with human pathogens in soil, air and water as a priority in strategic planning.

We are pleased to have the opportunity to provide comments on NIEHS’s 2006 strategic plan, and hope that these recommendations are of assistance.


Ruth Berkelman, M.D. Chair, Public and Scientific Affairs Board
Gary King, Ph.D. Chair, Committee on Environmental Microbiology
Charles Gerba, Ph.D. Member, Committee on Environmental Microbiology
Charles Haas, Ph.D. Member, Committee on Environmental Microbiology
Joan Rose, Ph.D. Member, Committee on Environmental Microbiology
Mark Sobsey, Ph.D. Member, Committee on Environmental Microbiology