[Air Toxins][Safe Water][Nonpoint Sources of Pollution][Rabies]
Vermonters depend on a high-quality physical environment for some of the most basic necessities of life, including clean air to breathe and safe water to drink. Since its inception in 1970, a central task for the Agency of Natural Resources has been to ensure that Vermont remains a healthy place to live. This is why the Agency's three departments concern themselves with issues ranging from sewage disposal to forestry practices to leaking underground storage tanks to controlling rabies.
An unpolluted natural environment and its accessibility for recreation are essential elements of a healthy, productive, and enduring society. We seek the outdoors to escape, to renew, and to refresh. Outdoor recreation helps us accomplish personal goals and challenges, from relaxation and fitness for a longer, healthier life to family time together, friendship, adventure, personal reflection, and developing a greater appreciation of nature and its beauty.
For some Vermonters, time in the outdoors primarily comes through brief walks in the woods to sort their thoughts. For others, it is weekend camping trips with their children, to pass on to the next generation an appreciation of the natural world. And then there are people like Bob Northrop, who in 1996, at the age of 75, hiked the entire length of the Long Trail for the sixth time. His end-to-end hike not only raised money for protecting the trail, but also raised awareness of what the Long Trail has meant in his life and for the state of Vermont.
As the outdoors leads to attainment of personal goals, it becomes a catalyst for the achievement of societal goals: better health, education, employment, family cohesion, a lower crime rate, economic vitality, and environmental quality. Businesses have discovered that the most productive and highly motivated employees are those who possess challenging and fulfilling lives apart from their jobs.
Our natural environment also offers a tangible connection to our heritage, a connection for individuals and communities across time and generations. The Vermont landscape of villages, farms, and fields surrounded by forested hillsides characterize the quality of life sought by so many Vermonters and visitors to our state. Yet, it is more than simply a landscape that maintains the bonds between generations; it is outdoor activity as well. For example, the traditions of deer camp in November and canoeing favorite rivers are passed from generation to generation, strengthening the bonds within families.
Vermonters place a high value on our natural environment. It is central to the quality of our lives and the cohesion of our communities.
Enjoyment of the outdoors is sometimes tempered by threats to our well-being, such as health hazards presented by air pollution. Many of Vermont's air pollutants of most concern come from upwind urban and industrial regions. At the same time, a number of home-grown pollutants also pose concerns for Vermonters.
The Hazardous Air Contaminant Monitoring Program started sampling air for toxic pollutants in Vermont in 1993. Monitoring sites range from a high-traffic, urban site in downtown Burlington to a rural "background" site on the western slope of Mt. Mansfield in Underhill. Two classes of compounds are monitored: volatile organic compounds (VOCs) and carbonyls, which include formaldehyde and acetone. VOCs are emitted in large quantities by motor vehicles and at gasoline pumps. They consist of compounds such as benzene, toluene, and xylene.
Of the 71 pollutants analyzed, more than half are present in sufficient quantities to be detectable. Eight pollutants (1,2,4-trimethylbenzene, benzene, carbon tetrachloride, chloroform, formaldehyde, chloromethane, methylene chloride, and 1,3-butadiene) consistently exceed state health standards. Of these eight pollutants, one is a known carcinogen and five are reasonably assumed to be carcinogenic. Pollutant concentrations are generally higher in more populated urban sites than rural locations (Figure 1).
Average concentrations of benzene, 1,3-butadiene, and formaldehyde are several times higher than Vermont health standards even at the rural Underhill site. At urban sites, concentrations of these three pollutants are as much as 40 times higher than state health standards. Benzene is associated with gasoline, auto emissions, and wood burning. It is a known carcinogen that can cause leukemia. 1,3-butadiene is exclusively associated with auto emissions and is reasonably assumed to be carcinogenic. Sources of formaldehyde are combustion (including wood burning, illegal trash burning, and auto emissions) and atmospheric chemical reactions from precursor pollutants (VOCs). Formaldehyde is reasonably assumed to be carcinogenic and causes irritation to both the eyes and the upper respiratory tract. It is also an important precursor to the photochemical production of ozone.
Safe drinking water is indispensable, and more than half of all Vermonters rely on public community water systems to provide safe drinking water. Water quality standards for the 39 million gallons per day supplied from these systems are set by state and federal laws. To ensure that standards are met, system operators must sample for and report on inorganic, volatile organic, and synthetic organic chemicals, along with radiological and bacteriological constituents. Bacteriological contamination is the most common violation associated with drinking water. Bacteria and associated microbial agents - viruses, giardia, and cryptosporidium - have been linked to waterborne disease outbreaks.
Of the 466 public community water systems in Vermont, 240 have received at least one notice of violation regarding bacteriological contamination within this past decade. Violations such as these require users to boil water for five minutes prior to drinking to kill viruses and bacteria. This requirement is triggered when coliform or fecal coliform is present in a water system. Its presence indicates sewage or animal waste in the water. In turn, this waste may contain waterborne parasites such as cryptosporidium and giardia which can make people ill.
In 1995, Vermont had 315 confirmed cases of giardiasis, an infection caused by giardia and frequently associated with water consumption. Department of Health officials interview individuals about their drinking water sources in order to identify possible outbreaks. Vermonters on private water systems (47 percent of reported cases) are given information on how to test their home water supplies. Fortunately, only two documented waterborne disease outbreaks have occurred within the past 10 years at community water systems. Symptoms resulting from giardiasis and cryptosporidosis include diarrhea, abdominal cramps, headaches, nausea, fever, and vomiting. Vermonters with these symptoms should test and boil their water and see their physicians.
Nonpoint Sources of Water Pollution
The pathogens associated with the waterborne diseases cited above originate in the wastes of humans and other warm-blooded animals. Because most point sources are treated to eliminate pathogens, contamination of water supplies is most often a result of pollutants discharged in run-off containing human or other animal wastes to surface water or ground water from diffuse, or nonpoint, sources. These sources may include failed septic systems and surface run-off from agricultural and developed land. In some instances, combined sewer overflows can discharge untreated human wastes into surface waters used as public water supplies.
These same nonpoint sources of pathogens can put recreational users of surface waters at risk of becoming ill when contaminated water is ingested, primarily while swimming. Many of Vermont's public swimming beaches are monitored on a regular basis for indicators of contamination by bacteria and associated microbial agents such as viruses, giardia, and cryptosporidium. While non-public recreational areas are not routinely monitored for indicators of bacterial contamination, some private groups have established monitoring programs in areas where recreational activities such as swimming occur.
Without monitoring, it is difficult to know whether a water body is safe for swimming as there are usually few visible signs of contamination. However, monitoring has clearly identified some specific conditions that are known to increase the potential for contamination and thus the chance of contracting waterborne illnesses. For example, choosing to swim downstream from a highly developed or heavily used agricultural area following a rainstorm clearly increases the risk of exposure to potentially pathogenic contaminants. Recent improvements in combined sewer overflow controls and improved regulation of agricultural management practices will help reduce future health risks to Vermonters. Improvements in the management of urban run-off will be critical to providing adequate protection to public and private beaches exposed to run-off from developed areas.
Some threats to our health are the result of human degradation of the environment, while others occur naturally, such as rabies, an invariably fatal viral infection of mammals. Humans are susceptible to rabies and must undergo aggressive treatment when either bitten by a rabid animal or if an open wound is exposed to the saliva of a diseased animal. Rabies is considered a significant public health threat, and the Agency of Natural Resources, working with the Health Department, places considerable emphasis on prevention, education, and treatment.
Vermont is currently experiencing an outbreak of rabies that extends back to 1992 when the fox strain of the virus first appeared in northwestern Vermont. In that year, 24 cases of the fox strain were documented (Figure 2). In 1994, the Mid-Atlantic raccoon strain of the virus entered southern Vermont. This strain has moved northward, primarily infecting the raccoon population, and was recently documented in Chittenden County. Skunks and bats in Vermont also have been identified as carriers of rabies.
Since February, 1992, a total of 514 rabid animals have been documented in Vermont. This has created additional work for officials at the municipal and state levels. Fish and Wildlife wardens responded to more than 5,000 calls in 1995 alone. In addition, the State-Federal Cooperative Rabies Hotline has provided technical assistance to more than 13,000 Vermonters since 1992. When human exposure to rabies is suspected, a higher level of response is required, including the testing of the potentially infected animals and post-exposure treatment for people.
Although rabies will persist in Vermont's wildlife for the foreseeable future, the threat of this infection should not cause undue alarm or fear. Instead, it should promote a healthy respect for all wild mammals, especially skunks, foxes, raccoons, and bats. Vermonters need to avoid all direct contact with these species, including young or injured individuals. We must educate our children to stay away from such animals and vaccinate our pets and livestock against rabies.