When people are not careful to properly dispose of of trash and household toxic substances, wild animals suffer. Many animals are injured, become ill, and die each year due to human carelessness with litter and pollution. Animals can swallow or get entangled in many of the litter items people leave in the environment. They can also ingest toxic substances like motor oil and pesticides, which are often dumped into storm drains and end up in our waterways.
Even if a toxin originally entered the environment or water in small amounts, it can be concentrated by "biomagnification." This means that the pollutant is concetrated ten times with each step up the food chain from plankton to humans. By remembering the following simple tips, you can help protect wildlife.
Every once in a while an animal comes to CWC that really makes one think about our effects on the environment and on wild animal habitats. Over the last few years we have received a number of animals that have shown signs that make us suspect toxic poisoning.
Nothing is more bewildering than receiving an animal that has no obvious injuries yet is still showing vague signs of illness. It is difficult to ascertain the root cause of signs such as seizures, lack of blood clotting, balancing problems, and general fatigue. Since the animal cannot relay its medical or environmental history to us, diagnosis can be a series of educated guesses when treating these signs. And we may never understand the true cause of the illness.
Most animals, including humans, accrue chemicals through ingestion, absorption through the skin, and inhalation. If a chemical is not degraded naturally, it can remain in the environment for hundreds of years. If this chemical is consumed by an organism such as a bacterium or an alga and cannot be broken down or excreted, it can accumulate in the organism as the organism continues to consume. Over time, the level of the toxin in the organism becomes greater than the level in the environment. When the bacterium or alga is then consumed by another organism, the new organism inherits its prey's chemicals.
An example of bioaccumulation appeared in a study published in 1997 by Japanese and Russian scientists. They found polychlorinated biphenyls (PCBs) in fish in Lake Baikal, Siberia and seriously toxic levels of PCBs in the Baikal seal that eats these fish. This process of bioaccumulation is very important for the accumulation of vitamins and minerals, but can be disastrous when it occurs with harmful chemicals.
Because of the accumulation process, an organism can acquire a level much higher than is normally found in the environment. Therefore, if a pesticide such as Chlordane enters a river, it can settle to the bottom where bacteria and algae are found, yet be virtually undetectable when the river water is tested at a level above the bottom.
At this point, several things can happen. The toxin can be consumed by organisms to begin the bioaccumulation process, it can travel down the river to another location, or it can leach into the groundwater below the river where the paths the chemical can take are endless.
When we turn on the water tap to get a drink, few of us really stop to think of the quality of our drinking water. We assume that it meets current standards for consumption. It usually does, but more and more we hear how our water has been contaminated by bacteria and chemicals. A study by the Department of Environmental Quality found perchloroethene (PCE) (traced to a logging company and former dry cleaning businesses) in the drinking water of 21 wells in Sweet Home, Oregon (1995) and 18 wells in Lebanon, Oregon (1990).
PCE is suspected of causing cancers in humans, and its break-down product of trichloroethylene (TCE) is toxic. Additionally, chemicals and sewage are released into our rivers, streams, and lakes. According to the USEPA Toxic Release Inventory System, in 1996, businesses released 1,230,992 pounds of toxic chemicals in Linn county, and 13,940 pounds of toxic chemicals in Benton county (Oregon).
In February, 1998, The Gazette-Times (Corvallis, Oregon) reported that according to a U.S. Geological Survey study of the Willamette River Basin, Dixon Creek in Corvallis contained nine pesticides, fecal coliform, and E. coli bacteria. All of these toxins have an effect on wildlife and on us.
The Department of Environmental Quality has listed the Willamette River Basin as a Priority 1 site for cleanup due to the presence of endangered and threatened fish species.The Oregon Health Division has issued a fish consumption advisory, which means that young children and pregnant women should limit their consumption of bass and squawfish from rivers in the Willamette River Basin because of high levels of mercury. The Draft Executive Summary by the Willamette River Task Force appointed by Governor Kitzhaber, stated in late 1997 that in a stretch of the Willamette River southwest of Portland, Oregon (known as the Newburg Pool), 74 percent of the squawfish had deformities. These deformities are believed to be caused by exposure to heavy metals and toxic chemicals.
The Draft Executive Summary also stated that a recent study taken from the mouth of Oregon's Willamette River found otters with deformities and reproductive-tract disorders from organochlorine contamination (probably from the fish and sellfish that these otters eat).
The toxins that wildlife consumes from these rivers is bioaccumulated in them and in us.
Most of what ends up in our rivers as runoff begins on our soils, where it is much more difficult to track. These include common items such as bleach, motor oil, antifreeze, pesticides, paint thinner, and cleaning solutions. We all contribute to these problems.
Everything that touches the ground or goes in our trash eventually ends up in our rivers, drinking water, or on our plates as dinner. Plants are capable of taking up toxic chemicals from soil contamination. These toxins can then bioaccumulate through animals (including humans) eating the plants directly or from consuming another animal that has eaten the plants, such as cows, sheep, pronghorn antelope, deer, and elk.
In one way or another we all have consumed certain toxic substances. Some are broken down and excreted while others bioaccumulate. Although the results of this bioaccumulation are not well understood in humans, it is suspected to cause various cancers, low sperm counts, immune system problems, learning disabilities, and birth defects.
As the toxins in our environment continue to add up, more problems are likely to develop in the future. Are there solutions? Well, there is no magic, painless solution. It will require a lot work by the public and industries to decrease the level of chemical pollution we release into our environment.
There are things that we can do that can help.
Remember, everything that goes down a storm drain goes into a river, and eventually, the ocean. Understanding the process of bioaccumulation is the first step to making a difference in your life and in the lives of the wildlife sharing our communities.
Copyright © 1999 Chintimini Wildlife Rehabilitation Center