Be careful following herbicide treatment
Herbicide treatment for Eurasian milfoil appears to be the most practiced solution for abatement of this extremely invasive plant in waterways. Discussion based on scientific trials undertaken by both product manufacturers and independent universities focus on safety factors affecting humans, animals (rats, mice, guinea pigs, amphibians, and fish species), and plants (broadleaf and other aquatic plants such as microorganisms, fungi, mosses, and algae as well as surrounding flora that might be affected from overspray or groundwater translocation).
Most studies report low toxicity exposure due to the high dilution rate and the short half life of the ingredients in the herbicide. Trichlopyr, the form of herbicide being considered for use in our waterways as reported in the Bee (9/1/13), has come with mixed reviews by the reporting research organizations, some stating humans have nothing to worry about if exposed to the chemical, and some say to be careful to not become exposed for at least 3 hours after application to as long as 10 days. Complete dissipation of the herbicide depends on concentrations applied, water conditions, and adequate sunlight according to an article published online by the Californians for Alternatives to Toxics (CAT), dated 9/1/13).
Herbicides act on plants to disrupt hormone activity and stop new growth. Plants take up this chemical in its leaves and it stays with the plant long enough to kill it off. Then the plant withers and drops to the floor of the waterway to decompose. My concern at the moment is twofold. First, microorganisms and fish feed on these plants to some degree and live in the waters being treated. Fish bodies can accumulate this herbicide in their tissues, then our birds of prey can ingest the fish as we can also. The outreach along the food chain can be larger than laboratory testing can verify as safe. If sunlight is the major detoxifier of this chemical, then decomposition on the floor of a waterway may not allow for the reported rapidity of this chemical deteriorating to safe levels. Secondly, in our environment today, each of us is exposed to myriad man-made chemicals harmful to our health. While the research on this particular chemical focuses on its own studies, no studies compare what this chemical does in consort with all the other exposures we face. Chemicals bioaccumulate in our tissues and can interact with other chemicals often becoming more toxic. One study reported that the ring structure of the active and inert ingredients in Trichlorpyr disable it from breaking down into other known toxins. But with no further research about cross contamination, it becomes an even more serious concern for recreationalists enjoying our waterways.
Signs and symptoms of negative reactions to Trichlorpyr include irritation to eyes that might lead to permanent damage, skin sensitivity, dizziness or drowsiness, and respiratory and gastrointestinal irritation. Acute exposure could harm blood, liver, kidney, and nervous system function. Of course the researchers report this would only occur with extremely high exposure to the ingredients in the herbicide. Even at low doses, CAT reports behavioral defects, lower oxygen intake, and loss of motor control in amphibians and salmonid species that are more sensitive to this herbicide.
“Trichlorpyr has been shown to disrupt the normal growth and nutrient cycling properties of microorganisms, fungi, mosses and algae; all of which perform critical functions to maintain a healthy ecosystem” (CAT).
It then becomes critically important for all of us to be cautious when swimming, fishing, and playing in the waters of our beautiful lake and river following this herbicide treatment. Reduce exposures of as many man-made chemicals as you can to enable your body to detoxify those you cannot control where exposures are dictated by others.
• Krystle Shapiro holds a master of science degree in holistic nutrition degree.