According to the U.S. Geological Survey there are a significant number of pesticides, their break-down consituents and fertilizers in the lakes and streams of Central Florida. Further, there are an interesting number of pesticide mixtures that have not been studied... and this common occurrence of pesticide mixtures in the lakes means that the combined toxicity may be greater than that of any single pesticide compound.
Some of these pesticides have also been found in urban and residential areas in surface waters, indicating sources are not limited to just agriculture.
Because decades-long studies are difficult to conduct, the impact of chronic exposure to these mixtures is unknown, but what we should recognize is that these are toxic chemicals intended to kill pests, but that are just as likely to harm all animals in the chain...including humans.
Lakes in the area are not used for public drinking water, and none of the individual samples exceeded federal or state drinking-water benchmarks for nitrate or pesticide concentrations, but benchmarks have not been set for all of the pesticides detected in the USGS study, nor have combined levels been set.
Aquatic-life benchmarks exist for 10 of the 20 pesticide compounds found and no concentrations met or exceeded those benchmarks. Yet questions remain about the possible impacts of these substances. Benchmarks for some of these chemicals and for chemical mixtures are still in the process of development.
The Florida Department of Environmental Protection, the Southwest Florida Water Management District, and the USGS conducted this study as a 'regional reconnaissance' to look at what happens to currently-used pesticides and their break-down products known as 'degradates', after they are applied to the land surface.
The compounds most frequently found include norflurazon and its degradate, bromacil, simazine degradates, diuron and its degradate, aldicarb degradates, metalaxyl, and 2,4-D. The lakes in citrus areas also were enriched with chemicals used as citrus fertilizers.
This study is unique in that very few studies have looked for pesticides in small to medium-sized lakes, or tested as many pesticide break-down products. Since the water resources in the area are so interconnected, this kind of information helps scientists understand where these chemicals go, how they break down and if they are posing threats to our water resources.
More than 200 lakes occur in the Lake Wales Ridge, located in Florida's Polk and Highland counties. Many of the region's lakes are 'flow-through' lakes, meaning that water seeps in and out of the lakes and is connected with water found in aquifers near the surface.
Water from the lakes can also flow into deeper groundwater systems such as the Upper Floridan aquifer, which is the region's principal drinking-water source. This makes it critical to understand what happens to pesticides that are currently being used in the region, the scientists said.
Now the twist! Many of these pesticides, like simazine and atrazine, are common agricultural tools here in the US but have been banned in other regions (ex: atrazine in the EU). Are we the ones being safe, or are we the ones missing the point.
Testing shows that these chemicals generate cancer in laboratory animals, and we know that with the increase of pesticide usage (DDT in the 50s and others after DDT was eliminated) we have seen an increase in a wide range of cancers... more than a 50% rise in cancer overall for Baby-Boomer Americans who were young and developing physically when exposure to these chemicals began.
What we need to recognize is that, just like the laboratory animals, we are being impacted by these chemicals and we need to improve their handling, control exposure to them, and limit or eliminate them when we identify these risks, not abide by industry advice that promotes their use even beyond scientific evidence that they threaten our way of life through increased toxic exposure.
