This is in response to the article, “Testing for dioxin remains imprecise,” by Misty Edgecomb, published in the Jan. 13 Bangor Daily News.

What is the future for dioxin in our rivers? Dioxins are very stable compounds that ubiquitously persist in the environment. All pulp and paper mills in Maine that did bleach with chlorine have changed to an elemental chlorine-free bleaching process significantly reducing the release of dioxin in mill discharge. However, even with the reduction of local point sources such as papermaking, dioxin and related compounds will continue to come from other nonpoint sources (atmospheric deposition being the major culprit),

and will likely be stored in sediments for potential future release.

Contrary to what was quoted in the BDN article, progress has been made at the University of Maine in regard to developing an acceptable above and below (A/B) test. Unfortunately, a full resolution of the issue may still be a few years of research away though the Department of Environmental Protection’s will need to decide which test to use later this year. This is not due to a “lack of progress” at the university or a state of “confusion” in the DEP Dioxin Monitoring Program. Instead, the complexity of the issue, the variability of environmental sampling, and the difficulty of analysis have led to a need for more investigation and further understanding.

The University of Maine has been at the forefront of dioxin analysis in Maine since 1996. The university has the only facility in the northeast capable of performing dioxin analyses at parts per quadrillion concentrations keeping taxpayer money spent on analyses in the state and increasing educational opportunities. Grants to the university have fostered a unique partnership with the DEP to determine how much dioxin there is in our rivers, fish, and sediment. Research supported by funding from the National Science Foundation, US Geological Survey, and the DEP is investigating methods to meet the goals of the ‘upstream-downstream’ legislation including Semipermeable Membrane Devices and biotic tests (fish fillets, fish livers, and mussels).

Of the tests utilized by the DEP and the University of Maine within the last decade, two methods have proven to be the most promising for mill compliance to the upstream/downstream legislation. Among biotic samples, smallmouth bass and white sucker fillets have demonstrated the least amount of variability between samples increasing the sensitivity and statistical power of the A/B test. Smallmouth bass and white suckers are relatively abundant at the sampling locations, provide enough sample mass to detect dioxin at low levels, and can be used as toxicological indicators. Another method warranting consideration for the above/below test is the Semipermeable Membrane Device (SPMD) developed by a host of researchers led by Dr. James Huckins of the U.S. Geological Survey in the 1990’s. SPMDs are essentially plastic bags filled with fish fat which adsorb dissolved dioxin over a period of time when placed in a river near a mill. The SPMD research project conducted by the University since 1999 has developed an appropriate deployment scheme for the A/B test and results demonstrate SPMDs are effective at quantifying dissolved concentrations of dioxin.

There are several complications when utilizing fish for the A/B test. Fish are nonuniformly distributed in the environment, accumulate dioxin at different rates, and metabolize dioxin at different rates. More importantly, fish represent historical dioxin concentrations instead of current concentrations. In terms of an A/B test, this would mean pulp and paper mills could possibly be penalized for past discharges instead of current compliance with the legislation. SPMDs can provide a logical solution to the problem of a proper A/B test. Research being executed at the University of Maine using standards called Permeability Reference Compounds should allow monitors to avoid or correct the problems of biofouling, water temperature, and flow velocity.

Critics of the university’s SPMD research have claimed that the location of the SPMDs were too far from the discharging mills. This may be a valid argument and one which could be researched in the future. However, the reason for the distance from the mill was to ensure complete mixing of the mill discharge and river water.

We live in an imperfect world. No A/B test will be absolute. The goal of researchers, private interest groups, and state agencies should be to find the best possible solution to dioxin contamination to safeguard the environment and way of life for the people. This is a perpetual process. We need to continue researching new methods, improve old methods, and be willing to compromise on differing opinions. The goal of the 1997 upstream-downstream legislation was to make pulp and paper mills accountable for discharging dioxin into our rivers. The hard work by the mills, university researchers and the Dioxin Monitoring Program has improved the health of our rivers

by reducing dioxin concentrations dramatically since the 1980s.

Bjorn A. Lake is a masters student in ecology and environmental science at the University of Maine. Howard Patterson is a professor of chemistry at UMaine.