State says laboratory error lead to false positive for toxic chemical in Otsego wells

Jan 9, 2019

Residential wells in Otsego, that’s in Allegan County, have tested negative for dioxin chemicals after a state retest.


Last year, roughly 20 wells tested positive for dioxin at levels just under the safe drinking water standard.

The chemical is considered highly toxic and has been linked to reproductive problems and cancer.

Scott Dean is with the Michigan Department of Environmental Quality.

“We were able to determine that the laboratory equipment that we used was contaminated and we switched to a different laboratory and resampled.”

With resampling, Dean says all but one of the wells came back with non-detect for dioxin contamination.

“And the one that did have a trace amount was zero point one three parts per quadrillion and that’s well well below the drinking water standard of 30 parts per quadrillion.”

Dean said the state is doing some further soil testing in the area to determine if dioxin remains in the soil.

He said the state is also testing for perfluoroalkyl substances, or PFAs, in the area. PFAs are another chemical contaminant linked to health problems including cancer.

The residential wells the state has tested were non-detect for PFAs.

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