Ever wonder where the term "mad as a hatter" came from? Mercury, once used extensively in the hat making process, caused a brain illness in many hatters.
And though the hat making industry is gone from Danbury, Connecticut, mercury may still exist in the soil and river sediments that surround its old factories.
Danbury was known as the hat making capital of the world in the 19th century. During the industry boom of the 1880s, over five million hats a year were produced there in 56 different factories.
The production process involved using a mercury compound, mercury nitrate, to remove fur from pelts and turn it into felt more easily. Abraham Lincoln's famous beaver stovepipe hats were made in this fashion.
Hat makers, exposed to large amounts of vaporized mercury, began to experience its effects on their nervous systems. Doctors even recorded seeing "holes the size of quarters" inside some hatters' brains.
The state of Connecticut outlawed the use of mercury in hat making in the early 1940s. But there are signs that mercury remains in soil and river sediment not far from where factories once stood.
Connecticut Sea Grant researcher Johan Varekamp and his team, who had been studying the distribution of mercury contamination throughout Long Island Sound, discovered high levels of mercury in a marsh within the mouth of the Housatonic River.
Varekamp worked his way up the river in order to find the mercury's source. He found extremely high levels in the Still River, a tributary of the Housatonic that flows through Danbury.
He and his team have tested fields, rivers and soils inside the town, and have found mercury levels many times higher than natural levels. Now, the team is testing further sites to find out how far the contamination has reached.
The Still and Housatonic Rivers are both prone to flooding, and Varekamp worries that a future hurricane or storm may flush more mercury into Long Island Sound, threatening its fisheries and once again imperiling human health through seafood contamination.
[Contact: Johan Varekamp]