By 1990, it was apparent that a cancer cluster had developed among people who worked at the Simpson Lumber Company mill in Arcata. The State Health Department found a 16-fold increase in the number of blood cancers over statistically expected malignancies, but concluded the cluster was from unknown causes. The state was missing one critical piece of information in its investigation, however: for many years the company used a highly toxic product euphemistically called Woodlife.

Without a doubt one of the deadliest chemicals ever known to humans, dioxin pollution is a widespread but lesser-known problem associated with lumber mills on the North Coast. Numerous mills and lumber yards in Humboldt County are highly contaminated with dioxin, posing serious health hazards to people who work at the sites, those who consume seafood that is contaminated, and the fish, birds, and wildlife that are exposed.

Wood preservatives with dangerously high levels of dioxin were widely used from the 1960's to late 1980's. Coming in the form of pentachlorophenol (penta, also referred to as PCP), this chemical was included in a variety of wood preservatives, pesticides, and fungicides used during that time, being sold under such innocuous sounding names as Woodlife.

Penta itself is a known carcinogen, and is also contaminated with polychlorinated dioxins and furans. Recent studies have shown that dioxins provoke adverse effects in virtually every organ system studied, including alterations to the developing reproductive system, diminished prenatal viability, and learning behavioral problems. Once in the environment, dioxins bio-accumulate in organisms like fish, shellfish, marine mammals, birds, and humans, concentrating in the muscles, bone marrow, and fat, and doing long-term damage to the formation of blood cells.

The effects of exposure sometimes take many years to manifest, with most forms of cancer not appearing until between fourteen and seventeen years later. At Simpson's Arcata mill, four workers exposed to penta in the 1970's developed leukemia in the late 1980's. When the state investigated a potential cancer cluster, Simpson concealed from officials the fact that the company used Woodlife for many years. In one of these cases, comparative tests of a worker's fat and a sample of Woodlife confirmed his leukemia was linked to his exposure to this chemical.

Penta contamination is documented at six additional locations around Humboldt Bay, and eleven others are unconfirmed but probably also contaminated (click here to see map). The chemical is found at exceedingly high levels at many of these sites, such as Schmidbauer Lumber in Eureka, where it has been detected in the groundwater at 9,600 parts per billion (ppb). The legal limit for penta is 1ppb.

Nowhere have problems with penta been found to be more severe and alarming than at Sierra Pacific Industry's mill in Arcata. In 2001, the Ecological Rights Foundation filed suit against Sierra Pacific for serious problems relating to penta at this mill. Information obtained during the course of the lawsuit showed the problem was even more serious than was previously believed. Groundwater samples from the site revealed penta and a similar chemical, tetrachlorophenol, at concentrations as high as 100,000 ppb--100,000 times higher than the legal limit.

The Ecological Rights Foundation also sampled for dioxin in sediment, crabs and mussels found near Sierra Pacific's mill and the Mad River Slough. This area is popular as a public clamming spot and there are extensive areas in close proximity that are used to cultivate oysters for human consumption. Laboratory analysis revealed dangerously high levels of dioxin in all samples taken in the area.

These contaminated sites are a significant cause for concern, with approximately 70% of all shellfish harvested for human consumption in California coming from Humboldt Bay. Humboldt Bay is also one of the most biologically important coastal estuaries on the West Coast, and these problems threaten to harm hundreds of species that grace its waters and shores.

EPIC is closely monitoring the cleanup efforts the State has initiated at some of these sites and investigating the possibility of contamination at other locations as part of our Humboldt Bay Initiative. We are working with the Californians for Alternatives to Toxics in these efforts, and are committed to finding a solution to this serious problem.