GULFWATCH CONTAMINANTS

Contaminant

Sources

Gulfwatch Findings

Health and Environmental Effects

Heavy Metals

Naturally occurring elements that do not break down or degrade. Natural levels augmented by use in industrial and manufacturing processes and in products such as batteries, gasoline, paints, pesticides, and pharmaceuticals. Enter coastal ecosystems via wastewater discharge, runoff, mining, combustion, incineration, and via direct contact with water (in the case of anti-fouling paint used on vessels).

Distribution of most metals relatively uniform throughout the Gulf. Levels at or near natural levels for most of Bay of Fundy. Mussels in Boston’s inner harbour and Portland Harbour contain highest concentrations of lead. Some high lead concentration levels also found at some of the northern Gulf sites.

In certain concentrations, some metals can affect neurological, reproductive, developmental, cardiovascular, kidney, and liver health in humans and other animals. Many heavy metals are suspected or known to cause cancer. Metals of concern for the marine environment include Hg, Pd, Cd, Cu and Ag.

Chlorinated Pesticides

DDT, chlordane, heptachlor and other chlorinated pesticides once widely used in agriculture and forestry. Use of DDT restricted in US and Canada since early 1970s. Enter coastal ecosystems via runoff and disposal. Residues persist in sediments.

Levels decrease from south to north along the Gulf’s coast. Despite extensive use of DDT in Maine and N.B. in 1950s and 60s, levels found there not as high as expected. Pesticide concentrations at all sites below human health tolerance levels.

Can cause numerous immediate and long-term illnesses, including cancer. Affect reproductive systems of vertebrates and invertebrates. DDT and other chlorinated pesticides cause thinning of bird egg shells. Due to persistence many remain biologically available for decades.

Used to cool electrical capacitors and transformers and as heat and pressure resistant lubricant. Use curtailed in 1970s due to concerns about health effects. Enter coastal ecosystems via point and non-point sources. Persist in coastal sediments and recycle in food chains.

Concentrations decrease from south to north along Gulf’s coast. No concentrations in mussels exceed federal human health tolerance levels or levels considered protective of wildlife. Several sites do exceed USEPA screening values for possible human health concerns.

Classified as probable human carcinogens on the basis of animal tests. reproductive, neurological, immunological, endocrine, liver and other health effects are suspected for humans and other species. Toxicity of certain PCBs are similar to the highly toxic 2,3,7,8-dioxin.

Dioxins and Furans

By-products of chemical manufacturing processes including incineration, metals refining, combustion, manufacture and bleaching of paper, and herbicide production. US Government has banned herbicidal products containing dioxin and regulates it under the Clean Water Act. Enter coastal ecosystems via direct discharge, combustion and incineration.

As of 1998, mussels at 32 Gulf sites have been tested. Levels decrease from south to north along the Gulf’s coast and are below Canadian health limit for highly toxic 2,3,7,8-dioxin. No equivalent US federal health limit exists. Summed toxicities of dioxins, furans and planar PCBs at some sites exceed a proposed Canadian guideline for protection of birds and mammals.

Scientists disagree over degree of danger to human health posed by dioxins. A variety of health effects have been observed in terrestrial and aquatic animals. Growing scientific evidence suggests that much of the chlorinated hydrocarbon toxicity in aquatic ecosystems is due to dioxins and similar contaminants.

Polycyclic Aromatic
Hydrocarbons (PAHs)

Come from petroleum and its refined products. Enter coastal ecosystems as a result of wood, coal and petroleum combustion, urban runoff and sewage discharge.

Most highly concentrated and frequently detected in southern part of Gulf and near population/industrial centres.

Due to their toxicity, 16 PAH’s are on EPA’s priority pollutant list. Suspected human carcinogen and immune system suppressant. Suspected to affect health of other species in ecosystem due to their persistence, bioavailability and toxicity at very low levels.