WITH ALL THE TALK of Portland aiming to become the most sustainable city in America, it's easy to forget that a Superfund site (known as the Willamette River) cuts through our heart. Though the majority of toxic emissions come from city sources and private homes, the large industrial facilities cannot be ignored.

The Environmental Protection Agency's (EPA) Toxics Release Inventory collects data on emissions of over 650 harmful substances, including heavy metals and "persistent organic pollutants" like DDT.

Here are the big winners: the top five industrial emitters of toxic chemicals to Portland's air, water, and land.

1. SAPA Extrusions, Inc. (7933 NE 21st)

Pounds of toxic chemicals released in 2008: 1,015,100

SAPA is an aluminum extruder, meaning that they mold aluminum into shapes for many purposes, including bike frames and machine parts. Their emissions include 995,962 pounds of sulfuric acid that went into Portland's air. Breathing air with concentrations of sulfuric acid can cause damage to the respiratory system, especially among children. SAPA representatives did not return repeated calls for comment.

2. Siltronic Corporation (7200 NW Front)

Pounds of toxic chemicals released in 2008: 569,963

Siltronic is a major employer in job-strapped Portland, with its 850 workers building silicon wafers for semiconductors. Company spokesman Tom Fahey says the semiconductor business is a "very clean industry," but the fact stands that Siltronic emits an awful lot of chemicals into the water.

Just this past week, Siltronic pressed Portland City Hall to grant them an exemption from Portland's River Plan, hoping to avoid time-consuming environmental oversight processes if it chooses to expand further on its 80-acre lot near Forest Park. The River Plan is a city project with twin goals of economic prosperity on the waterfront and conservation of natural habitats on the Willamette River.

In exchange for an exemption from the plan's new "River Review Process," Siltronic would give Portland use of a seven-acre strip of land on the edge of its property as an environmental restoration site. Fahey says an underground stream there could be uncovered, and there might someday be salmon in this water, just yards up the river from where Siltronic discharges 567,528 pounds of nitric compounds a year.

3. Arclin Surfaces, Inc. (2301 N Columbia)

Pounds of toxic chemicals released in 2008: 309,681

In its 105-year-old factory, Arclin Surfaces' 35 employees produce special coatings and surfacing "solutions" used in construction and building. Their emissions, including methanol and formaldehyde, go into the air from machines called "paper treaters."

Arclin spokesman Kevin Griffin says that the company spent $1 million in 2009 on a new thermal oxidizer to reduce air emissions. So hopefully we'll be inhaling less of their toxins soon.

4. ESCO Corporation (2141 NW 25th)

Pounds of toxic chemicals released in 2008: 206,390

Scrap metal recycler ESCO has snagged media attention recently for its proximity to schools and communities. Neighbor Mary Peveto started a campaign last year to clean up the factory, after reading that the emission levels near her daughter's Chapman Elementary School were among the worst in the country ["Breathing Wheezy," News, Aug 13, 2009].

ESCO's 750 employees recycle scrap steel into new steel products, a process that produces air emissions that include metals. ESCO's Manager of Environmental Affairs Carter Webb says the company has heard its neighbors' concerns "loud and clear," and Peveto, surprise surprise, agrees. "ESCO has been engaged and willing to address their contribution to the problem," says Peveto.

5. Cascade General (5555 N Channel)

Pounds of toxic chemicals released in 2008: 189,036

Cascade General is the largest ship repair facility on the West Coast, located right here in North Portland. Pollutants at Cascade General come from the yard's painting and sandblasting operations.

Some of the shipyard's 850 employees paint ships using spray guns, and "overspray" results in toxic chemicals entering the air and water system. When ships are sandblasted, layers of copper and zinc turn into dust that spreads into the air.

Since the latest EPA numbers were released, Cascade General says it has invested in "paint simulators" to make workers more accurate with paint.