Cooperative Plating Company

Upon request, MDH gathers and analyzes information about hazardous waste sites, and industrial and other site-related environmental hazards that can affect the public's health. This information is used to provide a better understanding of the health risks associated with these sites, to assist regulatory decision makers, and to help the public avoid or reduce exposure to toxic chemicals.

At the request of the surrounding community and the Minnesota Pollution Control Agency, MDH has reviewed information about public health issues related to an accidental gas release that occurred on March 22, 1999, at the Cooperative Plating Company. Cooperative Plating is an electroplating operation with buildings at 1605 Iglehart Avenue and 271 Snelling Avenue North in St. Paul.

The release

At about 4:00 P.M. on March 22, 1999, the St. Paul Fire Department was called about a visible chemical emission at the Cooperative Plating Company. A brownish gas appeared to be coming from a roof vent above a mixed acid waste tank. At the time, employees at the facility were unaware of the emission.

The St. Paul Fire Department instructed Cooperative Plating to evacuate their buildings. At approximately 4:30, fire officials also evacuated homes and businesses within a six-block area around the facility. The evacuation order remained in effect for about three hours.

Initial air monitoring by the St. Paul Fire Department measured 2.47 parts per million (ppm) of nitrogen dioxide (NO2) in the air at the corner of Snelling and Carroll. Monitoring of NO2 continued throughout the incident. Subsequent monitoring recorded lower ambient air concentrations of NO2 near the Cooperative Plating facility. However, the amount of NO2 that may have been present before the monitoring began is not known. Altogether, a total of 14 air samples were taken from six locations over a 3 hour and 45 minute period. All monitored concentrations were 0.50 ppm or greater.

Fire officials and representatives of Cooperative Plating determined that the gases were being emitted from the mixed acid waste tank. The emissions were presumed to be the result of a chemical reaction, caused by the combining of nitric acid, sulfuric acid and iron. The acid mixture had recently been added to the tank, which contained a sludge made up of iron and other metals. The Fire Department decided to let the reaction run its course, and did not attempt to add chemicals or water to stop the air emissions.

The Minnesota Department of Health (MDH) has concluded that emissions from the tank during this incident probably contained NO2 and other forms of nitrogen oxide (NOx). Nitrogen oxides are the primary component of photo-chemical smog. The emissions may also have contained some sulfur oxides (SOx). Airborne nitrogen dioxide has been shown to form nitric acid vapor, and airborne sulfur dioxide has been shown to form sulfuric acid vapor. Emissions from the plating facility may have, therefore, contained limited amounts of nitric or sulfuric acid vapor.

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Public health concerns

Based on data collected by the St. Paul Fire Department, nitrogen dioxide levels in the vicinity of Cooperative Plating during the March 22 chemical release appear to have exceeded health-based guidelines developed by the State of California and used by MDH. These guidelines are known as "Reference Exposure Levels" (RELs). A REL represents the level of exposure to an airborne chemical that is considered to be safe for the general public, including sensitive sub-populations, for limited periods of time. The 1 hour REL for nitrogen dioxide is 0.25 parts per million (ppm).

Data collected by the Fire Department indicate that concentrations of NO2 near the plating facility remained above the REL for several hours. Some people in the area therefore may have experienced respiratory or eye irritation. However, once people moved to areas with cleaner air, those symptoms should have dissipated.

It should be emphasized that there is no way to calculate, with certainty, what any one person may have been exposed to — or how long the exposure may have lasted. Variations in wind speed and direction make that impossible.

No monitoring was done for compounds other than NO2 that may have been emitted during this incident. It is unlikely that there were ambient air concentrations of any other compounds that might represent a health concern. However, if people were exposed to NO2 and, at the same time, also exposed to other compounds with similar effects, the combined effects of these chemicals could be more severe.

Because of this "additive effect," the risks associated chemical exposure during this incident could be greater than those suggested by the NO2 monitoring data. But based on the recorded levels of NO2, and the fact that the area was evacuated so quickly, we would expect any health effects associated with this incident to be mild, and relatively brief.

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Community concerns

Community members from neighborhoods near Cooperative Plating have expressed concern about the March 22 incident, and about the potential for future exposure to chemical releases. Community members are also concerned that they may have been exposed previously to chemicals accidentally released from Cooperative Plating.

MDH is concerned that airborne levels of NO2 present during the March 22 incident were above health-based guidelines. In response to the incident, Cooperative Plating has agreed to change its operating procedures. Instead of being added to the mixed acid waste tank, wastes that contain nitric acid will be disposed of in clean drums.

While we cannot address any events or incidents that may have occurred prior to the March 22 release, we believe this new procedure should eliminate the possibility of another, similar incident in the future.

MDH has concerns about emissions from Cooperative Plating. However, we have no way to determine, scientifically, whether any one person's health symptoms are related to emissions from the facility. Like the residents of any community, the people who live near Cooperative Plating have a variety of different kinds of jobs, personal habits and biological characteristics, all of which contribute to health.

Further complicating the situation is the fact that heavy street traffic and other activities may also be affecting air quality in this part of St. Paul. For these reasons, there is no way to sort out the impact of a specific chemical exposure from the effect that other factors may have had on a person's health.

Our goal is to protect people from the effects of exposures to chemicals in the environment. Our ongoing health assessment activities are done to ensure that people are protected.

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Continuing investigation

MDH will continue to investigate potential health concerns that may be associated with chemical releases from Cooperative Plating. As we typically do in a situation like this, we will continue to make health-based recommendations to community, to the Minnesota Pollution Control Agency (MPCA), and to the company responsible for the emissions.

The use of large quantities of chemicals always involves some risk of potential accidents. However, Cooperative Plating has expressed interest in talking to and working with the community, MPCA, and MDH, as part of an effort to make improvements at the facility and reduce the likelihood of future accidents.

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MDH recommendations

MDH recommends that:

  • people contact their physician or health care provider if they believe they have experienced health effects as a result of a chemical exposure — either during the March 22 incident or at any other time. (Always seek medical advice as soon as possible after an exposure occurs.)
  • permanent monitors be installed, to provide a warning of any potentially significant accidental emissions from Cooperative Plating.
  • Cooperative Plating install a permanent disposal tank for nitric and sulfuric acid wastes.
  • on-site disposal tanks for non-compatible wastes be located in separate containment structures (berms).
  • the community, Cooperative Plating, MPCA, and MDH continue to discuss ways of decreasing health risks in the community surrounding the facility.
  • a health consultation (analysis and report) be conducted by MDH, to determine if future studies are warranted; and what, if any, measures may be taken to improve air quality in the vicinity of the facility.

References and public health reports on the Cooperative Plating facility are available from MDH. To request a copy call please contact us.

More detailed material regarding this incident will be available in a document known as a "health consultation," which is currently being prepared by the Minnesota Department of Health (MDH). An earlier health consultation regarding the Cooperative Plating site, prepared in 1996, is also available from MDH. It provides general information about past emissions at the site.

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Updated Friday, September 16, 2011 at 03:35PM