Risk management strategy for perfluorooctane sulfonate and its salts and precursors: chapter 5
5. Exposure Sources
There are no known natural sources of PFOS, its salts or its precursors in the environment. Release of PFOS to the environment varies with the process or product and disposal practices of the end user.
PFOS, its salts and its precursors may enter into the environment through treated or untreated municipal/industrial wastewater discharges to surface water and through leachates from landfills when products and materials containing these substances are sent for final disposal. PFOS may also be released directly to air, land and surface water when products containing PFOS are used. These exposure sources are discussed in this section.
Aqueous Film Forming Foams (AFFF)
AFFF manufactured and imported into Canada prior to the voluntary phase-out in production in 2002 contained PFOS. AFFF is used primarily to fight fuel related fires. Sectors using AFFF include the military and other Government of Canada operations, civil aviation, municipal fire departments, petroleum, petrochemical and emergency responders. Equipment used to dispense AFFF may be either fixed or portable. Fixed systems are mounted in buildings or other permanent structures and portable systems may include moveable fire extinguishers or systems mounted on emergency response vehicles used to access the location of the fire.
Releases of PFOS may occur when foam is discharged during testing and training exercises, when fighting fuel fires, during accidental releases or when out of date product must be retired and sent for disposal. These activities may result in direct discharge of AFFF to surface water, groundwater and land. Depending on the nature of the activity, it is not always possible to collect and pre-treat or contain the AFFF residual for proper disposal. AFFF that is collected is treated as hazardous waste and is sent to either a hazardous waste landfill or to an approved thermal destruction facility for high temperature incineration. Current industry estimates suggest that an average of 10% of the existing AFFF stock is expended each year.
Background information collected in this industry sector shows that PFOS-based AFFF has not been imported into Canada since 2002. However, given that the average lifespan of AFFF can be in the order of 25 years or longer and that the estimated existing stock of PFOSAFFF stock at airports, military installations and industrial facilities in Canada is approximately 300 tonnes (representing approximately 3 tonnes of PFOS), AFFF remains a potential PFOS emission source.
Surfactant Use in the Electroplating Sector
PFOS based surfactants are used to reduce the surface tension of plating solutions in the electroplating sector. This is the only sector importing PFOS (approximately 3 tonnes in 2004) into Canada at the present time. PFOS may enter the environment via the rinse water from the facility that is discharged directly to the municipal sewer systems if the effluent quality meets the sewer bylaw requirements. PFOS is not removed in these municipal systems and flows through into the downstream aquatic environment. PFOS may also be contained in the sewage sludge that is generated by the municipal treatment system that may be either applied as a bio-solid on land or sent to a residential landfill. PFOS is also a constituent of the metal sludge that is consolidated at the electroplating facility and then removed as a hazardous waste. This waste may be sent for recycling, used as an input to the steel industry where the residual PFOS is destroyed through high temperature incineration or placed in an approved hazardous waste landfill for final disposal.
The use of PFOS, its salts and its precursors in industrial and manufacturing processes includes a wide range of operations in which these substances are used as product aids to produce industrial, commercial and consumer materials.
PFOS, its salts and its precursors have been used as product aids in tanneries, textile mills, carpet manufacturers and packaging producers to treat surfaces for water, oil, and soil and grease repellency. The releases of PFOS, its salts and its precursors from these sources occur primarily through the discharge to process wastewaters from industrial or manufacturing processes. However, with the voluntary phase-out in production in 2002, it is believed that PFOS is no longer used in these manufacturing processes.
Materials refer to articles to which PFOS containing products have been applied. This may include rugs and carpets, furniture, fabrics, leather articles, paper, packaging and photographic material. However, since 2002, PFOS-based products have not been used in Canada for the treatment of these materials and the import of materials containing PFOS is believed to be limited.
The release of PFOS, its salts and its precursors from these sources may occur when legacy materials purchased prior to 2002 or when material imported from jurisdictions without PFOS restrictions are disposed of in landfill sites at the end of their operational life or in the case of some paper products, sent to recycling facilities for processing.
Landfilling may result in releases of PFOS, its salts and its precursors to soil, surface water and then potentially to groundwater. Releases from landfills are dependent on the concentration of these substances remaining in the material at their end of life, landfilling practices and the existence of leachate collection systems.
It should be noted that leachates that may contain PFOS that is collected from landfills is normally taken to municipal treatment facilities. Since PFOS is not removed from the influent at these facilities, the PFOS is either passed directly through and into the downstream aquatic environment or is contained in bio-solid sludge that is either applied on the land or returned to the landfill that originally generated the leachates.
The majority of the paper and packaging that was coated with PFOS is sent to landfills but there is a percentage that would have been sent to recycling facilities for re-processing into other products. Based on the phase-out in production in December 2002 and the limited retention time for this material in the manufacturing and recycling systems, it is believed that most of this material has already been processed.
Municipal incineration of solid waste is a potential source of PFOS emissions. However, incineration represents less than 5% of solid waste disposal in Canada.
Long-Range Atmospheric Transport
PFOS has been detected in remote sites around the world, including the Canadian Arctic where it is present at elevated levels, for example, in the livers of polar bears and ringed seals, which suggests that the precursors to PFOS undergo long-range transport. This possible long-range atmospheric transport of PFOS precursors through the atmosphere or through the ocean currents is a potential source of PFOS loadings to the Canadian environment. Manufacturing processes of PFOS, its salts and its precursors, as well as uses and disposal of formulations, products and materials outside of Canada may also contribute to the presence of PFOS in Canada. Although polar bear and ringed seal sample data from 2005 has shown the first decline in levels since the reduction in worldwide production that began in 2000, more sample data must be collected in future years before it can be confirmed if the reductions are indeed the start of a long term downward trend in PFOS levels.
The day-to-day use of certain materials that have been treated with PFOS based water, oil, soil and grease repellents have the potential to release PFOS, its salts and its precursors to the environment. Potential emissions to wastewater effluents have been identified from the washing of fabrics and by vacuuming or steam cleaning rugs and carpets. The output from these activities is usually in the form of liquid effluent which makes its way to the municipal treatment facility or is in the form of solid waste which is sent to a residential landfill. The final fate of the PFOS in these waste streams is described in the Material Disposal section 5 of this report. However, since 2002, PFOS-based products have not been used in Canada for the treatment of these materials and the current imports of materials containing PFOS are believed to be limited.
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