Environ. Sci. Technol. 2009, 43, 386–392
A First Global Production, Emission, And Environmental Inventory For Perfluorooctane Sulfonate ALEXANDER G. PAUL, KEVIN C. JONES, AND ANDREW J. SWEETMAN* Centre for Chemicals Management, Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, United Kingdom
Received August 7, 2008. Revised manuscript received October 17, 2008. Accepted November 3, 2008.
This study makes a new estimate of the global historical production for perfluorooctane sulfonyl fluoride (POSF), and then focuses on producing a first estimate of the global historical environmental releases of perfluorooctane sulfonate (PFOS). The total historical worldwide production of POSF was estimated to be 96 000 t (or 122 500 t, including unusable wastes) between 1970-2002, with an estimated global release of 45 250 t to air and water between 1970-2012 from direct (manufacture, use, and consumer products) and indirect (PFOS precursors and/or impurities) sources. Estimates indicate that direct emissions from POSF-derived products are the major source to the environment resulting in releases of 450-2700 t PFOS into wastewater streams, primarily through losses from stain repellent treated carpets, waterproof apparel, and aqueous fire fighting foams. Large uncertainties surround indirect sources and have not yet been estimated due to limited information on environmental degradation, although it can be assumed that some POSF-derived chemicals will degrade to PFOS over time. The properties of PFOS (high water solubility, negligible vapor pressure, and limited sorption to particles) imply it will reside in surface waters, predominantly in oceans. Measured oceanic data suggests ∼235-1770 t of PFOS currently reside in ocean surface waters, similar to the estimated PFOS releases. Environmental monitoring from the 1970s onward shows strong upward trends in biota, in broad agreement with the estimates of use and emissions made here. Since cessation of POSF production by 3M in 2002, a reduction in some compartments has been observed, although current and future exposure is dependent on emission routes, subsequent transport and degradation.
Ongoing uses within the European Union in 2004 included; metal plating, photographic, photolithography, and semiconductor industries, hydraulic fluids, and while current stocks last, in perfluorooctane sulfonate (PFOS) based aqueous fire fighting foams (AFFFs) (3-5). Perfluoroalkyl sulfonates (PFAS) continue to attract scientific, political, and regulatory interest. PFOS and its potential precursors have been classed as emerging chemicals of concern (6) due to their global distribution in biota (7-9) and humans (10). Despite a lack of knowledge about physical-chemical properties, fate, transport, and toxicity, the use of PFOS is regulated in the US (11) and was restricted from December 2007 in Europe, with remaining permitted uses to be phased out by 2011 (12). PFOS is a candidate POP under the Stockholm Convention (6). Only limited information is available on sources, volumes, and emissions of PFAS (including POSF and PFOS), although more is known about perfluorocarboxylic acids (PFCAs) (13). However, such information is necessary when assessing distribution, environmental fate, contamination, and final sinks or loss mechanisms for these compounds. This paper therefore assesses POSF production and use, including related products and/or PFOS precursors. Global production volumes of POSF, division of products into different use categories/applications and subsequent releases are estimated. A further calculation estimates PFOS releases from residuals in products. These values are then compared with environmental temporal trends and recent industry actions to reduce PFOS emissions, allowing comparisons to be made between estimated emission volumes and measured environmental concentrations. A schematic diagram (Figure SI1of the Supporting Information) shows the objectives and steps of the paper. From here on, “POSF” will be used to describe “PFOS equivalents”, i.e., POSF-derived fluorocarbons including (numerous) related secondary reaction products and precursors with the potential to breakdown to PFOS in the environment (14). Although PFOS is often the PFAS found in the greatest quantities during environmental monitoring campaigns (7, 8, 15-18), POSF was produced in much greater quantities. When commercialized PFOS is mentioned, this will be stated. Occurrence of PFOS in the environment arises from two sourcess“direct”, defined as releases during manufacture, application and use of PFAS, and “indirect”, defined as releases of PFOS as chemical impurities formed during manufacture of POSF, or by breakdown in the environment from POSF-derivatives to PFOS.
POSF Manufacture and Historical Production Volumes Introduction The 3M Company began producing perfluorochemicals (PFCs) in 1949, using the electro-chemical fluorination (ECF) process (1). From 1966 to the 1990s, production and use grew due to their unique chemical attributes, including chemical stability and surface tension/leveling properties. Uses ranged widely including: inks, varnishes, waxes, firefighting foams, metal plating and cleaning, coating formulations, lubricants, water and oil repellents for leather, paper and textiles (2). 3M was, prior to the phase-out announced in 2000, the major global producer of perfluorooctane sulfonyl fluoride (POSF; defined as the C8F17SO2F group by 3M), although smaller producers existed in Europe and Asia. * Corresponding author e-mail:
[email protected]. 386
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PFCs have been manufactured by four distinct routes. 3M was the only major company to commercially synthesize PFAS salts using ECF. Historically commercial PFAS product mixtures generally contained 8 or 9 fully fluorinated carbons as their major constituent. ECF is a fairly crude production technique, resulting in complex mixtures of both odd and even chain lengths, both branched and linear in format, with a range of physical-chemical properties. PFAS products may include up to 30% branched chains and homologues ranging from 4-9 carbons (2). From 1949 to 2002, 3M manufactured the majority of POSF using ECF. They manufactured approximately 3665 t POSF, or ∼78% of the estimated global POSF production of 4650 t in 2000 (4). Their two largest production sites were in the United States (Decatur, Alabama) and Belgium (Antwerp). 10.1021/es802216n CCC: $40.75
2009 American Chemical Society
Published on Web 12/11/2008
FIGURE 1. Estimated total global POSF production volumes (1970-2002). This work’s estimates of total global (green line) and 3M’s production (purple line) are compared to estimates from Smithwick et al. (9) (red line) and Prevedouros et al. (13) (blue line). (Note: Smithwick et al. (9) and Prevedouros et al. (13) assume POSF production stops with 3M). The U.S. EPA compiled a list of 20 non-U.S. companies producing and supplying the global market with PFOS related substances. Excluding the 3M plants in Belgium and North America, 6 plants were located in Europe (4 in EU member states), 6 in Asia (of which 4 were in Japan) and one in South America. On 16th May 2000, 3M announced that they would voluntarily phase out PFOS and similar chemicals by 2002 (2). There appears to be little additional information available in the public domain on the production volumes over time and the environmental releases, pathways and burdens arising from them. The next stages of the paper, therefore, derive such estimates. The estimate of the total global production of POSF derived here was calculated using publically available information. Smithwick et al. (9) estimated POSF production to be in the region of 43 500 t between 1985 and 2002. Quantities reported for 1985-1989 and 1990-1994 were averages based on 3M information, while 1997-2002 data were available in a published report (2). Using the OECD (4) global total production figures for 2000 and an estimation by 3M cited in Olsen et al. (10), POSF production was estimated to be 96 000 t of useful product between 1970 and 2002, with a further 26 500 t of mainly solid unwanted byproduct or wastes. Olsen et al. (10) reported a 5-fold increase in POSF production between 1975 and 1989 that then remained relatively constant during the 1990s, based on a personal communication with a senior 3M employee. Although 3M started POSF production using ECF in 1949 (2), it has been assumed that production was low in the development phases and that pre-1970 volumes were minimal. At this time, POSF-based AFFFs became the product of choice for fire fighting, due to their effectiveness, long shelf lives, and ease of use (19, 20)sso production volumes increased. Figure 1 shows the estimated growth in global production of total useful POSF (excluding manufacturing wastes) between 1970-2002, derived by the above assumptions. Estimates of POSF production by Smithwick et al. (9) and Prevedouros et al. (13) are also plotted for comparison. The new estimate derived here puts total global production of POSF at 96 000 t, similar to the value derived by Prevedouros et al. (83 000 t) (13), but over twice that derived by Smithwick et al. (44 000 t). Both authors received industry input which is not publically available. Possible reasons for the larger estimate made here include; Smithwick et al. covered a shorter time period of 1985-2002, while Prevedouros et al. covered the period 1960-2002 and was based on a lower estimated total global production. This paper estimates both 3M’s total estimated POSF production (∼75 000 t) and the global total POSF production using a higher OECD estimate (4).
The sharp drop-off between 2000 and 2003 shown in Figure 1 represents 3M’s phase-out period. In practice, 3M was unable to suddenly stop production without giving secondary users an opportunity to find alternatives, although a limit of 50% of previous orders was introduced (2). POSF/ PFOS production continues in southeast Asia, although exact volumes are unknown. Assuming there was no step-up of production by remaining producers to offset 3M’s POSF phase-out, production is likely to be ∼1000 t a-1 from 2002 onward. In addition to the calculated total POSF production (96 000 t), the production of deliberately produced PFOS (by 3 M only) was estimated to be ∼470 t over the same period. PFOS was an active surfactant in the AFFF mixture, while all other POSF products typically contained a small residual (0.1-5%) of PFOS (4, 18, 22).
Releases into the Environment The major use of POSF derivatives have been (i) treatment of carpets to impart stain and dirt repellence, (ii) in apparel to provide water repellence, (iii) in paper and packaging to afford oil and grease repellence, (iv) in performance chemicals such as hydraulic fluids for aviation, and (v) in AFFFs. AFFFs are perhaps the most prominent method of widespread environmental dispersal, with use for oil drilling and military fire fighting practice. Only about 5% of total POSF production went into AFFFs (21). Chemical industry sites are generally carefully controlled “bunded” sites with effective spillage capture and wastewater treatment systems, therefore releases to the environment from such sites should be minimal. 3M estimates that 85% of indirect emissions are as a result of losses from consumer products during use and disposal (e.g., from carpets, clothing, paper, and packaging, etc.) (14). The remaining 15% is associated with manufacturing releases from secondary application (e.g., to carpets). Secondary application wastes were generally related to start-up and shutdown operations (for example, during formulation or application tank cleaning), as well as losses from production wastes such as fabric/carpet remnants. No official figures were available from 3M for the percentages of fluorochemicals used for each product type (carpets, paper, and packaging, etc.); however, estimated uses were available for the UK and Canada (3). Estimates of the percentage of total fluorochemicals tonnages used in carpets ranged from 14-48%, apparel from 43-48% (higher figure includes carpet data), and paper and packaging from 15-28%. AFFFs use ranged from 6-16% depending on source and use in other performance chemicals from 8-20%. Calculations were performed for each product use sector (e.g., carpets, VOL. 43, NO. 2, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Global Historical POSF and PFOS Production, Use and Emissions Summary (1970 - 2002)
source
estimated total global POSF production/use (t)
estimated total global historical POSF emissions (t) to water/air
estimated total global historical PFOS emissions (t) to water/air
direct POSF sources POSF manufacture Inc. PFOS manufacture manufacturing wastes total manufactured
96 000 ∼470 26 500 122 500
total industrial application
secondary (industrial) applicationa ∼96 000 2600b-10 000
26-500
carpets P&P apparel performance chemicals AFFFs total industrial use
estimated consumer use/disposal 48 000 20 500 24 000 350 12 500 12 000 6000 45 10 000 9150 ∼96 000 4200b-42 000
205-1000 3.5-17 120-600
