163
Trifuoroacetic Acid from CFC Replacements
Canada, had concentrations less than 0.5 ng/L (Scott et al., 2000). Streams
along coastal Northern California, which represent Pacifc air masses, had
concentrations averaging 24.3 ng/L (Cahill and Seiber, 2000). Overall, these
data suggest that TFA is globally distributed at low concentrations as would
be expected with a compound degrading from HFC precursors. However,
most of these sites were sampled before 2001 and there are little recent data
available on TFA in remote areas, which are needed given the increase in the
atmospheric concentrations of HFC-134a.
9.5.3 Populated Regions
Considerable research has been conducted investigating TFA concentrations
in populated regions ranging from rural locations to large industrial cities.
This summary will focus on aqueous media, such as rain, fogwater, rivers,
and lakes, since there are more data available for comparisons. Other media,
such as air, soil, and plants (Cahill et al., 2001; Chen et al., 2018; Martin et al.,
2003; Scott et al., 2005; Tian et al., 2018; Wu et al., 2014; Xie et al., 2020; Zhang
et al., 2018), have also been sampled, but at a considerably lower frequency.
There have also been extensive modeling efforts to predict TFA concentrations resulting from precursor compounds such as HFC-134a and HFO-1234yf
(Henne et al., 2012; Kazil et al., 2014; Kotamarthi et al., 1998; Luecken et al.,
2010; Wang et al., 2018; Wu et al., 2014).
A summary of TFA in surface waters of populated areas (Table 9.4) shows
that most TFA concentrations are below 300 ng/L and effectively all measurements are below 1,000 ng/L. Higher concentrations were detected in
highly industrialized and/or populated areas. The high concentrations in
Germany were largely attributed to fuorochemical manufacturing in the
region (Janda et al., 2019; Scheurer et al., 2017). High concentrations of TFA
were also observed in Beijing, China, which was expected due to the large
population in the area. However, these samples also provided a time series
on how these concentrations changed over time since the same sites were
sampled in 2001 and 2012. During the decade between sample collections,
the concentrations in the surface waters increased approximately 17-fold
(Zhai et al., 2015). This increase could be attributed to many potential factors, such as increased industrialization in China, greater atmospheric HFC
concentrations, and/or greater consumer use of fuorinated chemicals in the
region. To put these surface water concentrations into perspective, the most
sensitive aquatic organism to TFA was an alga with a NOEC of 0.12 mg/L,
which equates to 120,000 ng/L. Since the surface water concentrations are
typically less than 1,000 ng/L, the concentrations are less than 100-fold the
toxic effect level.
A review of the literature on surface water concentrations of TFA showed
a diminished publication rate after approximately 2006 with the exception of
sampling near point sources. This can largely be attributed to the increased
attention to longer chain and more toxic fuorinated acids like PFOS and
Trifuoroacetic Acid from CFC Replacements
Canada, had concentrations less than 0.5 ng/L (Scott et al., 2000). Streams
along coastal Northern California, which represent Pacifc air masses, had
concentrations averaging 24.3 ng/L (Cahill and Seiber, 2000). Overall, these
data suggest that TFA is globally distributed at low concentrations as would
be expected with a compound degrading from HFC precursors. However,
most of these sites were sampled before 2001 and there are little recent data
available on TFA in remote areas, which are needed given the increase in the
atmospheric concentrations of HFC-134a.
9.5.3 Populated Regions
Considerable research has been conducted investigating TFA concentrations
in populated regions ranging from rural locations to large industrial cities.
This summary will focus on aqueous media, such as rain, fogwater, rivers,
and lakes, since there are more data available for comparisons. Other media,
such as air, soil, and plants (Cahill et al., 2001; Chen et al., 2018; Martin et al.,
2003; Scott et al., 2005; Tian et al., 2018; Wu et al., 2014; Xie et al., 2020; Zhang
et al., 2018), have also been sampled, but at a considerably lower frequency.
There have also been extensive modeling efforts to predict TFA concentrations resulting from precursor compounds such as HFC-134a and HFO-1234yf
(Henne et al., 2012; Kazil et al., 2014; Kotamarthi et al., 1998; Luecken et al.,
2010; Wang et al., 2018; Wu et al., 2014).
A summary of TFA in surface waters of populated areas (Table 9.4) shows
that most TFA concentrations are below 300 ng/L and effectively all measurements are below 1,000 ng/L. Higher concentrations were detected in
highly industrialized and/or populated areas. The high concentrations in
Germany were largely attributed to fuorochemical manufacturing in the
region (Janda et al., 2019; Scheurer et al., 2017). High concentrations of TFA
were also observed in Beijing, China, which was expected due to the large
population in the area. However, these samples also provided a time series
on how these concentrations changed over time since the same sites were
sampled in 2001 and 2012. During the decade between sample collections,
the concentrations in the surface waters increased approximately 17-fold
(Zhai et al., 2015). This increase could be attributed to many potential factors, such as increased industrialization in China, greater atmospheric HFC
concentrations, and/or greater consumer use of fuorinated chemicals in the
region. To put these surface water concentrations into perspective, the most
sensitive aquatic organism to TFA was an alga with a NOEC of 0.12 mg/L,
which equates to 120,000 ng/L. Since the surface water concentrations are
typically less than 1,000 ng/L, the concentrations are less than 100-fold the
toxic effect level.
A review of the literature on surface water concentrations of TFA showed
a diminished publication rate after approximately 2006 with the exception of
sampling near point sources. This can largely be attributed to the increased
attention to longer chain and more toxic fuorinated acids like PFOS and