What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

The quote only partly states this claim.

Human concentrations of longer-chained perfluoroalkyl carboxylic acids (PFCAs) with 9-14 carbon atoms are generally increasing.

“Human concentrations of longer-chained perfluoroalkyl carboxylic acids (PFCAs) with 9-14 carbon atoms are generally increasing or show insignificant trends with too low power to detect a trend.”

May combine two claims.

A majority of the trends are insignificant with low power to detect a trend.

“Most substances show mixed results, and a majority of the trends are insignificant with low power to detect a trend.”

The quote only partly states this claim.

Human concentrations of longer-chained PFCAs with 9-14 carbon atoms show insignificant trends with too low power to detect a trend.

“Human concentrations of longer-chained perfluoroalkyl carboxylic acids (PFCAs) with 9-14 carbon atoms are generally increasing or show insignificant trends with too low power to detect a trend.”

May combine two claims.

Nine of the twelve PFOS human datasets (75%), all in Europe, had a significant change point, and most change points were detected between 1998 and 2003.

“Nine of these twelve datasets (75%), all in Europe, had a significant change point and most change points were detected between 1998 and 2003.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For PFOS in human samples, twelve datasets containing at least 7 time points were evaluated by change point analysis.

“For PFOS in human samples, twelve datasets containing at least 7 time points were evaluated by change point analysis (Fig. 6).”

May combine two claims.

Among females in Munster, plasma concentrations of PFHpA significantly increased after the change point in 1998, whereas in plasma of males from Munster PFHpA concentrations decreased after the change point in 2002.

“Among females in Munster, plasma concentrations of PFHpA significantly increased after the change point in 1998, whereas in plasma of males from Munster PFHpA concentrations decreased after the change point in 2002 [146].”

Probably not a substantial claim: may not pass S3 (load-bearing).

The PFOS isomer pattern (linear:branched) in eggs became more linear over time, increasing from approximately 1:1 in year 2000 to approximately 3:1 in year 2010.

“One inconsistent result is that the PFOS isomer pattern (linear: branched) in eggs has become more linear over time, increasing from approximately 1:1 in year 2000 to approximately 3:1 in the year 2010 [99].”

May combine two claims.

In our independent analysis, no overall statistical temporal trend was detected for PFOA, and the overall dataset was underpowered to detect a significant trend in both males and females.

“Thus, in our independent analysis no overall statistical temporal trend was detected (Additional file 7, Figure S15), and the overall dataset was underpowered to detect a significant trend in both males and females.”

May combine two claims.

All other datasets for PFNA, PFDA, PFUnDA and PFDoDA in the US showed no significant changes over the time periods examined but were also all underpowered to detect a trend.

“All other datasets for PFNA, PFDA, PFUnDA and PFDoDA in the US showed no significant changes over the time periods examined but were also all underpowered to detect a trend.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For PFHxS in human samples, the same twelve datasets as for PFOS were evaluated by change point analysis.

“For PFHxS in human samples, the same twelve datasets as for PFOS were evaluated by change point analysis (Additional file 7, Figure S2).”

May combine two claims.

PFDS was only detected in up to 50% of the samples, and in later years (after 2005) the frequency of detection decreased, which prevented a quantitative temporal trend analysis across the whole dataset.

“PFDS was only detected in up to 50% of the samples, and in later years (i.e. after 2005) the frequency of detection decreased which prevented a quantitative temporal trend analysis across the whole dataset.”

May combine two claims.

Similar to the trends for PFHxS, PFOA concentrations did not continue to decline and may have risen in 2007-2008, particularly for males.

“Similar to the trends for PFHxS, PFOA concentrations did not continue to decline and may have risen in 2007-2008, particularly for males.”

May combine two claims.

One Canadian sediment core study (Kempenfeldt Bay, Lake Simcoe) showed a significantly increasing temporal trend before the change point in 2002 and an insignificant trend (power < 0.8) after the change point.

“One of the Canadian sediment core studies (Kempenfeldt Bay, Lake Simcoe [33]) showed a significantly increasing temporal trend in a sediment core before the change point (in 2002) and an insignificant trend (power < 0.8) after the change point.”

• cites [33] Armitage J, Cousins IT, Buck RC, Prevedouros K, Russell MH, MacLeod M, Korzeniowski SH. Modeling global-scale fate and transport of perfluorooctanoate emitted from direct sources. Environ Sci Technol. 2006;40(22):6969–75. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

No significant temporal trends for PFOS were observed in only 6 datasets of human samples and two datasets of dietary items, but in each case the power to detect a trend was low.

“No significant temporal trends for PFOS were observed in only 6 datasets of human samples [89, 102, 115, 121, 143], and two datasets of dietary items [99,142], but in each case the power to detect a trend was low.”

May combine two claims.

Change points were detected for PFOS in a snow core from Tibet and in three sediment cores from Canada.

“For PFOS in abiotic samples, change points were detected in a snow core sampled in Tibet [38] and in three sediment cores sampled in Canada in two separate studies [93] (Fig. 8).”

• cites [38] Wang X, Halsall C, Codling G, Xie Z, Xu B, Zhao Z, Xue Y, Ebinghaus R, Jones KC. Accumulation of perfluoroalkyl compounds in Tibetan Mountain snow: temporal patterns from 1980 to 2010. Environ Sci Technol. 2014;48(1):173–81. sourceNot checked yet

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• cites [93] Helm PA, Milne J, Hiriart-Baer V, Crozier P, Kolic T, Lega R, Chen T, MacPherson K, Gewurtz S, Winter J, et al. Lake-wide distribution and depositional history of current- and past-use persistent organic pollutants in Lake Simcoe, Ontario, Canada. J Great Lakes Res. 2011;37:132–41. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Based on NHANES data, Calafat et al. reported statistically significant decreases in PFHxS for 2003-2004 compared to 1999-2000 while accounting for age, sex and race/ethnicity; one exception was PFHxS in Mexican Americans, which was not significantly different between years.

“Based on NHANES data, Calafat et al. [74] reported statistically significant decreases in PFHxS for 2003-2004 (post phase-out) compared to 1999-2000 (pre phase-out) while accounting for age, sex and race/ethnicity (Additional file 8, Figure S5); one exception was PFHxS in Mexican Americans which was not significantly different between years.”

May combine two claims.

PFOS showed statistically significant declining trends in several surface waters: Tokyo Bay between 2004 and 2006, marine and fresh waters on the west coast of South Korea between 2008 and 2012, and Bohai Bay on the east coast of China between 2011 and 2013.

“PFOS showed statistically significant declining trends in several surface waters, namely; in Tokyo Bay between 2004 and 2006 [129], in marine and fresh waters on the west coast of South Korea between 2008 and 2012 [95] and in Bohai Bay on the east coast of China between 2011 and 2013 [140].”

• cites [129] Sakurai T, Serizawa S, Kobayashi J, Kodama K, Lee J-H, Maki H, Zushi Y, Sevilla-Nastor Janice B, Imaizumi Y, Suzuki N, et al. Temporal trends for inflow of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) to Tokyo Bay, Japan, estimated by a receptor-oriented approach. Sci Total Environ. 2015;539:277–85. sourceNot checked yet

  Not checked in the free run.

• cites [95] Hong S, Khim Jong S, Wang T, Naile Jonathan E, Park J, Kwon B-O, Song Sung J, Ryu J, Codling G, Jones Paul D, et al. Bioaccumulation characteristics of perfluoroalkyl acids (PFAAs) in coastal organisms from the west coast of South Korea. Chemosphere. 2015;129:157–63. sourceNot checked yet

  Not checked in the free run.

• cites [140] Wang S, Wang H, Zhao W, Cao Y, Wan Y. Investigation on the distribution and fate of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in a sewage-impacted bay. Environ Pollut. 2015;205:186–98. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

For Norwegian men (40-50 years), a significant increase of FOSA between 1977 and 1985 was followed by a statistically significant decline to 2006, with later concentrations being non-detectable.

“For Norwegian men (40-50 year) [92], a significant increase of FOSA between 1977 and 1985 (change-point) was followed by a statistically significant decline to 2006, with later concentrations being non-detectable.”

May combine two claims.

In our independent analysis of datasets from Kato et al., no significant temporal trend was detected for PFHxS for males nor females, consistent with our analysis of two other US datasets, all of which had low power to detect a trend.

“Thus, in our independent analysis of datasets from Kato et al. [103], no significant temporal trend was detected for males nor females (Additional file 7, Figure S2), consistent with our analysis of two other datasets for the US (female serum from 6 cities, and combined males and females from the same 6 cities [120]), all of which had low power to detect a trend.”

May combine two claims.

Among PFHxS datasets with a significant change point, five had change points detected between 2000 and 2005, while the three others had change points between 1985 and 1993.

“Among datasets with a significant change point, five had change points detected between 2000 and 2005, while the three others had change points between 1985 and 1993 [68,92,145].”

May combine two claims.

Analysis of hen eggs and of the broader Swedish diet between 1999 and 2010 showed no significant temporal trends for PFNA, PFDA or PFUnDA in food during this critical time period, however statistical power was also low in most cases.

“Analysis of hen eggs and of the broader Swedish diet between 1999 and 2010 showed no significant temporal trends for PFNA, PFDA or PFUnDA in food during this critical time period [99], however statistical power was also low in most cases.”

May combine two claims.

The exception was for PFDoDA, where a statistically significant increase in the Swedish diet was seen, consistent with the rate of increase of serum PFDoDA in adult females from Uppsala, Sweden over a similar time period.

“The exception was for PFDoDA where a statistically significant increase in the Swedish diet was seen [142], consistent with the rate of increase of serum PFDoDA in adult females from Uppsala, Sweden [85] over a similar time period.”

May combine two claims.

The increasing temporal trend of PFOA between 1983 and 1998 in adult male serum (but not females) from Kyoto, Japan, was similar in magnitude (~10% annual change) to what was observed before the change-points in Stockholm or Norway, but the lack of any samples after year 2000 in Kyoto prevents any extrapolation beyond this time.

“The increasing temporal trend of PFOA between 1983 and 1998 in adult male serum (but not females) from Kyoto, Japan, is similar in magnitude (~ 10% annual change) to what was observed before the change-points in Stockholm (milk of primiparous women) or Norway (serum of adults), but the lack of any samples after year 2000 in Kyoto prevents any extrapolation beyond this time.”

May combine two claims.

In the Greenland Inuit serum study, the authors reported some age-dependent statistically significant temporal trends for PFOS, but after age adjustment no significant temporal trends were evident for PFOS, nor for any other PFAS.

“While the authors reported some 'age-dependent' statistically significant temporal trends for PFOS, after ageadjustment no significant temporal trends were evident for PFOS, nor for any other PFAS.”

May combine two claims.

In 6 cities in the United States, PFHpA declined significantly in plasma of females, whereas no significant trend was detected for males.

“In 6 cities in the United States, PFHpA declined significantly in plasma of females, whereas no significant trend was detected for males [120].”

May combine two claims.

In Germany (Halle and Munster), declining concentrations of three PFOS-precursors (MeFOSAA, EtFOSAA, FOSAA) in human plasma were observed after 1995, whereas concentrations of Di-SAm-PAP showed no temporal trend at either location.

“Also, in Germany (Halle and Munster), declining concentrations of three PFOS-precursors (MeFOSAA, EtFOSAA, FOSAA) in human plasma were observed after 1995, whereas concentrations of another PFOS precursor (Di-SAm-PAP) showed no temporal trend at either location [145].”

Probably not a substantial claim: may not pass S3 (load-bearing).

For PFOA in human samples, eleven datasets were evaluated by change point analysis.

“For PFOA in human samples, eleven datasets were evaluated by change point analysis (Additional file 7, Figure S15).”

May combine two claims.

Two other more contemporary datasets from Asia, Hokkaido Japan (2003-2011) and Busan Korea (1994-2008), did not show a significant temporal trend but were both underpowered to detect a trend.

“Two other more contemporary datasets from Asia, Hokkaido Japan (2003-2011) and Busan Korea (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008), did not show a significant temporal trend but were both underpowered to detect a trend.”

May combine two claims.

Among sufficiently powered PFHxS datasets with a change point, all (six) showed a significant increasing trend prior to the change point, two showed a significant decrease after the change point, and one study showed no change after the change point.

“Among sufficiently powered datasets with a change point, all (six) showed a significant increasing trend prior to the change point, two showed a significant decrease after the change point, and one study showed no change after the change point.”

May combine two claims.

The other significant downward trends for PFOS were observed in digested sewage sludge in Hinwil, Switzerland between 1998 and 2008, in a snow core from the Devon ice cap, and in a sediment core in the Haihe River (core S6, dated 1952-2006) in China.

“The other significant downward trends for PFOS were observed in a digested sewage sludge sampled in Hinwil in Switzerland between 1998 and2008 [136], in a Snow core from the Devon ice cap [91] and in a sediment core in the Haihe River (core S6, dated 1952-2006) in China [149].”

• cites [136] Sun HW, Gerecke AC, Giger W, Alder AC. Long-chain perfluorinated chemicals in digested sewage sludges in Switzerland. Environ Pollut. 2011;159(2):654–62. sourceNot checked yet

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• cites [91] Hart K, Kannan K, Isobe T, Takahashi S, Yamada TK, Miyazaki N, Tanabe S. Time trends and transplacental transfer of perfluorinated compounds in melon-headed whales stranded along the Japanese coast in 1982, 2001/2002, and 2006. Environ Sci Technol. 2008;42(19):7132–7. sourceNot checked yet

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• cites [149] Zhao X, Xia X, Zhang S, Wu Q, Wang X. Spatial and vertical variations of perfluoroalkyl substances in sediments of the Haihe River, China. J Environ Sci China. 2014;26:1557–66. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Three human PFDS datasets for adult German serum (Munster and Halle) showed no significant trends, but were underpowered.

“Three of these were for adult German serum (Munster and Halle [145]) and showed no significant trends, but were underpowered.”

May combine two claims.

Kato et al. continued the NHANES analysis into 2005-2006 and 2007-2008 and confirmed the initial decline in PFHxS from 1999 to 2005, but by 2007-08 the concentrations had again increased.

“Kato et al. [103] continued the NHANES analysis into 2005-2006 and 2007-2008 and confirmed the initial decline, from 1999 to 2005, but by 2007-08 the concentrations had again increased.”

May combine two claims.

The two other PFDS datasets were for Uppsala, Sweden, and significant declining trends (>10% per year) were shown in both cases.

“The two other datasets were for Uppsala, Sweden [62,85], and significant declining trends (> 10% per year) were shown in both cases.”

May combine two claims.

The Tibetan snow core dataset had a change point in 1984, but showed no significant trend and low power over the whole period sampled.

“The Tibetan snow core dataset had a change point in 1984, but showed no significant trend and low power over the whole period sampled.”

May combine two claims.

Our analysis showed statistically significant downward trends (and in some cases large annual changes) for PFHpA, PFNA, PFDA, PFUnDA and PFDoDA in various products, whereas other products showed no significant trends (the statistical power to detect trends was however low in those cases).

“Our analysis showed statistically significant downward trends (and in some cases large annual changes) for PFHpA, PFNA, PFDA, PFUnDA and PFDoDA in various products (see Additional file 7, Figures S14, S22, S27, S32, S36 for details), whereas other products showed no significant trends (the statistical power to detect trends was however low in those cases).”

May combine two claims.

One study was available from Japan, otherwise no other studies from Asia nor from the southern hemisphere were available.

“One study was available from Japan, otherwise no other studies from Asia nor from the southern hemisphere were available.”

May combine two claims.

PFOA showed statistically significant declining trends in the same surface waters for which declining PFOS trends were also observed: Tokyo Bay between 2004 and 2006, marine and fresh waters on the west coast of Korea between 2008 and 2012, and Bohai Bay on the east coast of China between 2011 and 2013.

“PFOA showed statistically significant declining trends in the same surface waters for which declining PFOS trends were also observed, namely; in Tokyo Bay between 2004 and 2006 [129], in marine and fresh waters on the west coast of Korea between 2008 and 2012 [95] and in Bohai Bay on the east coast of China between 2011 and 2013 [140].”

• cites [129] Sakurai T, Serizawa S, Kobayashi J, Kodama K, Lee J-H, Maki H, Zushi Y, Sevilla-Nastor Janice B, Imaizumi Y, Suzuki N, et al. Temporal trends for inflow of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) to Tokyo Bay, Japan, estimated by a receptor-oriented approach. Sci Total Environ. 2015;539:277–85. sourceNot checked yet

  Not checked in the free run.

• cites [95] Hong S, Khim Jong S, Wang T, Naile Jonathan E, Park J, Kwon B-O, Song Sung J, Ryu J, Codling G, Jones Paul D, et al. Bioaccumulation characteristics of perfluoroalkyl acids (PFAAs) in coastal organisms from the west coast of South Korea. Chemosphere. 2015;129:157–63. sourceNot checked yet

  Not checked in the free run.

• cites [140] Wang S, Wang H, Zhao W, Cao Y, Wan Y. Investigation on the distribution and fate of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in a sewage-impacted bay. Environ Pollut. 2015;205:186–98. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

FOSA, a PFOS precursor, showed significantly increasing trends in two sediment cores from Canada in two separate studies, which is consistent with the increasing PFOS trends observed in the same sediment cores.

“FOSA, a PFOS precursor, showed significantly increasing trends in two sediment cores from Canada in two separate studies [70,93], which is consistent with the increasing PFOS trends observed in the same sediment cores.”

• cites [70] Benskin JP, Phillips V, St Louis VL, Martin JW. Source elucidation of perfluorinated carboxylic acids in remote alpine lake sediment cores. Environ Sci Technol. 2011;45(17):7188–94. sourceNot checked yet

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• cites [93] Helm PA, Milne J, Hiriart-Baer V, Crozier P, Kolic T, Lega R, Chen T, MacPherson K, Gewurtz S, Winter J, et al. Lake-wide distribution and depositional history of current- and past-use persistent organic pollutants in Lake Simcoe, Ontario, Canada. J Great Lakes Res. 2011;37:132–41. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

For PFNA and PFDA significant increasing trends were observed before the change point and significant decreasing trends after the change point.

“For PFNA and PFDA significant increasing trends were observed before the change point and significant decreasing trends after the change point.”

May combine two claims.

There is some indication of declines of N-alkyl perfluorooctane sulfonamides and N-alkyl perfluorooctane sulfonamidoethanols in the global atmosphere, but FTOHs appeared to be stable or even to have increased between 2006 and 2012.

“There is some indication of declines of N-alkyl perfluorooctane sulfonamides and N-alkyl perfluorooctane sulfonamidoethanols (precursors of both PFSAs and PFCAs) in the global atmosphere, but FTOHs (precursors of PFCAs) appeared to be stable or even to have increased between 2006 and 2012 [83] (see also AMAP, 2016 [153]).”

• cites [83] Gawor A, Shunthirasingham C, Hayward SJ, Lei YD, Gouin T, Mmereki BT, Masamba W, Ruepert C, Castillo LE, Shoeib M, et al. Neutral polyfluoroalkyl substances in the global atmosphere. Environ Sci-Process Impacts. 2014;16:404–13. sourceNot checked yet

  Not checked in the free run.

• cites [153] AMAP. Assessment 2015: temporal trends in persistent organic pollutants in the Arctic. Oslo: Arctic Monitoring and Assessment Programme; 2016.Not checked yet

  Not checked in the free run.

May combine two claims.

Similar to PFOS, sediment cores tended to show statistically significant increasing temporal trends for PFOA, although there were a few exceptions where no significant trend or a declining trend was observed (Haihe River).

“Similar to PFOS, sediment cores tended to show statistically significant increasing temporal trends for PFOA, although there were a few exceptions where no significant trend or a declining trend was observed (Haihe River).”

May combine two claims.

For PFNA and PFUnA there was no significant temporal trend before the change point (Power < 0.8) and a statistically significant increasing trend afterwards.

“For PFNA and PFUnA there was no significant temporal trend before the change point (Power < 0.8) and a statistically significant increasing trend afterwards.”

May combine two claims.

Statistically significant increasing trends were observed for PFNA and PFUnDA until a change point (in 1993) in Lake Opabin cores, after which there was no significant temporal trend observed.

“Statistically significant increasing trends were observed for PFNA and PFUnDA until a change point (in 1993) in Lake Opabin cores, after which there was no significant temporal trend observed.”

May combine two claims.

For PFHpA, PFNA, PFDA and PFUnDA statistically significant declining trends were also observed in marine waters on the west coast of South Korea between 2008 and 2012, but most surface water sampled showed no significant trends for PFCAs other than PFOA.

“For PFHpA, PFNA, PFDA and PFUnDA statistically significant declining trends were also observed in marine waters on the west coast of South Korea between 2008 and 2012 [95], but most surface water sampled showed no significant trends for PFCAs other than PFOA.”

• cites [95] Hong S, Khim Jong S, Wang T, Naile Jonathan E, Park J, Kwon B-O, Song Sung J, Ryu J, Codling G, Jones Paul D, et al. Bioaccumulation characteristics of perfluoroalkyl acids (PFAAs) in coastal organisms from the west coast of South Korea. Chemosphere. 2015;129:157–63. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

PFHxS showed a statistically significant declining trend in marine water on the west coast of South Korea between 2008 and 2012, and PFDS showed a significantly increasing trend in the same seawater.

“PFHxS showed a statistically significant declining trend in marine water on the west coast of South Korea between 2008 and 2012 [95] and PFDS showed a significantly increasing trend in the same seawater.”

• cites [95] Hong S, Khim Jong S, Wang T, Naile Jonathan E, Park J, Kwon B-O, Song Sung J, Ryu J, Codling G, Jones Paul D, et al. Bioaccumulation characteristics of perfluoroalkyl acids (PFAAs) in coastal organisms from the west coast of South Korea. Chemosphere. 2015;129:157–63. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Remote air has been sampled and there are indications that levels of N-alkyl perfluorooctane sulfonamides and N-alkyl perfluorooctane sulfonamidoethanols have declined in the remote atmosphere, but that FTOH levels have increased between 2006 and 2012.

“Remote air has been sampled and there are indications that levels of N-alkyl perfluorooctane sulfonamides and N-alkyl perfluorooctane sulfonamidoethanols have declined in the remote atmosphere, but that FTOH levels have increased between 2006 and 2012.”

May combine two claims.

Four of the six PFNA change point datasets showed insignificant change both prior and post change point, but concentrations after the change point were significantly higher than before the change point (stepwise increase rather than a continuous increase).

“with four showing insignificant change both prior and post change point, but the concentrations after the change point were significantly higher than before the change point (stepwise increase rather than a continuous increase)”

May combine two claims.

For the Chinese study, there was no significant temporal trend in one sediment core (core 1) before the change point in 1967, after which a significant increasing trend was observed.

“For the Chinese study [64], there was no significant temporal trend in one sediment core (core 1) before the change point in 1967, after which a significant increasing trend was observed.”

• cites [64] Sturludottir E, Gunnlaugsdottir H, Nielsen OK, Stefansson G. Detection of a change-point, a mean-shift accompanied with a trend change, in short time-series with autocorrelation. In: Statistical analysis of trends in data from ecological monitoring (PhD thesis). School of Engineering and Natural Sciences, Faculty of Physical Sciences, Reykjavik; 2015.Not checked yet

  Not checked in the free run.

May combine two claims.

For PFHpA no significant change was observed before the change point and a significant decrease was observed after the change point.

“For PFHpA no significant change was observed before the change point and a significant decrease was observed after the change point.”

May combine two claims.

One study included seven herring gull datasets from seven Canadian Great Lakes colonies, with two showing increasing PFNA concentrations and five showing insignificant changes.

“One of these studies included seven datasets for herring gulls from seven colonies in the Canadian Great Lakes, with two datasets showing increasing PFNA concentrations and five showing insignificant changes [84].”

• cites [84] Gebbink WA, Letcher RJ, Hebert CE, Weseloh DVC. Twenty years of temporal change in perfluoroalkyl sulfonate and carboxylate contaminants in herring gull eggs from the Laurentian Great Lakes. J Environ Monit. 2011;13(12):3365–72. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

PFOA showed statistically significant downward trends in several different consumer products, whereas it showed significant increasing trends in food contact paper.

“PFOA showed statistically significant downward trends in several different consumer products, whereas it showed significant increasing trends in food contact paper (Category H in Additional file 7, Figure S17) [108].”

• cites [108] Liu X, Guo Z, Krebs Kenneth A, Pope Robert H, Roache Nancy F. Concentrations and trends of perfluorinated chemicals in potential indoor sources from 2007 through 2011 in the US. Chemosphere. 2014;98:51–7. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

For PFUnDA a significant increasing trend was observed before the change point and no observable trend was observed after the change point.

“For PFUnDA a significant increasing trend was observed before the change point and no observable trend was observed after the change point.”

May combine two claims.

The large majority of included time trends show increasing concentrations or non-significant changes with low power to detect changes.

“The large majority of included time trends show increasing concentrations or non-significant changes with low power to detect changes.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For 8 of the studies whose authors' statistical analyses were shown, the review could not perform change point or regression analyses.

“For 8 of these, we were not able to perform change point or regression analyses.”

May combine two claims.

Overall, 18 of the 38 PFNA datasets showed increasing trends, two showed decreasing trends, and 18 showed insignificant trends over time.

“Overall, 18 of the 38 PFNA datasets showed increasing trends, two showed decreasing trends and 18 showed insignificant trends over time”

May combine two claims.

For PFUnA (in Lake Oesa and Kempenfeldt Bay) and PFTrDA (in all cores) statistically significant increasing trends were observed for the entire time period sampled.

“For PFUnA (in Lake Oesa [7] and Kempenfeldt Bay [33]) and PFTrDA (in all cores) statistically significant increasing trends were observed for the entire time period sampled.”

• cites [7] Smart BE, Dixon DA. Bond-energies and stabilities of poly(perfluoroethers). In: Abstracts of papers of the American chemical society, vol. 207. 1994. p 31–FLUO.Not checked yet

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• cites [33] Armitage J, Cousins IT, Buck RC, Prevedouros K, Russell MH, MacLeod M, Korzeniowski SH. Modeling global-scale fate and transport of perfluorooctanoate emitted from direct sources. Environ Sci Technol. 2006;40(22):6969–75. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

The general trend in mammals and birds indicates significantly increasing or insignificant trends, and only insignificant trends in other species.

“The general trend in mammals and birds indicates significantly increasing or insignificant trends, and only insignificant trends in other species.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The systematic review included numerous studies using archived samples and directly highlights the value of such material.

“The systematic review included numerous studies using archived samples and directly highlights the value of such material.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Differences between males and females have also recently been observed in Australia and the USA but were not fully understood.

“Differences between males and females have also recently been observed in Australia and the USA [154] but were not fully understood.”

• cites [154] Gomis MI, Vestergren R, MacLeod M, Mueller JF, Cousins IT. Historical human exposure to perfluoroalkyl acids in the United States and Australia reconstructed from biomonitoring data using population-based pharmacokinetic modelling. Environ Int. 2017;108(Supplement C):92–102. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

In Shenyang, China, there was a significant increase in PFOS concentrations in females from 1999 to 2002, whereas it was statistically insignificant in males.

“In Shenyang, China, there was a significant increase in PFOS concentrations in females from 1999 to 2002, whereas it was statistically insignificant in males.”

May combine two claims.

In this review only two studies from the southern hemisphere were included, one on PFAAs in human populations in Australia and one on PFCA precursors in air in South America.

“In this review only two studies from the southern hemisphere were included, one on PFAAs in human populations in Australia and one on PFCA precursors in air in South America.”

May combine two claims.

Only one study from China is available; it shows increasing trends for PFOS and PFOA whereas studies in Europe and North America show declining trends.

“Although there is only one study from China available, this study shows increasing trends for PFOS and PFOA whereas studies in Europe and North America show declining trends.”

May combine two claims.

In Munster, Germany, the trend for PFHpA after a change-point was increasing in females whereas it was decreasing in males.

“in Munster, Germany, the trend for PFHpA after a change-point was increasing in females whereas it was decreasing in males [145].”

• cites [145] Yeung Leo WY, Robinson Shona J, Koschorreck J, Mabury Scott A. Part II. A temporal study of PFOS and its precursors in human plasma from two german cities in 1982–2009. Environ Sci Technol. 2013;47:3875–82. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Taking NHANES data from the USA, there are significant decreasing trends for PFOS in all age groups, but for both females and males the magnitude of the decreasing trend increased with decreasing age.

“Taking NHANES data from the USA, there are significant decreasing trends for PFOS in all age groups, but for both females and males the magnitude of the decreasing trend increased with decreasing age [144].”

• cites [144] Wong F, MacLeod M, Mueller Jochen F, Cousins Ian T. Enhanced elimination of perfluorooctane sulfonic Acid by menstruating women: evidence from population-based pharmacokinetic modeling. Environ Sci Technol. 2014;48:8807–14. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based).

There are indications that concentrations are increasing in regions with weaker voluntary phase-outs and regulations.

“there are indications that concentrations are increasing in these regions.”

• AssumptionRests on an assumption: Production of PFASs has been picked up in regions with weaker voluntary phase-outs and regulations.

May combine two claims.

Concentrations of longer-chained PFCAs (PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA, PFTeDA) in humans are generally increasing, with no evidence of significantly declining trends in any global region.

“Concentrations of longer-chained PFCAs (PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA, PFTeDA) in humans are generally increasing, with no evidence of significantly declining trends in any global region.”

May combine two claims.

A small number of studies on coastal surface waters close to urbanized areas have shown decreasing concentrations of PFOS and PFOA, but it is unknown whether trends are similar in more remote areas.

“A small number of studies on coastal surface waters close to urbanized areas have shown decreasing concentrations of PFOS and PFOA, but it is unknown whether trends are similar in more remote areas.”

Probably not a substantial claim: may not pass S2 (checkable).

It is not always clear what the substitutes are and what to look for.

“However, it is not always clear what the substitutes are and what to look for.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Other potential reasons for heterogeneity could not be evaluated based on the available evidence.

“Other potential reasons for heterogeneity could not be evaluated based on the available evidence.”

May combine two claims.

Most substances show mixed results, and a majority of the trends are insignificant with low power.

“Most substances show mixed results, and a majority of the trends are insignificant with low power.”

May combine two claims.

In a study on polar bears, concentrations of PFHpA and PFOA in adult females (mothers) decreased from 1998 to 2008, whereas no significant change was observed in cubs.

“in a study on polar bears [73], it was shown that concentrations of PFHpA and PFOA in adult females (mothers) decreased from 1998 to 2008, whereas no significant change was observed in cubs.”

• cites [73] Bytingsvik J, van Leeuwen SPJ, Hamers T, Swart K, Aars J, Lie E, Nilsen EME, Wiig O, Derocher AE, Jenssen BM. Perfluoroalkyl substances in polar bear mother-cub pairs: a comparative study based on plasma levels from 1998 and 2008. Environ Int. 2012;49:92–9. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PFCAs are detected at low concentrations in the ambient atmosphere, where they may be directly emitted and/or formed indirectly by atmospheric oxidation of semivolatile PFCA-precursors such as fluorotelomer alcohols (FTOHs).

“PFCAs are also detected at low concentrations in the ambient atmosphere, where they may be directly emitted [20], and/or formed indirectly by atmospheric oxidation of semivolatile PFCA-precursors such as the fluorotelomer alcohols (FTOHs) [21].”

• cites [20] Barton CA, Zarzecki CJ, Russell MH. A site-specific screening comparison of modeled and monitored air dispersion and deposition for perfluorooctanoate. J Air Waste Manag Assoc. 2010;60(4):402–11. sourceNot checked yet

  Not checked in the free run.

• cites [21] Ellis DA, Martin JW, De Silva AO, Mabury SA, Hurley MD, Sulbaek Andersen MP, Wallington TJ. Degradation of fluorotelomer alcohols: a likely atmospheric source of perfluorinated carboxylic acids. Environ Sci Technol. 2004;38(12):3316–21. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

PFCAs can be transported long distances by rivers and ocean currents and now occur in the open marine environment, including remote oceans.

“PFCAs can thus be transported long distances by rivers and ocean currents and now occur in the open marine environment, even in the remote Northern Atlantic, Pacific, and Arctic Oceans [18,19].”

• cites [18] Benskin JP, Ahrens L, Muir DCG, Scott BF, Spencer C, Rosenberg B, Tomy G, Kylin H, Lohmann R, Martin JW. Manufacturing origin of perfluorooctanoate (PFOA) in Atlantic and Canadian Arctic Seawater. Environ Sci Technol. 2012;46(2):677–85. sourceNot checked yet

  Not checked in the free run.

• cites [19] Yamashita N, Taniyasu S, Petrick G, Wei S, Gamo T, Lam PKS, Kannan K. Perfluorinated acids as novel chemical tracers of global circulation of ocean waters. Chemosphere. 2008;70(7):1247–55. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The perfluoroalkyl moiety of PFAS molecules is both hydrophobic and lipophobic.

“The perfluoroalkyl moiety (C n F 2n+1 -) of PFAS molecules is both hydrophobic and lipophobic [1].”

• cites [1] Kissa E. Fluorinated surfactants and repellents, vol. 97. 2nd ed. New York: Marcel Dekker, Inc.; 2001.Not checked yet

  Not checked in the free run.

May combine two claims.

After the 3M phase-out of PFOA in 2002, other companies continued to manufacture PFOA mainly through the telomerization process, which produces a pure isomer product, typically the linear isomer.

“After the 3M phase-out of PFOA in 2002, other companies continued to manufacture PFOA mainly through the telomerization process which produces a pure isomer product, typically the linear isomer [17].”

• cites [17] Benskin JP, Yeung LWY, Yamashita N, Taniyasu S, Lam PKS, Martin JW. Perfluorinated acid isomer profiling in water and quantitative assessment of manufacturing source. Environ Sci Technol. 2010;44(23):9049–54. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The ECF manufacturing process produces a mixture of linear (approximately 70%) and branched (approximately 30%) isomers.

“The ECF manufacturing process produces a mixture of linear (approx.70%) and branched (approx.30%) isomers [17].”

• cites [17] Benskin JP, Yeung LWY, Yamashita N, Taniyasu S, Lam PKS, Martin JW. Perfluorinated acid isomer profiling in water and quantitative assessment of manufacturing source. Environ Sci Technol. 2010;44(23):9049–54. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The extreme strength and stability of the C-F bond renders perfluorinated carbon chains resistant to environmental degradation processes.

“The extreme strength and stability of the C-F bond [7] renders perfluorinated carbon chains resistant to environmental degradation processes.”

• cites [7] Smart BE, Dixon DA. Bond-energies and stabilities of poly(perfluoroethers). In: Abstracts of papers of the American chemical society, vol. 207. 1994. p 31–FLUO.Not checked yet

  Not checked in the free run.

May combine two claims.

Bioaccumulation and trophic magnification occur in mammals and birds and increase with perfluoroalkyl chain length.

“Bioaccumulation and trophic magnification have been shown to occur in mammals and birds, and increase with perfluoroalkyl chain length [22].”

• cites [22] Conder JM, Hoke RA, De Wolf W, Russell MH, Buck RC. Are PFCAs bioaccumulative? A critical review and comparison with regulatory lipophilic compounds. Environ Sci Technol. 2008;42(4):995–1003. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Kappa tests were used to test consistency.

“Kappa tests were used to test consistency.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Both reviewers extracted data from 10 articles each, checked each other's data extraction, and reconciled any disagreements.

“Both reviewers started by extracting data from 10 articles each (in total 20 articles were extracted).The reviewers then checked each other's data extraction and reconciled any disagreements.”

Classified as probably not a substantial claim.

Studies where the risk of bias was judged to be unclear or high for one or more quality aspects were excluded from the review.

“Studies where the risk of bias was judged to be unclear (inadequate information) or high (see criteria in Table 1) for one or more of the quality aspects were excluded from the review.”

Probably not a substantial claim: may not pass S3 (load-bearing).

There is a high level of concern in Sweden that continued emissions of PFASs may cause environmental as well as human health effects.

“There is a high level of concern in Sweden that continued emissions of PFASs may cause environmental as well as human health effects [61].”

• cites [61] Borg D, Håkansson H. Environmental and Health Risk assessment of perfluoroalkylated and polyfluoroalkylated substances (PFASs) in Sweden. Swedish Environmental Protection Agency: report 6513. ISBN 978-91-620-6513-3; 2012.Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

No time, document type, language or geographical constraints were applied in the searches.

“No time, document type, language or geographical constraints were applied in the searches.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Relevant articles were critically appraised by four reviewers, with double checking of 20% of the articles by a second reviewer.

“Relevant articles were critically appraised by four reviewers, with double checking of 20% of the articles by a second reviewer.”

Classified as probably not a substantial claim.

KEMI raised concerns about increasing concentrations of short-chain substances such as PFBS.

“In later discussions KEMI raised concerns about increasing concentrations of short-chain substances such as PFBS [62].”

• cites [62] Glynn A, Berger U, Bignert A, Ullah S, Aune M, Lignell S, Darnerud PO. Perfluorinated alkyl acids in blood serum from primiparous women in Sweden: serial sampling during pregnancy and nursing, and temporal trends 1996–2010. Environ Sci Technol. 2012;46(16):9071–9. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PFSAs are fully dissociated anions in environmental media and tend to accumulate in surface waters.

“PFSAs are fully dissociated anions in environmental media [53] and tend to accumulate in surface waters [31]”

• cites [53] Vierke L, Berger U, Cousins IT. Estimation of the acid dissociation constant of perfluoroalkyl carboxylic acids through an experimental investigation of their water-to-air transport. Environ Sci Technol. 2013;47(19):11032–9. sourceNot checked yet

  Not checked in the free run.

• cites [31] Armitage JM, Schenker U, Scheringer M, Martin JW, MacLeod M, Cousins IT. Modeling the global fate and transport of perfluorooctane sulfonate (PFOS) and precursor compounds in relation to temporal trends in wildlife exposure. Environ Sci Technol. 2009;43(24):9274–80. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Statistical power was evaluated according to a method suggested by Nicholson & Fryer to detect a fixed average trend of 10% a year.

“Instead, we evaluated the statistical power according to a method suggested by Nicholson & Fryer [63] to detect a fixed average trend of 10% a year, which the above-mentioned parameters affect, and indicated this for each time trend dataset in the results.”

• cites [63] Nicholson MD, Fryer RJ. The statistical power of monitoring programs. Mar Pollut Bull. 1992;24(3):146–9. sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Long-chain PFCAs are being incrementally phased out by the major manufacturers and to some extent are regulated in Japan, Western Europe and the United States.

“Although long-chain PFCAs are being incrementally phased out by the major manufacturers and to some extent are regulated in Japan, Western Europe and the United States (US) [24,25,27], new manufacturers (largely in continental Asia) have begun to produce long-chain PFCAs and their precursors [28,29].”

• cites [24] 3M. Letter to US EPA Re phase-out plan for POSF-based products (226-0600). US EPA Admin Record. 2000;226:1–11.Not checked yet

  Not checked in the free run.

• cites [25] 2010/2015 PFOA Stewardship Programme. http://www.epa.gov/oppt/pfoa/pubs/stewardship/index.html.Not checked yet

  Not checked in the free run.

• cites [27] Ritter S. Fluorochemicals go short. Chem Eng News. 2010;88:12–7.Not checked yet

  Not checked in the free run.

May combine two claims.

PFSAs are persistent, bind weakly to organic phases compared to other persistent organic substances, bioaccumulate in laboratory studies, and biomagnify in food webs.

“they are persistent, bind weakly to organic phases [54] compared to other persistent organic substances, bioaccumulate in laboratory studies [55,56] and biomagnify in food webs [57,58].”

• cites [54] Higgins CP, Luthy RG. Sorption of perfluorinated surfactants on sediments. Environ Sci Technol. 2006;40(23):7251–6. sourceNot checked yet

  Not checked in the free run.

• cites [55] Fernandez-Sanjuan M, Faria M, Lacorte S, Barata C. Bioaccumulation and effects of perfluorinated compounds (PFCs) in zebra mussels (Dreissena polymorpha). Environ Sci Pollut Res. 2013;20(4):2661–9. sourceNot checked yet

  Not checked in the free run.

• cites [56] Lasier PJ, Washington JW, Hassan SM, Jenkins TM. Perfluorinated chemicals in surface waters and sediments from northwest georgia, usa, and their bioaccumulation in lumbriculus variegatus. Environ Toxicol Chem. 2011;30(10):2194–201. sourceNot checked yet

  Not checked in the free run.

• cites [57] Fang S, Chen X, Zhao S, Zhang Y, Jiang W, Yang L, Zhu L. Trophic magnification and isomer fractionation of perfluoroalkyl substances in the food web of Taihu Lake, China. Environ Sci Technol. 2014;48(4):2173–82. sourceNot checked yet

  Not checked in the free run.

• cites [58] Kannan K, Tao L, Sinclair E, Pastva SD, Jude DJ, Giesy JP. Perfluorinated compounds in aquatic organisms at various trophic levels in a Great Lakes food chain. Arch Environ Contam Toxicol. 2005;48(4):559–66. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

To check consistency and compliance with inclusion/exclusion criteria, 10% of the retrieved articles were double screened by the other reviewers, and Kappa tests were used to evaluate consistency.

“To check that the screening was consistent and complied with the agreed inclusion/exclusion criteria, 10% of the retrieved articles were double screened by the other reviewers, and Kappa tests were used to evaluate the consistency of the screening.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In 2000, 3M announced a global phase-out by 2002 of its production of products based on perfluoroalkyl chains containing 6, 8 and 10 carbon atoms, including PFOA.

“In 2000, 3M announced a global phase-out by 2002 of its production of products based on perfluoroalkyl chains containing 6, 8 and 10 carbon atoms, including PFOA [24].”

• cites [24] 3M. Letter to US EPA Re phase-out plan for POSF-based products (226-0600). US EPA Admin Record. 2000;226:1–11.Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

PFSAs and their precursors have been manufactured almost exclusively by ECF, which produced a mixture of linear (70%) and many branched (total 30%) isomers.

“PFSAs and their precursors have been manufactured almost exclusively by ECF which produced a mixture of linear (70%) and many branched (total 30%) isomers [32].”

• cites [32] Martin JW, Asher BJ, Beesoon S, Benskin JP, Ross MS. PFOS or PreFOS? Are perfluorooctane sulfonate precursors (PreFOS) important determinants of human and environmental perfluorooctane sulfonate (PFOS) exposure? J Environ Monit. 2010;12(11):1979–2004. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

In 2006, the EU adopted a Marketing and Use Directive (2006/122/EC) that banned the use of PFOS in semifinished products (maximum content 0.005% by weight) as of summer 2008.

“In 2006 the EU adopted a Marketing and Use Directive (2006/122/EC) that banned the use of PFOS in semifinished products (maximum content of PFOS: 0.005% by weight) as of summer 2008.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The comprehensiveness of the searches was tested by cross-checking the obtained records with a list of papers the review team thought should be found and with bibliographies in relevant review articles.

“The comprehensiveness of the searches was tested by cross-checking the obtained records with (1) a list of papers that the review team a priori thought should be found by the searches, and (2) bibliographies in relevant review articles (see Additional file 2).”

Probably not a substantial claim: may not pass S3 (load-bearing).

At the title and abstract level all retrieved articles were screened by two reviewers.

“At the title and abstract level all retrieved articles were screened by two reviewers.”

Classified as probably not a substantial claim. May combine two claims.

We chose not to perform meta-analyses because there were too many sources of heterogeneity to allow for any meaningful meta-analysis.

“In contrast to what was set out in the protocol [9], we chose not to perform meta-analyses.This is because there were too many sources of heterogeneity to allow for any meaningful meta-analysis.”

• cites [9] Land M, de Wit CA, Cousins IT, Herzke D, Johansson J, Martin JW. What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the enironment? A systematic review protocol. Environ Evid. 2015;4(3):1–13.Not checked yet

  Not checked in the free run.

• AssumptionThe authors state this as an assumption: There is a time lag between phase-out interventions and measurable effects on PFAS concentrations in the environment.
• AssumptionRests on an assumption: The relative importance of direct and indirect sources of PFCAs to the environment is temporally variable, specific to each substance, and not well quantified.

Probably not a substantial claim: may not pass S3 (load-bearing).

In 2009, PFOS and related substances derived from POSF were listed under Annex B of the Stockholm Convention on Persistent Organic Pollutants.

“In 2009, PFOS, and related substances derived from POSF, were listed under Annex B (restriction of production and use) of the Stockholm Convention on Persistent Organic Pollutants.”

Probably not a substantial claim: may not pass S3 (load-bearing).

PFOA, its ammonium salt APFO, and C9-C14 PFCAs were included in the Candidate list of substances of very high concern under REACH.

“PFOA, its ammonium salt ammonium perfluorooctanoate (APFO), and C9-C14 PFCAs were included in the Candidate list of substances of very high concern and under the European chemicals regulation, REACH [26].”

• cites [26] ECHA. Candidate list of substances of very high concern for authorisation. 2014. http://echa.europa.eu/web/guest/candidate-list-table.Not checked yet

  Not checked in the free run.

May combine two claims.

In 2000, the major US manufacturer of PFOS, 3M, announced it would cease production of C6, C8 and C10 PASF-based products and completed the phase-out in 2002.

“In 2000 the major manufacturer of PFOS in the US (3M) announced they would cease the production of C6, C8 and C10 perfluoroalkane sulfonyl fluoride (PASF)based products and completed the phase out in 2002 [59].”

• cites [59] Olsen GW, Mair DC, Church TR, Ellefson ME, Reagen WK, Boyd TM, Herron RM, Medhdizadehkashi Z, Nobilett JB, Rios JA, et al. Decline in perfluorooctanesulfonate and other polyfluoroalkyl chemicals in American Red Cross adult blood donors, 2000–2006. Environ Sci Technol. 2008;42(13):4989–95. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

According to Zhang et al., the production volume of PFOS in China increased from 30 tonnes in 2002 to 247 tonnes in 2006.

“according to Zhang et al. [60] the production volume of PFOS increased from 30 tonnes in 2002 to 247 tonnes in 2006.”

• cites [60] Zhang L, Liu JG, Hu JX, Liu C, Guo WG, Wang Q, Wang H. The inventory of sources, environmental releases and risk assessment for perfluorooctane sulfonate in China. Environ Pollut. 2012;165:193–8. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Dual screening of 10% of the articles was performed at title/abstract and full-text levels by all authors.

“Dual screening of 10% of the articles was performed at title/abstract and full-text levels by all authors.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The critical appraisal tool checklist highlights five aspects of quality directly affecting internal validity: selection bias, accuracy of dating of samples, sample integrity, analytical quality, and study design.

“The checklist highlights five aspects of quality directly affecting the internal validity of a temporal PFAS trend study, including (1) selection bias (2) accuracy of dating of samples (3) sample integrity, (4) analytical quality, and (5) study design.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

An insignificant trend does not necessarily mean that there is no true trend.

“It is especially important to note that an insignificant trend does not necessarily mean that there is no 'true' trend.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Articles with conflicting judgements and those for which a reviewer was uncertain during single critical appraisal were discussed by the entire review team before any decision was made.

“Articles with conflicting judgements and those for which a reviewer was uncertain during single critical appraisal were discussed by the entire review team before any decision was made.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Critical appraisal of relevant studies was carried out by four reviewers.

“Critical appraisal of relevant studies was carried out by four reviewers.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Repeatability was tested qualitatively.

“Repeatability was tested qualitatively.”

Classified as probably not a substantial claim. May combine two claims.

Included studies were divided into Medium and Low risk of bias groups and compared qualitatively for systematic differences in study results.

“To be able to evaluate the effects of including doubtful cases (where the risk of bias potentially is high) we divided the included studies into two groups.Studies where a majority of the quality aspects were doubtful were categorized as Medium risk of bias, and studies where a majority of the aspects had low risk of bias were categorized as Low risk of bias.These two groups were then compared and”

Probably not a substantial claim: may not pass S3 (load-bearing).

Due to the historical dominance of POSF-based products, PFOS is usually the most abundant PFSA found.

“Due to the dominance of POSF-based products historically, PFOS is usually the most abundant PFSA found.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

To ensure high consistency between reviewers, 20% of the included articles after full text screening were double-checked and Kappa tests were used to test consistency.

“To ensure high consistency between the reviewers, 20% of the included articles after full text screening were double-checked and Kappa tests were used to test the consistency.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Sources of PFSAs include release during manufacture and use, as well as from the degradation of various precursor substances.

“Similar to PFCAs, sources of PFSAs include release during manufacture and use, as well as from the degradation of various precursor substances [5,31].”

• cites [5] Paul AG, Jones KC, Sweetman AJ. A first global production, emission, and environmental inventory for perfluorooctane sulfonate. Environ Sci Technol. 2009;43(2):386–92. sourceNot checked yet

  Not checked in the free run.

• cites [31] Armitage JM, Schenker U, Scheringer M, Martin JW, MacLeod M, Cousins IT. Modeling the global fate and transport of perfluorooctane sulfonate (PFOS) and precursor compounds in relation to temporal trends in wildlife exposure. Environ Sci Technol. 2009;43(24):9274–80. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Full-text screening was conducted in the same manner as title/abstract screening, including double screening and kappa tests.

“Screening at the full-text level was conducted in the same manner as at the title and abstract level, including double screening and kappa tests.”

Probably not a substantial claim: may not pass S3 (load-bearing).

PFOS and various salts were manufactured for direct use in products such as aqueous film-forming foams (AFFFs) for firefighting and mist suppressants in acid baths used for metal plating.

“PFOS and various salts were manufactured for direct use in a variety of products {e.g.aqueous film-forming foams (AFFFs) for firefighting and mist suppressants in acid baths used for metal plating (see Paul et al. [5])}.”

• cites [5] Paul AG, Jones KC, Sweetman AJ. A first global production, emission, and environmental inventory for perfluorooctane sulfonate. Environ Sci Technol. 2009;43(2):386–92. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Commercial use of PFOS and its salts started around 1970, and estimated uses and emissions of PFSAs and their precursors steadily rose to the end of the twentieth century.

“Commercial use of PFOS and its salts started around 1970 [5] and estimated uses and emissions of PFSAs and their precursors steadily rose to the end of the tweentienth century [5].”

• cites [5] Paul AG, Jones KC, Sweetman AJ. A first global production, emission, and environmental inventory for perfluorooctane sulfonate. Environ Sci Technol. 2009;43(2):386–92. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PFOS and other PFSAs are widely distributed in the global environment, biota, and humans.

“PFOS and other PFSAs are widely distributed in the global environment [34][35][36][37][38], biota [39][40][41][42][43][44] and humans [15,[45][46][47][48][49][50][51][52].”

• cites [34] Benskin JP, Muir DCG, Scott BF, Spencer C, De Silva AO, Kylin H, Martin JW, Morris A, Lohmann R, Tomy G, et al. Perfluoroalkyl acids in the Atlantic and Canadian Arctic Oceans. Environ Sci Technol. 2012;46(11):5815–23. sourceNot checked yet

  Not checked in the free run.

• cites [35] Filipovic M, Berger U, McLachlan MS. Mass balance of perfluoroalkyl acids in the Baltic Sea. Environ Sci Technol. 2013;47(9):4088–95. sourceNot checked yet

  Not checked in the free run.

• cites [36] Hu JY, Yu J, Tanaka S, Fujii S. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in water Environment of Singapore. Water Air Soil Pollut. 2011;216(1–4):179–91.Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

In 2006, eight major PFCA, fluoropolymer and fluorotelomer manufacturers joined the US EPA 2010/15 Stewardship Program to work towards the elimination of long-chain PFCAs and their precursors from emissions and products by 2015.

“In 2006, eight major PFCA, fluoropolymer and fluorotelomer manufacturers joined the US EPA 2010/15 Stewardship Program to work towards the elimination of long-chain PFCAs and their precursors from emissions and products by 2015 [25].”

• cites [25] 2010/2015 PFOA Stewardship Programme. http://www.epa.gov/oppt/pfoa/pubs/stewardship/index.html.Not checked yet

  Not checked in the free run.