Environmental Sciences, 12, 6 (2005) 293–313
MYU Tokyo

S. Nakayama et al.

293

ES600

Distributions of Perfluorooctanoic Acid (PFOA)
and Perfluorooctane Sulfonate (PFOS)
in Japan and Their Toxicities
Shoji Nakayama, Kouji Harada, Kayoko Inoue, Kazuaki Sasaki1,
Benjamin Seery, Norimitsu Saito1 and Akio Koizumi*
Department of Health and Environmental Sciences,
Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
1
Research Institute for Environmental Sciences and Public Health of Iwate Prefecture,
Morioka 020-0852, Japan(Received June 30, 2005; accepted November 11, 2005)
Key words: perfluorooctanoic acid, perfluorooctane sulfonate, distribution in Japan, toxicology,
toxicokinetics

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are end productsof many fluorochemical compounds in the natural environment. The aim of this review is
to summarize several studies in Japan and characterize the toxicities of these compounds.
We also compared the levels of contamination with those reported from various countries
to illustrate the unique situation of the toxicological issues within Japan.
PFOA and PFOS concentrations in surface water in Japan are in the ranges of 0.1–67,000
ng/L and 0.1–526 ng/L, respectively. While the origin of PFOS in surface water remains
unknown, PFOA present in surface water is very likely to have been released from a few
industries. The levels of PFOA and PFOS in the atmosphere are 71.8–919 pg/m3 and 2.3–
21.8 pg/m3, respectively. The concentrations of PFOA and PFOS in Japanese serum range
from an undetectable level to 52.2 ng/ml and from 0.2 to 57.7 ng/ml, respectively. The levels
of PFOA and PFOS present in the serum of the inhabitants of Kyoto are higher than thoseof other cities. One epidemiological study conducted by 3M revealed an increase in prostatecancer mortality [3.3-fold increase (95% CI, 1.02–10.6)] among workers exposed to PFOA.
Another study conducted by 3M revealed an increase in bladder cancer mortality (SMR
12.77, 95% CI 2.63–37.35) among workers exposed to PFOS.
PFOA and PFOS had a low order of toxicity in an acute toxicity study in rodents;
however, they exhibited versatile toxicities in primates. Both chemicals are carcinogenic inrodents, causing reproductive toxicity, neurotoxicity, and hepatotoxicity. Additionally,
peroxisome proliferation and calcium channel modulation are demonstrated effects. There
are large interspecies differences in toxicokinetics.
*E-mail: koizumi@pbh.med.kyoto-u.ac.jp

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1.

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Introduction

Perfluorinated alkyl compounds (PFCs), of which representative chemicals include
perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) (Fig. 1), are a classof special chemicals used in a variety of applications, such as lubricants, paints, cosmetics,
and fire-fighting foams.(1,2) PFCs are produced because of their advantageous physical andchemical properties, which include chemical stability, thermal inertness, low surface
energy, and their intrinsic amphiphilic nature. These favorable characteristics have resulted
in the production of a wide variety of perfluoroalkylated chemicals for application in firefighting foams, carpet surface repellent, textile protection, leather protection, paper andwood board protection, special surfactants, and as a polymerization aid forpolytetrafluoroethylene (Teflon®).(3,4) According to the OECD’s report,(5) approximately
4000–4500 metric tons of PFOA and PFOS were produced in 2002, however, thisinformation is quite limited and these values are not certain. PFOA and PFOS (Fig. 1) are
assumed to be the final biodegradation or environmental degradation products of fluorotelomer
compounds or perfluorooctanyl sulfonamides.(6,7)
PFOS and PFOA have been important perfluorinated surfactants; however, in 2002, after
50 years of production, 3M Company, one of the largest company that had been producing
these compounds, phased out their manufacture.(8)PFOA and PFOS have been found globally in a variety of living organisms, including
humans(9) and wildlife.(10) The worldwide distribution of these compounds has been
attributed to their resistance to degradation in ecological systems(2) and their bioaccumulative
characteristics.(11) These chemicals have been regulated by various countries including
Japan, USA, Canada, Sweden and Denmark.

Fig. 1. Structures of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS).

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295

There is a large difference between the distributions of PFOA and PFOS. PFOA is only
detected in selected areas, whereas PFOS is found worldwide.(12,13) There are many studies
revealing that these compounds have various toxicities on living organisms including humanbeings.(14–18)
With increasing worldwide attention to these compounds and the increasing number ofstudies of these compounds, several reviews are available that describe the occurrence of
these chemicals within the global environment.(14–19)
Recent studies revealed a unique situation in Japan in that PFOA contamination more
profoundly progressed than PFOS contamination environmentally.(20–22) In agreement withthis observation, the serum concentrations of PFOA among Japanese, although representing
a limited population in Japan, are assumed to be higher than those among Americans whereas
vise versa in the case of PFOS.(36,37)
Our primary aim in this review is twofold. First, we will review the distributions of PFOS
and PFOA in the environment in Japan. Second, we will characterize the toxicities of PFOS
and PFOA. We have compared data collated in Japan with those from other countries as wasnecessary to present the unique situation in Japan.

2.

Distributions of PFOA and PFOS in Environment in Japan

2.1

Surface water

Several studies have shown the concentrations of PFOA and PFOS in surface water inJapan.(20–23) We summarized the data in the order of the nine districts of Japan from Hokkaido
to Okinawa (Table 1).

2.1.1 PFOA
The geometric mean concentrations of PFOA in eight districts were within the range of
1 to 3 ng/L except for the Kinki district. In the Kinki district, PFOA concentrations in surface
waters were much higher than those in other districts.(21) The systematic investigation of the
Kanzaki River system by our group has revealed that there is a single source of PFOA within
the Ai River, which is located upstream of the Kanzaki River. The levels of PFOA were 447.74
ng/L in Koshienhama, ranged from 2.14 to 3,750 ng/L in the Kanzaki River and were at a
maximum of 67,000 ng/L in the Ai River.(21) The highest concentration was recorded inwastewater from the Ai River Wastewater Treatment Plant. A high concentration PFOA of
87,000 ng/L was also recorded in released sewage water from the same site in a separate
survey.(24)The concentrations of PFOA in other countries are also shown in Table 1. These values
are relatively higher than the values in Japan excluding the Kanzaki River system. For
example, the PFOA concentrations in Lake Erie and Lake Ontario, Canada/USA, are 30–40
ng/L(25) and the PFOA concentration is 366 ng/L in the Tennessee River.(26) In the Etobicoke
Creek in Canada, which has been contaminated by a spill of aqueous fire fighting foam into
the groundwater in a fire-training area at a U.S. Air Force Base, PFOA concentration isextremely high, as much as 1000-fold higher than the general water concentrations in Japaneven long after (5 or more years) the spill had occurred.(27,28) It should be noted, however,296

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Table 1
Observed levels of PFOA and PFOS in surface water in Japan and in other countries.
DistrictRiver
Hokkaido
Hokkaido
TohokuTohoku
Kanto
Kanto
Kanto (Tama river)
Chubu
Chubu
Kinki
Kinki
Kinki (Kanzaki River)
Chugoku
Chugoku
Shikoku
Shikoku
KyushuKyushuSea
Hokkaido
Tohoku
Kanto
Kanto
Chubu
Kinki
Hokkaido
Kanto
Kinki
Kinki (Koshien hama)
Chugoku
KyushuOkinawa
Lake
Hokkaido
Kinki
Tap Water
Tohoku
Kinki
River

n
2
1
18
15
26
14
25
20
17
34
8
52
9
9
7
7
10
8
1
2
1
3
1
1
1
4
3
1
4
5
4

PFOA (ng/L)
GM (GSD)
Range

1.20 (1.13)
0.40
1.11 (2.74)

0.1–4.22

2.84 (3.56)

0.33–15.08

2.50 (2.23)

0.28–16.28

21.2 (6.16)

2.14–456.41
4.5–67,000

1.51 (2.28)

0.51–8.11

3.02 (2.05)

1.35–13.82

1.30 (2.35)

0.20–3.28

2.04 (1.06)
166 (1.13)

1.90
2.09–2.13
32.21
154.3–192.0
11.5
448

1.07 (2.34)
1.15 (2.49)
6.48 (4.42)
3.66 (3.93)
1.40 (3.74)
1.07 (2.36)
4.44 (3.47)
5.72 (3.61)
1.14 (3.04)
1.00 (3.42)
1.44 (3.79)
1.11 (4.65)
0.78 (1.82)
0.72 (1.91)
1.04 (1.90)
20.1 (1.49)

26
8.7
447.74
4.8

1
3
15
15

PFOS (ng/L)
GM (GSD)
Range

3.8
0.25 (2.26)
15.3 (2.29)

0.00–1.00
4.91–42.19

0.21 (1.72)
3.84 (3.58)

Ref. Comment

1.10–1.30
1.90
0.34–5.47
0.25–4.62
0.44–157.0
0.33–31.42
0.7–440
0.36–135.0
0.24–6.04
0.30–32.33
0.78–37.32
1.5–526
0.48–19.58
0.42–25.10
0.44–15.78
0.24–14.86
0.30–1.68
0.29–1.72

(20)
(21)
(20)
(21)
(20)
(21)
(20)
(20)
(21)
(20)
(21)
(21)
(20)
(21)
(20)
(21)
(20)
(21)

2.12
0.61–0.87
2.58
12.7–25.4
0.65
27.69
<2.5
8–59
<4–21
27.69
<4
<9–11
<2.5

(21)
(21)
(21)
(23)
(21)
(21)
(22)
(22)
(22)
(21)
(21)
(22)
(22)

<2.5
<4–7.4(22)(22)

0.10–0.45
0.27–12.69

(21)
(21)

d
d
d

d

Tennessee, USA
40 366 (1.50)
140–498 55.1 (2.00)
16.8–144 (26)aEtobicoke Creek, Canada 13
11–1.1×104
nd to 2.2×106 (29)b
SeaHong Kong
0.73–5.5
0.09–3.1 (30)South Chi Sea
0.14–16
0.02–12 (30)Korea
0.24–320
0.04–730 (30)
Lake
Erie, Canada/USA
8 34.8 (1.28)
21–47 29.5 (1.50)
11–39 (25)
Ontario, Canada/USA
8 41.6 (1.57)
15–70 46.2 (2.00)
15–121 (25)Groundwater
Air Force Base, USA
nd–105×103(4–110)×103 (31)ca: Concentrations following spill of aqueous fire fighting foam into Etobicoke Creek. b: River directly influenced byfluorochemical production facility. c: Fire-training area at Air Force Base. d: Average was taken as arithmetic mean.
GM: geometric mean, GSD: geometric standard deviation, nd: not detectedEnvironmental Sciences, 12, 6 (2005) 293–313

S. Nakayama et al.

297that the concentration of PFOA is significantly higher in the Kanzaki River system including
the Ai River than within the general surface waters in USA. It is therefore very likely that
this may be the highest PFOA concentration ever reported excluding an accidental spill.
Taken together, the surface water PFOA contamination in districts other than the Kinki
district may not be deleterious; however, for those within the Kinki district, preventive
action to halt the release of PFOA into the environment may be urgently required.

2.1.2 PFOS
The current surface water PFOS contamination level is shown in Table 1. PFOS
concentrations in Japan were lower in six districts than in the Kanto and Kinki districts. The
concentrations were high in the Tama River in the Kanto and Kanzaki River in the Kinki
region. A systematic sampling of surface water by our group revealed the highest PFOS
concentrations of 440 ng/L in the Tama River and 526 ng/L at Osaka airport.(21) It isinteresting to note that the highest recorded water concentration in the Tama River contained
wastewater discharged from the Yokota Air Force Base. High concentrations of PFOS werealso found in wastewater from Osaka airport. It is confirmed that Light Water that contains
PFOS had been used in Osaka airport (Personal communication). However, detail
information regarding the type of fire fighting foams used at these airports is not available,aqueous fire fighting foams (AFFFs) have been widely used in the control of oil-related fires
at the airport and at other sites.(29,31) Recently, a large amount of AFFF was released fromTomakomai oil refinery fire followed on the heels of the offshore earthquake caused obvious
contaminations of PFOA and PFOS.(32) Taking these reports into consideration, thecontamination of PFOS around the airport seems to be derived from activities using firefighting foams.
PFOS concentration in general surface water in Japan are much lower than those in the
USA and Canada.(22) The contamination of the Etobicoke Creek continued for more than 5
years after the occurrence of the spill as shown by a study conducted at the U.S. Air Force
Base (Table 1).(28)

2.2

Airborne

There are limited literatures all over the world that report airborne PFOA and PFOS. This
work has been pioneered by Sasaki et al.,(33) who demonstrated discernible amounts of PFOS
in urban dust (Table 2). Moriwaki et al.(34) has confirmed discernible amounts of PFOA andPFOS in indoor dust. Boulanger et al. reported that the mean concentration of PFOS inparticulate-phase air samples is 6.4 pg/m3 (standard deviation, 3.3) in the U.S.(35) According
to the study of Sasaki et al.,(33) the concentrations ranged from 69 to 3,700 ng/g-dust for
PFOA and from 11 to 2,500 ng/g-dust for PFOS. Harada et al.(36) has recently shown thatthe concentrations of PFOA detected within urban airborne samples were 50-fold higher
than those of PFOS. PFOS was found to be significantly higher in the urban atmosphere of
Oyamazaki than in the suburban atmosphere of Morioka for both PFOA and PFOS (p <0.01). The authors estimated the inhaled PFOA and PFOS levels as follows; assuming that
adult humans inspire 15 m3 of air per day, all particles are respirable, and that PFOA andPFOS on the particles are completely absorbed into the body; the daily intakes of PFOA and298

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S. Nakayama et al.

PFOS at the Oyamazaki station, Kyoto are 4 ng/day and 0.1 ng/day, respectively. On theother hand, the estimated daily intakes of PFOA and PFOS from city water were calculated
as follows; the mean concentrations of PFOA and PFOS in the city water of Kyoto(21) are
multiplied by a daily water intake of 2 L/day, that is, 10.8 ng/day and 9.8 ng/day,
respectively. The estimated amount of inhaled PFOA is approximately 40% of the amountingested from drinking water in Kyoto, whereas the amount of inhaled PFOS is quite lower
than that of the ingested PFOS. Even if these estimations have uncertainties, these estimateson the airborne concentrations of PFOA and PFOS have important roles for speculating theorigin of contamination and the impact of these compounds on human beings (Table 2).

2.3

Human exposure

Table 3 shows the serum concentrations of PFOA and PFOS in Japanese people.(22,37–40)
This table shows that the concentrations of PFOA and PFOS are higher in males than infemales. A time course measurement for the Miyagi and Akita prefectures was performed
by Harada et al.(37) The study revealed that serum concentrations were increased by a factorof 3 for PFOS and by a factor of 14 for PFOA between 1977 and 2003 in the Miyagi
prefecture. The serum concentrations of PFOA increased significantly between 1995 and2003 in the Akita region, whereas those of PFOS did not increase between 1991 and 2003
(ANOVA, 0.05 as the level of significance).
The city water concentrations of both PFOA and PFOS are higher in the Kinki district
than in the Tohoku district.(21) Serum concentration seems to correlate with the city water
concentration, although it remains unknown whether the higher PFOA concentrations in citywater can explain the higher levels present in the serum of the residents of the Kinki district

Table 2
Indoor and outdoor airborne PFOA and PFOS levels in Japan and in other countries.
Sampling site
Oyamazaki Town
(on a highway)
2001/04–2002/03

NUnit
12 pg/m3-air
ng/g-dust
12 pg/m3-air
ng/g-dust
12 pg/m3-air
ng/g-dust

GM

262.7
3413.0PFOA
GSD Range

2.4
2.4

71.8–919.4
469–9049

GM
5.3
97.4
5.2
72.2
0.6
19.2

Fukuchiyama city
(on a local road)
2001/04–2002/03
Morioka city
8 pg/m3-air
2.0 1.2
1.6–2.6
0.7(on a local road)
2003/07
Indoor dust
16 ng/g-dust
177.7 2.6
69.0–3700 39.5
(general home)
Lake Ontario
8
pg/m3
6.4
(particulate-phase)
GM: geometric mean, GSD: geometric standard deviation, nd: not detected

PFOS
GSD
Range
1.2
2.3–21.8
1.2
38.0–427.4
1.4
2.5–9.8
1.8
19.7–168.0
1.3
nd’–2.1
1.2
nd–60.6

Ref.
(33)
(35)
(33)

1.4

0.5–1.2(35)

3.9

11.0–2500

(34)

3.3

(36)

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299

Table 3
Serum or whole blood concentrations of perfluorochemicals in Japanese people.
PFOA (ng/mL)
PFOS (ng/mL)
Sex
N GM GSD Range
GM GSD
Range
Ref.
M
32
3.3 2.0 0.8–52.2 5.7 2.0 0.4–16.9 (37)F
23
2.8 1.5
1.1–8.4
3.5 2.9 0.2–11.4
1977
M
F
39
0.2 2.0
nd–1.1
1.1 1.8
0.2–3.3
Yokote city (Akita) 2003
M
66
3.4 1.5 1.6–14.6 12.9 1.5 4.1–36.2 (37)(Serum)F
50
2.5 1.6
0.4–9.2
6.9 1.4 0.9–14.9
1995
M
F
40
1.9 1.4
1.0–4.8
8.7 1.3 5.8–16.1
1991
M
16
2.2 1.4
0.9–3.5 10.2 1.5 6.0–29.2
F60
1.8 1.5
0.7–4.1
7.9 1.4 3.7–20.2
Tsukuba city
2002
M
11
8.1 1.8 2.4–20.5 (22)(Whole blood)F2
9.1–11.0
Yokohama city
2001
M
12
6.2 1.6 2.3–15.2 (39)
(Whole blood)
F10
8.7 1.7 3.1–20.2
Kyoto city
2003
M
14 12.4 1.4 7.1–19.8 28.1 1.5 16.3–57.7 (37)(Serum)F
20
7.1 1.4 3.3–11.7 13.8 1.5 6.1–37.2
2004
M5
7.5 1.4 5.2–13.2 12.1 1.4 9.0–19.4 (38)F
5 10.7 1.5 7.6–20.6 10.8 1.3 8.6–16.4
M(>60 yr) 5 11.6 1.3 7.6–15.8 23.3 1.7 11.8–49.2
F(>60 yr) 5 14.0 1.1
12.6–15 22.9 1.3 16.2–33.0
Hokkaido
2003
F
15 0.93 2.23 nd–2.3
8.4 1.4 4.9–17.6 (40)
(Serum, UC)
fetus 15nd
2.7 1.5
1.6–5.3
GM: geometric mean, GSD: geometric standard deviation, UC: umbilical cord serum, nd: not detected
Sampling site
Taiwa (Miyagi)(Serum)Year
2003(Harada et al. Submitted for publication). We suspect that there is an industrial emission
source of these compounds. To solve these questions, further studies are required to reveal
the origin of contamination and the ability of water treatment facilities to remove PFOA andPFOS from drinking water.
Inoue et al. reported the concentrations of PFOA and PFOS in maternal and fetal cord
serum samples in Hokkaido.(40) The geometric mean PFOS concentrations (GM) in maternal
and fetal cord serum samples were 8.4 ng/ml (range, 4.9–17.6 ng/ml) and 2.7 ng/ml (1.6–
5.3 ng/ml), respectively. The concentration of PFOA in maternal serum is relatively lower
than that of PFOS, 0.93 ng/ml for GM (range, nd to 2.3 ng/ml), whereas these compounds
were undetectable in fetal cord serum. Although the serum PFOS concentrations in
Hokkaido(40) are in agreement with those in other places in the study of Harada et al.,(37) thoseof PFOA are not. These results suggest geographical differences in the exposure intensities
of PFOA as predicted in the study.(37)

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It should be noted that there is a discrepancy between the USA and Japan in terms of thelong-term exposure trends of PFOA. From our observations,(37) the serum concentrations of
PFOA are still increasing in Japan, whereas those in the USA reached a plateau during the
1980s.(41) Studies in the USA and in Japan both showed that serum PFOS concentrations
reached a plateau in the 1990s (Table 3).(37,41) In conclusion, PFOA exposure levels are likely
to be heterogeneous even within Japan; thus, a large geographical area should be covered toensure that higher exposure populations are not overlooked.

3.

Toxicology of PFOA and PFOS

3.1 Epidemiological study
3.1.1 Mortality of PFOA
A retrospective cohort mortality study, which included 2,788 men and 749 women andthus a total of 3,537 people, was performed on employees at a PFOA-treating fluorochemicalplant, wherein PFOA production was limited to the Chemical Division.(42) The cohort was
followed up from 1947 to 1989. Standardized mortality ratios (SMRs) adjusted for age, sex,
and race were calculated.
The all-causes standardized mortality rates were 0.75 [95% confidence interval (CI)
0.56–0.99] for women and 0.77 (95% CI, 0.69–0.86) for men. Among the men, thecardiovascular standardized mortality rate was 0.68 (95% CI, 0.58–0.80) and that for allgastrointestinal diseases was 0.57 (95% CI, 0.29–0.99). Ten years of exposure during
employment, however, was associated with a 3.3-fold increase (95% CI, 1.02–10.6) inprostate cancer mortality. Human mortality profile and animal studies(42) suggest that PFOA
may increase prostate cancer mortality by altering reproductive hormones in male workers.
Olsen et al. conducted cross-sectional studies that measured PFOA level in serum in relation
to several reproductive hormones to determine whether PFOA is associated with changes in
reproductive hormones.(43) However, significant hormonal changes that were associatedwith serum PFOA concentrations were not found.
In conclusion, the absence of both hormonal effects of PFOA and having only a small
number of prostate cancer deaths in these workers suggest that this observed increase inmortality from prostate cancer may be due to chance rather than by a cause and effectrelationship.

3.1.2 Mortality of PFOS
Alexander et al. conducted a retrospective cohort mortality study for PFOS in which they
followed up all workers with a minimum of one year of cumulative employment at theirplace of work.(45) By biomonitoring the exposure intensities were classified into three
discrete groups, namely, the high exposure group, the low exposure group, and the nonexposed group. A total of 145 deaths occurred among the 2,083 members of the cohort.
Sixty-five deaths had occurred among workers in the high exposure employment group. The
overall mortality rates for the cohort and exposure groups were lower than expected. The
risk of death from bladder cancer was increased for the entire cohort. Three cases of bladdercancer occurred among the workers who held high-exposure jobs (SMR 12.77, 95% CI

Environmental Sciences, 12, 6 (2005) 293–313

S. Nakayama et al.

301

2.63–37.35). The authors argued whether these three cases could be attributed tofluorochemical exposure because the possibility by chance alone could not be ruled out. One
confounding factor is that although the workers were mainly exposed to PFOS, they werealso exposed to other perfluoroalkyl compounds including PFOA.

3.1.3 Other risks of PFOA and PFOS
There are several studies that show the effects of PFOA and PFOS on biomarkers suchas hepatic enzymes, cholesterol, or lipoprotein of 3M company employees(46,47) and reproductive hormones.(44) No increase in the levels of these biomarkers has been attributed to
exposures to PFOA and PFOS.
Two independent studies targeting workers handling PFOA and PFOS in Japan havesuggested the probable association of PFOA and PFOS exposures with cancer risk. Suchstudies might have strong statistical power by applying meta-analyses.

3.2 Animal studies
3.2.1 Acute toxicity
3.2.1.1 PFOAThe oral LD50 values of PFOA for CD rats were greater than 500 mg/kg for males and
250–500 mg/kg for females,(48) and < 1000 mg/kg for male and female Wistar rats.(49) There
was no mortality following an inhalation exposure of 18.6 mg/L PFOA for 1 h in rats.(50) The
dermal LD50 in rabbits was determined to be greater than 2000 mg/kg.(51)

3.2.1.2 PFOS
The oral LD50 values of PFOS were 233 mg/kg (95% CI, 160–339) for male rats, 271 mg/kg(95% CI, 200–369) for female rats, and 251 mg/kg (95% CI, 199–318) for the combined
values of both sexes.(52) A 1-h LC50 of 5.2 mg/L (95% CI, 4.4–6.4) in rats has beenreported.(53) PFOS was found to be mildly irritating to the eyes and not an irritant to the skinof rabbits.(54)

3.2.2 Subchronic toxicity
3.2.2.1 PFOA
Dietary exposure to PFOA for 90 days resulted in a significant increase in liver weightand hepatocellular hypertrophy in male rats at doses as low as 100 ppm (5 mg/kg/day) andin female rats at 1000 ppm (76.5 mg/kg/day).(55)
In a 90-day study of rhesus monkeys, exposure to PFOA at 30 mg/kg/day and above
resulted in death, lipid depletion of the adrenal glands, hypocellularity of the bone marrow,moderate follicular atrophy of the lymphoid tissues in the spleen and lymph nodes (Table
4).(55)
In a 6-month study of male cynomolgus monkeys,(56) mortalities were observed inmonkeys treated with PFOA at 3 mg/kg/day and at 30/20 mg/kg/day (the dose was decreased
to 20 mg/kg/day during the experiment while it was initially 30 mg/kg/day because of severe
toxicity). There were no consistent effects on hormone levels. Increased absolute and

0.15
0.03

0.75

Death (not related to treatment, 1/4)

Soft stools; diarrhoea; anorexia; emesis; occasional
decreases in activity
Death (pulmonary necrosis with severe inflammation,
1/6). Absolute liver weight; liver to body weightpercentages; liver to brain weight ratios (females)
Excessive salivation; laboured respiration;
hypoactivity and ataxia; constricted pupils; pale gums;
liquid and black-coloured feces; dehydration; andrecumbent position.

0.5

1.5

Death between weeks 5–7 (4/4). Anorexia; emesis;
black stool; and dehydration. Diffuse lipid depletion ofadrenals; diffuse atrophy of pancreatic acinar cells; anddiffuse atrophy of serous alveolar cells
Soft stools; diarrhoea

Death by week 5 (4/4). Anorexia; emesis; pale faceand gums; swollen face and eyes; prostration; andbody trembling (4/4)
Death by week 13 (3/4). Emesis; ataxia; swollen face,eyes, and vulva; pale face and gums; black stools;
dehydration; and eyelids ptosis. Plt, PT, APTT, AST
Anorexia; pale and swollen face; and black stools (1/4)
Occasional soft stools; diarrhoea; and emesis
Death (1/6). Oedema and inflammation ofoesophagus and stomach; necrosis of heart tissue;and histopathological liver injury(and rhabdomyolysis) (1/6). TG.
Body weight loss
Death (not related to treatment, 1/4)

4.5

10
3

10
3
20 followed
by 30*

30

100

Elevated/AppearedFood consumption and mucoid in mouth. Totalcholesterol and HDL-cholesterol (significant),
triiodothyronine.

Body weight, ALP, K (female, significant), cholesterol(1/2 females), P (1/2 females)
ALP (slight)

serum cholesterol (significant)Body weight and body weight gain
Food consumption, body weight and body weight gain,
little or no feces (1/4)

ALP and ALT
ALP
Food consumption, body weight and body weight gain,
little or no feces (6/6)

Activity, body weight and body weight gain. RBC, Hb,
Hct, ALP, and ALT

Activity, body weight and body weight gain (4/4)

Reduced/
Decreased
Environmental Sciences, 12, 6 (2005) 293–313

Triiodothyronine and cholesterol
Food consumption, body weight and body weight gain,
little or no feces (1/4)
aGoldenthal, 90-day test;(55) bButtenhoff et al., 6-month test;(56) cGoldenthal, 90-day test;(58) dSeacat et al., 6-month test(59)*Initial dose (30 mg/kg/day) was changed to 20 mg/kg/day because PFOA showed severe toxicity at the initial dose.
RBC: erythrocyte, Hb: haemoglobin, Hct: haematocrit, Plt: platelet, PT: prothrombin time, APTT: activated partial thromboplastin time, AST: aspartate
aminotransferase, ALT: alanine aminotransferase, ALP: alkaline phosphatase, TG: triglyceride, K: potassium, P: phosphorus.

Cynomolgus
Monkeyd

PFOS
Resus
Monkeyc

Cynomolgus
Monkeyb

PFOA
Resus
MonkeyaDose(mg/kg/day)Table 4
Subcronic toxicities manifested in monkeys treated with PFOA and PFOS.

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relative liver weights were observed at 3, 10 and 30/20 mg/kg/day. The observed clinicalsigns included low food consumption, body weight loss, little or no feces, elevation of serum
triglycerides, oedema, and inflammation of the oesophagus and stomach in the 30/20 mg/
kg/day group. Body weight loss occurred in the 10 mg/kg/day group. Necrosis of the hearttissue and liver injury occurred in one monkey, which died prematurely. The correlation
between the doses administered and serum PFOA levels was nonlinear. An amendment of
the original protocol was an obligatory decision because of the high mortality exhibited at
the highest dose. One animal died during examination even after the protocol had beenchanged. Although the authors argued that these deaths were not considered to be treatment
related, multiple deaths in the highest dose group suggest PFOA toxicity, which is in contrast
to the conclusion presented.

3.2.2.2 PFOS
The adverse signs of PFOS toxicity observed during the 90-day rat study included
increases in liver enzyme levels, hepatic vacuolation, hepatocellular hypertrophy, gastrointestinal effects, haematological abnormalities, weight loss, convulsions, and death.
These effects were reported at PFOS doses of 2 mg/kg/day and above.(57)Goldenthal performed a 90-day study of rhesus monkeys (Table 4).(58) All monkeys in
the 4.5 mg/kg/day group died between weeks 5 and 7. The clinical signs in this group
included anorexia, emesis, black stool, and dehydration. The following abnormalities werealso observed in this group: a significant reduction in serum cholesterol level, marked diffuse
lipid depletion of the adrenal glands, moderate diffuse atrophy of pancreatic acinar cells, andmoderate diffuse atrophy of serous alveolar cells. The 1.5 mg/kg/day group had soft stools,
diarrhoea, reduced body weight, significant reductions in serum alkaline phosphatase andpotassium levels, and a reduced serum cholesterol level. Digestive organ symptoms
including soft stools, diarrhoea, anorexia, and emesis were also observed in the low dosegroup receiving PFOS at 0.5 mg/kg/day.
In a 6-month study conducted in cynomolgus monkeys, low food consumption, excessive salivation, labored breathing, hypoactivity, ataxia, hepatic vacuolization and hepatocellular hypertrophy, significant reductions in serum cholesterol levels, and death wereobserved in monkeys receiving PFOS at 0.75 mg/kg/day.(59) No monkeys survived beyond
3 weeks of treatment at 10 mg/kg/day or beyond 7 weeks of treatment at doses as low as 4.5
mg/kg/day. Pulmonary necrosis with severe inflammation was observed in the histopathology of one of the monkeys in the 0.75 mg/kg/day dose group. Reductions in serum
cholesterol and HDL-cholesterol levels were significant in the 0.75 and 0.15 mg/kg/day
groups. Triiodothyronine levels were reduced in the 0.15 and 0.75 mg/kg/day groups. No
abnormal signs were observed in the 0.03 mg/kg/day group, except for a monkey that diedprematurely. The serum concentration of PFOS reached a plateau at approximately 100 daysin the 0.75 mg/kg/day group, whereas no plateau was observed in the 0.15 and 0.03 mg/kg/
day groups. However, the correlation between the doses administered and serum PFOS
levels was nonlinear. A dose-response relationship was not clear in this study and was
similar to the study of PFOA.
In summary, although dose-response relationships were established for PFOA and PFOS
in rodent studies, they were not established in monkey studies. These compounds seemed
to affect the central nervous system of monkeys. Such toxicity warrants further studies.

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3.2.3 Chronic toxicity
3.2.3.1 PFOA
The chronic dietary exposure of rats to 300 ppm PFOA (14.2 and 16.1 mg/kg/day formales and females, respectively) for 2 years resulted in increased liver and kidney weights,
haematological effects and liver lesions in males and females.(60) In addition, testicularmasses were observed in males exposed to PFOA at 300 ppm and ovarian tubular
hyperplasia was observed in females after exposure to PFOA at the lowest dose of 30 ppm(1.6 mg/kg/day).(60)
Carcinogenicity studies in Sprague-Dawley (CD) rats show that PFOA is carcinogenic,
inducing Leydig cell adenomas in male rats and mammary fibroadenomas in female rats,
following dietary exposure to 300 ppm for 2 years (equivalent to 14.2 mg/kg/day in male rats
and 16.1 mg/kg/day in female rats).(60) PFOA has also been reported to be carcinogenic to
the liver and pancreas of male CD rats at 300 ppm.(61,62)

3.2.3.2 PFOS
In a dietary 2-year study conducted in Sprague-Dawley rats, hepatotoxicity, characterized by centrilobular hypertrophy, the presence of centrilobular eosinophilic hepatocytic
granules, the presence of centrilobular hepatocytic pigment, or centrilobular hepatocytic
vacuolation was noted in male and/or female rats given 5 or 20 ppm PFOS. Hepatocellular
centrilobular hypertrophy was also observed in male rats receiving a mid-strength dose (2ppm PFOS).(63) Significant increases in the incidence rate of cystic hepatocellular degeneration were found in all the male treated groups (0.5, 2, 5, or 20 ppm) compared with the control
group. From the pathological findings of the liver, the least observed adverse effect level(LOAEL) was 5 ppm and the no observed adverse effect level (NOAEL) was 2 ppm in female
rats. In male rats, the LOAEL was 0.5 ppm and the NOAEL was not established.
The potential carcinogenicity of PFOS has been examined in a dietary 2-year study inSprague-Dawley rats.(63) Compared with the control group, there was a significant increasein the incidence rate of hepatocellular adenomas in male and female rats receiving thehighest dose of 20 ppm; female rats receiving 20 ppm also had significant increases in the
combined incidence rates of hepatocellular adenomas and carcinomas. In addition, there
were significant increases in the incidence rates of thyroid follicular cell adenomas andcombined thyroid follicular cell adenomas and carcinomas in the male recovery group at 20ppm.

3.2.4 Genotoxicity
PFOA or PFOS is neither mutagenic nor clastogenic in a variety of tests.(64–75)

3.2.5 Reproductive toxicity
3.2.5.1 PFOA
In a two-generation reproductive toxicity study of PFOA in rats administered at 0, 1, 3,
10, and 30 mg/kg/day,(76) PFOA had significant effects on the fetal growth and developmentof male rats but to a much lesser degree in female rats. The difference in sensitivity waspresumed to be a gender-related difference in the elimination of PFOA.

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305

3.2.5.2 PFOS
A two-generation reproductive toxicity study of PFOS was conducted in SpragueDawley rats.(77) Reductions in body weight gain and food consumption were observed in theF0 and F1 generations receiving 0.1 mg/kg/day (male rats) and 0.4 mg/kg/day (female rats).
In the F1 generation, there are significant reductions in the number of implantation sites, litter
size, pup viability, pup body weight, and survival at 1.6 mg/kg/day. In the F2 generation,
significant reductions in mean pup body weight were observed at 0.4 mg/kg/day.

3.2.6 Neurotoxicity
There are limited studies on the neurotoxicities of PFOS and PFOA. Austin et al.
reported that the treatment of rats with PFOS affected estrous cyclicity and increased serum
corticosterone levels while decreasing serum leptin concentrations.(78) PFOS treatment also
increased norepinephrine concentrations in the paraventricular nucleus of the hypothalamus.

3.3 Toxicology at cellular and molecular levels
3.3.1 Peroxisome proliferation
The common carboxylic functional group shared by peroxisome-proliferating substances and their metabolites plays a role in their ability to induce peroxisome proliferation.
Most perfluoroalkyl compounds cause peroxisome proliferation in rats and mice.(79–82)
Investigations using sulfur-substituted PFOS were also shown to induce peroxisome
proliferation.(82,83)

3.3.2 Membrane effects
The effects of perfluorinated compounds (PFCs) on membrane fluidity, mitochondrial
membrane potential and membrane permeability were investigated.(84) In the PFCs tested,
only PFOS increased cell membrane permeability to the hydrophobic ligands utilized.
PFOS increased membrane fluidity in fish leukocytes in a dose-dependent manner, whereas
perfluorohexane sulfonic acid and perfluorobutane sulfonic acid had no effects in theconcentration range tested. The lowest effective concentrations for the membrane fluidity
effects of PFOS were 5–15 mg/L. Effects on mitochondrial membrane potential occurredin the same concentration range as that in the effects on membrane fluidity. This suggeststhat PFOS affects membrane properties at relative low concentrations.

3.3.3 Toxic effects on gap junctions
The inhibition of gap junctional intercellular communication (GJIC) has been linked tothe tumor-promoting properties of many carcinogens.(85) Upham et al. reported thatperfluorinated fatty acids (PFFAs) with carbon lengths of 7 to 10, including PFOA, inhibited
GJIC in a dose-dependent manner, whereas both shorter and longer chain PFFAs did not.(86)
Hu et al. also reported the inhibition of GJIC by PFOA and PFOS.(87) They concluded that
PFFAs including PFOA could potentially act as hepatocarcinogens at gap junctions inaddition to their ability to induce peroxisome proliferation.

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3.3.4 Effects on calcium channels
We have recently found that both PFOS and PFOA had effects on action potential andL-type Ca2+ currents using isolated guinea-pig ventricular myocytes by the whole-cell patch
clamp electrophysiology technique.(88) These discernible effects were as low as 3 μM for
PFOS at 1.5 ppm, whereas PFOA was less potent. The practical implications of this study
are two-fold. First, PFOS and PFOA have pharmacological effects similar to calcium
antagonists such as nifedipine in a relatively shallow resting potential.(88) Second, thesepharmacological effects may explain rhabdomyolysis that was observed in subacute studies
conducted in monkeys.(56,59) Both studies show the associations of PFOS and PFOA withcalcium homeostasis. It should also be noted that nifedipine is reported to be linked with ageneral increased risk of cancer.(89)4.

Toxicokinetics in Humans and Animals

A recent study has shown interspecies differences in the pharmacokinetics of PFOA andPFOS.(90) An ongoing 5-year, half-life study of 9 retired workers has suggested mean serum
PFOA and PFOS half-lives of 4.37 years (range 1.50–13.49 years, SD = 3.53) and 8.67 years(range 2.29–21.3 years, SD = 6.12), respectively.(90) These data provide evidence of thepotentials of PFOA and PFOS to accumulate in humans. Their serum half-lives in otheranimals are summarized in Table 5. There are large interspecies differences in the half-livesof PFOA and PFOS. The rapid excretion of PFOA by female rats compared with male rats
is due to active renal tubular secretion (organic acid transport system); this renal tubular
secretion is believed to be hormonally controlled. This gender-related difference has notbeen observed in primates; however, this difference in elimination kinetics in humans is
known, and may be associated with blood loss caused by menstruation.(38)Harada et al.(38) has recently built a simple one-compartment model. This model can
predict the fates of PFOA and PFOS in sera of rats, monkeys and humans when species
specific half-lives are selected. The application of such a simple model suggests thatinterspecies differences can be attributed to differences in clearance kinetics, which areprobably mediated by organic anion transporters(OAT1-3) specific to each species (Table
5).(38)
Table 5
Serum half-lives of PFOA and PFOS.
Species
Rat

Japanese macaque
Cynomolgus monkey
Human

Sex
male
femalemale
femalemale
male
femalemale
male

Serum half-life (days)
PFOA
PFOS
5.63 days
0.08 days
105 hours
60 hours
7.5 days
5.6 days
2.7 days
200 days4.31 years
8.67 years

Ref.
(91)
(92)
(93)
(94)
(59)
(90)

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307

Conclusions

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and other fluorinated compounds have been considered to be very useful chemicals for many purposes witha low order of toxicity. Perfluorinated compounds or telomers with longer carbon chain
lengths than those of PFOA and PFOS will degrade naturally to PFOA and PFOS.
In the Kinki district, the environmental contamination with PFOA and human exposure
to it have been occurring insidiously over the last 20 years. The geographic heterogeneity
in the exposure intensities of PFOA is very likely to be associated with industrial activities
that might discharge PFOA in wastewater. The correlation of the higher-exposure levels ofperfluorinated compounds and the densities of major fluorochemical industries in the Kinki
district is not considered to simply have occurred by chance but rather is indicative of theemission of fluorochemicals from these industrial facilities. If this is indeed the case, theidentification of the sources and the appropriate regulation of PFOA release are urgently
required to be discussed.
However, there is uncertainty regarding the toxicities caused by PFOA and PFOS. There
are two major reasons for this uncertainty. First, there are large interspecies differences intoxicities. Primate studies for PFOA and PFOS have revealed new aspects of the manifested
toxicity, which had not been detected when carried out in rodents. Thus, subchronic andchronic studies using monkeys will be much more informative and worthwhile for extrapolation to humans to determine the associated effects. Second, the adverse effects of PFOA
and PFOS have been reported in epidemiological studies, although they remain inconclusive
because of low statistical power. There are many workers in Japan who are being or havebeen exposed to PFOA and other perfluorochemicals. Epidemiological studies are required
for workers in Japanese industries. If conducted appropriately, meta-analysis can beestablished to present conclusive evidence of these toxicities such as the carcinogenicities
of PFOA and PFOS by increasing the statistical power.
For proper risk assessment, dose-response relationship on the toxicities of PFOA andPFOS are still not sound enough at present, while various toxicities are identified. In
addition, few data are available for the exposure assessments of PFOA and PFOS. Further
studies are indispensable to make risk assessments of PFOA and PFOS. These studies
should be directed to include the source of exposure and the pharmacokinetics of thesecompounds in general population.

Acknowledgements
This study was supported by grants-in-aid to AK for Health Science Research from the
Ministry of Health, Labour and Welfare of Japan (H15-Chemistry-004), the Nippon Life
Insurance Foundation (Environment-04-08) and the River Fund in charge of the Foundationof River and Watershed Environment Management, Japan (H17-1215-23), and a grant-inaid to KH for JSPS Fellows from the Japan Society for the Promotion of Science. We are
grateful to Dr. Takeo Yoshinaga (School of Food Science, Osaka Yuhigaoka Gakuen JuniorCollege).

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53 Rusch, G., Rinehart, W. and Bozak, C. (1979): An acute inhalation toxicity study of T-2306 CoC
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78 Austin, M., Kasturi, B., Barber, M., Kannan, K., MohanKumar, P. and MohanKumar, S. (2003):
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