Exposure
of the human body to sunlight
and UV
A/UV
B-light and being
tanned became fashionable,
particularly during summer
and holidays. However, with
the rise in sunlight exposure
an impressive increase in the
number of skin cancer cases
occurred (English et al.,
1997, Whiteman and Green
1999). A direct link between
the carcinogenic action and
sunlight radiation has been
made and the International
Agency for Research on Cancer
(IARC) has classified solar
radiation, UV
A and UV
B, as human
carcinogens (IARC,
1992).
National
and international health
authorities have urged the
public to take protective
measures, among these to use
sunscreens. IARC has recently
evaluated the
cancer-preventive activity of
sunscreens (IARC, 2000). They
conclude that the use of
sunscreens reduces the risk
of sunburn in humans and
probably prevents
squamous-cell carcinoma of
the skin. No conclusion could
be drawn about cancer
preventive activity against
basal-cell carcinoma and
cutaneous melanoma. However,
use of sunscreens can extend
the duration of intentional
sun exposure and such an
extension may increase the
risk for cutaneous
melanoma.
Sunscreens
today contain one or several
UV-B filters, often enriched
with UV-A filters. UV-filters
usually are synthetic organic
chemicals but may also be
inorganic in nature. Their
safety for human use is
regulated by national and
international bodies. In the
EU, before a new UV-filter is
allowed on the market, a
stringent toxicological
safety evaluation is carried
out and only in the case of a
safe toxicological profile
and a margin of safety of at
least 100, the molecule can
be approved by the SCCNFP for
human use (Notes of Guidance
for testing of cosmetic
ingredients for their safety
evaluation SCCNFP/0321/00
Final).
Comparable
safety approval procedures
exist in the USA and
Japan.
2. Terms of
Reference
The SCCNFP
has been asked to evaluate
the possible estrogenic
effects of organic UV filters
used in cosmetic products and
to respond to the following
questions :
* Could
the SCCNFP provide a critical
analysis of the article "
In vitro and
in vivo estrogenicity
of UV screens" by Margret
Schlumpf et al?
* More
generally, does the SCCNFP
consider that organic UV
filters used in cosmetic
sunscreen products have any
estrogenic effects which have
the potential to affect human
health?
3. Expert review
Introduction
There is
growing concern regarding
possible harmful consequences
of exposure to xenobiotic
compounds that are capable of
modulating or disrupting the
endocrine system. This
concern for endocrine
disrupting chemicals is
directed at both wildlife and
humans. It should be noted
that although there are
associations between
endocrine disrupting
chemicals, so far
investigated, and human
health disturbance, a
causative role of these
chemicals in diseases and
abnormalities related to an
endocrine disturbance has not
been established. The
Scientific Committee on
Toxicity, Ecotoxicity and the
Environment (CSTEE) has
recently discussed
toxicological test guidelines
and testing strategies and
has concluded that reliance
on
in vitro assays for
predicting
in vivo endocrine
disrupter effects may
generate false-negative as
well as false-positive
results. Thus, the
development of
in vitro pre-screening
test methods is not
recommended. The current
enhancement by OECD of the
existing
Repeated Dose 28-day Oral
Toxicity Study in Rodents
(406) and the
Two-Generation
Reproduction Toxicity
(416) tests has high priority
support [CSTEE, 1999].
Recently, an article by
Schlumpf et al (2001)
suggested that several UV
screens show estrogenic
activity. They used an
in vitro test with the
MCF-7 breast cancer cell line
and an
in vivo rat
uterotrophic assay. The
investigations of this Swiss
group on the safety of
UV-filters have alerted the
popular press and the public.
Controversial interpretations
of the results initiated
vigorous debates about the
safety of sunscreens. More
particularly estrogenic
properties were attributed to
a number of UV-filters
including benzophenone-3,
homosalate,
4-methyl-benzylidene camphor,
octyl-methoxycinnamate and
octyl-dimethyl-PABA, even
suggestions towards
carcinogenic effects were
made.
On
27/4/2001, an ad hoc working
group of the SCCNFP has
discussed the issue and
published a preliminary
report on the scientific
review of the investigations
of Schlumpf et al. (2001).
Serious concerns were
expressed as to the validity
of the results
published.
As a
follow-up, a final expert
opinion of the SCCNFP is
given below, consisting of
:
(1) a
scientific review of the
investigations of Schlumpf et
al. (2001),
(2) a scientific
review of the investigations
carried out by the industry
concerned,
(3) a risk assessment
and margin of safety
according to the EU-procedure
for UV-filters,
(4) data on human
exposure to environmental and
dietary estrogens,
(5)
conclusions.
3.1. Scientific Review
of the Results of Schlumpf
et al. (2001)
3.1.1. Study protocol
and results
The
in vitro and
in vivo estrogenicity
of 5 UV
B-filters,
benzophenone-3 (Bp-3),
homosalate (HMS),
4-methyl-benzylidene camphor
(4-MBC),
octyl-methoxycinnamate (OMC)
and octyl-dimethyl-PABA
(OD-PABA) and 1 UVA-filter,
butyl-methoxydibenzoylmethane
(B-MDM) were studied.
3.1.1.1.
In vitro study
A general
screening assay (E-screen)
with a human breast cancer
cell line, MCF-7 cells, was
carried out. A positive test
was based upon the binding of
the test compound with the
estrogen receptor leading to
cell proliferation.
As a
positive control, 17
b
-estradiol,
was used and it was, as
expected, positive in the
assay. The 5 UV-B filters were
found to be positive in the
assay and caused cell
proliferation. The UV-A filter
gave a negative result. EC
50 values for
17
b
-estradiol,
Bp-3, 4-MBC, OMC, OD-PABA and
HMS were found to be 1.22 pM,
3.73 µM, 3.02 µM, 2.37 µM, 2.63
µM and 1.56 µM, respectively
.
The
results were supported by the
expression of the
estrogen-dependent pS
2 protein and by
an inhibition of effects with
the anti-estrogen ICI
182,780.
3.1.1.2.
In vivo tests
A
uterotrophic assay was
carried out using two
different exposure routes,
namely
- oral
exposure of young Long-Evans
rats to the 6 UV-filters from
day 21 of life until
day 24 of life, with
ethinylestradiol serving as a
positive control;
- dermal
exposure of hairless Nu rats
to 4-MBC from day 21 of life
until day 26 of life by
immersion of the animals in
warm olive oil containing
2.5%, 5% and 7.5% of 4-MBC,
respectively.
For the
oral exposure, a
dose-dependent increase of
uterine weights was observed
for 4-MBC and OMC, a slighter
response was seen for Bp-3,
but no maximal effect was
seen as was the case for the
positive control.
ED
50 values were
found to be 0.818 µg/kg/day,
1000-1500 mg/kg/day, 309
mg/kg/day and 934 mg/kg/day,
for the positive control,
Bp-3, 4-MBC and OMC,
respectively. OD-PABA, HMS
and B-MDM were found to be
inactive.
For the
dermal exposure assay, 4-MBC
exhibited a dose-dependent
increase in uterine weight,
with a significant effect at
a concentration of 5% and
7.5% in olive oil.
3.1.2. Comments by
SCCNFP
3.1.2.1.
In vitro study
- The
potency of the positive control
is in the order of picomoles;
the
in vitro potency of the
UV-filters tested lays in the
range of micromoles, which
means a difference of
1 million units. The
in vitro potency of the
UV-filters is thus importantly
lower than the one observed for
17
b
-estradiol.
Probably a lot of industrial
chemicals would show some
in vitro estrogenic
effects when this type of
comparisons is taken
seriously.
- It
should be emphasized here
that
in vitro assays can
only demonstrate whether
UV-filters bind on the
estrogen receptor or not, but
they do not provide evidence
whether the compounds have
estrogenic activity or not.
In vitro assays are
therefore screening tests
useful in setting priorities
for further
in vivo testing. The
CSTEE committee clearly
stated in its report on
endocrine disrupters (1999)
that utilising
in vitro data for
predicting
in vivo endocrine
disrupter effects may
generate false negative as
well as false positive
results and that major
emphasis should therefore be
put on
in vivo assays.
Claiming that 5 UV-filters
have estrogenic properties
based on an
in vitro test is
premature.
The
in vitro ranking for
the UV-filters going from
Bp3, 4-MBC, OMC, OD-PABA to
HMS, did not correspond with
the
in vivo results.
Indeed, in the latter test
4-MBC was most active,
followed by OMC and Bp-3. The
most active UV-filter
in vitro displayed
only a weak activity
in vivo. In addition
OD-PABA and HMS were found to
be inactive. Only precise
toxicokinetic data can link
the
in vitro and
in vivo data, a
conclusion that was also
reached by the
authors.
3.1.2.2.
In vivo studies
- The OECD
draft protocol on the
rodent uterotrophic assay,
was issued on April 21, 2000.
The protocol used by the
Swiss group dates from before
that time and therefore shows
some important deviations.
Moreover, GLP conditions have
not been applied.
Deviations
from the current OECD
guideline
proposal :
·
the choice
of the rat strains is unusual
and not explained.
·
the exposure
period of the rats runs until
the 26
th day of life,
which is too close to the onset
of puberty.
·
the dermal
exposure conditions are
inappropriate : dipping
pups into olive oil is not a
standard procedure and the
galenic form to deliver the
UV-filter, namely a solution in
warm olive oil, is not
reflecting in use
conditions : indeed, today
sunscreens are formulated as
poorly penetrating
o/w-emulsions.
·
the
calculation of the absorbed
dose via dermal exposure is
unclear and oral intake by the
animals cannot be
excluded.
- The
potency of the positive
control, ethinylestradiol, is
in the order of 1 µg/kg/day;
the potency of the UV-filters
tested lays in the range of
100 to 1000 mg/kg/day; which
means a difference of 100.000
to 1 million units. The
in vivo potency of the
UV-filters is thus
importantly lower than the
one observed for the control
hormone. Furthermore, 3 of
the 6 UV-filters have no
measurable potency at
all.
- The
uterotrophic assay can only
serve a limited function as a
test for
in vivo identification
of chemicals with estrogenic
activity. The uterotropic
assay is a short-term
high-dose test.
3.2. Scientific Review
of the Investigations
carried out by Industry
3.2.1. Submission of
4-methyl-benzylidene
camphor (Colipa code
S60)
Two
uterotrophic assays have been
carried out in immature female
Sprague Dawley rats
[
Crl :
CD (SD) BR rats
]
either by
the subcutaneous route
(subcutaneous injections)
either by the oral route
(gavage). Animals were dosed on
3 consecutive days, day
19-20-21 of life; the positive
control was
17-ethinylestradiol. The
protocol was according to the
OECD guidelines proposal and
the tests were carried out
under GLP
conditions.
Six groups
were tested :
- 0, 10,
100,1000 mg/kg/day S60 in
corn oil
- 0.3 µg/kg/day of
control in ethanol
- 1 µg/kg/day of
control in ethanol
Subcutaneous
study : A
statistically significant
lower mean body weight gain
was observed in the 1000
mg/kg/day S60-treated group
during the interval
day 19-day 20,
compared to the vehicle
control group.
Oral study : A
statistically significant
lower mean body weight gain
was observed in the 100
mg/kg/day and the 1000
mg/kg/day S60-treated group
during the interval days
19-20 and day 20-21,
respectively, together with a
lower mean daily food
consumption.
For both
studies, the positive control
induced a significant
dose-related increase of the
uterus weight (both as wet
uterus and blotted uterus).
S60 did not induce a
significant increase of the
uterus weight at 10, 100 and
1000 mg/kg/day.
3.2.2. Submission of
octylmethoxycinnamate
(Colipa code S28)
A
uterotrophic assay of OMC was
carried out using female
immature Wistar rats
[
CRL :
WI(GLX/BRL/HAN) IGS BR
]
by the oral
route (gavage) for 3
consecutive days. The positive
control was DES-SP
(diethylstilbestrol
dipropionate).
Four
groups were
tested :
- 0, 250,
1000 mg/kg/day S28 in olive
oil,
- 5 µg/kg/day of
positive control in olive
oil.
The
protocol deviated from the
OECD guideline proposal, but
was carried out under GLP
conditions. A statistically
significant lower mean body
weight gain was observed in
the 250 mg/kg/day
S28-treated group during the
interval
day 2-day 3; the
same was true for the
1000 mg/kg/day
S28-treated group during the
interval
day 0-day 3.
The
positive control induced a
significant uterotrophic
effect and showed
histopathologic changes in
the uterus.
S28 did
not induce a uterotrophic
effect and no histopathologic
changes could be shown in the
uteri concerned.
3.2.3. Submission of
benzophenone-3 (Colipa code
S38)
A
uterotrophic assay of Bp-3 was
carried out using female
immature Wistar rats
[
Chbb :
THOM, SPF
]
of 22 days
old. The compound was given by
the oral route (gavage) for 4
consecutive days. The positive
control was DES-SP.
Four
groups were
tested :
- 0, 500,
1000 mg/kg/day S38 in sesame
oil,
- 5 µg/kg/day of
control in sesame oil.
Appropriate
control groups were included.
The protocol deviated from
the OECD guideline proposal,
but the test was performed
under GLP-conditions. Dosing
was carried out until
day 26, which is too
close to the onset of
puberty. A statistically
significant lower body weight
gain was observed in the 1000
mg/kg/day S38-treated group
during the interval
day 0-day 1.
The
positive control induced a
significant increase in
uterine weight (absolute and
relative). S38 did not
promote growth of the uterus
and therefore does not
exhibit estrogenic
activity.
Industry
made 4 uterotrophic studies
available on UV-filters of
which 2 were performed with
4-MBC (subcutaneous and oral
administration), one with
Bp-3 (oral route) and one
with OMC (oral route). The
results of the 4 studies show
no evidence for any
uterotrophic response and
doses up to 1000 mg/kg/day
were used for the 3
UV-filters concerned. The
animals were female immature
Sprague-Dawley or Wistar rats
treated for 3 to 4
consecutive days.
Only the
4-MBC study is strictly
carried out according to the
OECD guideline proposal and
no evidence for uterotrophic
activity could be seen,
although 4-MBC was found to
be the most active UV-filter
in the study of Schlumpf et
al. (2001), showing a
significant increase in
uterine weight at a dose of
119 mg/kg/day. In the same
study Bp-3 had a weak effect
at a dose of 1.500 mg/kg/day
but in the study conducted by
industry no uterotrophic
effect could be detected at
dosing of 1000 mg/kg/day. The
dosing at 1.500 mg/kg/day is
higher than the top dose
present in the OECD guideline
proposal and should therefore
be seen as a negative
result.
Thus as
far as Bp-3 is concerned, the
results of Schlumpf et al and
industry are in line. A
negative finding for Bp-3 was
also reported earlier by
Baker et al (2000) during the
poster session in the SOT
meeting in Philadelphia. For
Bp-3 it was already known
that about 1% of the Bp-3
dose in rats is metabolised
to p-hydroxy-benzophenone,
which might exhibit an
estrogenic effect (Hayden et
al.1997, Felix et al.1998,
Stocklinski et al.1980,
Nakagawa et al 2001).
A clear
discrepancy, however, exists
between the negative results
obtained by industry and the
positive ones of Schlumpf et
al. (2001), in particular for
4-MBC. Differences in strain
of the animal may be an
important factor. This was
highlighted in the expert
report of Bolt et. al [2001,
in press], which discusses
the significant differences
in toxicokinetics of
p-tert-octylphenol found in
different rat strains (Certa
et al. 1996, Upmeier et al.
2000).
Also
dosing of the animals was
different : oral
administration of UV-filters
was performed by gavage in
the industrial studies and by
mixing the chemicals in the
food by the Swiss
group.
3.3. Risk Assessment and
Margin of Safety
3.3.1. Some general
considerations
On a
general basis, the MoS is
calculated by dividing the
lowest No Observable Adverse
Effect Level (NOAEL) of a
compound by its Systemic
Exposure Dose (SED) during
normal foreseeable use. If
the MoS exceeds 100, the
compound is regarded as safe
for use.
The
question can be raised
whether an additional safety
factor should be introduced
for children with regard to
the use of sunscreens.
Based on a
number of previous
publications [Schaefer and
Riedelmayer 1996, Marzulli
and Maibach 1984, Jiang et
al. 1999 and Weltfriend et
al. 1996], Nohynek and
Schaefer [2001] recently
concluded that there is no
reason to assume that
children should be more
susceptible to potential
adverse effects of topically
applied sunscreens than
adults. This conclusion was
based upon the findings
that
- there is
no significant difference
between the skin of children
and adults regarding the
penetration of topically
applied substances;
- Skin
permeability to externally
applied substances remains
relatively constant
throughout life; this
particularly being confirmed
for sunscreens;
- The skin
of children is not more
susceptible to local irritant
effects of topically applied
substances than adult
skin.
Thus the
major difference between
adults and children, relevant
for risk assessment of a
topically applied substance,
is the larger body
surface / body
weight ratio of children,
when compared with that of
adults. As a consequence, the
relative systemic exposure of
children to a topically
applied substance may be
somewhat (about
1.4 times) higher than
that of a typical
adult.
Based on
this relatively small
difference between the
systemic exposure of adults
and children, no additional
safety factor is introduced
for children.
3.3.2. Risk assessment
and margin of safety for
4-MBC
3.3.2.1. According to
SCCNFP notes of
guidance
The safety
of 4-MBC has been reviewed by
the SCCNFP (XXIV/1377/96
rev.1/98) in 1998. It was
concluded that tests for skin
irritation, sensitisation,
phototoxicity,
photosensitisation,
photocontact allergy,
mutagenicity and
photomutagenicity were
negative. Percutaneous
absorption was estimated to
be 1.9%. Teratogenicity tests
were negative and via dermal
application no stimulating
effect on the thyroid
function could be seen as was
suggested by subchronic oral
tests.
The Margin
of Safety [
MoS = NOAEL / SED] was
found to be
110, which is
acceptable.
3.3.2.2 According to
data of Schlumpf et al.
(2001)
The NOEL
(estrogenic activity) of
4-MBC in the uterotrophic
assay in immature Long-Evans
rats published by Schlumpf et
al (2001) is 66
mg/kg/day.
SED = 0.23
mg/kg/day
"
Screening MoS" = 66
mg/kg/day / 0.23 mg/kg/day =
289, which is higher
than 100 and would
consequently be
acceptable.
Important
to notice is the calculation
of a
"
Screening MoS",
since :
·
the exposure
time can hardly be called
long-term or chronic, but is
clearly short-term, which is of
great significance for the use
of the deduced "NOEL"-value.
A 2-generation study
would be able to generate the
real NOEL value necessary for
the calculation of the MoS
related to reproduction
toxicity. However, this
particular type of study should
only be considered as a last
resort because of the large
number of animals required to
perform it
correctly.
·
as long as
the relevance for humans of
positive results in a
uterotrophic assay is not
known, it remains questionable
whether it is correct to use a
safety margin for hormonal
activity.
3.3.3. Risk assessment
and margin of safety for
OMC
3.3.3.1. According to
SCCNFP notes of
guidance
The safety
of OMC has been reviewed by
the SCC (SPC/1037/93, S28) in
1993. It was concluded that
the compound has a low acute
toxicity. OMC is not
irritating or sensitising in
animals, but can be very
rarely responsible for
allergic contact dermatitis
in man.
Mutagenicity,
photomutagenicity and
photoclastogenicity tests
were negative. The
teratogenic activity has a
NOAEL of more than 500 mg/kg
bw/day, which was the highest
dose tested.
The
percutaneous absorption was
estimated to be 2%, a figure
derived from experiments in
human and animal skin
in vitro, plus the
results of an
in vivo human study
via oral uptake.
The
MoS was calculated to
be
750, which is
acceptable.
3.3.3.2. According to
data of Schlumpf et al
(2001)
The NOEL
(estrogenic activity) of OMC
in the uterotrophic assay in
immature Long-Evans rats
(Schlumpf et al. 2001) is 522
mg/kg/day.
SED = 0.6
mg/kg/day
"
Screening MoS" =
522/0.6 =
870, which would be
acceptable (>100).
3.3.4. Risk assessment
and margin of safety of
Bp-3
3.3.4.1. According to
SCCNFP notes of
guidance
Bp-3 was
taken up in the Annex of the
UV-filters before the
activities of the SCC
started. Therefore, Bp-3 has
not undergone the standard
safety procedure review by
the SCCNFP.
It is advised to ask
the industry for a complete
toxicological dossier on Bp-3
so that a full risk
assessment and a calculation
of the margin of safety can
be performed according to the
SCCNFP standards.
According
to the
Final Report on the Safety
Assessment of
Benzophenones-1, -3, -4, -5,
-9 and -11)
(Cosmetic Ingredient Review
2000), the risk assessment
can provisionally be
performed as
follows :
LD
50 oral rat
> 2000 mg/kg
LD
50 dermal rabbit
> 16.000 mg/kg
NOEL (27d oral, rat) =
1% in diet
NOEL (90d oral, rat) =
0.1% in diet
[effects (90d oral,
rat) noticed at 0.5% to
1% in diet]
Bp-3 is
not irritating to skin and
eyes of rat, not
photosensitising, not
phototoxic in guinea pigs and
rabbits, not sensitising in
guinea pigs and not mutagenic
in the Ames-test. Bp-3 is not
irritating or sensitising on
human skin, although some
cases of positive patch tests
have been seen in
humans.
From these
data a NOEL (90d, oral rat)
can be
estimated :
food uptake
of adult rat is
»
10g/100g bw
no effect when Bp-3 0.1%
in diet
»
1g/kg/day
(diet)
»
100
mg/kg/day in rat
thus the estimated NOEL
is 100 mg/kg/day.
The
percutaneous absorption is
not known; therefore the real
SED cannot be calculated.
However, assuming a
percutaneous absorption in
the order of 1% (Nohynek and
Schaefer, 2001), a SED = 0.3
mg/kg can be
calculated.
MoS =
333, acceptable
(>100)
Note that
this is an estimation.
3.3.4.2. According to
Schlumpf et al (2001)
NOEL
(estrogenic activity) of Bp-3
in the uterotrophic assay in
immature Long-Evans rats
published by Schlumpf et al
(2001) is 937 mg/kg/day.
Since the SED is not known,
the MoS cannot be calculated.
Assuming the SED = 0.3
mg/kg/day,
"
Screening MoS" =
NOEL/SED = 937/0.3 =
3123 >100, would be
acceptable.
3.4. Data on Human
Exposure to Environmental
and Dietary Estrogens
In table 1
recently published data are
shown with respect to the
potency of xenoestrogens in
the rodent uterotrophic
assay.
Table
1 : Potency of
xenoestrogens in the rodent
uterotropic assay.
a
in alfalfa
and leguminosae
b soybeans
c soybean-containing
bread sold in UK health food
stores (Ashby and Tinwell,
1998).
d from Casanova et
al. 1999.
From these
data it appears that
UV-filters have an extremely
small relative potency in
comparison with
ethinylestradiol (1 to 1
million) but also a low
relative potency in
comparison with dietary
estrogens.
When the
mass balance of human
exposure to environmental and
dietary estrogenic compounds
was estimated, data as
represented in table 2 were
found (Safe 1995).
It is known
that several food formulas
contain soy products. Soy
contains phytoestrogens
including genistein and
daidzein. The total
phytoestrogen content of infant
food formulas for instance,
represents 135
±
5 µg/g total
genistein and daidzein (Irvine
et al. 1998) and may go up as
high as 600µg/g (Zimmerli et
al. 1997).
From these
data it seems that the
estrogenic potency of
UV-filters is several orders
of magnitude lower as
compared with that of natural
dietary estrogens.
During the
last years, it became evident
that a variety of different
mechanisms of endocrine
disruption exist for
different compounds [CSTEE,
1999]. For pragmatic reasons
this will not be further
discussed here.
Table
2 : Estimated mass
balance of human exposure to
environmental and dietary
estrogens (Safe 1995).
3.5.
Conclusions
(i) A
number of important technical
shortcomings in the study of
Schlumpf et al. were
detected. This was mentioned
in the first part of this
report as well as in a
preliminary report of an ad
hoc working Party.
(ii)
Industry has performed a
further uterotrophic assay in
rats for 4-MBC according to
the OECD guideline proposal
and under GLP conditions; no
evidence was found for an
increase in uterus weight
(part 2 of this
report).
(iii)
Industry has provided data on
uterotrophic assays in rats
for Bp-3 and OMC (not
according to OECD guidelines,
but under GLP conditions), in
which no positive
uterotrophic effect could be
detected for both UV-filters
(part 2 of this
report).
(iv) The
margins of safety for 4-MBC
and OMC, calculated according
to the SCCNFP, using NOAELs
obtained from subchronic
animal studies, are higher
than 100.
The estimated margin
of safety for Bp-3 is higher
than 100 (part 3 of this
report).
(v) The
calculated
"
Screening MoS", in
which the experimental
non-estrogenic-effect-level
data, obtained by Schlumpf et
al. (2001), are used in the
official MoS calculations of
the EU, are found to be
higher than 100 for 4-MBC,
OMC and Bp-3 (part 3 of this
report).
However,
the data presented by
Schlumpf et al (2001) are
unsuitable for long-term risk
assessment. Use of the data
of Schlumpf et al will only
give a rough approximation of
the possible risk. A
two-generation reproduction
toxicity test might possibly
generate more accurate
data.
(vi) The
activity of the UV-filters
found in the study of
Schlumpf et al. (2001) is
very low in comparison with
exposure to "estrogenic"
substances in food
(flavonoids) and hormonal
therapy (birth control pill,
morning after pill,
post-menopausal therapy)
(part 4 of this
report).
With the
information available above,
the SCCNFP concludes that
there is no need for
regulatory actions to protect
the consumer with regard to
potential estrogenic effects
of the UV-filters
studied :
- Although
positive data were observed
for the UV-filters HMS and
OD-PABA in the
in vitro assay
(Schlumpf et al., 2001), this
in vitro test with
MCF-7 cells remains only a
screening. The uterotrophic
assay (
in vivo test) was
negative in the Schlumpf
study.
- The UV-A
filter B-MDM was negative in
both the
in vitro and
in vivo assay.
- Bp-3
showed to be positive in the
in vitro assay by
Schlumpf et al. (2001) and
weakly positive in the
in vivo test. The
SCCNFP recommends that
industry is asked to submit a
complete toxicological
dossier on Bp-3 in order to
perform a full risk
assessment and to calculate a
final MoS for Bp-3 according
to the EU standards for
UV-filters.
As
UV-filters are an effective
tool to protect humans from
excessive exposure to
sunlight, a known carcinogen,
their use is recommended by
the SCCNFP.
3.6. Opinion (answer to
the questions)
Answer to the question
'
Could the SCCNFP provide a
critical analysis of the
article "In vitro and in vivo
estrogenicity of UV screens"
by Margret Schlumpf et
al?' :
The
article of "
In vitro and
in vivo estrogenicity
of the UV screens" by M.
Schlumpf et al. has been
critically analysed and the
comments of the SCCNFP can be
summarised as follows
:
In vitro study :
- The
potency of the positive control
is in the order of picomoles;
the
in vitro potency of the
UV-filters tested lays in the
range of micromoles, which
means a difference of 1 million
units. The
in vitro potency of the
UV-filters is thus importantly
lower than the one observed for
17
b
-estradiol.
Probably a lot of industrial
chemicals would show some
in vitro estrogenic
effects when this type of
comparisons is taken
seriously.
- It
should be emphasised here
that
in vitro assays can
only demonstrate whether
UV-filters bind on the
estrogen receptor or not, do
not provide evidence whether
the compounds have estrogenic
activity or not.
In vitro assays are
therefore screening tests
useful in setting priorities
for further
in vivo testing. The
CSTEE committee clearly
stated in its report on
endocrine disrupters (1999)
that utilising
in vitro data for
predicting
in vivo endocrine
disrupter effects may
generate false negative as
well as false positive
results and that major
emphasis should therefore be
put on
in vivo assays.
Claiming that 5 UV-filters
have estrogenic properties
based on an
in vitro test is
premature.
The
in vitro ranking for
the UV-filters going from
Bp3, 4-MBC, OMC, OD-PABA to
HMS, did not correspond with
the
in vivo results.
Indeed, in the latter test
4-MBC was most active,
followed by OMC and Bp-3. The
most active UV-filter
in vitro displayed
only a weak activity
in vivo. In addition
OD-PABA and HMS were found to
be inactive. Only precise
toxicokinetic data can link
the
in vitro and
in vivo data, a
conclusion that was also
reached by the
authors.
I
n vivo study :
The OECD
draft protocol on the
rodent uterotrophic assay,
was issued on April 21, 2000.
The protocol used by the
Swiss group dates from before
that time and therefore shows
some important deviations.
Moreover, GLP conditions have
not been applied.
Deviations
from the current OECD
guideline proposal :
* the
choice of the rat strains is
unusual and not
explained
* the
exposure period of the rats
runs until the 26
th day of life,
which is too close to the
onset of puberty
* the
dermal exposure conditions
are inappropriate: dipping
pups into olive oil is not a
standard procedure and the
galenic form to deliver the
UV-filter, namely a solution
in warm olive oil, is not
reflecting in use conditions:
indeed, today sunscreens are
formulated as poorly
penetrating
o/w-emulsions.
* the
calculation of the absorbed
dose via dermal exposure is
unclear and oral intake by
the animals cannot be
excluded.
* The
potency of the positive
control, ethinylestradiol, is
in the order of 1
m
g/kg/day;
the potency of the UV-filters
tested lays in the range of 100
to 1000 mg/kg/day; which means
a difference of 100.000 to 1
million units. The in vivo
potency of the UV-filters is
thus importantly lower than the
one observed for the control
hormone. Furthermore, 3 of the
6 UV-filters have no measurable
potency at all.
* The
uterotrophic assay can only
serve a limited function, as
a test for
in vivo identification
of chemicals with estrogenic
activity. The uterotrophic
assay is a short- term
high-dose test.
The SCCNFP
came to the conclusion that a
number of important technical
and scientific shortcomings
are present in the study of
M. Schlumpf et al.
Answer to the question
'
More generally, does the
SCCNFP consider that organic
UV filters used in cosmetic
sunscreen products have any
estrogenic effects which have
the potential to affect human
health?' :
Based on
the actual scientific
knowledge, the SCCNFP is of
the opinion that the organic
UV-filters used in cosmetic
sunscreen products, allowed
in the EU market today, have
no estrogenic effects that
could potentially affect
human health.
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th SOT meeting
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V.A., Jones, P.A. and Lea,
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