Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

After oral administration, Bisphenol A is rapidly metabolised by intestinal tissue and the liver to Bisphenol A glucuronide. In humans, the glucuronide is released from the liver into the systemic circulation and cleared rapidly by urinary excretion. In contrast, Bisphenol A glucuronide is primarily eliminated in bile in rodents with some partial urinary excretion. The Bisphenol A glucuronide excreted via the bile in rodents undergoes enterohepatic recirculation after cleavage to Bisphenol A and glucuronic acid by glucuronidase in the intestinal tract.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
30
Absorption rate - inhalation (%):
100

Additional information

Criteria for IUCLID chapter 7 dossier preparation applied in the initial dossier 2010 and the update 2015:

 

Initial dossier submitted in 2010:

Due to the large data set on Bisphenol A, criteria were established to define Key-Studies, Supporting-Studies and additional studies to cover all available data for the human health hazard assessment. In the original dossier submitted in 2010 the human health hazard assessment was based on the initial EU Risk Assessment Report 2003 on Bisphenol A and the EU Risk Assessment Update in 2008. For each endpoint the conclusion of the EU Risk Assessments in 2003 and 2008 are cited and, if available, additional relevant information not evaluated in one of the Risk Assessments is indicated. Key studies were defined as comprehensive studies conducted according to scientifically accepted methods and performed according to or exceeding validated guidelines (e.g. OECD testing guidelines). Supporting studies were defined as comprehensive studies conducted to scientifically accepted methods and performed similar to validated guidelines with only very minor deviations. Additional exploratory studies were cited in chapters 7.9.3.” specific investigations: other studies” and 7.12. “additional toxicological information”.

 

Dossier update in 2015:

The summaries and conclusions of the initial dossier are included in the endpoint summaries of the update.

 

A literature search is performed to cover literature between the initial dossier submission (July 2009) and July 2015. As in the initial dossier key studies are defined as comprehensive studies conducted according to scientifically accepted methods and performed according to or exceeding validated guidelines (e.g. OECD testing guidelines). Supporting studies are defined as comprehensive studies conducted to scientifically accepted methods and performed similar to validated guidelines with only very minor deviations. Starting in 2008 and continuing through 2015, researchers at several US federal government laboratories (EPA, FDA, National Toxicology Program, CDC, Pacific Northwest National Laboratory) have been conducting in-depth research to answer key scientific questions and resolve uncertainties about the safety of Bisphenol A. These studies e.g. are included in the updated dossier with robust study entries.

 

Recently SCOEL recommendation (2014) and EFSA opinion (2015) became available and for each endpoint their conclusion is cited.

 

Additional exploratory studies identified during the updated literature search are also cited in chapters 7.9.3.” specific investigations: other studies” and 7.12. “additional toxicological information”.

 

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Discussion on toxicokinetics:

Initial dossier submitted in 2010:

The 2003 EU RAR concluded:

"Animal data indicates that absorption of Bisphenol A from the gastrointestinal tract is rapid and extensive following oral administration, although it is not possible to reliably quantify the extent of absorption. Following dermal exposure, available data suggest limited absorption of about 10% of the applied dose. Bisphenol A is removed rapidly from the blood and the data indicate extensive first pass metabolism following absorption from the gastrointestinal tract. In view of this first pass metabolism, the bioavailability of unconjugated Bisphenol A is probably limited following oral exposure to no more than 10 to 20% of the administered dose. The major metabolic pathway in rats involves glucuronide conjugation, with approximately 10% and 20% of the administered dose recovered in urine as the glucuronide metabolite in males and females, respectively. The major route of excretion is via the faeces with the urinary route being of secondary importance. Over seven days post dosing, approximately 80% and 70% of the administered dose was eliminated in the faeces in male and female rats, respectively. The first pass metabolism and extensive and rapid elimination of Bisphenol A suggest that the potential for transfer to the foetus and bioaccumulation may be limited. There are no data on the toxicokinetics of Bisphenol A following inhalation exposure."

The 2008 updated EU RAR concluded:

"New information on the toxicokinetics of Bisphenol A in humans and in pregnant and non-pregnant rodents of different ages provides an important contribution to the knowledge of kinetic properties of Bisphenol A. Human studies have demonstrated that at comparable exposure levels the blood concentrations of free Bisphenol A in humans are much lower than those in rodents. In rats, mice, monkeys, and humans, the available evidence suggests that following oral administration, Bisphenol A is rapidly and extensively absorbed from the gastrointestinal tract. For the purposes of risk characterisation, absorption via the oral and inhalation routes will be assumed to be 100%; dermal absorption will be taken to be 10%. A number of studies in rats suggest that Bisphenol A metabolites and free Bisphenol A have a limited distribution to the embryo/foetal or placental compartments following oral administration. Maternal and embryo/foetal exposure to free Bisphenol A did occur, but systemic levels were found to be low due to extensive first-pass metabolism. There are differences between humans and rodents in the distribution of Bisphenol A. After oral administration, Bisphenol A is rapidly metabolised in the gut wall and the liver to Bisphenol A glucuronide. In humans, the glucuronide is released from the liver into the systemic circulation and cleared by urinary excretion. In contrast, Bisphenol A glucuronide is eliminated in bile in rodents and undergoes enterohepatic recirculation after cleavage to Bisphenol A and glucuronic acid by glucuronidase in the intestinal tract."

Additional relevant information since 2010 taken into account for the dossier update:

EFSA 2015 Conclusions on toxicokinetics:

"The kinetic data available indicate species- and life stage-dependent differences. Such variability has to be considered when data of different species are compared. Conjugation to Bisphenol A-glucuronide, which is a biologically inactive form, is the major metabolic pathway of Bisphenol A in humans and animals. A study in humans on high Bisphenol A diets (Teeguarden et al., 2011) showed that unconjugated Bisphenol A in serum was below the LOD of 0.3 ng/ml (= 1.3 nM), confirming under the condition of the study that internal exposure to unconjugated Bisphenol A is low. The percentage of unconjugated Bisphenol A in blood is only a few percent of total Bisphenol A (sum of conjugated and unconjugated Bisphenol A). Based on the analysis of oral (gavage) versus intravenous toxicokinetic data, the oral systemic bioavailability of unconjugated Bisphenol A in rats is 2.8 %, in mice 0.45 % and in monkeys 0.9 % (Doerge et al., 2010a,b, 2011a, b, 2012). The concentrations measured in the animal studies and also in the human study render the relevance of serum or blood concentrations in humans, which were measured and reported by some authors in the literature (see Section 4.6.3 in Part I – Exposure assessment) as rather unplausible. Experimental data on the systemic availability of unconjugated Bisphenol A in humans has until now not been published. From studies on physiologically based pharmacokinetic (PBPK) modelling it can be concluded, that at relevant oral exposures (e.g. < 1 μg/kg bw per day) the maximum serum concentrations (Cmax) of unconjugated Bisphenol A are in the 3.2–160 pg/ml (7–37 pM) range, depending on the model used (Mielke and Gundert-Remy, 2009; Edginton and Ritter, 2009; Fisher et al., 2011; Yang et al., 2013). Bisphenol A does not accumulate in the body even though the concentration of unconjugated Bisphenol A is somewhat higher in fat compared to serum.

Some new animal data in particular in mice, rats and monkey give more insight into the kinetics of Bisphenol A, in particular into the age-dependent maturation of conjugation reactions. Also, diaplacentar transfer of Bisphenol A has been measured in rat and monkey. Data in rats indicate that in early pregnancy transfer to the fetus might be greater compared to later pregnancy after IV injection exposure of Bisphenol A (fetus/dam concentration ratios: 2.8 at GD 12, 1.2 at GD 16, 0.4 at GD 20). Unconjugated Bisphenol A and Bisphenol A-conjugates are measured in the amniotic fluid of rats and rhesus monkeys at low concentrations. Bisphenol A is found in milk of rat dams exposed to Bisphenol A at a level of 100 ug/kg bw per day in the unconjugated and conjugated forms. The amount delivered to the pups is so small that the concentrations in pup serum are below 0.2 nM (45.6 pg/ml), and therefore pup exposure via lactation is extremely low (1/300 of the maternal dose). These data are in marked contrast to the average concentrations reported for human breast milk (unconjugated Bisphenol A 0.3 ng/ml; total Bisphenol A 1.1 ng/ml )despite the fact that the average human exposure is 1/1000 of the rat exposure exposure (see Chapter 4.6.4. in Part I – Exposure assessment).

Polymorphisms have been described for the enzymes relevant for the conjugation of Bisphenol A. Since Bisphenol A conjugation can be carried out by several enzymes, a single polymorphism in one gene, resulting in a reduction or loss of enzymatic activity of functional enzymes may result in a change in the plasma levels of unconjugated Bisphenol A. Since Bisphenol A is glucuronidated by two UTGs and is conjugated not only to glucuronides but also to sulphates, it can be assumed that the increase in blood concentration is modest. This assumption has been confirmed also in the PBPK modelling study by Partosch et al. (2013) showing a 4-fold difference in AUC and Cmax between the human PBPK models with the highest and the lowest metabolic activity. This difference in sensitivity of Bisphenol A in the human population is covered by the assessment factors used in the risk assessment of Bisphenol A.

A solid base of toxicokinetic studies in various laboratory animal species (Doerge et al., 2010a,b,c; 2011a,b; 2012) provide internal dose metrics for neonatal-to-adult stages and for different routes of exposure (oral and intravenous/subcutaneous). Moreover, PBPK models have been developed to predict the internal exposures in laboratory animals and humans in a route-specific manner. Overall, this body of information permits extrapolation to humans and the application of the HED concept for providing HEDF which account for the toxicokinetic portion of the interspecies differences. Multiplying the HEDF by a reference point of a critical toxicity study yields a human-equivalent oral dose that is used for risk assessment. The assessment of the physiological plausibility of the derived HEDF values for adult animals with oral dosing revealed a good agreement of the HEDF for monkeys with the allometric scaling-derived DAF. In rats, the HEDF was 3-times higher than the DAF which can be explained by the effect of enterohepatic recirculation, serving to extent the exposure to Bisphenol A. For mice, the HEDF was 2-times lower than the DAF, which suggests a greater metabolic capacity, serving to reduce the AUC. The Panel noted that due to limitations in the analytical detectability of unconjugated Bisphenol A in mouse serum, the HEDF for mice may be conservative by a factor of 5.

The available evidence from in vitro skin absorption experiments with human, pig and rat skin and from in vivo studies on dermal absorption in rats suggests a 24-h dermal absorption for human skin of 2.3–8.6%. For exposure scenarios with dermal contact to thermal paper, the CEF Panel decided to use a skin penetration of 10%. The CEF Panel decided not to consider the amount deposited in the stratum corneum as becoming available for systemic uptake for reasons emerging from the PBPK modelling of dermal exposure. The CEF Panel further decided not to consider skin metabolism in dermal exposure scenarios as the available information does not permit to arrive at a reliable estimate of the extent of skin metabolism. Not to consider skin metabolism is a conservative decision. The CEF Panel noted that the assumption of 10% dermal absorption for the hand contact to thermal paper is also a further conservative decision, since the absorption across the skin of the palms can be expected to be lower than in other body parts because of the thicker stratum corneum. For scenarios with aggregated oral and dermal exposures, PBPK modelling was used to estimate the internal dose metrics for unconjugated Bisphenol A and to convert external dermal doses into an equivalent oral doses."

ECHA requested an in vitro dermal penetration study to be conducted by the registrant. As requested by ECHA this study was performed in accordance with Good Laboratory Practice regulations (Toner 2015). This study was also performed in accordance with the following guidelines:

- OECD Guideline for Testing of Chemicals, Guideline 428: Skin Absorption:In VitroMethod (2004).

- OECD Environmental Health and Safety Publications Series on Testing and Assessment No. 28. Guidance Document for the Conduct of Skin Absorption Studies (2004).

- Scientific Committee on Consumer Safety (SCCS). Basic Criteria for theIn VitroAssessment of Dermal Absorption of Cosmetic Ingredients. SCCS/1358/10, 22 June 2010.

 

ECHA indicated that there are a number of points that require special attention that shall be considered:

The design of the diffusion cell (technicalities and choice between static and flow through system).

An automated flow-through diffusion cell apparatus was used. Continuous sampling is the advantage of a flow-through system compared to a static system. Receptor fluid was collected at regular intervals between 0.5 and 24 h. The selected laboratory has extensive experience with flow-through diffusion cell experiments.

 

The choice of the receptor fluid (physiological pH, solubility and stability of chemical in receptor fluid should be demonstrated, no interference with skin/membrane integrity, analytical method, etc.):

The receptor fluid was a tissue culture medium (Dulbecco's Modified Eagle Medium; DMEM) containing ethanol (ca1%, v/v), Uridine 5’‑diphosphoglucuronic acid (UDPGA, 2 mM) and 3’-phosphoadenosine-5’-phosphosulfate (PAPS, 40 µM). 

DMEM was selected since the laboratory has experience with this medium as receptor fluid and it does not interfere with the skin/membrane integrity (see below).

To support UGT and SULT metabolism the cofactorsUridine 5'-diphospho-glucurunic acid (UDPGA; 2 mM) and 3’-phosphoadenosin-5’-phosphosulfate (PAPS;0 µM)) were added.

A separate solubility experiment demonstrated that the applied dose of Bisphenol A in in the high concentration (300 mg/l) could potentially be collected within the first hour of receptor fluid collection of the 24 h monitoring period. Therefore, this receptor fluid was not rate limiting for solubility and was acceptable for use on this study.

Stability of Bisphenol A and Bisphenol A-glucuronide in receptor fluid was demonstrated over the whole incubation time (24h).

 

Skin integrity is of key importance and should be verified.

Membrane integrity was demonstrated by electrical resistance at the beginning of the experiment and at the end of the experiment (24h).

 

Skin temperature has to be ascertained at normal human skin temperature.

The flow-through diffusion cells were placed in a manifold heatedviaa circulating water bath set to maintain a skin surface temperature at 32 °C ± 1 °C.

 

The test substance has to be rigorously characterized.

Carbon-14 labelled Bisphenol A ([ring14C(U)]-Bisphenol) was supplied by Moravek Biochemicals Inc, 577 Mercury Lane, Brea, California 92821, USA. The Certificate of Analysis stated that the specific activity and radiochemical purity were 474 µCi/mg and 99.8%, respectively. 

Non-radiolabelled Bisphenol A was supplied by Sigma-Aldrich, 3050 Spruce Street, Saint Louis, MO 63103, USA. A copy of the Certificate of Analysis is provided in Appendix 3. The Certificate of Analysis stated chemical purity of 99.9%.

GLP certified metabolite reference standards (Bisphenol A glucuronide sodium salt and Bisphenol A sulfate sodium salt were available.

 

Dose (several small dosages shall be used) and vehicle (aqueous solution)/formulation should be representative for the in-use conditions;

Phosphate buffered saline (PBS) was used as a vehicle. Initially the use of artificial sweat was considered but there are >40 formulations reported in the literature (e.g. Stefaniak et al. Toxicology in vitro 2006, 20:1265-83) with different complexity (Harvey et al. 2010,24:1790-96) and no rational when to use individual formulations. In addition no information was available if any of these formulations interfere with the skin/membrane integrity, viability of the fresh skin used or potential metabolic activity of UGTs and/or SULTs.

The low dose, 2 mg/l, was selected to give ca. 2000 dpm radioactivity (limit of quantification) as a measure for absorption. (Skin surface area (cm2): 0.64; Application rate of Formulation (µL/cm2): 10 (standard according to guideline; higher values have to be justified); Specific activity Bisphenol A: 474 µCi/mg; Assumption concerning absorption: 10% of applied dose will be absorbed).

The high dose was selected at the solubility limit of 300 mg/l. This concentration will lead to a surface dose of 1,92 µg/0.64 cm2= 3 µg/cm2, which is in same order as Biedermann et al (Anal. Bioanal. Chem. 2010. 398: 571-576) reported in a worst-case assumption on exposure via thermo paper (4-16 µg/cm2).

The dose level between the high and low-dose is covered by 2 interim doses spaced by a constant factor of 5.

Overall, the following concentrations were selected for the main study: 300, 60, 12, 2.4 mg/l

 

Dose, volume and contact time with the skin have to mimic in-use conditions. The duration has to be at least 24 hours. For measurements and calculation of the percentage of absorption the low end of the anticipated exposure should be tested.

For measuring the metabolism also the highest exposure should be included;

Additionally, the study shall investigate metabolites of Bisphenol A in the relevant compartments of the skin since at least the Zalko study gave evidence for a significant formation of Bisphenol A metabolites in the skin.

 

Absorption rates were relative constant over the dose levels investigated.

Fresh skin was used since a pilot experiment verified that Bisphenol A-G and Bisphenol A-S is observed after incubation of fresh skin and by that confirmed some metabolic capability of the skin under the above mentioned conditions.

 

Regular sampling is required over the whole exposure period;

Absorption of Bisphenol A was assessed by collecting fractions of receptor fluid at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 h post dose.

 

Appropriate analytical techniques should be used. Their validity, sensitivity and detection limits should be documented in the report;

HPLC-UV analysis was conducted and the sensitivity and detection limits are documented.

 

The test compound is to be determined in all relevant compartments:

- product excess on the skin surface (dislodgeable dose),

- stratum corneum (e.g.adhesive tape strips),

- living epidermis (without stratum corneum),

- dermis,

- receptor fluid;

Data on all mentioned compartments are reported.

 

Mass balance analysis and recovery data are to be provided. The overall recovery of test substance (including metabolites) should be within the range of 85-115%; and

Mass balance is reported and within the given range.

 

8 skin samples from at least 4 donors shall be used. Variability / validity / reproducibility of the method shall be demonstrated and discussed.

 

Fresh human skin samples from 4 donors were investigated. Each donor was run in triplicate (each donor contains 3 skin disks for absorption). Overall, 12 skin samples were were used for each dose level.

 

The amount measured in the dermis, epidermis (with stratum corneum) and receptor fluid will be considered as dermally absorbed and taken into account for further calculations.

The followingdermal absorption rates were reported in this study:

Target Concentration (mg/L)

300

60

12

2.4

 

(% Applied Dose)

Total Dislodgeable Dose

72.34 ±5.64

70.91 ±6.20

71.95 ±7.98

71.57 ±9.11

WholeStratum Corneum

10.25 ±5.44

9.25 ±4.30

7.31 ±3.33

7.70 ±4.92

Total Unabsorbed Dose

82.61 ±8.37

80.31 ±6.92

79.33 ±9.97

79.37 ±9.91

Epidermis

10.66 ±6.40

10.45 ±5.73

10.38 ±5.36

11.91 ±4.86

Dermis

3.28 ±2.44

3.97 ±1.99

6.19 ±4.28

4.51 ±3.73

Total Absorbed Dose

1.98 ±1.42

1.68 ±1.20

2.72 ±1.95

3.62 ±1.69

Dermal Delivery

15.92 ±8.14

16.10 ±7.01

19.28 ±8.54

20.04 ±6.24

Mass Balance

98.53 ±1.99

96.41 ±1.45

98.62 ±2.18

99.40 ±6.54

 

There are two guidance documents to calculate the potential dermal absorption based on in vitro data.

a) EFSA Guidance on Dermal Absorption (EFSA Journal 2012. 10, 2665)

EFSA defines absorption= receptor fluid + receptor chamber washes + skin sample (excluding tape strips 1 and 2). The guidance indicates:There is a general practise within EFSA PRAPeR9 meetings that the first 2 tape strips will represent material that will not become bioavailable due to desquamation. The Panel proposes to follow this approach. Thus, the first 2 tape strips can be excluded when calculating dermal absorption …If there is significant variation between replicates (i.e. the standard deviation is equal to or larger than 25% of the mean of the absorption as defined in section 5.6. and 5.8.) consideration should be given to using a value other than the mean or rejecting the study entirely. The preferred approach would be the addition of a standard deviation to the mean value. that the application site was swabbed to remove the test material before termination of the study.”

 

Applying the EFSA guidance leads to the following potential absorption values;bold values denote value to be used according to the EFSA Guidance.

Test Preparation

Mean Potentially Absorbable Dose

Mean+1SD

SD>25% of mean

300 mg/L

23.70

31.84

Yes

60 mg/L

23.09

29.13

Yes

12 mg/L

24.80

31.79

Yes

2.4 mg/L

25.42

30.79

No

 

b)SCCS Basic Criteria for the in vitro assessment of dermal absorption of cosmetic ingredients (SCCS/1358/1)

 

SCCS defines absorption as follows:“In a classicalin vitrodermal absorption setting, the amounts of penetrated substance(s) found in the receptor fluid are considered to be systemically available.Both the epidermis (except for the stratum corneum) and dermis are considered as a sink, wherefore the amounts found in these tissues are considered as absorbed and are added to those found in the receptor fluid.The amounts that are retained by the stratum corneum at the time of sampling are not considered to be dermally absorbed, and thus they are not expected to contribute to the systemic dose.

When studies correspond to all of the basic requirements of the SCCS, themean + 1SDwill be used for the calculation of the MoS… In case of significant deviations from the protocol and/or very high variability, themean + 2SDwill be used as dermal absorption for the calculation of the margin of safety.”

 

Applying the EFSA guidance leads to the following potential absorption values;no clear guidance is given on guideline to define if 1 or 2 SD should be used.

Test Preparation

Mean dermal delivery

Mean+1SD

Mean+2SD

 300 mg/L

15.92

24.06

32.20

 60 mg/L

16.10

23.11

30.12

12 mg/L

19.28

27.82

36.36

2.4 mg/L

20.04

26.28

31.59

 

Overall, a potentially bioavailable portion of Bisphenol A of 30% is taken to derive a corrected dermal starting point for DNEL derivation.

 

 

Potential metabolism was also investigated in this study. No metabolism was observed in any of the epidermis samples, however limited levels of metabolism were observed in dermis and receptor fluid samples (0-14%) with formation of Bisphenol A-glucuronide and Bisphenol A-sulfate identified in supernatant from incubation of viable skin disks for 24 h (<25%). Metabolites with retention consistent with Bisphenol A-glucuronide and Bisphenol A-sulfate, and also more polar components, were identified. It might be assumed, but is not analytically verified, that these polar compounds are mixed sulfate/glucuronide bis-conjugate Bisphenol A metabolites. It can be concluded qualitatively that fresh human skin has somein vitrometabolic capacity but further experiments may be necessary to optimize the experimental conditions to quantify that metabolism.

Overall, as a conservative approach no metabolism was taken into account.

 

Comparison with available in vitro data:

EFSA (2015) summarized the available data as followsIn Demierre et al. (2012), the specific permeation kinetics with an initial high penetration rate and a subsequent low penetration rate are suggestive of effects arising from finite dosing (i.e. partial depletion of the dose on the skin surface) and/or evaporation of the aqueous vehicle (→ reduced hydration of the SC), which both are realistic conditions applicable to consumer exposure. In spite of differences in the diffusion-cell design, skin type, vehicle type and applied dose, the in vitro studies of Marquet et al. (2011), Mørck et al. (2010), and Kaddar et al. (2008) support the percutaneous penetration estimate of 8.6 % of Demierre et al. (2012), although tending to somewhat lower values: a rough calculation based on the comparison of permeability coefficients or the normalization of percutaneous penetration to 24 h incubation yielded estimates of 2.3 % (Marquet et al., 2011) and 6.5 % (Mørck et al., 2010) for human skin, and of 4.1 % (Kaddar et al., 2008) for pig skin.

For exposure scenarios with dermal contact to thermal paper, the CEF Panel used a conservative value of 10% dermal absorption. The CEF Panel did not consider skin metabolism (conservative decision). “

 

Comparison of the in vitro data between Mørck et al. (2010), Demierre et al. (2012) and Toner (2015)

Parameter

Mørck et al. (2010)1

Demierre et al.(2012)1

 Toner (2015)

Number of skin sections

 

human skin samples from breast surgery

dorsal part of the upper leg from 2 human cadavers.

abdominal skin obtained fresh from surgery from 4 different donors (3 female, 1 male)

Number of skin sections

11

7

12

Skin viability

non-viable

non-viable

Fresh skin

Skin Section thickness

800–1000 μm

200 μm

350-400 µm

Exposed area

2.12 cm2

0.64 cm2

0.64 cm2

Applied volume

32.6 μl

6 μl

6.4 µl

Applied volume per area

 

15.4 μl/cm2

 

9.4 μl/cm2

 

10 µl/cm2

Applied concentration

 

3995 mg/l (= 17.5 mM)

 

194 mg/l

 

4 different concentrations:300, 60, 12, 2.4 mg/l

Applied surface density

 

259 μg/cm2

1.82 μg/cm2

 

3, 0.6, 0.12, 0.04μg/cm2

Applied dose

 

452 μg

 

1.16 μg

 

1.9, 0.4, 0.08, 0.015 µg

Temperature

 

≈32 °C

30–32 °C

32 °C ± 1 °C

Method

 

static Franz diffusion cell

OECD TG 428

flow-through Franz cell

OECD TG 428

flow-through Franz cell

OECD TG 428; SCCS

Skin integrity check

 

capacitance measurement

 

permeability coefficient within acceptance range

electrical resistance > 10.9 kΩ

donor solution (vehicle)

 

0.9% NaCl + 2% EtOH

 

water

 

Phosphate buffered saline (PBS)

receptor fluid

 

physiol. saline + BSA

 

physiological saline

 

DMEM;ca1%, v/v) + UDPGA (2 mM) + PAPS (40 µM). 

 

Duration of incubation

48 h

24 h

24 h

Recovery

 

82.1 %

101.5 ± 1.6 %

96.4 – 99.4 %

Percutaneous penetration

 

13.0 ± 5.4 %

8.6 ± 2.1 %

 

1.7 – 3.6 %

  1: Information derived from EFSA (2015)

 

Taking into account the above mentioned 10 % dermal penetration taken by EFSA for their dermal risk assessment based on the ca. 10% Bisphenol A found in the receptor fluid in the Demierre et al. (2012) study a significantly lower penetration value into the receptor fluid was observed in the in vitro dermal penetration study using viable skin (1.7 – 3.6 %). The approach mentioned in the study request by ECHA to consider the dermis, epidermis (with stratum corneum) and receptor fluid for further calculations lead to substantially higher potential penetration values compared to the EFSA 2015 evaluation of Bisphenol A.