CSTEE opinion on Chapters 6 and 8 (on risk issues) of the RPA ETD/99/502498 Final Report – July 2000 - The Availability of Substitutes for Soft PVC Containing Phthalates in Certain Toys and Childcare Articles. Opinion expressed at the 22nd CSTEE plenary meeting, Brussels, 6/7 March 2001.
Terms of reference
The Committee on the basis of examination of the following report
- The Availability of Substitutes for Soft PVC Containing Phthalates in Certain Toys and Childcare Articles, RPA ETD/99/502498, chapters 6 and 8 (on risk issues),
is to answer the following two questions:
1. Is the reported degree of risk sufficiently justified by the study
2. Is the study of a good quality.
Introduction
The aim of the study was to provide an overview of the situation on the EU market following restrictions on the use of phthalates in certain childcare articles and toys. The study should address the risks to the health of children, including safety aspects, of possible substitutes. Information on toxicological profile and potential migration as well as an appreciation of the sufficiency of data were requested. The CSTEE is invited to comment on the risk assessment chapters of the report.
General comments
Response to question 1:
The reported degree of risk from the use of the plasticisers o-acetyltributyl citrate (ATBC) and diethylhexyl adipate (DEHA) in PVC childcare articles and toys is not sufficiently justified, since it is not possible to perform an adequate exposure assessment on these substances.
Response to question 2:
The quality of the study leaves much to be desired. The toxicological information on ATBC and DEHA is simply duplicated from a previous CSTEE opinion. The report presents margins of safety and guidance values for ATBC and DEHA. This is not justified given the lack of exposure information. Also, the report fails to refer to the safety assessment on butylated hydroxytoluene (BHT) performed by the EC Scientific Committee on Food.
Specific comments
Chapter 6
The heading for the Chapter 6 incorrectly uses the term "risk analysis", whereas the correct one would be "risk assessment".
The Chapter 6 purports to perform a risk assessment of two plasticisers which may be used in PVC plastics, o-acetyltributyl citrate (ATBC) and diethylhexyl adipate (DEHA), and one additive which may be used in substitute plastics, butylated hydroxytoluene (BHT). The text presented on ATBC and DEHA on exposure and toxicological effects is almost exclusively an abridged duplication of the CSTEE opinion (of 28 September 1999) on those substances. In this respect, the present report has no additional value.
The CSTEE has several critical comments to the Table 6.1 – Summary of Risk Analysis for ATBC. The table refers to the estimate of the CSTEE for the intake dose for children from toys. It should have been pointed out that this was a maximal figure given certain assumptions, namely that ATBC is extracted more or less as effectively as the phthalates from PVC and that the same concentrations are used in the polymers. The table also presents a margin of safety (MOS) value. The CSTEE disagrees to this, since its conclusion was that it is not possible to estimate the exposure levels to ATBC from mouthing soft PVC toys and its NOAEL, due to the data gaps. Therefore, a guidance value for maximum tolerable extractable amount of ATBC in PVC toys cannot be assigned, in contrast to what the table presents.
Regarding the risk assessment of DEHA presented in Table 6.2, the CSTEE has the same critical comments as to the one on ATBC above. It is not possible to estimate DEHA intake doses for children from PVC toys, maximum emission rates from the toys and an intake dose. Thus, the presentations of a MOS value and a guidance value are not warranted by the existing data.
The report has presented some documentation on BHT as an example of an additive used in substitute plastics. Why BHT in particular has been singled out from the many additives that are used in substitute plastics, is not well substantiated. The intention of the study has been to highlight that there exists a potential risk associated with other organic additives used in such products. This would be the case for any substance that may be extracted from plastics during use, making this example of limited value. It is remarkable that the report does not refer to the safety assurance performed by the EC Scientific Committee for Food (SCF) on BHT (22nd Series, 1989). The SCF has identified a NOAEL of 5 mg/kg bw/day and established an ADI of 0-0.05 mg/kg bw based on thyroid, reproduction and haematological effects in the rat (the present report gives a NOAEL of 7.5 mg/kg bw/day and a TDI of 0.075 mg/kg bw/day). The SCF's view was that there was a threshold for BHT carcinogenesis related to liver enzyme induction, reinforced by an overall lack of evidence of genotoxic effect in in vivo systems. Since the NOAEL demonstrated for carcinogenesis was higher than that obtained for other toxicological effects, the ADI was determined from the latter.
The report recommends that a thorough risk assessment of the use of BHT as an anti-oxidant in children's toys is clearly needed. The CSTEE does not agree to this, although information on the exposure to BHT from use of substitute plastics would be desirable. Since the concentration of BHT in substitute plastics is approximately a hundred-fold lower than the concentration of phthalates in PVC plastics, and the NOAELs of BHT, DEHP and DINP are within the same order of magnitude, it is unlikely that BHT in substitute plastics will represent a health risk.
Chapter 8
The report concludes that the margin of safety for DEHA would appear to be less than for ATBC. This would only be true if migration rates for the two substances were known and the preliminary effects assessments would hold up as more effects data become available. The CSTEE does not agree to the suggestion that ATBC may be preferable to DINP on health grounds but that DEHA may not, since the exposure assessments of ATBC and DEHA are not possible to conduct due to lack of data. Any discussion of preferability from a risk assessment standpoint would have to be made on a comparison of the respective margins of safety, for this both the exposure information and the NOAEL values need to be factored in.
The statement that BHT should be considered more hazardous than phthalates, ATBC and DEHA is not quite correct, since the NOAEL of DEHP is 3.7 mg/kg bw/day vs. the NOAEL for BHT of 5 mg/kg bw/day. However, the NOAEL for BHT is lower than those for DINP (15 mg/kg bw/day), ATBC (100 mg/kg bw/day) and DEHA (30 mg/kg bw/day). As pointed out, the likely risk associated with the use of BHT in substitute plastics would be decreased compared to the use of plasticisers in PVC plastics. This could have been made more explicit by comparing the concentration of BHT in substitute plastics (0.2-0.5%) vs. the concentration of plasticisers in PVC plastics (10-60%).
Terms of reference
The Committee on the basis of examination of the following report
- The Availability of Substitutes for Soft PVC Containing Phthalates in Certain Toys and Childcare Articles, RPA ETD/99/502498, chapters 6 and 8 (on risk issues),
is to answer the following two questions:
1. Is the reported degree of risk sufficiently justified by the study
2. Is the study of a good quality.
Introduction
The aim of the study was to provide an overview of the situation on the EU market following restrictions on the use of phthalates in certain childcare articles and toys. The study should address the risks to the health of children, including safety aspects, of possible substitutes. Information on toxicological profile and potential migration as well as an appreciation of the sufficiency of data were requested. The CSTEE is invited to comment on the risk assessment chapters of the report.
General comments
Response to question 1:
The reported degree of risk from the use of the plasticisers o-acetyltributyl citrate (ATBC) and diethylhexyl adipate (DEHA) in PVC childcare articles and toys is not sufficiently justified, since it is not possible to perform an adequate exposure assessment on these substances.
Response to question 2:
The quality of the study leaves much to be desired. The toxicological information on ATBC and DEHA is simply duplicated from a previous CSTEE opinion. The report presents margins of safety and guidance values for ATBC and DEHA. This is not justified given the lack of exposure information. Also, the report fails to refer to the safety assessment on butylated hydroxytoluene (BHT) performed by the EC Scientific Committee on Food.
Specific comments
Chapter 6
The heading for the Chapter 6 incorrectly uses the term "risk analysis", whereas the correct one would be "risk assessment".
The Chapter 6 purports to perform a risk assessment of two plasticisers which may be used in PVC plastics, o-acetyltributyl citrate (ATBC) and diethylhexyl adipate (DEHA), and one additive which may be used in substitute plastics, butylated hydroxytoluene (BHT). The text presented on ATBC and DEHA on exposure and toxicological effects is almost exclusively an abridged duplication of the CSTEE opinion (of 28 September 1999) on those substances. In this respect, the present report has no additional value.
The CSTEE has several critical comments to the Table 6.1 – Summary of Risk Analysis for ATBC. The table refers to the estimate of the CSTEE for the intake dose for children from toys. It should have been pointed out that this was a maximal figure given certain assumptions, namely that ATBC is extracted more or less as effectively as the phthalates from PVC and that the same concentrations are used in the polymers. The table also presents a margin of safety (MOS) value. The CSTEE disagrees to this, since its conclusion was that it is not possible to estimate the exposure levels to ATBC from mouthing soft PVC toys and its NOAEL, due to the data gaps. Therefore, a guidance value for maximum tolerable extractable amount of ATBC in PVC toys cannot be assigned, in contrast to what the table presents.
Regarding the risk assessment of DEHA presented in Table 6.2, the CSTEE has the same critical comments as to the one on ATBC above. It is not possible to estimate DEHA intake doses for children from PVC toys, maximum emission rates from the toys and an intake dose. Thus, the presentations of a MOS value and a guidance value are not warranted by the existing data.
The report has presented some documentation on BHT as an example of an additive used in substitute plastics. Why BHT in particular has been singled out from the many additives that are used in substitute plastics, is not well substantiated. The intention of the study has been to highlight that there exists a potential risk associated with other organic additives used in such products. This would be the case for any substance that may be extracted from plastics during use, making this example of limited value. It is remarkable that the report does not refer to the safety assurance performed by the EC Scientific Committee for Food (SCF) on BHT (22nd Series, 1989). The SCF has identified a NOAEL of 5 mg/kg bw/day and established an ADI of 0-0.05 mg/kg bw based on thyroid, reproduction and haematological effects in the rat (the present report gives a NOAEL of 7.5 mg/kg bw/day and a TDI of 0.075 mg/kg bw/day). The SCF's view was that there was a threshold for BHT carcinogenesis related to liver enzyme induction, reinforced by an overall lack of evidence of genotoxic effect in in vivo systems. Since the NOAEL demonstrated for carcinogenesis was higher than that obtained for other toxicological effects, the ADI was determined from the latter.
The report recommends that a thorough risk assessment of the use of BHT as an anti-oxidant in children's toys is clearly needed. The CSTEE does not agree to this, although information on the exposure to BHT from use of substitute plastics would be desirable. Since the concentration of BHT in substitute plastics is approximately a hundred-fold lower than the concentration of phthalates in PVC plastics, and the NOAELs of BHT, DEHP and DINP are within the same order of magnitude, it is unlikely that BHT in substitute plastics will represent a health risk.
Chapter 8
The report concludes that the margin of safety for DEHA would appear to be less than for ATBC. This would only be true if migration rates for the two substances were known and the preliminary effects assessments would hold up as more effects data become available. The CSTEE does not agree to the suggestion that ATBC may be preferable to DINP on health grounds but that DEHA may not, since the exposure assessments of ATBC and DEHA are not possible to conduct due to lack of data. Any discussion of preferability from a risk assessment standpoint would have to be made on a comparison of the respective margins of safety, for this both the exposure information and the NOAEL values need to be factored in.
The statement that BHT should be considered more hazardous than phthalates, ATBC and DEHA is not quite correct, since the NOAEL of DEHP is 3.7 mg/kg bw/day vs. the NOAEL for BHT of 5 mg/kg bw/day. However, the NOAEL for BHT is lower than those for DINP (15 mg/kg bw/day), ATBC (100 mg/kg bw/day) and DEHA (30 mg/kg bw/day). As pointed out, the likely risk associated with the use of BHT in substitute plastics would be decreased compared to the use of plasticisers in PVC plastics. This could have been made more explicit by comparing the concentration of BHT in substitute plastics (0.2-0.5%) vs. the concentration of plasticisers in PVC plastics (10-60%).