Assessment of the impact of the IARC Monograph Vol. 121 on the safety of the substance styrene (FCM No 193) for its use in plastic food contact materials

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) was requested by the European Commission to re-evaluate the safety of styrene (FCM No 193) for use in plastic food contact materials (FCM) following the classification by the International Agency for Research on Cancer (IARC) as 'probably carcinogenic to humans'. The IARC Monograph pertains to hazard identification, based on studies on high-dose occupational exposures by inhalation and animal studies, also mainly by inhalation. The Panel considered that the IARC conclusions cannot be directly applied to the evaluation of risks for consumers from the oral exposure to styrene, but also concluded that, based on the data provided in the IARC Monograph and by the industry, a concern for genotoxicity associated with oral exposure to styrene cannot be excluded. The migration of styrene into foods packed in styrenic plastics is below 10 μg/kg for the majority of the foods, but up to 230 μg/kg was reported. Migration tends to be high for contact with fatty foods, and/or with high surface to volume ratios of the FCM. Dietary exposure of the consumers to styrene migrating from styrenic plastics was estimated in the order of 0.1 μg/kg body weight (bw) per day. It is in the same range as exposure from styrene present in foods as such. The dietary exposure (food component plus migration from styrenic plastics) is similar or lower than that by inhalation in the general population. Taking the human exposure data into account, the Panel concluded that a systematic review of genotoxicity and mechanistic data, comparative toxicokinetics and analysis of species differences is required for assessing the safety of styrene for its use in FCM.

A European inter-laboratory pre-validation of in vitro assays to evaluate immunotoxicity (47.18)

The new European Union REACH (Registration, Evaluation and Authorisation of new and existing CHemicals) policy will increase the use of laboratory animals if alternative methods are not available. The immune system is a target for many chemicals and drugs, with potential adverse effects on human health. We performed an inter-laboratory pre-validation of a set of in vitro assays to detect immunosuppressive capacity.

Human PBMC and murine and rat splenocytes were used. Six immunosuppressive compounds (benzo(a)pyrene, cyclophosphamide, methotrexate, rapamycin, dexamethasone, and urethane) and one non-immunosuppressive compound (D-mannitol) were tested. Basal cytotoxicity was assessed by measuring LDH-release. Human PBMC were stimulated with anti-CD3/anti-CD28, murine splenocytes with anti-CD3/anti-CD28, Con A, LPS, and anti-CD40/IL-4, and rat splenocytes with Con A and LPS. Cell proliferation and IFN-γ and TNF-α production were measured.

Five out of 6 immunosuppressive compounds could be identified as such, and the non-immunotoxic one came out as negative. This suggests that in vitro assays are able to detect immunosuppressive capacity. The sensitivity of the various species/stimulant/endpoint combinations ranged between 38 and 61%, while the specificity ranged between 67 and 100%. This suggests that from these results a choice for specific species/stimulant/endpoint combinations cannot be made.

Area postrema glutamate receptors mediate respiratory and gastric responses in the rabbit

The role of NMDA and non-NMDA receptors of the area postrema (AP) in the control of respiration and gastric motility was investigated in anaesthetized rabbits using microinjections (10-20 nl) of specific agonists or antagonists. NMDA (20 mM) or AMPA (10 mM) caused excitatory effects on respiration and gastric relaxation. Selective blockade of NMDA or non-NMDA receptors, respectively with D(-)-2-amino-5-phosphonopentanoic acid (D-AP5; 10 mM) and 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione (NBQX; 5 mM), decreased respiratory frequency and increased gastric tone. Both these effects were more marked following non-NMDA receptor blockade and were prevented by vagotomy. These findings show that NMDA and non-NMDA receptors are present on AP neurones and have a role in the tonic control of respiration and gastric motility.