Rudolf Antonius Woutersen

The saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson

SummaryThe saccus dorsalis of the brain of the rainbow trout, Salmo gairdneri Richardson, has been investigated by means of histological, cytochemical, enzyme-cytochemical, electron microscopical and autoradiographical techniques.The saccus dorsalis is a rostro-dorsal evagination of the diencephalic roof, and consists of a partly folded epithelial wall separating the cerebrospinal fluid from the meningeal matrix fluid. The well-developed vascular system around the epithelial wall, consisting of capillaries with different diameters, seems to be part of the pineal vascular system. No structures were found that may be involved in a possible mechanical or nervous blood flow control.The single-layered epithelium consists of highly specialized cells of one specific type. These cells are mainly characterized by infolded basal membranes, long microvilli of a peculiar shape, non-folded lateral membranes bordering intercellular spaces, apical concentrations of elongate and cupshaped macromitochondria, a basally located rough endoplasmic reticulum, an apically situated smooth endoplasmic reticulum and apical concentrations of micropinocytotic vesicles. Morphological evidence is presented of a multiple function of these cells: (1) fluid secretion, (2) extrusion of low molecular weight organic substances into the ventricular system, (3) uptake of high molecular weight substances, and (4) uptake of low molecular weight organic substances (aminergic neurotransmitters [GABA]) from the cerebrospinal fluid. The significance of light and dark cells is discussed. Indications of a possible innervation of the saccus dorsalis epithelial cells were not observed.The functional significance of the saccus dorsalis (possible analogue of the choroid plexus?) is discussed.

Eradication of tumour cells by successive injections of allogeneic immune and hyperimmune peritoneal cells in a murine lymphoma system

Allogeneic C57BL immune and hyperimmune (vs SL2) peritoneal cells are used for eradication of DBA/2 derived SL2 lymphoma cells injected into the peri- toneal cavity of DBA/2 mice. SL2 bearing DBA/2 mice are treated with 3, 5, or 8 successive i.p. injections of 2 x 106 allogeneic C57BL immune or hyperimmune peritoneal macrophages (contami- nated with lymphocytes). 2 x 10 v SL2 cells could be eradicated successfully with five injections of immune or three injections of hyperimmune C57BL peritoneal cells. This is a ten-fold improvement compared to the result obtained with single injections of immune or hyperimmune peritoneal cells. The number of injections with immune or hyperimmune cells, time intervals between the injections and the total length of the period of the therapy was important for the result of the therapy.

Guidance on the assessment of the biological relevance of data in scientific assessments

Abstract EFSA requested its Scientific Committee to prepare a guidance document providing generic issues and criteria to consider biological relevance, particularly when deciding on whether an observed effect is of biological relevance, i.e. is adverse (or shows a beneficial health effect) or not. The guidance document provides a general framework for establishing the biological relevance of observations at various stages of the assessment. Biological relevance is considered at three main stages related to the process of dealing with evidence: Development of the assessment strategy. In this context, specification of agents, effects, subjects and conditions in relation to the assessment question(s): Collection and extraction of data; Appraisal and integration of the relevance of the agents, subjects, effects and conditions, i.e. reviewing dimensions of biological relevance for each data set. A decision tree is developed to assist in the collection, identification and appraisal of relevant data for a given specific assessment question to be answered.

Re‐evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400–E 404) as food additives

Abstract The present opinion deals with the re‐evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400–E 404) when used as food additives. Alginic acid and its salts (E 400–E 404) are authorised food additives in the EU in accordance with Annex II and Annex III to Regulation (EC) No 1333/2008. Following the conceptual framework for the risk assessment of certain food additives re‐evaluated under Commission Regulation (EU) No 257/2010, the Panel concluded that there was no need for a numerical Acceptable Daily Intake (ADI) for alginic acid and its salts (E 400, E 401, E 402, E 403 and E 404), and that there was no safety concern at the level of the refined exposure assessment for the reported uses of alginic acid and its salts (E 400, E 401, E 402, E 403 and E 404) as food additives. The Panel further concluded that exposure of infants and young children to alginic acid and its salts (E 400, E 401, E 402, E 403 and E 404) by the use of these food additives should stay below therapeutic dosages for these population groups at which side‐effects could occur. Concerning the use of alginic acid and its salts (E 400, E 401, E 402, E 403 and E 404) in ‘dietary foods for special medical purposes and special formulae for infants’ (Food category 13.1.5.1) and ‘in dietary foods for babies and young children for special medical purposes as defined in Directive 1999/21/EC’ (Food category 13.1.5.2), the Panel further concluded that the available data did not allow an adequate assessment of the safety of alginic acid and its salts (E 400, E 401, E 402, E 403 and E 404) in infants and young children consuming the food belonging to the categories 13.1.5.1 and 13.1.5.2.

Enzyme-cytochemistry of the saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson

SummaryIn the saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson, the activity of various enzymes (transferase, lyases, oxidoreductases, hydrolases) have been studied in detail.The results of this enzyme-cytochemical study firmly demonstrate that the organ is metabolically highly active. The epithelial cells have a strong energy metabolism. Energy production can take place under aerobic as well as under anaerobic conditions. Evidence is presented that glucose from blood is directly utilized for energy demands. The epithelial cells show also high synthetic activities. The moderate amino acid metabolism may participate in the synthesis of an acid mucopolysaccharide-protein complex, especially in the so-called dark cells. Lipid metabolism appears to be restricted to the mitochondria, indicating a high turnover of lipid moieties in the membranes. In contrast to the normal looking mitochondria, the macromitochondria — besides shape and localization — have an extremely high lipid and monoamine metabolism, which may point to a special function in the cellular economy. The high activity of enzymes involved in the degradation of monoamines and in the hydration of CO2 is of particular physiological interest. The significance of the observations is discussed in relation to formerly obtained indications on the involvement of the saccus dorsalis in fluid secretion, extrusion of organic substances of low molecular weight into the ventricular system and uptake of organic substances from the cerebrospinal fluid.The hypothesis of the saccus dorsalis being an analogue of the choroid plexus is supported by several relevant data.

Re‐evaluation of guar gum (E 412) as a food additive

Abstract The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of guar gum (E 412) as a food additive. In the EU, guar gum was evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1970, 1974 and 1975, who allocated an acceptable daily intake (ADI) ‘not specified’. Guar gum has been also evaluated by the Scientific Committee for Food (SCF) in 1977 who endorsed the ADI ‘not specified’ allocated by JECFA. Following the conceptual framework for the risk assessment of certain food additives re‐evaluated under Commission Regulation (EU) No 257/2010, the Panel considered that adequate exposure and toxicity data were available. Guar gum is practically undigested, not absorbed intact, but significantly fermented by enteric bacteria in humans. No adverse effects were reported in subchronic and carcinogenicity studies at the highest dose tested; no concern with respect to the genotoxicity. Oral intake of guar gum was well tolerated in adults. The Panel concluded that there is no need for a numerical ADI for guar gum (E 412), and there is no safety concern for the general population at the refined exposure assessment of guar gum (E 412) as a food additive. The Panel considered that for uses of guar gum in foods intended for infants and young children the occurrence of abdominal discomfort should be monitored and if this effect is observed doses should be identified as a basis for further risk assessment. The Panel considered that no adequate specific studies addressing the safety of use of guar gum (E 412) in food categories 13.1.5.1 and 13.1.5.2 were available. Therefore, the Panel concluded that the available data do not allow an adequate assessment of the safety of guar gum (E 412) in infants and young children consuming these foods for special medical purposes.

Re‐evaluation of glycerol (E 422) as a food additive

Abstract The ANS Panel provides a scientific opinion re‐evaluating the safety of glycerol (E 422) used as a food additive. In 1981, the Scientific Committee on Food (SCF) endorsed the conclusion from the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1976 of ‘acceptable daily intake (ADI) for man not specified’. The Panel concluded that glycerol has low acute toxicity and that local irritating effects of glycerol in the gastrointestinal tract reported in some gavage studies was likely due to hygroscopic and osmotic effects of glycerol. Glycerol did not raise concern with respect to genotoxicity and was of no concern with regard to carcinogenicity. Reproductive and prenatal developmental studies were limited to conclude on reproductive toxicity but no dose‐related adverse effects were reported. None of the animal studies available identified an adverse effect for glycerol. The Panel conservatively estimated the lowest oral dose of glycerol required for therapeutic effect to be 125 mg/kg bw per hour and noted that infants and toddlers can be exposed to that dose by drinking less than the volume of one can (330 mL) of a flavoured drink. The Panel concluded that there is no need for a numerical ADI and no safety concern regarding the use of glycerol (E 422) as a food additive at the refined exposure assessment for the reported uses. The Panel also concluded that the manufacturing process of glycerol should not allow the production of a food additive, which contains genotoxic and carcinogenic residuals at a level which would result in a margin of exposure below 10,000. The Panel recommended modification of the EU specifications for E 422. The Panel also recommended that more information on uses and use levels and analytical data should be made available to the Panel.

Re‐evaluation of propane‐1,2‐diol (E 1520) as a food additive

Abstract The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of propane‐1,2‐diol (E 1520) when used as a food additive. In 1996, the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) of 25 mg/kg body weight (bw) per day for propane‐1,2‐diol. Propane‐1,2‐diol is readily absorbed from the gastrointestinal and is expected to be widely distributed to organs and tissues. The major route of metabolism is oxidation to lactic acid and pyruvic acid. At high concentrations, free propane‐1,2‐diol is excreted in the urine. No treatment‐related effects were observed in subchronic toxicity studies. The available data did not raise concern with respect to genotoxicity. Haematological changes suggestive of an increased red blood cell destruction with a compensatory increased rate of haematopoiesis were observed at the highest dose level (5,000 mg/kg bw per day) in a 2‐year study in dogs. No adverse effects were reported in a 2‐year chronic study in rats with propane‐1,2‐diol (up to 2,500 mg/kg bw per day). The SCF used this study to derive the ADI. No adverse effects were observed in the available reproductive and developmental toxicity studies. Propane‐1,2‐diol (E 1520) is authorised according to Annex III in some food additives, food flavourings, enzymes and nutrients and it is then carried over to the final food. Dietary exposure to E 1520 was assessed based on the use levels and analytical data. The Panel considered that for the food categories for which information was available, the exposure was likely to be overestimated. Considering the toxicity database, the Panel concluded that there was no reason to revise the current ADI of 25 mg/kg bw per day. The Panel also concluded that the mean and the high exposure levels (P95) of the brand‐loyal refined exposure scenario did not exceed the ADI in any of the population groups from the use of propane‐1,2‐diol (E 1520) at the reported use levels and analytical results.

Approach followed for the refined exposure assessment as part of the safety assessment of food additives under re‐evaluation

Abstract This statement describes the approach followed by the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) for performing refined exposure assessment in the framework of the re‐evaluation of already permitted food additives. Estimation of exposure is obtained through combination of different type of data originating from different sources: food additive concentration is obtained from information provided to EFSA on use levels and/or information obtained by means of analytical measurements. In recent years, the use of market research data has also been used. The statement provides also a description of the three different scenarios used for the exposure assessment of food additives under re‐evaluation, from the more conservative regulatory maximum level exposure assessment scenario to more refined ones. Lastly, a description is provided on the approach used for the uncertainty analysis which accompanies the exposure assessment.

Safety of nisin (E 234) as a food additive in the light of new toxicological data and the proposed extension of use

Abstract The present scientific opinion deals with the evaluation of the safety of nisin (E 234) in the light of new toxicological data and with the proposed extension of use in unripened cheese and heat‐treated meat products. Nisin (E 234) is currently an authorised food additive in the EU under Annex II of Regulation (EC) 1333/2008 for use in several food categories. The safety of nisin (E 234) as a food additive has been evaluated in 2006 by the EFSA Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food, where an acceptable daily intake (ADI) of 0.13 mg/kg body weight (bw) was confirmed as previously established by Scientific Committee on Food (SCF). In addition to the studies previously evaluated by EFSA in 2006, the Panel considered in the present opinion, data from a new subchronic toxicity study. No adverse effects were observed in a repeated dose oral toxicity study in which rats were administered nisin A for 90 days. A no observed adverse effect level (NOAEL) of 225 mg nisin A/kg bw per day, the highest dose tested, was identified for this study. Using this NOAEL, an ADI of 1 mg nisin A/kg bw per day for nisin (E 234) was calculated applying a default uncertainty factor of 200 for extrapolation of subchronic to chronic exposure and inter‐ and intra‐species variability. The Panel calculated exposure estimates for both the current and the proposed uses based on the data available in the EFSA Comprehensive Database. The Panel considered that the overall exposure estimate was below the new ADI for nisin A for all population groups. The Panel concluded that the proposed extension of use of nisin (E 234) as a food additive in unripened cheese (at maximum level of 12 mg/kg) and in heat‐treated meat products (at maximum level of 25 mg/kg) would not be of safety concern.