GLYCEROL ESTER OF WOOD ROSIN First draft prepared by Dr. C.B. Johnson and Dr. M.J. Bonner Division of Health Effects Evaluation Office of Premarket Approval Center for Food Safety and Applied Nutrition Food and Drug Administration, Washington, DC, USA Explanation Biological data Biochemical aspects Absorption, distribution, and excretion Toxicological studies Acute toxicity studies Short-term toxicity studies Long-term toxicity/carcinogenicity studies Special studies on genotoxicity Observations in humans Comments Evaluation References 1. EXPLANATION Glycerol ester of wood rosin was previously considered by the Committee at its eighteenth, twentieth and thirty-third meetings (Annex 1, references 35, 41 and 83). At its twentieth meeting, the Committee, in the light of the strong ester bond and anticipated stability of this material, expressed the view that long-term and reproductive toxicity studies should be done on the specific substance before further evaluation. Because of early concerns on the part of the Committee about the lack of food grade specifications for glycerol ester of wood rosin, plans for a further toxicological evaluation had to be postponed. Such specifications were adopted at the thirty-seventh meeting of the Committee (Annex 1, reference 94). The specifications define the material as a complex mixture of tri- and diglycerol esters of resin acids from wood rosin. This monograph summarizes relevant data in the previous monograph and data that have become available since the previous evaluation. 2. BIOLOGICAL DATA 2.1 Biochemical aspects 2.1.1 Absorption, distribution, and excretion 2.1.1.1 Rats Ester gum 8BG, a commercial preparation of glycerol ester of wood resin, was fed in the diet to groups of 6 male and 6 female F344 rats under two treatment regimens: (1) for 24 hours at concentrations of 7000 or 28 000 mg/kg and (2) for 10 days at concentrations of 14 000 or 28 000 mg/kg. Food consumption was measured during the treatment periods and ester gum 8BG intake was calculated for each of the treatment groups. Faeces were collected during each 24-hour treatment period and for subsequent 24-hour periods until no ester gum 8BG was detected. The bulk of ingested ester gum 8BG was excreted in the faeces within the first 48 h, and only small quantities were present in the faeces between 48 and 72 h. At the 7000 mg/kg dietary level, 73% of the ingested ester gum 8BG was accounted for in the faeces. At the 14 000 and 28 000 mg/kg dietary levels, 92% and 89-96%, respectively, of the ingested ester gum 8BG was recovered in the faeces. The author postulated that the lower recovery from the 7000 mg/kg group was due to the lack of sensitivity of the analytical method (HPLC of solvent extract). No necropsy was performed. The author concluded that in the rat gut, no measurable hydrolysis of ester gum 8BG took place, and that no absorption from the intestine was apparent (Blair, 1994). In recovery experiments, 4 male rats received a single oral dose of 100 mg (300 mg/kg bw) or 1 mg (3 mg/kg bw) tritiated resin acids from wood rosin (dehydroabietic, tetrahydroabietic or isopimaric acids) as a 5% solution in corn oil. After administration of dehydroabietic acid, the rats excreted on average 80% of the 100 mg dose in faeces and 7.2% in urine over a 15-day post-treatment period. Total recoveries in the 4 animals ranged from 71% to 99% at the end of 15 days. Four additional total recovery experiments were conducted, utilizing a 1mg dose of labelled dehydroabietic acid, and sampling carried out at various times ranging from 28 to 51 h post-treatment. In these studies, the amount of dehydroabietic acid recovered averaged 70% in faeces, 8% in urine, 17% in the GI tract, 0.5% in breath, and 1% in the carcass, for a total recovery of 96.5%. In recovery experiments with tetrahydroabietic acid, 2 rats were given 45.7 µCi of the tritiated derivative and the radioactivity monitored at regular intervals after administration (1, 2, 3, 4, 5-8, 9-12 and 13-16 days). Recovery of tritiated tetrahydroabietic acid averaged 92% in faeces, 5% in urine and 3% in breath for all average total recovery of 100%. In concurrent studies with isopimaric acid, recovery also averaged 100% total with 83% found in faeces, 15% in urine, and 2% in breath. Four rats were given 30 µCi (105 mg) dehydroabietic acid and quantitative chromatographic analyses were made of faeces and urine collected over 2 days. Analysis revealed 3 major metabolites, which were not identified but for convenience were called A, B, and C. Recovery in faeces amounted to 89% of the administered activity, of which 14% was dehydroabietic acid, 33% metabolite A, 8% metabolite B, and 14% metabolite C. Of the 8% of the administered activity recovered in urine, 0.13% was dehydroabietic acid, 7% was metabolite B, and 0.55% metabolite C. In rats given labelled tetrahydroabietic or isopimaric acids, the bulk of the radioactivity in faeces and urine consisted of the unchanged acids. In tissue distribution studies with dehydroabietic acid, 4 male and 4 female rats each were given 50 mg (5.5 µCi), and distribution of radioactivity measured at various time intervals after administration (1, 2, 4 or 8 h). Radioactivity was distributed among all major organs, fat, and muscle, with peak levels occurring 4 h after administration. After 8 h, the highest concentrations of radioactivity were found in the liver (approximately 12%) and in kidney (approximately 5%) (Radomski, 1965). 2.2 Toxicological studies 2.2.1 Acute toxicity studies The results of acute toxicity studies with wood rosin are summarized in Table 1. Table 1. Results of acute toxicity studies on pale wood rosin. Species Route LD50 Reference (mg/kg bw) Mouse Oral 4100 Hercules, 1974 Rat Oral 8400 " Guinea-pig Oral 4100 " 2.2.2 Short-term toxicity studies 2.2.2.1 Rats In a 90-day oral toxicity study, groups of Sprague-Dawley rats (10/sex) were fed a stock diet containing Ester Gum 8D (prepared as a 30% suspension in corn oil and blended into the diet) at dietary levels of 0.01, 0.05, 0.2, 1.0 or 5.0%, equal to 6, 31, 120, 630 or 2660 mg/kg bw/day. The diets of controls and all ester gum 8D groups contained 2.3% corn oil except the diet of the 5.0% group, which contained 11.7% corn oil. Test parameters for the study included: clinical observations, mortality, body weights and body-weight gain, food consumption, food efficiency, haematology, urinalysis, organ weights and gross and microscopic pathology. During the course of this study no mortality occurred among treated rats or controls. No significant effects were noted on body weight, food intake, haematology, urinalysis, or gross and microscopic histology at dietary levels up to and including 1.0%. Food consumption at the 5.0% level was slightly lower than controls. This difference probably reflected the higher dietary corn oil concentration at this dose level. No microscopic pathological changes related to treatment were observed in any organ. The 1.0% treatment level, equal to 630 mg/kg bw/day, was considered to be the NOEL in this study (Kay, 1960a). In a 13-week oral toxicity study, groups of Charles River Fischer 344 rats (20/sex), approximately 6 weeks of age, were fed NIH Open Formula Diet at ester gum 8BG dose levels of 0, 625, 1250 or 2500 mg/kg bw/day. Test parameters included behavioural observations, ophthalmoscopic examinations, body weights, food consumption, haematological and clinical chemistry analyses (at the mid-point and end of the study), organ weights and macroscopic and microscopic pathology. There were no deaths among treated or control rats during the course of the study and no changes were observed in appearance, behaviour, or ophthalmoscopic examinations that were attributed to treatment. There were slight significant decreases noted by the author in body-weight gain in female rats at the 1250 and 2500 dose levels during the last few weeks of the study. However, these minor effects on body-weight gain were negligible and probably can be attributed to dietary dilution. Dietary dilution can probably also account for a slight increase in food consumption that was dose-related, present at all dose levels among groups of both sexes, and sometimes reaching statistical significance. There were no dose-related statistically significant differences in mean haematological and clinical chemistry values between treated and control groups. At necropsy, the author noted minor differences between controls and high-dose groups in male caecum(full)/body weight and in female liver, thymus and thymus/brain weight. However, these differences were small and did not appear to be an important effect of treatment. There were no macroscopic or microscopic changes in any organs that were related to treatment and none of the organs for which weight changes were noted had histological abnormalities. The NOEL in this study was 2500 mg/kg bw/day (Blair, 1991, 1992). In a 90-day study, groups of Sprague-Dawley rats (10/sex) were fed a stock diet containing 0, 0.01, 0.05, 0.2, or 1.0% N-wood rosin (added to the diet as a 40% suspension in corn oil), equal to 0, 6.4, 36, 119, or 674 mg/kg bw/day, respectively. Two identical control groups were utilized. Feeding at a 5.0% level was attempted, but discontinued early in the study, as all the animals died during the first 8 days of the treatment period. Final corn oil content was 2.3% in all test and control diets (except for 11.7% in the 5.0% test diet). Test parameters included clinical observations, food consumption, body weights, haematology, urinalyses, organ weights and gross and microscopic pathology. There was no mortality in controls or in animals receiving lower doses of wood rosin, and no significant differences between treated groups and controls were observed in analyses for haemoglobin, haematocrit, total leucocyte count, differential leucocyte count or urine analysis parameters. Body weights were significantly reduced throughout the study for male and female rats fed 1.0% wood rosin. The decrement in weight gain at this level occurred during the first 2 weeks of the study; thereafter, weight gains of this group were comparable to controls. However, in males fed 1.0% wood rosin, body weight was only significantly lower when compared to the first control group but not the second control group. Organ weights revealed statistically significant increases in both liver to body-weight and brain to body-weight ratios for male and female rats at the 1.0% wood rosin level when compared to control groups. However, brain to body-weight ratio for female rats at the 1.0% level were only significantly increased compared to those of the second control group but not the first. No pathological lesions, either macroscopic or microscopic, related to wood rosin treatment were observed in any of the organs of treated animals (Kay, 1960b). 2.2.3 Long-term toxicity/carcinogenicity studies 2.2.3.1 Rats Groups of weanling Sprague-Dawley rats (30/sex, individually housed) were ted dietary levels of 0, 0.05, 0.2 or 1% rosin in corn oil for 24 months, equal to 0, 24, 88 or 434 mg/kg bw/day. Final corn oil content was 2.3% in all test and control diets. At the end of 12 months, 5 animals of each sex were sacrificed for gross and microscopic pathology studies. All surviving animals were killed at 24 months, organ weights were recorded and pathological examinations were conducted. At both 12 and 24 months, body weights were significantly lower than controls in both males and females at the 1% diet level. The decreased body weight may reflect the reduced food consumption also noted at the 1% diet level, which was attributed to non-palatability. There were no significant differences between wood rosin treated groups and controls with respect to mortality, tumour rate, haematology, urinalysis, gross or microscopic pathology. Elevated liver to body-weight ratios were noted in high-dose females, with some sporadic significant differences noted between treated groups and one or other of the control groups with respect to organ to body-weight ratios for the kidneys, spleen and gonads (Kohn, 1962a). 2.2.3.2 Dogs Groups of beagle dogs (3/sex) were fed dietary levels of 0.05% or 1.0% (equal to 14 or 260 mg/kg bw/day) N-wood rosin in corn oil for 24 months. A control group consisting of 6 animals of each sex received the basal diet. Test parameters included body weight, food consumption, mortality and behavioural changes, haematology and urine analysis, liver and kidney function tests, and gross and microscopic pathological examinations. No significant effects were seen on any test parameter other than weight, except at the 1.0% level, where some increase in liver and kidney size was noted (although no pathology was present). Both mean body weight and food consumption in high-dose males were approximately 30% less than in low-dose males, which would be consistent with lack of diet palatability. The author concluded that the NOEL in this study was 1.0% (Kohn, 1962b). 2.2.4 Special studies on genotoxicity The results of genotoxicity assays on glycerol ester of wood rosin and resin acids present in wood rosin are summarized in Tables 2 and 3, respectively. 2.3 Observations in humans Medical doctors reported that a 22-year old woman developed papules, dryness and pigmentation on the lips after application of a lipstick several times a day. Patch tests showed that the woman tested positive for only one of the ingredients in the lipstick, ester gum at a level of 0.1%. In further patch testing she did not show positive reactions for rosin, balsam of Peru, nor oil of turpentine. The subject was diagnosed as sensitized to ester gum in the lipstick (Ogino et al., 1989). A medical doctor reported a case of an 8-year old boy who suffered from recurring perioral dermatitis for 18 months; the subject frequently chewed gum before each episode of dermatitis developed. Patch testing was positive to cobalt, rosin, fragrance-mix, oakmoss, and isoeugenol as well as chewing gum and bubble gum. The perioral dermatitis improved but did not disappear after the child stopped chewing gum. Possible sensitivity to allergens other than rosin could not be ruled out (Satyawan et al., 1990). Table 2. Results of genotoxicity assays on glycerol ester of wood rosin. Test System Test Object Concentration Results Reference Ames test (1) S. typhimurium 10 000 µg/plate Negative Ishidate et al., TA92, TA94 1984 TA98, TA100 TA1535, TA1537 Ames test (1) S. typhimurium 2.5-500 µg/plate Negative Jagannath, TA98, TA100 1988 TA1535, TA1537 TA1538 Chromosome Chinese hamster 8000 µg/ml Negative Ishidate et al., aberration fibroblast 1984 CHO/Cytogenetic Chinese hamster 127-507 µg/ml Negative Murli, 1988 assay (1) ovary Unscheduled DNA rat primary 5.1-102 µg/ml Negative Cifone, 1988 synthesis hepatocyte Note that application of treatment in above experiments was single dose. (1) Both with and without rat liver S-9 fraction. Table 3. Results of genotoxicity assays on resin acids present in wood rosin Test System Test Object Concentration Results Reference Ames test (1) S. typhimurium 250-1000 Positive for Nestmann TA98, TA100 µg/plate neoabietic acid in et al., 1979 TA1535, TA1537 absence of S-9 TA1538 activation Mutagenicity Yeast strains D7, 50-2000 Positive for Nestmann & test XV185-14C µg/ml neoabietic acid in Lee, 1983 XV185-14C cells (1) Both with and without rat liver S-9 fraction. A dentist reported a case of a 33-year old man with contact allergy to rosin from a periodontal dressing. Periodontal surgery was performed with no post-operative complications. One week after the first operation a new surgical dressing was applied. Four days later the patient began to experience both oral and dermatological symptoms, but the symptoms disappeared 24 h after the periodontal dressing was replaced with a wax packing. Patch tests showed that the patient had contact allergy to rosin, but not to eugenol or zinc oxide which were also components of the original periodontal dressing (Lysell, 1976). Patch testing in dental patients who exhibited stomatitis after repeated applications of periodontal dressing revealed some sensitization to colophony (rosin). Out of 18 patients (6 men and 12 women, aged 33-71 years), 3 (17%) had a positive reaction to colophony (Koch et al., 1971). A total of 133 dental patients who were preoperatively negative to medication and materials used in dentistry showed negligible sensitization to colophony, with only one (0.8%) positive result in patch tests (Koch et al., 1973). A patch testing study in 150 women investigated contact allergy caused by cosmetics and toiletries (including those containing rosin). The type of rosin was not identified in the report. Only one positive reaction to rosin (0.7%) was observed out of the 150 women tested (De Groot et al., 1988). A patch testing study in 1785 patients investigated contact sensitivity to several suspected allergens, including colophony (rosin). The specific type of rosin tested was not identified. A total of 50 patients (2.8%) tested positive for colophony 48 or 72 h post application. On a gender basis, males experienced a 1.8% incidence (11/613) and females a 3.3% incidence (39/1172); this difference in sex distribution was not considered to be significant. Sensitivity to colophony occurred at a higher incidence (4.4%) in patients aged 50 or older (Young et al., 1988). 3. COMMENTS Several recent studies, including a metabolic study in rats, a 13-week toxicity study in rats and mutagenicity studies, have been conducted on glycerol ester of wood rosin. In the 13-week toxicity study, the NOEL was 2500 mg/kg bw/day, the highest dose tested. Mutagenicity studies were negative. The results of the recent metabolic study showed that glycerol ester of wood rosin given to rats in the diet was, for the most part, recovered unchanged in the faeces, and suggested that it was not hydrolyzed in the gut to a significant extent and was largely unabsorbed. However, the lack of sensitivity of the analytical method used was such that a firm conclusion could not be reached as to the non-bioavailability of glycerol ester of wood rosin and/or its component resin acids. Absorption studies with tritiated resin acids from wood rosin (e.g., dehydroabietic, tetrahydroabietic and isopimaric acids) indicated that more than 90% were recovered in urine or faeces within 2 weeks (most within 4 days) after oral administration. The small amount of dehydroabietic acid absorbed appeared to have been metabolized in the liver to three or four uncharacterized metabolites, which were then excreted in the bile and urine. Little evidence was found to show that tetrahydroabietic and isopimaric acids were metabolized. 4. EVALUATION The Committee noted the absence of adequate long-term toxicity/ carcinogenicity studies and reproductive toxicity studies on glycerol ester of wood rosin. Because of the limited toxicological information available, the Committee was unable to establish an ADI. It is considered that, as a minimum, studies demonstrating the metabolic stability and non-bioavailability of glycerol ester of wood rosin under conditions resembling those present in the human gastrointestinal tract would be required to permit further evaluation of this material. 5. REFERENCES BLAIR, M (1991). Ester Gum 8BG. 13-week dietary toxicity study in rats. Unpublished report No. 548-007 from International Research and Development Corporation, Mattawan, MI, USA. Submitted to WHO by Hercules Inc., DE, USA. BLAIR, M. (1992). Ester Gum 8BG. 13-week dietary toxicity study in rats. Amendment to the Final Report. Unpublished report No. 548-007 from International Research and Development Corporation, Mattawan, MI, USA. Submitted to WHO by Hercules Inc., DE, USA. BLAIR, M. (1994). A dietary excretion study with Ester Gum 8BG in Fischer 344 Rats. Unpublished report No. 3352.1 from Springborn Laboratories, Inc., Spencerville, OH, USA. Submitted to WHO by Hercules Inc., DE, USA. CIFONE, M.A. (1988). Mutagenicity test on Ester Gum 8BG in the rat primary hepatocyte unscheduled DNA synthesis assay. Unpublished Report No. 10349-0-447 from Hazleton Laboratories America, Inc., Kensington, MD, USA. Submitted to WHO by Hercules Inc., DE, USA. DE GROOT, A.C., BEVERDAM, E.G.A., AYONG, C.T., COENRAADS, P.J. & NATER, J.P. (1988). The role of contact allergy in die spectrum of adverse effects caused by cosmetics and toiletries. Contact Dermatitis, 19: 195-201. HERCULES POWDER CO (1974). Unpublished report submitted to WHO. ISHIDATE, M., Jr., SOFUNI, T., YOSHIKAWA, K., HAYASHI, M., NOHMI, T., SAWADA, M. & MATSUOKA, A. (1984). Primary mutagenicity screening of food additives currently used in Japan. Fd. Chem. Toxic., 22: 623-636. JAGANNATH, D.R. (1988). Mutagenicity test on Ester Gum 8BG in the Ames salmonella/microsome reverse mutation assay. Unpublished report No. 10349-0-401 from Hazleton Laboratories America, Inc., Kensington, MD, USA. Submitted to WHO by Hercules Inc., DE, USA. KAY, J.H. (1960a). Ninety-day subacute oral toxicity of Ester Gum 8D. Unpublished Report (no study no. given) from Industrial Bio-Test Laboratories Inc., Northbrook, IL, USA. Submitted to WHO by Hercules Inc., DE. USA. KAY, J.H. (1960b). Ninety-day subacute oral toxicity of N-wood rosin. Unpublished report (no study no. given) from Industrial Bio-Test laboratories, Inc., Northbrook, IL, USA. Submitted to WHO by Hercules Inc., DE, USA. KOCH, G., MAGNUSSON, B. & NYQUIST, G. (1971). Contact allergy to medicaments and materials used in dentistry (II). Odont. Revy, 22: 275-289. KOCH, G., MAGNUSSON, B., NOBRÉUS, N., NYQUIST, G. & SÖDERHOLM, G. (1973). Contact allergy to medicaments and materials used in dentistry (IV). Odent. Revy, 24:109-114. KOHN, F.E. (1962a). Two-year chronic oral toxicity of N-wood rosin - albino rats. Unpublished report (no study no. given) from Industrial Bio-Test Laboratories, Inc., Northbrook, IL, USA. Submitted to WHO by Hercules Inc., DE, USA. KOHN, F.E. (1962b). Two-year chronic oral toxicity of N-wood rosin - dogs. Unpublished report (no study no. given) from Industrial Bio-Test Laboratories, Inc., Northbrook, IL, USA. Submitted to WHO by Hercules Inc., DE, USA. LYSELL, L. (1976). Contact allergy to rosin in a periodontal dressing. J. Oral Medicine, 31: 24-25. MURLI, H. (1988). Mutagenicity test on Ester Gum 8BG OSR in an in vitro cytogenetic assay measuring chromosomal aberration frequencies in Chinese hamster ovary (CHO) cells. Unpublished report No. 10349-0-437 from Hazleton Laboratories America, Inc., Kensington, MD, USA. Submitted to WHO by Hercules Inc., DE, USA. NESTMANN, E.R., LEE, E.G., MUELLER, J.C. & DOUGLAS, G.R. (1979). Mutagenicity of resin acids identified in pulp and paper mill effluents using the Salmonella/mammalian-microsome assay. Environ. Mutagen., 1: 361-369. NESTMANN, E.R. & LEE, E.G. (1983). Mutagenicity of constituents of pulp and paper mill effluent in growing cells of Saccharomyces cerevisiae. Mutat. Res., 119: 273-280. OGINO, Y., HOSOKAWA, K., SUZUKI, M., MATSUNAGA, K., HIROSE, O., ARIMA, Y. & HAYAKAWA, R. (1989). Allergic contact dermatitis due to ester gum in a lipstick. Skin Research, 31(Suppl. 6): 180-184. RADOMSKI, J.L. (1965). The absorption, fate and excretion of dehydroabietic acid, isopimaric acid and tetrahydroabietic acid in rats. Unpublished report (no Study No. given) from University of Miami School of Medicine, Coral Gables, FL, USA. Submitted to WHO by Hercules Inc., Wilmington, DE, USA. SATYAWAN, I., ORANJE, A.P. & VAN JOOST, T. (1990). Perioral dermatitis in a child due to rosin in chewing gum. Contact Dermatitis, 22: 182-183. YOUNG, E., VAN WEELDEN. H. & VAN OSCH, L. (1988). Age and sex distribution of the incidence of contact sensitivity to standard allergens. Contact Dermatitis, 19: 307-308.
See Also: Toxicological Abbreviations Glycerol ester of wood rosin (WHO Food Additives Series 37) GLYCEROL ESTER OF WOOD ROSIN (JECFA Evaluation)