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Bliley PM

Summary of Data on Propylparaben

Date: 20 May 1992
Length: 14 pages
2029185821-2029185834
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Abstract

Summarizes available data on propylparaben, discusses it's chronic and subchronic effects, its use as an antimicrobial, a preservative in food as well as cosmetic and pharmaceutical formulations, and accordingly, its recognition as a GRAS substance. Notes propylparaben's use in manufacturing reconstituted tobacco "to prevent spoilage." Discusses toxicology, metabolism of propylparaben, genotoxicity and mutagenicity, chronic animal studies, and human health effects, noting that "parabens may afford some benefit in controlling yeast overgrowth of the intestinal flora during antibiotic therapy." Includes an appendix, bibliography, and references. Duplicates Bates #2029185701 and #2029185775.

Fields

Company
Philip Morris Cos., Inc.
Type
Report
Author (Organization)
Covington & Burling
Named Organization
United States Food and Drug Administration
FEMA (Flavors and Extracts Manufacturers Association) (Trade association of flavor ingredient manufacturers)
Food Extract Manufacturers Association
Council of Europe
Flavor and Fragrance Materials
U.K. Ministry of Agriculture, Fisheries and Food
International Fragrance Association
European Council
Flavor and Fragrance Materials
U.K. Ministry of Agriculture, Fisheries and Food
International Fragrance Association
Region
United Kingdom
Germany
Keyword
Propylparaben
Methylparaben
Generally_Recognized_As_Safe
Vaginal candidiasis
Antimicrobial
Benzoate
Sorbic acid
Sorbate
p-hydroxybenzoic acid
Glucuronide
p-hydroxybenzoic acid
Chronic studies
Pyrolysis
Animal testing
Genotoxicity
Propyl-parahydroxybenzoate
Parabens
Cosmetics
Antifungal
Antibacterial
Preservatives
Pharmaceuticals
Excretion
Antibiotics
Thesaurus Term
metabolism
weight loss
mainstream smoke
reconstituted tobacco
chromatography
adverse effects

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Page 1: 2029185821
'PRIVILEGED & CONFIDENTIAL ATTORNEY WORK PRODUCT Coving.ton & Burling Draft May 20, 1992. sUMMARY OF DATA ON PROPYLPARABEN AbstraCt. Propylparaben is used as a flavoring, ~reservatlve, and antlmlcrobial (Se~ Appendix I). In tobacco it is used in the manufacture of reconstituted tobacco to prevent Spoilage.~ It has been recognized as GRAS by both FEMA and the FDA. It is also listed by the Councll of Europe.as a natural flavoring substance and is approved for use in tobacco in the United Kingdom and Germany. Chromographlc analysls of propylparaben pyrolysls ~ndicate~ that the substance dlstills when heated to 315°C and generates a small amount of phenol when heated to 590°C. The vast majority of propylparaben transfers unchanged. The chemical iS quickly metabolized by the llver and kidney and excreted in the urine; it does not accumulate in the body~ It appears to help control body yeast overgrowth~ In chronic ~tudi~S,propyiparaben's only effect was weight lOss... Chronic feeding studies have reported decreases in body Welght gain in rats consuming 1.4 g/kg/day of propylparaben for 18 months. In acute studies it was discovered that the larger the paraben ester side chain, the Smaller the LD dose, and that propylparaben is less toxic than its sodiu~ salt. St only had an effect in those subchronic studies on dermal tissue. In a ~ubchronlcstudy male rats were exposed to diluted ~ainstr4am cigarette smoke with propylparaben concentrations of 0, 250 and 750 ppm. The propylparaben had no influence on the rats under the conditions tested. In acute toxicity Studies, the LDs0 dose decreases as the paraben ester side chaln.group gets larger. There are studies on the genotoxicity of propyl- paraben, but they are unexplalnablycontradictory. There is no information concerning the reproductive toxicity of propylparaben. I. Background° Prop~iparaben (CAS RN 94-13-3) (propyl-parahydroxyben~oate) is an ester of parahydroxybenzoic ~cid and i~ a member of the paraben family (i.e., methyl,
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ethyl, propyl, butyl). These materialS~have been in use as antimicrobials for over 60 years~. The u~e of propylparaben as ~ preservative and antimicrobial agent is widespread, and the chemical is present in approximately 6,000 cosmetic formulations at levels up. to 25 percent 4. The antimicrobial activity of propylparaben is apparently related to the phenolic and antimetabolic activities of the parahydroxy- benzoic acid.I Generally, parabens have good antifungal, but limited antibacterial, function when used alone.2 Combinations of methyl- and propylparaben exhibit a good antibacterial response (e.g., when applied in ophthalmic preparations).3 For further discussion of propylparaben's antimicrobial activity, see Appendix I, infra p. 10.~ Propylparaben is a common preservative in food and cosmetic and pharmaceutical formulations, which are administered by different routes (e.q.., injectables, ophthalmic, suppositories and orally). The amount of propylparaben in pharmaceutical products is generally less than one percent. The chemical is also used as an antifungal agent in textiles, gelatins, photographic emulsions, bone glues, and malt. Parabens are synthesized by combining para- hydroxybenzoic acid in the presence of an acid with an excess of the specific alcohol. The resultant mixture is base neutralized and the product cooled and crystallized.6 Propylparaben is prepared as small colorless crystals or white - 2 -
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crystalline powders with little or no organoleptic properties. ~ -- Cigarettes that contained propylparaben were subjectively evaluated and exhibited a weak smoke taste and 7 aroma. The parabens have official approval for food use in at least twelve countries. Both FEMA (#2951) and FDA have recognized propylparaben as a GRAS substance (#2951)~ for use in food (21 CFR § 172.515). According to the Flavor and Fragrance Materials (1989), propylparaben is listed by the Council of Europe as "flavoring substance or natural source of flavoring" (COE 678). The average daily intake of propylparaben is listed by FAO/WHO as 0-10 mg/kg body weight and the maximum level in jams an~ jellies is i000 mg/kg alone or with other benzoates, sorbic acid, or potassium sorbate.9 Propylparaben also appears in a report on review of flavoring in food by the U.K. Ministry of Agriculture, Fisheries and Food. It is also referred to in the guidelines of the International Fragrance Assoclatlon. II. Use in Tobacco. A. Function. Propylparaben is used by the tobacco industry in the manufacture of reconstituted tobacco to prevent spoilage. B. Use Level. The Industry maximum use level for propylparaben is 101-250 ppm. The level of_propylparaben in
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reconstituted tobacco is no more~ thah.0.07 percent} and less than 0.02 percent in a finished ciga~.eth4.:, Propylparaben is permitted for use in tobacco in Germany at 0.5% levels and in the United Kingdom at 0.2% levels. ~II Chemistry and Pyrolysis. phic 315°C, 9 amount propylparaben transfers unchanged. STRUCTURE I COOCH~ [BENZENE RING] OH IV. Toxicology. .A. Metabolism. Propylparaben is readily absorbed via the oral, intravenous (IV), and dermal routes, and is hydrolyzed to p-hydroxybenzoic acid by esterases in the liver and kidney. Following metabolism, propylparaben undergoes conjugation and is excreted primarily in the urine. The chemical does not accumulate in the body following chronic administration. When propylparaben was administered by the IV (50 mg/kg) and oral routes (i mg/kg) to fasting dogs, very little propylparaben was detected in the blood shortly after dosing. Propylparaben metabolites were evident in the blood six hours - 4 -
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post-IV and 24 hours post-ingestion. Recovery of the chemical was near 100 percent of the administered:i~ose. No accumulation was detected in the tissues of dogs receiving 1 gm/day propylparaben orally for a year. In this study, propylparaben and its [me6a~oiite exc~o~reached 96 percent of the administered dose/day. The liver and kidney esterases (dog) could hydrolyse i00 percent of propylparaben within three minutes. When 0.4-0.8 mg/kg propylparaben wa~ administered orally to rabbits, 0.~-0.9 percent was e~e~te~ i~ t~e ~rine ~ ~nchanged within 24 hours. ~t thie t~me, ~5-~9 percent o£ the propylparaben administered was excreted as p-hydroxybenzoic acid, 15-29 percent as the glycine conjugate, 5-8 percent as the ester glucuronide, 10-18 percent as ether glucuronide, and 7-12 percent as the sulfate. Rats were given i00 mg of propylparaben orally, and their blood and urine levels were analyzed. Propylparaben metabolites were evident 30 minutes after dosing, while unmetabolized propylparaben could not be detected. By 90 minutes post-dosing, metabolite excretion was at a:maximum and then started to decline. Metabolites which were detected over a two-hour observation period included p-hydroxyhippuric acid, p-hydroxybenzoic acid, the glucuronides, and the ethereal sulfates. Similar results were obtained administering radio- labeled (14C)-propylpgraben orally to cats. - 5 -
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B. Human Health Eff~ts. Propylparabe~ has very limited use as a therapeutic modality, t~0ugh it has wide use in eertain ~ products. A combination of methyl- and propylparabens in formulations administered to humans prevented the development of candidlasis during antibiotic therapy. In addition, three patients with vaginal candidiasls who were administered propylparaben on a daily basis exhibited alleviated symptoms but no toxic side effects. In another study, patients undergoing antibiotic treatment were given a combination of methyl- and propylparaben. The authors concluded that parabens may afford some benefit in controlling yeast overgrowth of the intestinal flora during antibiotic therapy. Methyl- and propylparabens are present in a number of over-the-counter preparations, including eyewashes, dentifrices, contraceptives, and topical analgesics. They are listed in these products either as preservatives or inert-ingredients. C. Chronic Animal Studies. Rats were fed a 60:40 ~ mixture of propylparaben and methylparaben for 18 months at doses of 0.014, 0.14, 1.4 g/kg/day. There was a decrease in body weight gain for those rats fed 1.4 g/kg/day, and a stimulation in growth for those rats fed the lower doses (226). In another chronic feeding study, rats were fed propylparaben at 2 percent and 8 percent in the diet for 96 weeks. There was a decrease in body weight gain only for the rats fed the 8 percent dose, and no other changes were noted - 6 -
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(194). Weanling dogs were exposed to 1 gm/kg/day propylparaben for 378-422 days or 0.5 "g/~g~/day propylparaben for--318-394 days; the exposure did hot.result in any toxic changes (194). D. Acute & Subchronic Animal Studies. Propyl- paraben exhibits a low order of acute toxicity. Also, it appears that as the paraben ester side chain group gets larger, the LDs0 dose of propylparaben decreases. This conclusion is attributable to the persistence of the parent compound due to decreased hydrolysis. /7 o~-4~-~%~ ~/~'~ The acutely lethal oral dose of propylparaben in dogs and rabbits is 3-4 g/kg and 6 g/kg, respectively. In mice, 8 g/kg propylparaben given orally is acutely toxic, while only 3.7 g/kg is required of the sodium salt. In another report using a different strain of mouse (dd), the reported LDs0 was approximately 6 g/kg, and mixtures of the parabens were not synergistically toxiC. The reported LDs0 for propylparaben in mice via the subcutaneous route is 1.65 g/kg, and the a/c~t~ LD~0 in mice (IV) for the sodium salt of propylparaben is 180 mg/kg. The ~ LDs0 in miee~for 'u~-~i~ propylparaben and its sodium salt is 640 mg/kg and 490 mg/kg respectively. The LDs0 was 2 g/kg for rabbits treated on intact or abraded skin with a hairdressing product containing a mixture of methyl (0.2%) and propylparaben (0.1%). - 7 -
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Dogs given propylparaben by IV at doses of 1-1400 g/kg exhibited a transient fall in blood/pressure and an increase invenous pressure (jugular). Death was associated ~_~yp~t_e~_o_~ ~._d.. ~ ~. o~f propylparabe_~~_~ ~ect ~ffects on the nervous system were reported. ~t~------'~ Rats were dosed orally for one month • formulation containing 0.2 percent methylparaben and 0.2 percent propylparaben at 0.40 and 200 mg/kg. No gross or microscopic treatment-related changes (220) occurred. In a similar study, the animals were dosed with 0.2 percent butylparaben instead of methylparaben; again, the authors observed no significant gross or microscopic changes (220). A formulation containing 0.2 percent methylparaben and 0.2 percent propylparaben was tested for three months in rabbits; mild to severe dermal inflammation and hyperkeratosis with acanthosis were observed. No other changes (i.e.., gross, blood chemistry, urinalysis) were observed that could be attributed to the treatment (224). Except for specific dermal applications, propyl- paraben has shown no adverse effects in subchronic studies. In one study, groups of male Sprague Dawley rats were head- only exposed to the diluted mainstream smoke of three different cigarette types for three and six hours/day, six days/week, for 90 days. One cigarette type contained 750 ppm propylparaben, one contained 250 ppm propylparaben, and one - 8 -
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contained no p~opylparaben (control)' The total particulate matter (TPM) concentrati0n Was 200 m~er~rams/liter. No relevant differences between the three cigarette types were seen in the general condition and behavior of the rats, or in their mortality, body weight development, gross pathology, organ weights, hlstopathology of the entire respiratory tract (nose, larynx, trachea, and lungs), and laryngeal epithelium thickness. Therefore, propylparaben in mainstream smoke had no influence on rats under the conditions tested. E. Genotoxicity & Mutagenicity. The data on the genotoxic effects of propylparaben remain contradictory. Currently, no explanation for the differences in the published reports .is available. Propylparaben was evaluated in ~. typhimurium strains TAI00, TA98, TA1535 and TA1537, with and without metabolic activation, and no mutagenic activity was observed (261). In another study, propylparaben genotoxiclty was assessed in ~. cerevisiae strain D-4 and in ~. typhimurium strains TA1535, TA1537, TA1538, with and without ~microsomes from the liver, lung and testes of ihe mouse, rat, and monkey. Propylparaben was without activity in all assays (262). However, one study (263) reported that although propylparaben was non-mutagenic in an Ames-type assay in the absence of metabolic activation, propylparaben was mutagenic in TAI00 with metabolic activation (PCB-induced rat liver - 9 -
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