Gallates: What Are They and Where Are They Found?

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Allergic contact dermatitis (ACD) is a type IV hypersensitivity that develops after cutaneous exposure and sensitization to a variety of haptens. Although the potential for sensitization is ubiquitous, some of the most common culprit antigens include metals, preservatives, fragrances, surfactants, and rubbers.¹ A suspected ACD diagnosis is confirmed via patch testing, where antigens/haptens are applied directly to the patient’s skin and then allowed time to react via a delayed-immune response, resulting from priming and expansion of antigen-specific CD4+ and CD8+T cells.² The primary treatment is avoidance of the identified allergens, which can be aided by databases, such as the Contact Allergen Management Program (CAMP) and SkinSAFE.³ These databases can be extremely helpful to patients; however, not all categories of products are included and not all brands participate. It is important for providers to be aware of common allergens and where they are found to help patients obtain the best outcomes.

Gallates are antioxidant preservatives that are infrequently found in certain foods and personal care products. The most common esters of gallic acid in products are propyl gallate, octyl gallate, and dodecyl gallate.⁴ Dodecyl gallate has the strongest sensitization potential of these gallic acid esters, and propyl gallate is the most common source of sensitization in the literature and the most commonly used in industry.^5-6 In practice, all gallates are considered cross-reactors of each other and avoidance of all gallates is recommended, regardless of the specific allergens to which the patient tests positive.⁷

Allergy to gallates is considered rare, but rates of allergy identified with patch testing have risen over the past 3 decades.⁸ Although gallates are considered to have a low irritant potentialand reactions to them on patch testing are often felt to represent true allergy, these reactions frequently lack clear relevance, withrelevance rates varying from only 3% to 15% in some cases.⁷
 

Gallates in Food
Because gallates are not found naturally in foods, they are always considered food additives and as such should explicitly be listed on packaging labels. They are typically used in oily foods or those high in fats. Propyl gallate is the most common gallic acid ester used in foods.⁴ Peanut butter commonly contains gallates, as well as certain cheeses, lard, and various processed foods; even frozen pizza can contain gallates.^4,9-10 Another potential source of gallate exposure is in bakery items, which often contain octyl gallate.^11-12 Use in food products has decreased since 1976, which may havecounterintuitively contributed to increased rates of ACD, giventhat oral intake of gallates increases systemic tolerance.¹³

Sensitization can occur in both consumers and producers of these products; thus, they can be a source of occupational- and workplace-related sensitization. Patients with a gallate allergy should become familiar with reading product labels.

Gallates in Personal Care Products
Cosmetics are another common source of gallates, predominantly in overseas oil-based cosmetics. Of 106 patients patch tested at a single center in New Delhi, India, 13 patients (12.3%) had a positive reaction to a gallate mix (octyl gallate, propyl gallate, dodecyl gallate). In all 13 patients, the reactions were considered relevant given the presence of this allergen in their oil-based cosmetics.¹⁴ A similar study of 201 students with suspected contact allergy in Beijing, China, revealed dodecyl gallate as the fifth most common cosmetic allergen (positivity rate, 1.5%).¹⁵

Historically, lipstick has been a common source of gallates.^16-21 A systematic review found 74 reported cases of ACD due to gallates,and 27% of those cases implicated lipstick as the off endingagent.^4,16 Similarly, a study of 46 patients with positive patchtesting for 1 or more gallates identified that 54.3% of cases werecaused by lipstick.¹¹ Other potential sources include face creams,blushes, concealers, over-the-counter topical preparations, andsoaps.^4,22 Similar to foods, propyl gallate is the most commonlyused gallic acid ester in cosmetics.²²

Localization of Gallate-Induced Dermatitis
Gallate-induced dermatitis is focal to areas of topical application. Consequently, it most commonly localizes to the face or hands, which are the most in contact with the cosmetics during application. Of the 74 cases assessed by Holcomb et al, 51 were reported on the face or lips, with predilection for the lips or perioral region (n = 24); the next most common locations were the hands and arms, with an additional 14 cases reported.⁴ Fingertips were also a common location from handling of food or cosmetics containing gallates.^10,23

Recommendations
As ACD caused by gallates continues to become more prevalent, providers should be aware of common food and cosmetic sources of these preservatives. ACD from gallates most often localizes to the face and hands, which is not a dead giveaway considering that these are by far the most common sites of ACD. However, dermatitis isolated to the lips should raise suspicion.¹ Clinical correlation between positive patch test results, patient products containing suspect allergens, and where they use those products remains paramount, as is the case for all ACD diagnoses. For patients with a history of exposure to numerous cosmetics or regular consumption of preserved and fatty foods, providers should maintain a healthy suspicion for gallate allergy so patients can see improvement in dermatitis sooner rather than gallate-er.

Reference
1. DeKoven JG, Warshaw EM, Reeder MJ, et al. North American Contact Dermatitis Group patch test results: 2019–2020. Dermatitis. 2023;34(2):90-104. doi:10.1089/derm.2022.29017.jdk

2. Brites GS, Ferreira I, Sebastião AI, Silva A, Carrascal M, Neves BM, Cruz MT. Allergic contact dermatitis: from pathophysiology to development of new preventive strategies. Pharmacol Res. 2020;162:105282. doi:10.1016/j.phrs.2020.105282

3. Nassau S, Fonacier L. Allergic contact dermatitis. Med Clin North Am. 2020;104(1):61-76. doi:10.1016/j.mcna.2019.08.012

4. Holcomb ZE, Van Noord MG, Atwater AR. Gallate contact dermatitis: product update and systematic review. Dermatitis. 2017;28(2):115-127. doi:10.1097/DER.0000000000000263

5. Hausen BM, Beyer W. The sensitizing capacity of the antioxidants propyl, octyl, and dodecyl gallate and some related gallic acid esters. Contact Dermatitis. 1992;26(4):253-258. doi:10.1111/j.1600-0536.1992.tb00238.x

6. van der Meeren HL. Dodecyl gallate, permitted in food, is a strong sensitizer. Contact Dermatitis. 1987;16(5):260-262. doi:10.1111/j.1600-0536.1987.tb01449.x

7. Gamboni SE, Palmer AM, Nixon RL. Allergic contact stomatitis to dodecyl gallate? A review of the relevance of positive patch test results to gallates. Australas J Dermatol. 2013;54(3):213-217. doi:10.1111/j.1440-0960.2012.00941.x

8. Perez A, Basketter DA, White IR, McFadden J. Positive rates to propyl gallate on patch testing: a change in trend. Contact Dermatitis. 2008;58(1):47-48. doi:10.1111/j.1600-0536.2007.01150.x

9. van Ketel WG. Dermatitis from octyl gallate in peanut butter. Contact Dermatitis. 1978;4(1):60-61. doi:10.1111/j.1600-0536.1978.tb03732.x

10. Raccagni AA, Frattagli M, Baldari U, Righini MG. Lauryl gallate hand dermatitis in a cheese counter assistant. Contact Dermatitis. 1997;37(4):182.doi:10.1111/j.1600-0536.1997.tb00195.x

11. García-Melgares ML, de la Cuadra J, Martín B, Laguna C, Martínez L, Alegre V. Sensibilización por galatos. Revisión de 46 casos [Sensitization to gallates: review of 46 cases]. Actas Dermosifiliogr. 2007;98(10):688-693.

12. Bojs G, Nicklasson B, Svensson A. Allergic contact dermatitis to propyl gallate. Contact Dermatitis. 1987;17(5):294-298. doi:10.1111/j.1600-0536.1987.tb01480.x

13. Kahn G, Phanuphak P, Claman HN. Propyl gallate-contact sensitization and orally-induced tolerance. Arch Dermatol. 1974;109(4):506-509.

14. Sharma VK, Bhatia R, Yadav CP. Clinical profi le and allergens in pigmented cosmetic dermatitis and allergic contact dermatitis to cosmetics in India. Dermatitis. 2018;29(5):264-269. doi:10.1097/DER.0000000000000407

15. Z hao J, Li LF. Contact sensitization to cosmetic series of allergens in a general population in Beijing. J Cosmet Dermatol. 2014;13(1):68-71. doi:10.1111/jocd.12078

16. Giordano-Labadie F, Schwarze HP, Bazex J. Allergic contact dermatitis from octyl gallate in lipstick. Contact Dermatitis. 2000;42(1):51.

17. Wilson AG, White IR, Kirby JD. Allergic contact dermatitis from propyl gallate in a lip balm. Contact Dermatitis. 1989;20(2):145-6. doi:10.1111/j.1600-0536.1989.tb03124.x

18. Yu Y, Scheinman PL. Lip and perioral dermatitis caused by propyl gallate. Dermatitis. 2010;21(2):118-119.

19. Cronin E. Lipstick dermatitis due to propyl gallate. Contact Dermatitis. 1980;6(3):213-214. doi:10.1111/j.1600-0536.1980.tb05602.x

20. Athavale NV, Srinivas CR. Contact cheilitis from propyl gallate in lipstick. Contact Dermatitis. 1994;30(5):307. doi:10.1111/j.1600-0536.1994.tb00610.x

21. Serra-Baldrich E, Puig LL, Gimenez Arnau A, Camarasa JG. Lipstick allergic contact dermatitis from gallates. Contact Dermatitis. 1995;32(6):359-60. doi:10.1111/j.1600-0536.1995.tb00625.x

22. Kumar P, Paulose R. Patch testing in suspected allergic contact dermatitis to cosmetics. Dermatol Res Pract. 2014;2014:695387. doi:10.1155/2014/695387

23. Holzer DG, Akhiyat SM, Chaney K. A Fishy situation: allergic contact dermatitis of the fingertips due to propyl gallate. Dermatitis. 2021;32(2):e29-e30. doi:10.1097/DER.0000000000000611