In response to an ongoing discussion about the safety of using tea tree (Melaleuca alternifolia, Myrtaceae) oil (TTO) in cosmetic products, mainly focused on the lack of accurate data on consumer exposure to TTO in those products, this author used a web survey to provide reliable exposure data based on consumption levels to support a reliable safety assessment of TTO in consumer cosmetic products. The author is affiliated with Ri*QUESTA GmbH (Teningen, Germany), which was commissioned by the Australian Tea Tree Industry Association (ATTIA) to conduct this study.
Collected from 2535 qualified users of validated TTO-containing cosmetics in five European countries, the data included the frequency of use of the products, the amount used per product application, and the percentage of TTO present (TTO-inclusion) in the products. Data on the frequency and amount used were collected using a single-source consumer survey completed by every respondent. TTO-inclusion data were provided by manufacturers.
During October 2015 and November 2015, the author identified 1326 individual TTO-containing products under 360 brands that were available to consumers in Europe. The author documented each product by brand name, product name, package size(s), product image, supplier address, and manufacturer address, and assigned them to one of 42 categories. The inventory was updated as new TTO-containing cosmetics were identified during the consumer and manufacturer surveys. In total, 1429 individual TTO-containing products representing 370 brands or suppliers were identified.
In January 2016, Research Now GmbH, the German subsidiary of Research Now Group, Inc. (Plano, Texas), conducted a web survey of 17,595-panel members in France, Germany, Great Britain, Italy, and Spain, who were required to participate in and compensated for a set number of surveys yearly. The investigators aimed to gather data on the use of TTO-containing cosmetics from at least 2400 respondents in total and from at least 400 in each country for up to four products per respondent.
The author reports that 12.7% of the 2903 total respondents reported using TTO-containing products (mostly hand and face creams, deodorant sprays, and hair sprays) that did not actually contain TTO; data from those respondents were deleted from the database.
Among the 7957 product use-reports for validated TTO-containing cosmetics, the total average number of product use-reports identified from the 2535 respondents was 3.14. The numbers for the individual countries were 3.37 for Italy, 3.35 for France, 3.33 for Spain, 2.95 for Germany, and 2.90 for Great Britain.
Beginning in early December 2015, the manufacturer survey was mailed to 156 brand owners, suppliers, and manufacturers who offered three or more TTO-containing cosmetics in the European market. Several companies provided product data before the end of 2015. For the 43 brand owners, suppliers, and manufacturers who represent 80% of the products but had not responded, a follow-up survey was mailed in February and March 2016, resulting in receipt of data from 32 respondents by July 1, 2016. Their data cover 321 individual TTO-containing products and 3264 product use-reports from consumers, which equated to an overall 41% coverage rate of the 7957 valid product use-reports received.
TTO-inclusion data from manufacturers were available for 321 of the 855 product use-reports on body lotion, with the mean amount of TTO exposure being 47.023 mg daily. The use of 119 individual face-cream products was mentioned in 531 product use-reports. Data on TTO-inclusion were linked to 247 of those reports, with the mean TTO exposure being 5.992 mg daily. For hand cream, 214 product use-reports referred to one of 39 individual products. Data on TTO-inclusion were linked to 170 of those reports. The mean daily TTO exposure was 17.367 mg.
Among the consumers, 170 reported the use of one of 70 blemish-spot-gel or lip-balm products; 90 could be linked to manufacturer data on product-specific TTO-inclusion. The mean TTO exposure was 0.385 mg daily. The number of foot deodorant spray use-reports was 434, with 152 linked to TTO-inclusion. Fifty-nine of 331 product use-reports for body deodorant sprays were used to assess TTO exposure. The mean TTO exposures were 6.319 mg daily for foot deodorant sprays and 0.706 mg daily for body deodorant sprays. For face cleansers, 513 reports could be linked to product-specific data on TTO-inclusion. The mean TTO exposure was 0.646 mg daily. Other product use-reports included 445 use-reports of shower and body wash gels and 82 use-reports of body scrub products. The mean daily TTO exposure for shower and body wash gels was 0.714 mg.
Results from this study indicate a significant positive correlation between TTO focus and frequency of product use daily for body lotion (P<0.0001), hand cream (P<0.0001), face cleanser (P=0.0006), shampoo (P=0.0054), and shower and body wash (P=0.0064). In other words, the more consumers look for TTO when buying these products, the more often they are likely to use the products and vice versa.
A significant negative correlation was seen between frequency of daily use and amount of product applied per application for body lotion (P=0.0017), hand cream (P=0.0001), face cleanser (P<0.0001), shampoo (P<0.0001), shower and body wash (P=0.0023), and blemish-spot treatment (P=0.0006). As a consumer uses these products more often, he or she uses a smaller amount each time.
The frequency of TTO-containing product use daily was higher than that of respective general product categories, and the distribution curve characteristics for the amount of product used per application were lower than personal care products (PCPs) in general, as reported in earlier studies.
These results show that consumption patterns of TTO-containing PCPs can be very different from those of PCPs in general. “From this, it does not seem to be appropriate to evaluate the toxicological safety of TTO as [an] ingredient of PCPs from exposure data on ‘generic’ types of PCPs,” writes the author.
The author acknowledges that the lack of consumption data on TTO-containing cosmetics for more European countries prevents extending the results beyond the five surveyed countries. This study presented other challenges, such as dealing with the off-label use and the possibility that multiperson use of the products could have inflated the amounts used.
“This is, to our knowledge, the first single source study to enable the calculation of consumer exposure to a particular ingredient of cosmetic products across several countries as a contribution to the safety assessment of TTO in consumer cosmetic products,” writes the author. Results of the study could help guide future research on consumers’ exposure to certain ingredients in cosmetics and other types of products.
This study was financed by ATTIA Ltd, with financial support from the Australian Commonwealth through the Department of Agriculture and Water Resources.
Rieder BO. Consumer exposure to certain ingredients of cosmetic products: The case for tea tree oil. Food Chem Toxicol. 2017;108(Part A):326-338.