Frequently asked questions regarding the BfRshort forGerman Federal Institute for Risk Assessment's reassessment of aluminium in antiperspirants from 20 July 2020

The data available in 2014 showed a wide variation in the amount of the possible dermal uptake of aluminium from antiperspirants. There are uncertainties especially in the extent to which the results obtained under experimental conditions reflected to the uptake that would be obtained under realistic conditions of use. A further uncertainty was the extent to which armpit shaving influences uptake through the skin.

A study was carried out in 2014/2015 on twelve test subjects (TNO 2016) to reduce these uncertaintiesExternal Link:[1]. To obtain as comprehensive as possible data, also e.g. for uptake via freshly shaved armpits, this study was performed in a crossover design. Each group ultimately consisted of four subjects because there were three different treatment regimens, which were sequentially applied in a different order for each group. The extremely rare radionuclide aluminium-26 (²⁶Al) was used to unambiguously identify the amount of aluminium taken up through the skin and to distinguish it from background exposureClose dialogexposureExposureTo glossary from aluminium intake trough all other sources. The ²⁶Al was specifically produced and its annual production quantity is limited. For the dermal application, a ²⁶Al-labelled formulation containing aluminium chlorohydrate was used, which was thickened with hydroxyethylcellulose in the same way as in commercially available antiperspirants to achieve the viscosity typical for roll-on products. The intention was to measure the aluminium concentration in the blood as a correlate for uptake through the skin. In addition, urine samples were taken sporadically. The data were not available until 2016 because of the crossover design and the need to have the radionuclide ²⁶Al synthesised separately. After examination, the EU Commission’s Scientific Committee on Consumer Safety (SCCS) decided that the data situation was not sufficient for an assessment; in the blood, ²⁶Al was only measurable in a few samples and an evaluation of the urine data was marked by uncertainty because these data had only been collected sporadically. However, the study provided important information for designing the new TNO study in 2019External Link:[2].

The new study, for which the rare ²⁶Al isotope was again synthesised, involved a group size of six subjects and a different design. Urine data was systematically collected. Furthermore, a higher amount of ²⁶Al was used to obtain a higher proportion of blood concentration values above the limit of quantification. These data were available to the SCCS in 2019. The SCCS’ final opinion was published in 2020.

External Link:[1] TNO. Assessment of bioavailability of aluminium, as aluminium chlorohydrate, in humans after topical application of a representative antiperspirant formulation using a [26Al] microtracer approach. Study commissioned by the Cosmetics Industry via Cosmetics Europe. 2016

External Link:[2] TNO. Assessment of bioavailability of aluminium in humans after topical application of a representative antiperspirant formulation using a [26Al] microtracer approach. Study commissioned by the Cosmetics Industry via Cosmetics Europe. 2019

The 2019 study involved the use of a larger quantity of the extremely rare radionuclide aluminium-26 (²⁶Al). Moreover, in contrast to the 2016 study, urine data were systematically collected to enable determination of the cumulative urinary excretion of ²⁶Al. The mass balance (the question of whether the aluminium applied to the skin with the antiperspirant can also be recovered later from e.g. the dermal layers or the clothing) is sufficiently acceptable for this type of study. Also see answer to the question above.

Group sizes of 4-6 individuals are common in toxicology for studies on bioavailability and toxicokinetics (uptake, distribution, metabolism and excretion) of a substance. These are controlled studies in which the experimental conditions, including the administered dose, are kept constant so that the variation in the target parameter largely reflects the interindividual variabilityClose dialogvariabilityVariabilityTo glossary. Interfering variables, such as background exposure to a substance, can be minimised by using a rare nuclide of the substance. Special experimental designs, such as a crossover study, in which the substance is administered to the same individuals in a sequential manner in different ways (e.g. intravenously and dermally) or after various pre-treatments (e.g. with and without shaving the skin), can be used to optimise group sizes.

There are a number of human studies on toxicokinetics and oral bioavailability for aluminium that have been carried out with the extremely rare radionuclide ²⁶Al. Group sizes ranged from 1-6 subjects. ²⁶Al was also used in the two new human studies on dermal bioavailability. The 2016 TNO study used a crossover design with 12 subjects divided into three groups of four. The 2019 TNO study was carried out on 6 subjects. The group sizes are therefore within the typical range for these kinds of studies.

The criteria for evaluating a study’s reliability or robustness include the variability in the target parameter (variation around the meanClose dialogmeanMeanTo glossary value) and comparability with the results of previous studies. In the case of the 2019 TNO study, the proportion of the dose excreted via the urine showed a relatively low variation. Furthermore, the results from intravenous administration agreed very well with those from the 2016 TNO study. The reasons for the differences between the two studies regarding the results of dermal administration are discussed in opinion 030/2020:

• External Link:https://www.bfr.bund.de/cm/349/new-studies-on-antiperspirants-containing-aluminium-impairments-to-health-unlikely-as-a-result-of-aluminium-uptake-via-the-skin.pdf

TWI and MoSshort forMargin of Safety are two different assessment concepts that come from different regulatory areas. The BfRshort forGerman Federal Institute for Risk Assessment pointed out in 2014 that uptake via the skin must be better investigated because the tolerable weekly intake (TWI), as defined by the European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) for food, was exceeded in connection with aluminium intake from other sources such as food or drinking water.

Consumers cannot generally avoid aluminium intake from food or drinking water, however, they can avoid uptake from antiperspirants by not using them. In its 2014 opinion, the BfRshort forGerman Federal Institute for Risk Assessment pointed out that antiperspirants may contribute to the total intake permanently exceeding the TWI.

Reliable data are now available on the uptake of aluminium from antiperspirants through the skin. In its revised opinion, the BfRshort forGerman Federal Institute for Risk Assessment has, therefore, applied the relevant guideline, i.e. the SCCS Notes of Guidance (10th revision), for the assessment of cosmetics, which foresees an assessment in terms of the Margin of Safety (MoSshort forMargin of Safety).

According to the current state of scientific knowledge, adverse health effects resulting from the daily use of antiperspirants containing ACH are unlikely.

Further information on the subject from the BfR website:

Publications about aluminium on the BfRshort forGerman Federal Institute for Risk Assessment website:

• External Link:https://www.bfr.bund.de/en/a-z_index/aluminium-129853.html

About the BfR

The German Federal Institute for Risk Assessment (BfRshort forGerman Federal Institute for Risk Assessment) is a scientifically independent institution within the portfolio of the Federal Ministry of Food and Agriculture (BMELshort forGerman Federal Ministry of Food and Agriculture) in Germany. It advises the German federal government and German federal states (“Laender”) on questions of food, chemical and product safety. The BfRshort forGerman Federal Institute for Risk Assessment conducts its own research on topics that are closely linked to its assessment tasks.