An irritation index of 0.00: what sits behind the number and how to check it
Many Korean manufacturers write “tested on sensitive skin”. What separates a signed laboratory report from a line on the packaging, and what to ask so that you are not buying words.
“Tested on sensitive skin” is a common line on Korean packaging. It is worth nothing until there is a document behind it, and that document is rarely asked for. Which is a pity: it exists more often than you would think, and it takes five minutes to read.
What is actually measured
The standard procedure is a patch test. A chamber holding the product is fixed to the participant's skin and left for twenty-four hours. After removal a dermatologist examines the skin twice: thirty minutes later and twenty-four hours later.
Reactions are scored on a scale, and the scores produce an irritation index. Zero means no participant reacted. The index is then translated into a verbal category, and non-irritating is the top one.
How this differs from a line on the pack
A claim on packaging is written by a marketing department. A report is issued by an independent laboratory: it is signed, it has a number, a date and a named client. Those four fields are the difference.
Something else matters more: a report covers one specific product, not a line and not a company. Three products in one line means three separate documents. If a manufacturer shows one report and says the whole line is like that, you are getting one tested product and two untested ones.
Five things to look at in the document
First: the product name in the header matches exactly what you are ordering, down to the variant. Second: the date. A report from three years ago says nothing about a formula that has been changed since.
Third: the number of subjects. A small group gives a weak result even when the figure looks good. Fourth: who commissioned the test — it should be the manufacturer, not an intermediary. Fifth: whether there is a signature and a report number the laboratory can be asked about.
What to ask the manufacturer in one line
“Send the irritation test reports for the items we are taking, and tell us whether the formula has changed since the test date.” The second half of that question is the one people skip, and it is the decisive one.
At Korea's ABEREDE, for instance, such reports exist for three products of the PRINCIPLE line: the toner, the serum and the cream. Human Co., Ltd. Skin Clinical Trial Center, September 2023, an index of 0.00 on each, with no adverse reactions recorded. That is exactly why on our showcase the 0.00 mark sits only on those three items and is not spread across the rest of the range.