Prove the In vivo SPF Water Resistance Evaluation of your product
following international methodologies

In vivo SPF Water
Resistance Evaluation

After water immersion or intense sweating, it is possible that the sunscreens efficacy is reduced. So, for cosmetic product intended to protect the skin even after immersion or intense sweating, it is necessary to conduct the study to determine the water resistance. The immersion time might range from 40 minutes to 6 hours, depending on the product label.

The currently adopted methodologies for water resistance are:

  • FDA, Department of Health and Human Services, Sunscreen drug products for overthe-counter human use. Final Rule; 21 CFR Parts 201 and 310, June 17th 2011
  • COLIPA – Guidelines for Evaluating Sun Product Water Resistance, 2005 em conjunto com a ISO 24444:2010
In vivo SPF Water Resistance Evaluation

Both methodologies present similar aspects on the procedure, but they present important divergences in the experimental design and in the way of evaluating the result, generating different responses.

For COLIPA methodology, first, it is necessary to determine the static SPF on dry skin and then determining the SPF after water immersion. The water resistance evaluation is made through the ration between the result obtained after the immersion and the result obtained on dry skin (static SPF). In general, for a sunscreen to be considered with water resistance, the mean SPF value after the water immersion should be at least 50% of the static SPF, taking into consideration the variation obtained in the clinical study.

For the FDA methodology, it is possible to directly determine the SPF after water immersion, without the static SPF, since there is the demand that the SPF on the label is the one obtained after the immersion.

In vivo SPF Water Resistance Evaluation

Allergisa has 4 bathtubs with controls of the parameters of the water, such as agitation (flow), temperature, pH, conductivity and hardness, which might affect the SPF after immersion results. The bathtubs are individual and projected for more comfort to the subjects, they are equipped with televisions for entertainment.

We also take part in proficiency tests (interlaboratorial), in order to assure that our results are always close to the main labs in the world.

Certificate of participation in BIFEA in interlaboratory comparisons in - 2013-2014

In vivo SPF Water Resistance Evaluation