The Importance of End-Product Testing

By Marilee Nelson |

In the US cosmetics and personal care products, typically mixtures of 5-20 individual ingredients, are generally self-regulated. The United States and Food and Drug Administration’s guidance is limited to advising manufacturers that their products should be “…safe under labeled or customary conditions of use,” although no formal standard exists for this term. Products may be introduced into the marketplace with limited scientific backing of their safety profiles. In the past, animals were used as testing subjects to determine whether a formulation might be a potential irritant to either human skin or eyes. Within the last 20 years, animal models have been replaced by technologically advanced systems including bioengineered tissue models derived from human cell lineages.

The Results Are In

Branch Basics has contracted with the Institute for In Vitro Sciences (IIVS), a non-profit Contract Research Organization focused exclusively on non-animal testing for toxicological profile assessment, to understand the safety of their formulation: the Branch Basics Concentrate. Although Branch Basics thoroughly vetted their product internally, they were interested in having a third party with experience in safety testing verify their findings. IIVS performed the validated in vitro Skin Irritation Test (OECD Test Guideline 439, 2015) which employs a biochemical assay to determine cell viability relative to a negative control (a saline-based solution) and a positive control (a known irritant with soap-like properties). A viability score similar to the negative control would indicate that the test material is no more irritating than the saline. The product developed by Branch Basics, when tested in this assay, exhibited a viability score in the tissues similar to a saline solution, which means it is not classified as a skin irritant and, has an effect no greater than saline on skin tissue in terms of irritating capacity.

This result was very surprising as most products that contain surfactants are at least somewhat irritating to the skin.
Branch Basics went one step further and asked IIVS to perform the Eye Irritation Test (OECD Test Guideline 492, 2018). Results in this assay revealed the Branch Basics product is not an irritant to the eye as well.
IIVS is pleased to work with an organization such as Branch Basics that has dedicated the resources needed to understand the safety profile of their products.

What is End-Product Testing?

End-product testing illustrates that a final product may not directly reflect the ingredients (and their properties) used to create a formula, but that synergistic amplification or mitigation of properties and ingredients can occur. Perhaps in no other area is this truer than in the science of product safety testing and toxicology. The literature is replete with cases of individual substances exhibiting a vastly different safety profile than a formulation of the components when they are combined. Castile soaps, for example, are generally manufactured by mixing a strong alkali (often Sodium or Potassium Hydroxide - Lye) with lipids in a process known as saponification. The lye is extremely caustic, can burn the skin, cause blindness, and if ingested can even cause death. End product testing reveals that this harmful chemical, lye, is significantly reduced, may be altered, or might even completely disappear when processed and cured. The final product is a mild, soap that is safe but typically may still present some eye or respiratory irritation (when aerosolized). Since such reactions frequently occur and mixtures may exhibit different profiles than the individual components, testing a finished product is currently the only viable option when attempting to develop safety profiles for formulations.

IIVS is a GLP compliant Contract Research Organization with expertise in the application of in vitro methods for safety and efficacy testing. We work with a variety of industries, including personal care, cosmetics, household products and pharmaceuticals, to implement testing strategies for internal decisions or regulatory submissions. As a non-profit organization, IIVS utilizes contributions to fund our education and outreach initiatives which are designed to help implement non-animal testing approaches worldwide. To learn more about our testing, education and outreach services, please visit or email

Marilee Nelson

Marilee Nelson

Marilee Nelson is an Environmental Toxins expert who has spent nearly 30 years advocating for the chemically-sensitive and chronically-ill. She is a Board Certified Nutritionist, Certified Bau-Biologist and Bau-Biology Inspector and specializes in Food As Medicine. She has helped thousands of families and individuals identify, heal and recover from toxic exposures and is on a mission to revolutionize the way American families view their health.