Why Quality Control Matters for Products Used on Skin

When a consumer opens a product intended for use on the skin, there is a reasonable expectation that what is inside the package is what the manufacturer intended to put there.

The product should have the expected appearance and consistency. The correct ingredients should have been used. The batch should have been manufactured according to its established process. Packaging and labeling should be correct. And, where appropriate, testing should provide evidence that established specifications have been met.

Those expectations sound simple.

Achieving them consistently is not.

That is the purpose of quality control.

What Is Quality Control?

Quality control, often abbreviated QC, is the part of a manufacturing quality system concerned with determining whether materials, processes, and finished products meet established requirements.

It can involve:

• examining incoming raw materials;
• checking materials against specifications;
• monitoring production;
• taking samples during manufacturing;
• performing physical, chemical, or microbiological tests when appropriate;
• evaluating packaging and labeling;
• reviewing results;
• and determining whether a batch meets established acceptance criteria.

FDA's cosmetic GMP guidance specifically discusses examination or testing of raw materials, in-process samples, and finished products to determine whether they comply with specifications.

That distinction is important.

Quality control does not begin only after the finished product is sitting in a bottle.

Quality Control and Quality Assurance Aren't Quite the Same Thing

The terms quality control and quality assurance are sometimes used interchangeably, but they describe related rather than identical ideas.

A useful simplified distinction is:

Quality assurance asks:
Do we have an appropriate system for consistently making the product correctly?

Quality control asks:
Does this material, sample, or finished batch meet the requirements we've established for it?

Quality assurance therefore encompasses the broader system of procedures, documentation, training, responsibilities, manufacturing controls, investigations, and continual oversight.

Quality control operates within that system.

Neither replaces the other.

What Is a Specification?

A specification is an established requirement or set of acceptance criteria.

Depending upon the product or material, specifications might concern characteristics such as:

• identity;
• appearance;
• odor;
• color;
• viscosity;
• pH;
• specific gravity;
• concentration;
• microbial limits;
• packaging characteristics;
• or other relevant physical or chemical properties.

Not every product needs every test.

A specification should be meaningful to the particular material or product being evaluated.

FDA's cosmetic GMP guidance contemplates testing raw materials, in-process samples, and finished products for relevant physical and chemical properties, microbial contamination, and unwanted chemical contaminants.

Why Test Raw Materials?

Because the finished product begins with them.

Suppose a formula calls for a particular raw material at a particular grade or concentration.

If the wrong material enters production, testing the finished product later may reveal a problem—but by then an entire batch may already have been manufactured.

Incoming-material controls provide an earlier opportunity to identify:

• incorrect materials;
• damaged containers;
• contamination;
• deterioration;
• incorrect labeling;
• or material that does not meet established acceptance criteria.

FDA's GMP inspection guidance specifically addresses material identity, lot identification, control status, storage, sampling, examination or testing, and segregation of materials that fail acceptance specifications.

In other words:

Quality control can prevent a problem from becoming a finished-product problem.

What Does “In-Process” Testing Mean?

Not every useful measurement occurs at the beginning or end of manufacturing.

Some checks take place while the product is being made.

Depending upon the manufacturing process, in-process controls can help determine whether:

• ingredients were added correctly;
• mixing was adequate;
• processing conditions were appropriate;
• the batch is sufficiently uniform;
• or some measurable characteristic remains within the intended range.

FDA's cosmetic GMP material specifically discusses sampling during or after processing for adequacy of mixing, contamination concerns, and compliance with other acceptance specifications.

This gives manufacturers an opportunity to detect certain problems before the batch reaches final packaging.

Why Test the Finished Product?

Finished-product testing provides another layer of information.

The exact tests depend upon the formulation and its intended use, but testing can help determine whether the finished batch conforms to the manufacturer's established specifications.

That may include physical or chemical characteristics and, when relevant, microbiological considerations.

FDA does not prescribe one universal list of tests that every cosmetic must undergo. Manufacturers and distributors are responsible for ensuring cosmetic safety, and additional testing may be appropriate depending upon the product and the safety information already available.

That is why statements such as:

“This product passed quality control.”

don't tell us very much by themselves.

The useful questions are:

What was controlled?

What was tested?

Against what specification?

Using what method?

Does Quality Control Prove That a Product Is Safe?

Not by itself.

This is an important distinction.

A batch can meet its manufacturing specifications without one QC test somehow answering every possible question about safety.

Product safety can depend upon:

• ingredient toxicology;
• concentration;
• route and duration of exposure;
• intended use;
• foreseeable use;
• formulation;
• impurities;
• microbiological characteristics;
• packaging;
• labeling;
• and other available scientific evidence.

Under MoCRA, the responsible person for a cosmetic product must ensure and maintain records supporting adequate substantiation of safety. FDA also makes clear that it does not mandate one specific testing regimen for every cosmetic or ingredient.

So:

Quality control contributes to product quality and consistency. Safety substantiation addresses the broader question of whether the product is adequately supported as safe for its intended or customary use.

They overlap, but they are not synonymous.

Why Does Consistency Matter?

Imagine purchasing the same product several times.

One bottle is thin.

Another is unusually thick.

A third has a noticeably different appearance.

A fourth performs completely differently.

Even if none of those differences creates an immediate safety issue, substantial unexplained batch-to-batch variation makes the product less predictable.

Manufacturing controls and specifications help define what the product is supposed to be.

Quality control then provides information about whether actual production conforms to those expectations.

That is one of the fundamental reasons QC matters:

A formula is only useful if a manufacturer can reproduce it with reasonable consistency.

What Happens When a Result Is Outside Specification?

Suppose a test produces a result outside the established acceptance range.

The appropriate response isn't simply:

“Test another sample until one passes.”

An unexpected or out-of-specification result may require evaluation or investigation to determine what happened.

Possible questions include:

• Was the sample representative?
• Was the test performed correctly?
• Was there an equipment problem?
• Was an incorrect material used?
• Did something occur during processing?
• Is the batch actually outside specification?

A mature quality system treats an unexpected result as information requiring attention, rather than an inconvenience to be discarded.

Why Are Records Important?

Testing without documentation has limited value.

Records can establish:

• which batch was tested;
• when it was tested;
• what method was used;
• what result was obtained;
• whether it met specifications;
• and what disposition was ultimately assigned to the batch.

FDA's cosmetic GMP guidance addresses records for raw materials, batch manufacturing, sampling, laboratory controls, test results, finished products, and control status.

Documentation makes the quality process traceable.

What Is a Retained Sample?

Manufacturers may retain samples of raw materials or finished batches for an established period.

Why keep something that has already been manufactured?

Because a retained sample can become valuable if a question arises later.

For example, if a complaint is received concerning a particular lot, an appropriately stored retained sample may provide something from that production history that can be examined or retested.

FDA's cosmetic GMP inspection guidance specifically discusses retained samples and their storage under conditions intended to protect them from contamination or deterioration.

A retained sample is therefore a small piece of manufacturing history.

What About Microbiological Testing?

Microbiological control deserves particular attention for products capable of supporting microbial growth.

Cosmetics do not have to be sterile, but FDA states that they must not contain harmful microorganisms and that microbial levels need to be appropriately controlled.

Whether microbiological testing is appropriate—and what type—is heavily dependent upon the formulation.

Water-containing products generally present different considerations from substantially anhydrous products.

Packaging matters too.

A product repeatedly exposed to fingers and the environment during use may face different contamination opportunities from one dispensed through packaging that limits direct contact.

So once again:

appropriate testing depends upon the product.

More Testing Isn't Automatically Better Testing

It's tempting to think that a company performing 30 tests must have better quality control than one performing 10.

Not necessarily.

Testing has value when it addresses meaningful characteristics or risks using appropriate methods and acceptance criteria.

A large collection of irrelevant tests can create an impressive-looking certificate without providing much useful information.

Good quality control is therefore not a contest to generate the longest laboratory report.

It is about asking:

What do we actually need to know about this material or product—and what is a scientifically appropriate way to determine it?

What Is a Certificate of Analysis?

A Certificate of Analysis, often called a CoA, is a document reporting analytical or quality information associated with a material or product.

Depending upon the supplier and product, it may identify:

• the material;
• lot or batch number;
• specifications;
• tests performed;
• acceptance limits;
• results;
• and disposition.

A CoA can be useful evidence.

But the existence of a certificate does not eliminate the need for an appropriate supplier-quality program.

Documents themselves must correspond to the correct material and lot, and manufacturers need appropriate procedures for deciding how supplier information is qualified and used.

The principle remains:

paperwork supports quality control; paperwork is not a substitute for quality control.

Quality Control Doesn't End With the Laboratory

Visual inspection can matter.

Packaging can matter.

Labels can matter.

Lot codes can matter.

Storage conditions can matter.

FDA's GMP guidance specifically addresses checking labels to prevent mix-ups, permanent code marks on finished packages, storage conditions, and records associated with production and finished products.

A beautifully formulated product placed in the wrong package with the wrong label is still a quality failure.

Why Does This Matter for Products Used on Skin?

Skin-contact products are intentionally placed against the body.

That makes consistency and manufacturing control particularly meaningful.

Customers generally cannot independently verify:

• raw-material identity;
• manufacturing cleanliness;
• batch composition;
• laboratory results;
• contamination controls;
• or production records.

They rely upon the manufacturer and the surrounding quality system to do that work before the product reaches them.

That trust should be supported by processes and evidence, not merely marketing language.

What Should Consumers Look For?

Consumers don't need to demand laboratory notebooks every time they buy a bottle of something.

But they can distinguish meaningful quality information from vague claims.

Statements such as:

“premium quality”

“laboratory tested”

“professional grade”

or

“made to the highest standards”

sound reassuring.

By themselves, however, they tell the consumer very little about what actually happened.

More meaningful information concerns things such as:

• traceable lots;
• defined specifications;
• controlled manufacturing;
• appropriate testing;
• documented quality procedures;
• ingredient transparency;
• and responsible handling of complaints or unexpected results.

Those concepts are much harder to fit on the front of a package.

They're also much more informative.

Quality Is a Process, Not a Slogan

Quality control is not a single stamp placed on a product after manufacturing.

It is one component of a larger manufacturing system.

Raw materials are evaluated.

Processes are controlled.

Samples may be taken.

Relevant characteristics are measured.

Results are compared with established criteria.

Unexpected results are investigated.

Records are maintained.

Finished products are evaluated before release.

That doesn't guarantee that no product will ever experience a problem.

It does something more realistic:

It creates an organized way to detect, reduce, investigate, and respond to variation before that variation reaches the customer whenever possible.

For products intended for skin contact, that is a far more meaningful description of quality than simply printing the word “quality” on the label.

Related Articles

What Does Good Manufacturing Practice Mean for Products Used on Skin? 

What Happens Before a Skin-Contact Product Is Released for Sale?

Why Raw Material Quality Matters in Skin-Contact Products

How Manufacturers Help Control Contamination

What Do Certifications Really Tell You About a Product?

Sources

• U.S. Food and Drug Administration. Good Manufacturing Practice (GMP) Guidelines/Inspection Checklist for Cosmetics. FDA material addressing raw-material controls, production sampling, laboratory controls, specifications, retained samples, batch records, finished-product records, labeling and storage.
• U.S. Food and Drug Administration. Product Testing of Cosmetics. Explains manufacturer responsibility for product safety, the use of existing safety information and additional testing, microbiological considerations, and FDA's lack of a universal required testing program for cosmetics.
• U.S. Food and Drug Administration. Modernization of Cosmetics Regulation Act of 2022 (MoCRA). FDA overview of current cosmetic-industry responsibilities, including adequate safety substantiation and records supporting it.
• U.S. Food and Drug Administration. Draft Guidance for Industry: Cosmetic Good Manufacturing Practices. FDA's nonbinding GMP guidance addressing quality systems and factors affecting cosmetic-product quality.
• International Organization for Standardization. ISO 22716:2007 — Cosmetics — Good Manufacturing Practices (GMP). International guidelines covering quality aspects of cosmetic production, control, storage and shipment.
• Gilchrist AJ. Quality Control and Quality Assurance. In: Making Quality Cosmetics: Good Manufacturing Practice and ISO 22716:2007. Royal Society of Chemistry; 2022. Discusses QC/QA distinctions, sampling, acceptance criteria, test methods, out-of-specification results and retained samples.