How Manufacturers Help Control Contamination in Skin-Contact Products

When people hear the word contamination, they often imagine bacteria growing in a product.

That is certainly one possibility.

But manufacturing contamination is a much broader subject.

An unwanted material can potentially enter a product through:

• raw materials;
• water;
• equipment;
• personnel;
• air or the surrounding environment;
• containers;
• cleaning processes;
• other products manufactured nearby;
• packaging;
• storage;
• or even later consumer use.

Good contamination control therefore isn't one procedure or one laboratory test.

It is a collection of preventive controls designed around the product, process, facility, and risks involved.

The objective is not to create an imaginary world in which contamination is impossible. It is to understand where contamination could reasonably come from and establish appropriate ways to reduce and detect it.

What Does “Contamination” Actually Mean?

In manufacturing, contamination generally means the unintended presence of something that should not be present—or should not be present at that level.

That might include:

Microbiological contamination
Bacteria, yeasts, molds, or other microorganisms.

Physical contamination
Dust, fibers, fragments, particles, or other foreign material.

Chemical contamination
Cleaning compounds, lubricants, unwanted residues, or other chemicals.

Cross-contamination
Material unintentionally carried from another raw material, product, process, or production area.

These categories can overlap.

What matters is that the unwanted material may affect the identity, quality, consistency, or safety of the finished product.

Where Can Contamination Come From?

Almost anywhere a product or ingredient is exposed.

FDA identifies several potential sources of microbiological contamination in cosmetics, including:

• contaminated raw materials or water;
• poor manufacturing conditions;
• ineffective preservation;
• packaging that does not adequately protect the product;
• shipping or storage conditions;
• Heating/Air Conditioning circulation
• and consumer use.

That list demonstrates something important:

Contamination control begins long before the finished product is tested.

Testing can detect some problems.

Preventive manufacturing controls attempt to keep those problems from occurring in the first place.

The Facility Is the First Line of Defense

A manufacturing building does not need to be a pharmaceutical cleanroom simply because products used on skin are being produced there.

But the facility should be appropriate for the operations performed within it.

FDA's cosmetic GMP guidance addresses facility characteristics including:

• cleanliness and orderly operation;
• adequate space;
• appropriate lighting;
• ventilation;
• plumbing and drainage;
• cleanable surfaces;
• pest control;
• waste handling;
• and protection of materials and products from contamination.

Facility design matters because manufacturing occurs in a physical environment.

If that environment is difficult to clean, poorly organized, or allows materials to become confused or contaminated, controlling the finished product becomes more difficult.

Clean Is Not the Same as Sterile

This distinction is particularly important.

Most cosmetics and similar skin-contact products are not manufactured as sterile products.

FDA states that cosmetics do not have to be sterile, but they must not contain harmful microorganisms.

So when we talk about a clean manufacturing environment, we should not automatically picture surgical operating rooms, sterile gowns, or completely microorganism-free production areas.

The appropriate level of environmental control depends upon the product and manufacturing process.

A water-containing cream may require different microbiological controls from a solvent-based or substantially anhydrous product.

The principle is:

Control the environment appropriately for what you are manufacturing.

People Can Be a Source of Contamination

Human beings shed things.

Hair.

Skin cells.

Microorganisms.

Fibers from clothing.

And people touch equipment, materials, controls, containers, and surfaces.

Personnel practices are therefore part of contamination control.

FDA's cosmetic GMP guidance addresses employee cleanliness, clothing, personal hygiene, handwashing, eating and drinking restrictions, and measures intended to protect products from contamination.

Depending upon the operation, manufacturers may use:

• gloves;
• hair restraints;
• protective clothing;
• handwashing procedures;
• restricted production access;
• or other appropriate controls.

The objective isn't to imply that employees are somehow “dirty.”

It is simply recognition of a biological reality:

People are part of the manufacturing environment.

Therefore, personnel practices are part of controlling that environment.

Equipment Has to Be Designed With Cleaning in Mind

Imagine trying to manufacture a product in equipment containing inaccessible cracks, corroded surfaces, or areas where yesterday's batch can remain trapped.

That creates obvious problems.

Equipment that contacts products should be appropriate for its intended use and maintained so it does not become an avoidable source of contamination.

FDA's GMP guidance addresses equipment construction, maintenance, cleaning, sanitization where appropriate, and protection from contamination.

This can include:

• mixing vessels;
• transfer hoses;
• pumps;
• filling equipment;
• utensils;
• storage tanks;
• measuring devices;
• and other product-contact surfaces.

The details vary dramatically among manufacturing operations.

The principle does not:

Product-contact equipment should not contribute unwanted material to the product.

Why Does Cleaning Need a Procedure?

“Clean the equipment” sounds simple.

But manufacturing needs more precision than that.

Questions may include:

What gets cleaned?

How is it cleaned?

With what material?

At what concentration?

How long does cleaning take?

Does it require rinsing?

How do we know cleaning was completed?

What happens before the equipment is used again?

Written procedures help make cleaning repeatable rather than dependent entirely upon individual judgment.

ISO 22716 includes sanitation, equipment, premises, materials, production, and related controls within its cosmetic GMP framework.

Consistency matters here for exactly the same reason it matters in formulation.

A procedure works best when people know what the procedure actually is.

Can Cleaning Products Become Contaminants?

Potentially.

This is an interesting little paradox.

A chemical used to remove contamination can itself become an unwanted residue if it isn't appropriately selected or used.

Cleaning compounds therefore need to be suitable for their purpose, and procedures should address their use appropriately.

The same consideration can apply to:

• sanitizers;
• lubricants;
• maintenance chemicals;
• processing aids;
• and other substances present in a manufacturing environment.

Contamination control is not merely:

“Use more cleaning chemicals.”

It is:

Use appropriate cleaning methods without creating a different problem in the process.

What Is Cross-Contamination?

Cross-contamination occurs when material associated with one product, ingredient, or process unintentionally reaches another.

Imagine a facility manufacturing Product A followed by Product B using some of the same equipment.

If equipment isn't adequately cleaned between production runs, residues from Product A might potentially enter Product B.

Cross-contamination can also occur through:

• utensils;
• transfer equipment;
• storage containers;
• personnel;
• airborne material;
• spills;
• or incorrect material handling.

This is why equipment cleaning, material identification, production scheduling, physical separation where appropriate, and good housekeeping can all matter.

Why Does Production Organization Matter?

A cluttered manufacturing environment is not merely unattractive.

It can increase opportunities for:

• material mix-ups;
• incorrect labels;
• misplaced utensils;
• cross-contamination;
• accidental use of rejected material;
• or confusion about production status.

FDA's GMP inspection guidance emphasizes adequate space, orderly storage, identification, and controls intended to prevent mix-ups and contamination.

Organization is therefore a quality-control tool.

There is a reason manufacturing facilities often care very much about what belongs where.

Water Deserves Special Attention

Water is one of the most important potential contamination routes in many cosmetic formulations.

It may be:

• an ingredient;
• used for cleaning;
• used in processing;
• or present in the manufacturing environment.

Water can carry:

• microorganisms;
• dissolved minerals;
• organic material;
• and other contaminants.

FDA's cosmetic GMP guidance recommends that water used as a cosmetic ingredient be of defined quality and regularly monitored for chemical and microbiological quality.

Water systems themselves may therefore require appropriate design, maintenance, monitoring, and sanitation.

This becomes particularly important when water is a substantial part of the finished formulation.

Why Are Water-Containing Products Different?

Microorganisms generally need suitable conditions in which to grow.

Available water is one of those conditions.

That is why many water-containing products require careful attention to:

• preservation;
• formulation;
• pH;
• manufacturing hygiene;
• packaging;
• and microbiological control.

A substantially anhydrous product may present a different microbial-growth environment.

But different risk does not mean zero risk.

Raw materials, manufacturing conditions, packaging, and consumer handling can still introduce contamination concerns.

The appropriate control strategy depends upon the formulation.

What Do Preservatives Do?

Preservatives can help control microbial growth in formulations that would otherwise support it.

But a preservative is not a substitute for poor manufacturing hygiene.

Think of preservation and GMP as complementary controls.

A formulation shouldn't be manufactured carelessly under the assumption:

“The preservative will kill whatever gets into it.”

Preservative effectiveness can depend upon:

• concentration;
• pH;
• formulation chemistry;
• microorganisms involved;
• packaging;
• and interactions with other ingredients.

Good microbiological control therefore begins with preventing unnecessary contamination and designing the formulation appropriately.

What Is Preservative-Effectiveness Testing?

For some formulations, manufacturers may evaluate whether the preservative system can adequately control microorganisms introduced under defined test conditions.

This is often called preservative-effectiveness testing or a challenge test.

Standards such as ISO 11930 describe approaches for evaluating antimicrobial protection of cosmetic products.

That does not mean every product requires identical preservative testing.

ISO 11930 itself is intended primarily for cosmetic products that are not considered microbiologically low-risk.

Again:

The test should fit the product.

Packaging Helps Control Contamination Too (or, add to it)

Once manufacturing is complete, the package becomes part of the product's protective system.

Consider the difference between:

an open jar repeatedly contacted by fingers

and

a pump bottle that dispenses product while limiting direct contact with the remaining contents.

Those packages create different opportunities for contamination during consumer use.

FDA specifically identifies inadequate packaging as one potential contributor to cosmetic microbial contamination.

Packaging decisions therefore involve more than appearance and branding.

They can influence how the formulation interacts with the outside world.

What Happens After the Consumer Opens It?

The manufacturing facility no longer controls the environment.

The customer does.

Products may be exposed to:

• fingers;
• bathroom surfaces;
• water;
• heat;
• humidity;
• applicators;
• open air;
• shared use;
• or storage far outside recommended conditions.

That is why contamination control has two phases:

Manufacturing controls reduce what enters the product before sale.

Packaging and appropriate use help limit what enters afterward.

Manufacturers cannot control every action after purchase, but product and package design can help account for reasonably foreseeable use.

Does Microbiological Testing Guarantee a Product Will Never Become Contaminated?

No.

A microbiological test examines a sample at a particular time using a particular method.

It does not create an invisible protective force field around every future unit.

Testing is valuable because it provides information.

But contamination control depends upon a broader system:

raw materials + water + facility + equipment + people + cleaning + formulation + preservation + packaging + storage + testing

That is considerably more robust than relying upon one finished-product test.

Can You Tell Whether a Product Is Contaminated by Looking at It?

Sometimes.

But not reliably.

Visible mold, unusual odor, separation, gas formation, discoloration, or other obvious changes may indicate a problem.

However, microbiological or chemical contamination does not necessarily produce an immediately visible change.

That is why manufacturers use controls and testing rather than relying exclusively upon someone looking into the container and saying:

“Looks fine.”

Appearance is useful information.

It isn't a complete analytical method.

What Happens If Contamination Is Suspected?

The affected material or product may need to be held while the situation is evaluated.

An investigation could examine:

• raw materials;
• water;
• equipment;
• cleaning records;
• environmental conditions;
• manufacturing records;
• laboratory results;
• packaging;
• retained samples;
• and related production lots.

Traceability becomes extremely important here.

If a problem can be connected to a particular raw-material lot, production run, piece of equipment, or time period, the investigation becomes much more focused.

This is another reason the topics we've covered in earlier articles—documentation, lot numbers, raw-material controls, QC, and release procedures—are interconnected.

Does Good Contamination Control Guarantee Nobody Will React to a Product?

No.

And this distinction deserves emphasis.

Contamination and individual sensitivity are different issues.

A properly manufactured, uncontaminated product can still contain an ingredient to which a particular person is sensitive.

Likewise, irritation can result from factors such as:

• concentration;
• exposure duration;
• skin condition;
• occlusion;
• repeated use;
• adhesive removal;
• or individual biology.

Contamination control addresses unwanted materials entering the product.

It does not eliminate every possible biological response to the ingredients intentionally present.

That subject deserves its own discussion later in this cluster.

Good Contamination Control Is Mostly Preventive

The best contamination problem is the one that never develops.

That is why manufacturing systems emphasize preventive controls:

Control the materials entering the facility.

Keep the facility appropriate for the operation.

Maintain and clean equipment.

Establish personnel hygiene practices.

Control water quality where relevant.

Prevent cross-contamination.

Design the formulation appropriately.

Use suitable packaging.

Test where testing provides meaningful information.

And if something unexpected occurs:

identify it, investigate it, document it, and respond appropriately.

That is much more meaningful than claiming that a product was made in a “clean facility.”

Cleanliness is a condition. Contamination control is a system.

And for products intended to come into contact with skin, understanding that difference matters.

Related Articles

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

Why Quality Control Matters 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

What Do Certifications Really Tell You About a Product?

Can Any Skin-Contact Product Guarantee That Nobody Will React to It?

Sources

• U.S. Food and Drug Administration. Microbiological Safety and Cosmetics. Discusses contamination routes including raw materials, water, manufacturing conditions, ineffective preservation, packaging, shipping, storage, and consumer use.
• U.S. Food and Drug Administration. Good Manufacturing Practice (GMP) Guidelines/Inspection Checklist for Cosmetics. Addresses facilities, personnel, equipment, sanitation, raw materials, water quality, manufacturing controls, storage, contamination prevention, records, and related GMP considerations.
• U.S. Food and Drug Administration. Product Testing of Cosmetics. Discusses microbiological safety and notes that cosmetics need not be sterile but must not contain harmful microorganisms.
• International Organization for Standardization. ISO 22716:2007 — Cosmetics — Good Manufacturing Practices (GMP) — Guidelines on Good Manufacturing Practices. International guidance addressing production, control, storage, shipment, sanitation, premises, equipment, personnel, materials and other GMP controls.
• International Organization for Standardization. ISO 11930:2019 — Cosmetics — Microbiology — Evaluation of the Antimicrobial Protection of a Cosmetic Product. Describes approaches to assessing the overall antimicrobial protection of cosmetic formulations, including preservative-effectiveness testing.