10 Questions You Should to Know about Optical Brightener 4BK

Before we dive deep into the exciting world of optical brighteners (we know you’re on the edge of your seat), we want to tell you a bit about Dr. Pete.

A product inventor, innovator, and sustainability expert, he’s the brains behind our Bio Laundry Detergent and was a founding member of The Sustainability Consortium. Previously in our The Dirt series he’s covered topics on such things like, Hard Water and How it Affects Our Cleaning, What is Green Chemistry, and How to Remove Balsamic Vinegar Stains. Now he’s back to explain what optical brighteners are and why you should care.

Ok, so what are these things we keep hearing called ‘optical brighteners?’

Optical brighteners are often referred to as fluorescent whitening agents. Essentially, they are large molecules composed of (excuse my Science) phenyl and heterocyclic groups with conjugated double bonds. Most optical brighteners used in consumer products such as laundry detergents are with stilbene derivatives (1) or biphenyl derivatives (2). Fun fact: Stilbene means “glittering” in Greek.

For more information, please visit Ogilvy.

What is Stilbene used for?

Before these fluorescent molecules were invented in the s, blue dyes were used in laundry detergents and textiles to add a little bit of blue hue to help offset the “yellowing” of white clothes and linens due to aging and staining. But those blue dyes only make laundry visually appear whiter, not brighter. The fluorescent optical brighteners work differently by absorbing invisible UV light and turn it into visible lights in blue color. Once deposited on laundry fibers, those fluorescent molecules make clothes and sheets appear to be both whiter and brighter by hiding the yellowing hue away from our visual detections. Optical brighteners have gained huge popularity in applications for laundry detergents, textiles, cosmetics, paper, and hair care products over the years. Nowadays, millions of pounds of optical brighteners are used and discharged as wastewater into our ecosystems every year. 

Are they harmful for clothes, people, or the planet?

There are more than 400 optical brighteners that have been made in history. Due to performance, health and environmental concerns, less than 50 of them are still in mass production for commercial uses. Those remaining have much more acceptable safety profiles in terms of their toxicity to the environment and human health. However, they remain as concerned chemicals in commercial applications such as laundry detergents for the following reasons:

1. Lack of biodegradability

Once discharged as wastewater, those optical brighteners escape from water treatment plants and get released into open or underground water. They biodegrade slowly and may end up accumulating in marine lives. Some optical brighteners are acutely harmful for aquatic organisms.

2. Reproductive toxicity concerns

Under natural lighting, those optical brightener molecules slowly go through a photodegradation (the alteration of materials by light) process and break down to smaller pieces as metabolites. The data from a few research reports suggests that potential estrogen disruption and reproductive toxicity concerns from certain stilbene derivatives and their metabolites need to be further investigated.

3. Potential irritation to sensitive skin

The functionality of optical brighteners has NOTHING to do with laundry cleaning.

They are designed to dissolve in water and then absorb onto laundry fibers during the washing cycle. Resisting to be rinsed off, they stay on fibers in order to create an optical illusion to make clothes and linens appear whiter and brighter. Once absorbed and accumulated onto laundry fibers after rinsing and drying, those optical brighteners and related metabolites are in direct contact with our skin and may cause harm for some people with sensitive skin.

Wow as nerdy as this all is, it’s pretty enlightening. So then, what is the future of optical brightening in laundry products or even within household cleaning products?

Have you ever wondered how laundry detergent companies can claim their product creates “brighter colors and whiter whites”? What makes that happen anyway?

They’re referring to specific ingredients known as optical brighteners or chemical fluorescent whitening agents designed to absorb UV light to create the illusion of whiter, brighter clothes.

While optical brighteners in laundry may create the illusion of white clothes, they come with a hefty price in terms of potential health and environmental risks.

In this article, you’ll learn all about optical brighteners, including how they work, toxicity issues, how to find laundry detergents without optical brighteners, and safer alternatives for a healthier laundry room.

How Do Optical Brighteners Work?

Prior to the introduction of optical brighteners in the s, laundry detergent manufacturers would add blue dye to their products to help mitigate the natural yellowing and dulling of clothing.

This worked fairly well to whiten clothes but did not impart a brightening effect.

The discovery of optical brighteners solved this problem, and they are now used in many conventional laundry detergents.

They’re also used in textiles, hair care, cosmetics, and paper.

As previously mentioned, optical brighteners work by absorbing UV light and emitting a visible bluish-violet light. This effect enhances the whiteness or brightness appearance of white or lightly colored fabrics.

Optical brighteners used in laundry detergents are designed to permeate fabrics and build up over time, which enhances clothing’s brightness and whiteness. They are also used in clothing manufacturing to improve the appearance of clothing and textiles, extend clothing life, and enhance color.

Common Optical Brighteners Found in Laundry Detergents 

Many synthetic chemical laundry detergents contain one or more optical brighteners.

Since their discovery, hundreds of types of optical brighteners have been created, many of which have been removed from the market due to safety or toxicity issues.

The remaining types of optical brighteners are considered safer and less eco-toxic, but concerns remain about their short-term, long-term, and cumulative effects .

As usual, spotting optical brighteners on labels isn’t straightforward as they’re not labeled “optical brightener.” In addition, laundry detergent companies are not required to list all the ingredients in their products. However, now most brands allow you to view their complete ingredient lists online.

The following are the most common names for optical brighteners in laundry detergents:

• Disodium distyrylbiphenyl disulfonate (DDD)
• Fluorescent brightener
• Fluorescent brightener #71
• Fluorescent brightener 28 sodium salt 
• Tinopal CBS-X

Disodium distyrylbiphenyl disulfonate is the most common and has received a “D” from the Environmental Working group due to toxicity issues, which we’ll discuss next.

For more information, please visit Optical Brightener 4BK(pt,th,tr).

Are Optical Brighteners Safe? Health and Environmental Concerns

Toxicity issues with optical brighteners, which are persistent on fabrics and in water systems, soil, etc., can negatively impact people and the environment.

Environmental Impact

The optical brighteners in use today are considered more environmentally friendly than those from the past.

However, studies suggest these are persistent environmental chemicals, meaning they biodegrade slowly, which creates more significant exposure to animals and aquatic life.

Health Risks 

Optical brighteners are designed to permeate fabrics and accumulate over time, which enhances their brightening effects.

Unfortunately, this means the more you wash your clothing, sheets, towels, etc., the more optical brighteners you’re exposed to.

Plus, since optical brighteners biodegrade very slowly and may not be filtered out by water treatment plants, many people likely ingest them through tap water.

This is problematic because studies suggest a possible link between optical brighteners used in laundry detergents and reproductive toxicity, skin and eye irritation, and developmental toxicity.

How to Find Laundry Detergents Without Optical Brighteners + Safer Alternatives

Optical brighteners may do a great job brightening colors, but there are plenty of less toxic options to achieve the same results.

When looking for laundry detergents without optical brighteners, always choose the most natural and least toxic options available. 

That means avoiding  laundry detergents with harmful ingredients , which may include optical brighteners (along with dozens of other potentially harmful ingredients). We discuss this at length in: How To Toss Your Toxic Laundry Detergent.

Branch Basics, for example, is  Made Safe certified, biodegradable, ultra-gentle, fragrance-free, optical-brightener-free Concentrate you can use to make your own safe and natural laundry soap. 

Paired with our best-selling Oxygen Boost, which naturally brightens and whitens clothes using the power of natural baking soda and sodium percarbonate, it’s a human—and environmentally safe—match made in laundry heaven!

Get more tips on choosing a healthier laundry detergent in: 5 Best Laundry Detergent Alternatives Without Chemicals.

Ditch Optical Brighteners With Branch Basics

Most of us have been taught we need harsh synthetic laundry detergents to get our clothing clean, fresh, bright, white, and stain-free. 

Yet, this couldn’t be further from the truth!

In reality, nature, in the form of natural soaps, surfactants, minerals, salts, and enzymes, provides everything we need to clean our clothes, remove stains, and whiten and brighten whites without polluting our bodies or the environment.

Branch Basics Laundry Detergent. is incredibly convenient and simple to use, requiring just one scoop per load with no additional products needed and thoughtfully formulated with your health in mind. It does not contain fragrance, dyes, optical brighteners, ammonia, chlorine, endocrine disruptors or 1,4-dioxane. It excels in stain removal, odor elimination, and fabric preservation, streamlining your laundry routine.

Plus, it's good for the earth! This powder is biodegradable, septic-safe and prevents toxic runoff. Because it performs excellently in cold water, it saves energy and protects your fabrics. 

We also have sustainably sourced Wool Dryer Balls to round out your healthy and eco-conscious laundry experience.

For more information, check out: Branch Basics Laundry Instructions.

Eager to learn more about human-safe laundry and stain removal? Check out the following articles:

Are you interested in learning more about Optical Brightener CBS-X? Contact us today to secure an expert consultation!