Energy Curing Users Resource Group

The chemical bonds in ozone that are generated by UV curing lamps are not very strong. As the ozone molecules drift through 30 to 50 feet of atmosphere, they revert to oxygen. There is no accumulation of ozone over time that would cause issues to the surrounding environment. Ozone generated by UV lamps has a short life and is not a concern like the ozone emissions created by internal combustion engines and other processes that the EPA regulates.

UVC output below 240 nm breaks the bonds in oxygen molecules (O2) and produces two oxygen atoms. An oxygen atom combines with an oxygen molecule to form O3. As soon as the ozone (O3) is produced, the molecules immediately begin breaking apart to form (O2 and O). The single oxygen atoms then combine with each other to form O2.

It is not easy to calculate or predict the amount of ozone generated. It depends on lamp power, wavelength emissions, and airflow. Every installation is different. To know exactly, end users need to measure ozone concentration at the lamp heat exhaust, at the exhaust duct on the roof, and at ground level. In doing so, you will find the greatest concentration of ozone is at the lamp(s).

What is emitted from the roof should just be warm and, depending on the length of duct, minimal ozone. It should be zero at vertical and horizontal distances from the roof or ground level of the plant.

Ozone emitted by mercury vapor lamps is a respiratory irritant and has an odor that is bothersome to operators and plant personnel. This is why UV curing lamps should be ducted outside the roof of the building. Exhausting to the roof provides a safe worker environment with no impact on the surrounding environment.

RadTech thanks Jennifer Heathcote, VP Business Development,
GEW (EC) Limited for preparing this response and assisting a UV user on behalf of RadTech

My company already has a robust internal hazard communication program and workers are wearing appropriate PPE, and most of the potential exposure only happens incidentally. While we recognize the need to communicate with the team about the newer hazards associated with these chemicals, we don’t want to cause alarm/panic given the new hazards are carcinogenicity and reproductive toxicity, which never sounds good. We would appreciate recommendations regarding how to communicate with employees so that they aren’t alarmed.

A: It is best to work with your safety coordinator to educate employees on the risks of chemicals and ways to minimize those risks through good chemical handling, engineering controls, and PPE. One of the key items to discuss regarding new or revised hazard warnings is that the chemical hasn’t changed; the hazard warnings are based on new information and/or regulations. Risk assessments, like the RadTech one for TMPTA, can also help with educating employees on the actual risk.

A: Quaternary Ammonium Salts can provide a degree of conductivity. Stick to the chloride versions or
carbonate/Bicarbonate versions. Cetyltrimethylammonium chloride or DDAC or similar. Sulfoquats are bad for conductivity. Ionic liquids based on imidazolines (Unamine O or C from Arxada).

A:  The first step to ensure proper cure is to practice good maintenance of UV/LED/EB equipment. LED andEB are low maintenance (but not “no maintenance”), and UV lamps are high maintenance. Old bulbs, dirty reflectors or quartz windows, substrate web out of focus and/or poorly functioning power supplies can all contribute to reduced UV energy output which in turn results in under-cured coatings, inks and/or adhesives.

For testing, there are three basic methods, please see Cure Test Methods: UV/EB/LED Coatings & Inks.
Other considerations include:

• Residence time for the product being cured. For printing operations, this translates into press or coater speed. It needs to be evaluated to ensure that the coating is not over-cured or under-cured.
• Maintenance of equipment (e.g., printing press or coating unit) is also important to make sure that the proper amount of coating is being applied to the substrate and that the substrate is being transferred correctly through the curing area.
• Ensure that the coating application equipment has been properly set up to make sure the proper amount of coating is being applied to the substrate. Too much coating on the substrate could cause curing problems.

RadTech has developed a No Significant Risk Level (NSRL) for TMPTA and studied likely exposure scenarios. This work shows that human exposure to finished UV+EB products is well below the NSRL, for the products tested. Please contact RadTech for more information.

A: “This question kicked off a good discussion in our lab.” There seems to be no regulation that prohibits the use of NVP. It is interesting now that VCAP was reclassified, and its use is now more restricted by EuPIA than NVP. But EuPIA Exclusion Policy does not apply nor is it restricted by Nestle. The two areas of emphasis in use would be Odor and Migration. It is Swiss A listed and has a No Detect for Migration. So, it probably limits the amount of use in a formula rather than exclusion.

A: Here are a few links to commercial testing labs that are familiar with the FDA Food Contact Substances
testing protocols:

• www.smithers.com/home
• www.intertek.com/packaging/testing/migration-and-food-contact
• www.qima.com/testing/food-packaging-and-containers
• foodinnovation.rutgers.edu/what-is-fic/thomas-hartman-bio

This is a bit of an unusual inquiry. The question asks about “personal care products.” Migration in packaging of this sort does not normally contact the product. Many personal care products are regulated under “Cosmetics” of the Food, Drug and Cosmetics Act (FDCA). Info on personal care products is regulated by FDA. If the company is worried about potential migration and safety, they can do testing. They could also do a risk assessment based on the ingredients and some worst-case assumptions for migration, but ultimately there is no threshold for safety with cosmetic packaging nor would there be the same amount of rigor required for the risk assessment for a cosmetic package as would be done for food packaging, which requires contaminants be less than 50 ppb to be considered “safe”.

You must comply with the Federal Food, Drug, and Cosmetic Act (the Act). Section 601 of the Act, which deals with cosmetics, states that a cosmetic is adulterated if it “has been prepared, packed, or held under insanitary conditions whereby it may have become contaminated with filth, or whereby it may have been rendered injurious to health” or if “its container is composed, in whole or in part, of any poisonous or deleterious substance which may render the contents injurious to health.” In other words, the packaging material must be sufficiently clean so that it does not contaminate the skin care product.”

www.packaginglaw.com/ask-anattorney/what-are-requirements-skin-care-packaging-materials

A: Ensure that the press operators are diligent about avoiding exposure to UV chemicals. Do they wear
adequate PPE (long sleeve shirts and pants, impervious gloves, chemical resistant disposable sleeves, safety glasses/goggles, face shields, etc.)? Do they wash chemicals off their skin quickly if skin contact does occur, using warm water and soap? Solvents or pumice soap can increase the risk of skin absorption.

If liquid materials get on clothing, remove clothing, and wash separately from normal clothes or have them
cleaned in commercial laundry. Leather items that are contaminated should be discarded.

If the coating is misting during application, that would be a health concern for exposure. Misting can appear like steam which may lead some people to not recognize the risk it poses.

Many UV chemicals have an odor which can sometimes be unpleasant. That doesn’t necessarily equate to
negative health effects.

Resin 3D printing is gaining in popularity for people crafting at home, and I’ve read many comments about the odor it generates. People are starting to be exposed to UV/LED chemicals in their homes which can increase the risk of sensitization. I frequently share the link to RadTech’s 3D printing chemical safety poster with crafters on social media.

radtech.org/safe-handling-of-3d-printing-resins

A: The first step is to evaluate the area, let the reaction finish and contact the appropriate emergency
responders. We would not advise having any employees attempt to handle the container due to safety concerns.

The response depends on the scale of the reaction. Usually, the reaction tends to generate a heat spike and
polymerize into a solid chunk of plastic. In a typical lab scale, it is often sufficient to close the hood or position additional shields around the reaction setup and move out of the room for a few minutes and let the reaction run its course. We would caution against ever moving the reaction to an outside or safe area due to the risks while moving to both the person moving the runaway reaction and to the environment on the way to the safe location.