3D printers toxic

3D Printing Safety at Work | NIOSH

3D printing, or additive manufacturing, is increasing in popularity. This technology is becoming less expensive and more accessible to both businesses and consumers. It is currently used in a wide variety of settings, such as labs, factories, hospitals, schools, libraries, and homes. Despite its popularity, 3D printing is still a relatively new technology and there are many gaps in the information available about health and safety risks. The National Institute for Occupational Safety and Health (NIOSH) is studying the potential hazards of 3D printing and ways to reduce health and safety risks for workers.

What is 3D printing?

3D printers create three-dimensional (or 3D) objects via computers. A computer file “tells” the 3D printer what object to create and how. 3D printers essentially stack layers of a material to get the desired product. Different types of 3D printers do this in different ways. For example, some use high temperatures, some use ultraviolet light, and others use lasers. 3D printers also use different print materials, such as plastics, rubbers, and metals.

Industries traditionally used 3D printing for prototyping. However, it is now also used for production. Industries using 3D printing include the automotive, aerospace, electronics, medical, and many others.

Potential Hazards of 3D Printing

3D printing hazards vary depending on the type of printer and materials used. For example, print materials that are powders are more likely to be inhaled or cause skin problems than others. 3D printers that use lasers have different hazards than printers that use high temperatures to melt materials. Some common hazards include:

Breathing in harmful materials: 3D printing can release particulates and other harmful chemicals into the air.
Skin contact with harmful materials: Users can get hazardous materials, such as metal powders, solvents and other chemicals, on their skin.
Static, fire and explosion: Some materials used can be flammable or combustible. High temperatures from some printers can cause burns.

Ways to Protect Workers from 3D Printing Hazards

NIOSH has studied multiple ways to reduce exposure to 3D printing hazards. Some options include

Limiting equipment access to trained or authorized personnel
Using enclosures for 3D printers and ventilation to capture chemical emissions
Using materials with lower emissions
Reducing time spent near the printer while it is running
Training workers on potential hazards and how to protect themselves
Wearing appropriate personal protective equipment, such as safety glasses, gloves, or lab coats

The ways to reduce exposure depend on the type of printer and materials used. NIOSH has created two posters to help workers explore ways to reduce potential 3D printing hazards. One poster focuses on 3D printing with metal powders and the other focuses on filaments:

3D Printing with Metal Powders: Health and Safety Questions to Ask
3D Printing with Filaments: Health and Safety Questions to Ask

Help NIOSH Learn More about 3D Printing

Do you use 3D printing in your workplace? You can help NIOSH continue assessing 3D printing hazards and controls. Companies can contact the Nanotechnology and Advanced Materials Field Studies Team to assess possible work-related health hazards with 3D printing in their workplace.

More Information

Additive Manufacturing
NIOSH Science Blog: Characterizing 3D Printing Emissions and Controls in an Office Environment
3D Printing with Metal Powders: Health and Safety Questions to Ask
3D Printing with Filaments: Health and Safety Questions to Ask

3D Printers May Be Toxic To Humans

The particles released during the printing process, which are small enough to infiltrate deep into ... [+] the lungs, can affect indoor air quality and public health.

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Several new studies found that 3D printers emit toxic particles that may be harmful to humans.

The studies, presented at the 2020 Society for Risk Analysis virtual Annual Meeting on December 15, showed that the particles released during the printing process can affect indoor air quality and public health.

For the uninitiated, 3D printers typically work by melting plastic filaments or other base materials such as nanoparticles, metals, thermoplastics etc. and then stacking the melted materials layer upon layer to form an object. When the plastic or other base materials are heated to melt they release volatile compounds into the air near the printer and the object.

The chemical by-products and particles that are released into the environment during the printing process can build up the longer the process takes and some are small enough that they can infiltrate the lungs, causing damage.

The studies presented today at the meeting looked at various types of emissions and how great the risk is.

For example, two of the studies from the Environmental Protection Agency (EPA) analyzed the emissions from a 3D printer filament extruder - a device used to create 3D printer filaments - and then used a simulation model to see how many particles were produced, as well as where they were deposited when using a 3D printer in different age groups.

The studies found that the filament extruder released amounts of small particles and vapors similar to those found in other studies of 3D printers, and the simulation model predicted higher deposition of particle mass per surface area in the lungs for children ages nine and younger. But more research is needed to determine how much the inhaled dose would be.

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Another one of the studies presented, conducted by Yong Qian from the National Institute for Occupational Safety and Health, looked at the potential toxicity of acrylonitrile butadiene styrene (ABS) emissions generated during 3D printing by examining human lung cells and rats exposed via inhalation. It revealed that the emitted particles cause moderate toxicity in human lung cells and minimal toxicity in rats.

It’s also worth noting that while much of this research presented today is still early stages, it does add to the growing evidence of the potential toxicity of 3D printers.

For example, research published last year found that both ABS and polylactic acid (PLA) particles negatively impacted cell viability, with the latter prompting a more toxic response.

"The toxicity tests showed that PLA particles were more toxic than the ABS particles on a per-particle comparison, but because the printers emitted so much more of the ABS — it's the ABS emissions that end up being more of the concern," said Rodney Weber, a professor in Georgia Tech's School of Earth & Atmospheric Sciences, who led the research. "Taken together, these tests indicate that exposure to these filament particles could over time be as toxic as the air in an urban environment polluted with vehicular or other emissions."

The study also found that the hotter the temperature required to melt the filament, the more emissions were produced and ABS particles emitted from the 3D printers had chemical characteristics that were different than the ABS filament.

"When the filament companies manufacture a certain type of filament, they may add small mass percentages of other compounds to achieve certain characteristics, but they mostly do not disclose what those additives are," Weber said. "Because these additives seem to affect the amount of emissions for ABS, and there can be great variability in the type and amount of additives added to ABS, a consumer may buy a certain ABS filament, and it could produce far more emissions than one from a different vendor."

This is important especially as 3D printers become more commonplace in homes, schools and other places where people spend a significant amount of time.

"To date, the general public has little awareness of possible exposures to 3D printer emissions," said Peter Byrley, one of the lead authors of the EPA studies, in a statement. "A potential societal benefit of this research is to increase public awareness of 3D printer emissions, and of the possibly higher susceptibility of children."

And 3D printing might not just be harmful to humans, another study conducted by Joana Marie Sipe from Duke University, found that the bi-products from the plastics made by the printer can also be damaging to the environment.

For the study, Sipe developed a machine that can measure how much a plastic product, like a water bottle, can break down through rubbing and sanding during use and in the environment. The plastic particles were then fed to fish to see the effects that the nanoparticles in the plastic had on their organs.

What she found was that when the plastics breakdown, the nanomaterials that were incorporated become exposed to the environment. The researchers were able to predict the percentage of nanoparticles that came out of the plastic when they were eaten by the fish, providing a Matrix Release Factor (MRF) which could be used to find out the quantity of plastic and nanoparticles that are released when someone chews a product or when it breaks down in the ocean.

"This research can help set regulations on how much nanomaterial fillers can be added to particular consumer products, based on their MRF value," said Sipe in a statement. "The data can help determine how much plastic and/or nano-filled products release contaminants into the environment or the human body. "

So while 3D printing makes numerous products more readily available, and at cheaper costs, as we’ve seen with the manufacturing of Covid-19 face shields, respirators and other personal protective equipment, it’s important to consider the potential risks. And as 3D printing technologies become more widespread, regulators, manufacturers, and users may need to focus their attention on better managing those risks.

For example, some measures that can be taken by operators of 3D printers to lessen their impact on air quality include:

Operating 3D printers only in well-ventilated areas
Setting the nozzle temperature at the lower end of the suggested temperature range for filament materials
Standing away from operating machines
Using machines and filaments that have been tested and verified to have low emissions.

How safe are 3D printing resins?

Filament Deposition Modeling (FDM) material extrusion is the most popular polymer 3D printing method, but resins are becoming more and more important to consumers. Resin technologies such as stereolithography (SLA) were previously only used in dental laboratories, engineering departments and manufacturing plants due to the high cost of the equipment. Now that machines have become more affordable, more and more ordinary users are using SLA technology, which calls into question their safety.

Unlike FDM devices, resin printers use photosensitive liquids to print, curing materials with ultraviolet light. Liquid polymers pose a greater potential health risk than raw materials in fiber form. The toxicity of the resource may put off some users, but printing with resin can be safe if the right algorithm is followed.

What are the Potential Risks of Resins

The word "toxicity" is troubling, but according to definitions developed by occupational health and safety professionals, any substance that, under certain conditions, can cause health problems or disease, is "toxic". According to this formulation, many substances around us are potentially dangerous, including perfumes and mattress filling. But are there any particular risks when using liquid resins for 3D printing?

The main concern with photopolymer resins is that they can cause skin irritation on contact. In some cases, contact of the substance with unprotected skin results in burns and blisters, which may require medical attention. If the materials come into contact with the eyes, they will cause irreparable damage.

Many resins are sensitizers, which means that prolonged exposure sometimes causes a mild allergic reaction. The chemicals that make up most resins are irritants that provoke the appearance of dermatitis - inflammation of the skin due to rejection of foreign elements. The skin quickly absorbs such chemicals, so prolonged contact with the composition or exposure to a large dose can lead to more serious consequences.

Another problem with resin 3D printing is air pollution. The material releases fumes, potentially reducing indoor air quality (IQA). Poor IQA scores can lead to headaches, fatigue, or more serious reactions such as breathing problems. These effects are due to volatile organic compounds (VOCs) and other small particles that cause an inflammatory response in the airways, leading to swelling or tenderness.

Long-term effects from working with liquid polymer are rare but significant:
• If the vapors are inhaled for a long time, chronic diseases of the respiratory system may appear.
• Some of the VOCs emitted by resins are suspected to be carcinogens, so they are likely to cause cancer after prolonged exposure.
• Constant physical contact can lead to severe allergies.

Standards and manufacturer's instructions

On the other hand, most resins on the market do not pose a significant hazard. Companies that produce such materials must comply with government standards and additional recommendations ISO 9001. Regulations ensure that chemicals produced by businesses are minimally harmful. However, some hazardous elements, such as asphalt fumes and synthetic mineral fibers used in fiberglass, are still widely used and over half a million workers are exposed to them.

Manufacturers usually provide Material Safety Data Sheets (MSDS) that list any potential health concerns. For example, corneal burns from overexposure to the eyes, or nausea and vomiting if swallowed. All these documents are provided in order to provide users with maximum safety when using consumables.

Some compounds may be more dangerous than others for certain people. If a person does not know if they are allergic to any materials, they should act as if they are and handle the product with care.

Safety Steps

Several government agencies have conducted research into the safety of epoxy 3D printing. They all showed that long-term emissions from printing are mostly negligible, although risks exist if proper precautions are not taken. Since studies have found traces of hazardous substances when working with resin formulations, safety regulations must be observed.

3D printing resins are not as scary as they seem, but they still need to be handled with care. First of all, direct contact of the mass liquid with any part of the body must be avoided. Safety goggles and nitrile or latex gloves should always be worn to prevent toxins from getting into the eyes or onto the skin.

Also make sure that the workplace is well ventilated. Ventilation is critical for any 3D printer, but especially for resin printing equipment. It is best to work under an exhaust hood, but if this is not possible, it is advisable to print near an open window with a fan.
Read the safety data sheet from the manufacturer before opening the photopolymer container. If there are any special instructions regarding the use of the material, then they are reflected in the document.

Finally, residues or waste must not be dumped into the sewer, as this can be harmful to the environment. Either dispose of it in the manner recommended by the manufacturer, or dry with UV light until the mass hardens.

Resin printing is safe when proper precautions are taken
When the user knows what risks resin compositions present, he will be safe from trouble. Although 3D printing consumables are toxic, but if the safety procedures are strictly followed, then working with these materials becomes not dangerous. With the right precautions, there is no reason to avoid 3D printing with resin.

Potential hazards of the 3D printer. Part 2 Consumables

In the first article, we talked about the dangers that await the owner of the printer if the device is used improperly. Let's imagine a situation where a person received an electric shock due to the open body of the device or inadvertently touched a heated extruder, receiving an unpleasant burn. These events will clearly indicate the culprit of the incident, his negligence and disregard for safety requirements. They cannot be completely eliminated, but the likelihood of their occurrence can be seriously reduced by following the manufacturer's instructions and common sense.

However, when working with a 3D printer, we inevitably expose ourselves to the risk of another property, which is much more difficult to deal with: inhalation of harmful substances released during the melting of consumables.

Let's make a reservation right away - in this material we do not set ourselves the goal of describing all possible consumables. Despite the expansion of the range, the main raw materials for the FDM printer are still two types of plastic: ABS and PLA. In addition to them, other filaments will be mentioned in the article, however, we will focus on these polymers. So, let's try to understand together how dangerous printing consumables are. First, a few terms.

ABS (acrylonitrile butadiene styrene, ABS) is an opaque thermoplastic material made from acrylonitrile, 1,3-butadiene and styrene monomers. Hard and strong even at low temperatures, it has good resistance to heat, chemicals and is easy to process.

PLA (polylactide, PLA) is a polyester based on lactic acid. Plants are used as its basis: corn or sugar cane.

Plastics are not hazardous at normal room temperature. A huge number of things are made from ABS, including cases of household appliances, stationery and children's toys. Polylactide is used for the manufacture of disposable tableware, medical products and other items with a short service life.

In Russia, plastic products are certified or declared (depending on the type of product) for compliance with safety requirements upon release. In our country, these requirements are spelled out in GOSTs or the Technical Regulations of the Customs Union. For example, there are TR “On the safety of toys”, “On the safety of packaging”, and so on, where, among other things, the standards for the content of residual chemicals are prescribed.

A certificate or declaration guarantees that the items in question are safe under normal use, which is why most plastic toys are made of ABS plastic. The main problems begin when the polymers are heated and melted. Surely everyone is familiar with the unpleasant smell of melting plastic. This smell indicates the release of various chemicals into the air, not all of which are harmless.

So, let's try to figure out what are the dangers of heated plastic?

1. Harmful fumes of the starting material

During melting, part of the polymer inevitably passes into a gaseous state and mixes with air. The type of starting material depends on the plastic. Due to the fact that natural ingredients are used to make PLA, it is considered to be biocompatible and safe for humans when melted. But in fact, there are practically no laboratory studies confirming this fact.

ABS plastic is a petroleum-based material, which already implies increased toxicity when heated. Unfortunately, the standards for the content of acrylonitrile butadiene styrene in the air in our country have not yet been released. GN 2.1.6.1338-03 “Maximum Permissible Concentrations (MACs) of Pollutants in the Atmospheric Air of Populated Areas” mentions acrylonitrile butadiene styrene dust, but it can be obtained at home only by grinding a plastic product, and not by printing.

Is ABS plastic safe? We asked an expert to answer this question.

Denis Cherepovich, head of Alfa-filament company:

“ABS (acrylonitrile butadiene styrene) is a copolymer of acrylonitrile with butadiene and styrene. From the name it is clear that three monomer substances are used in the production of this polymer. Accordingly, these three monomers may be present in residual amounts in the total bulk of the polymer. All, absolutely all, without exception, manufacturing plants have strict output control on the content of residual monomers. This data can be found in the hygiene certificates for ABS granules.

During printing, heating of the polymer in the nozzle causes it to melt and, accordingly, a certain amount of residual monomers is released from the plastic mass. I note right away that not all of the mass of residual monomers enters the air during melting.

Next, I will make a small reference to normative documents and concepts in order to freely use the data in the future and not cause questions from readers.

Maximum allowable concentration of a hazardous substance. This parameter shows the maximum concentration of a substance in the air, which does NOT have harmful effects and does NOT lead to the development of pathologies and diseases in the human body. There are quite a lot of MPC values for different living conditions, I will give further MPC of substances in the working area of enterprises (MPC). The data are taken from the normative legal document "Maximum Permissible Concentrations (MPC) of harmful substances in the air of the working area GN 2.2.5.1313-03", approved by the Chief State Sanitary Doctor of the Russian Federation on April 27, 2003.

MPCrz - the maximum concentration of substances in the air of the working area, with which, with an 8-hour working day and 40 working hours a week, no harmful changes occur in the human body.

Hazard class - conditional value, designed for quick classification of substances according to the degree of danger:
class 1 - extremely hazardous
class 2 - highly hazardous
class 3 - moderately hazardous
class 4 - low hazardous
class 5 - practically non-hazardous.

Let's analyze what kind of substances can be contained in ABS plastic and what are their properties:

Butadiene - a gas with a characteristic unpleasant odor, hazard class 4, MPCrz=100mg/m3. This gas is practically not dangerous to the body.

Styrene - MPCrz = 30 mg/m3, hazard class 2. Colorless liquid with a pungent odor, practically insoluble in water, volatile. Causes complex lesions of the nervous system, irritation of the mucous membranes.

And finally, the most dangerous substance:

According to the hygiene certificates of Russian manufacturers of conventional ABS, the content of residual acrylonitrile in the granulate is no more than 0.001%. For foreign manufacturers (Samsung, LG, Kumho, Ineos, etc.), these figures are even lower. In food and medical ABS plastics, this value is almost zero.

Now, having all the data, we can calculate how much ABS plastic needs to be processed/printed per hour in our room in order to reach the MPC of acrylonitrile equal to 0.5 mg/m3 (we make all calculations in terms of 1 hour, because do not forget that in 1 hour all the air in the room changes):
1) MPC = 0.5 mg/m3 multiplied by the volume of the room 25 m3:
0. 5 x 25 = 12.5
12.5 mg of gaseous acrylonitrile is the maximum allowed in our room
2) Next, we find what is the mass of ABS plastic contains 12.5 mg of acrylonitrile:
12.5 / 0.001% = 12.5 / 0.00001 = 1,250,000 mg, which is equal to 1250 g or 1.25 kg

Thus, we conclude: to achieve MPC of acrylonitrile in a room with a volume of 25m3, we need to process / print 1.25 kg of ABS plastic per hour, which is absolutely unrealistic.

Also, do not forget that in order to predict the most pessimistic scenario, we took into account many conventions: ABS is the most common and contains the maximum possible amount of acrylonitrile, all the monomer was released into the air during printing, the operator is constantly indoors, the ventilation in the room is only natural .

I hope that the calculation principle has been explained clearly, and exactly the same principle the reader will be able to calculate the "dangerous print speeds" of PLA, HIPS, SAN, MABS, PEEK, ASA, POM and other polymers.

In conclusion, I would like to once again assure users of the safety of FDM technology and wish them good luck in all their endeavors.”

2. Decomposition of the substance into monomers

Another danger is the decomposition of a part of the plastic into toxic components when heated and melted.

Irina Nikitina, Head of the Occupational Safety Control Department of the Federal State Budgetary Institution TsNMVL, an expert in special assessment of working conditions:

“The process of heating or melting plastics releases extremely toxic gases into the environment. Much depends on the type of active substance. In the solid state, plastics are relatively safe, but when melted, they can partially decompose into components, or oxidize and form other chemicals.

Let's take ABS plastic, that is, acrylonitrile butadiene styrene. It is a strong and resistant polymer used in many industries. Non-toxic under normal conditions. At present, there are no maximum permissible indicators regulating the concentration of this substance in the atmospheric air and the air of the working area in Russian state standards. However, the monomers that make it up are well known - these are acrylonitrile, butadiene, styrene (the very name of ABS plastic is formed from the initial letters of the names of the monomers). At a temperature of about 400ºС, acrylonitrile butadiene styrene partially decomposes into these monomers.

When released into the air, styrene can cause both acute reactions and chronic diseases of the liver, kidneys, and circulatory system. Butadiene-1,3 has a general toxic and irritating effect. Vapors of poisonous acrylonitrile are 20 times more toxic than styrene, signs of poisoning are headaches, weakness, sleep disturbances, memory loss, and general fatigue.

At elevated concentrations of these substances in the air, a person may experience a sharp and unpleasant odor. For example, the smell of styrene partially resembles acetone and alcohol.

To determine the exact concentration of a harmful substance released into the atmosphere, it is necessary to use chemical analysis methods and special equipment, such as gas analyzers. Therefore, regardless of whether a specific type of polymer is in the regulatory documents or not, it is necessary to follow simple rules: work in rooms with a ventilation system or good ventilation, install a local suction and pay attention to pungent odors. If any appear, it is better not to risk it, but to leave the room and ventilate the room.

It must be remembered that in industrial enterprises, the employer monitors and is responsible for working conditions, while when working at home, all potential dangers fall on the shoulders of the owner and household members.

Let's give an example from foreign practice. A study conducted in 2016 by a group of scientists from the Illinois Institute of Technology confirmed that the threat of releasing harmful substances into the air does not come from printers, but from consumables. More than 10 types of filament were tested by the Institute staff. The results showed that the level of harmful particles and vapors depends mainly on the filament material, and not on the type of printer.

When using ABS plastic, traces of styrene, a substance that is dangerous and carcinogenic, were found in the air. Nylon-based materials exuded caprolactam, less harmful than styrene, but also capable of causing poisoning. Polylactide released a harmless substance called lactide into the air. At the same time, nothing is reported about the concentrations of substances.

3. Ultrafine particles (nanoparticles)

Another risk factor is associated with ultrafine particles (nanoparticles) with a diameter of less than 1 micron, which are released in large quantities during 3D printing. These particles can penetrate directly into the alveoli of the lungs and the epidermis, causing various respiratory disorders and allergic reactions. Inhalation of toxic nanoparticles can cause lung pathologies in humans, such as bronchitis, tracheitis, and asthma. At the same time, the risk index for ABS is 3 to 30 times higher than for PLA. In tests conducted by Italian scientists Fabrizio Merlo and Stefano Mazzoni, it turned out that the time for which the content of nanoparticles in the air returns to normal levels is from 10 to 30 minutes after the end of the 3D printing process.

How can this be dealt with and the risks minimized? First, filtering. A number of devices are already using high efficiency (HEPA) filters that can purify the air before it leaves the 3D printer. Of course, this is not a panacea. Some ultrafine particles are as small as 15 nm, while HEPA filters typically have a bandwidth of 300 nm.

An additional barrier is also the closed housing of the device, which partially traps harmful fumes. It is these two factors that can contribute to protection against the overwhelming number of nanoparticles. According to the latest study from the Illinois Institute of Technology, a closed chamber 3D printer reduced UPF emissions by 74%, and an additional HEPA filter helped to increase this figure to 9one%.

Scientists also advise to work in well-ventilated rooms: it is ideal to use a ventilation system that can change the entire volume of air in the room three times per hour. This means that a 100 m3 room would require a ventilation system capable of handling 300 m3 of air per hour. 4. Other substances and impurities that are released when using plastic ammonia, cyanuric acid, phenol and benzene.

The presence of specific substances depends on the thread, or rather on the polymer of which it is composed. Both the filament itself and the plastic must have documents confirming the composition of the material and the residual content of impurities. Often these are the same certificates of conformity that we wrote about at the beginning of the article.

Plastics produced abroad have their own safety certificates. For example, the Alfa-filament company uses granules for the manufacture of ABS filament, which have food and biocompatible approvals from the FDA - the US Food and Drug Administration. However, regardless of the country of manufacture, the plastic manufacturer is obliged to have such documents and make them available to potential buyers.

Unfortunately counterfeit filament is not uncommon in the world market. In low-quality materials, the amount of harmful substances is many times higher than the established norms. For example, poisonous hydrocyanide was found in one type of Chinese ABS plastic. Therefore, before purchasing consumables for 3D printing, make sure the seller is reliable and, if necessary, ask him to provide documents confirming the safety of the filament.

But do not despair, because the problem of counterfeit filament is still more relevant for the world market than for the domestic one. The largest Russian companies guarantee the quality of their own products and often post all permits on their own websites, and sometimes conduct independent tests of their products. So, in 2015, the Russian manufacturer of consumables REC, with the help of an accredited testing laboratory, carried out its own measurements of the concentration of chemicals in the air during 3D printing with its own filament. In total, 5 types of plastic were used: ABS, PLA, FLEX, RUBBER, HIPS.

It turned out that HIPS, FLEX and RUBBER filament do not emit toxic substances at all during printing. When printing PLA plastic, acetone is formed, ABS plastic exuded vinyl chloride, however, in no case were values even close to the MPC of the air in the working area recorded.

Let's summarize how to protect yourself from the harmful effects of plastic fumes:

1. Use a ventilation system. In particular, the researchers advise working in well-ventilated areas: it would be ideal to use a ventilation system that can change the entire volume of air in the room three times per hour. If there is no ventilation, open windows and try to be as little as possible in the same room as the printing printer.

2. Pay attention to smells. A strong odor indicates an increase in the concentration of the active substance. Take extra precautions or leave the room altogether.