PLA 3D filament Safety Report.

This report will outline the relevant safety characteristics of PLA when used as a 3D printer feedstock. These uses include being heated to 200°C in poorly ventilated areas and contact with porous unprotected skin.

There are limited numbers of long term studies investigating the cumulative effects of exposure to 3D printing materials due to the relative infancy of the technology. Some pertinent studies have been conducted, the results of which are to follow.

While the conclusions arrived at in the following report indicate that PLA extrusion is relatively safe, some mitigating safety precautions have been outlined at the end as insurance against the lack of specific, long term investigations.

 

PLA Safety:

(1) PLA is Food Safe.

PLA was investigated by a team of scientists on behalf of the FDA to assess if it could be deemed safe for use in food products. They concluded that even in worst case scenarios, "PLA is safe and 'Generally Recognized As Safe' for its intended uses as a polymer for fabricating articles that will hold and/or package food."

While PLA is food safe, ingestion may cause gastrointestinal distress, nausea and/or vomiting. This is only a risk where large quantities are consumed orally and not a risk at the rate of ingestion possible through inhalation.

PLA can cause mild irritation if it makes contact with an exposed eye. This should not happen through the use of PLA as a 3D filament.

PLA enjoys a HIMS and NFP safety rating of 1 and is subject to an exposure limit by neither OSHA nor ACGIH.

While our PLA feedstock is food safe, the above simply points to the safety of PLA as a raw material. It can not be extrapolated from the above findings that 3D printed PLA models are safe for use as a receptacles or instruments to store or manipulate food.

While we can ensure strict quality control guidelines in the manufacturing process, the above findings do not take into account the possible contamination of PLA during the extrusion process. 

For example, many extrusion nozzles are machined from brass. Brass contains lead and lead is poisonous to humans.

Another factor to take into account when considering the disparity between the safety of PLA feedstock and PLA printed models is that the nature of FDM leads to many porous and minute ridges, gaps and hollows between layers of 3D filament. These areas can become ideal breeding grounds for a host of bacteria and other microorganisms.

(2) PLA FILAMENT is Made From Benign Organic Starches:

PLA is made of natural fibers and is 100% biodegradable. It can be completely decomposed making it one of the most sustainable and environmentally friendly 3D filament polymers available. Your obsolete prints need not clog up a landfill.

Due to its natural starch composition, it produces a pleasant, sweet smell when extruding.

While this is a pleasing consequence of the organic starch composition of PLA, it is not a measure of the relative safety of the material.

PLA is manufactured using fermentation, dehydration and lactide polymerization of corn starch and other similar materials. An infographic, including source material, reproduced with the kind permission of Viraj Joshi of MIT can be seen below.

While it is possible to compost and recycle your PLA prints, the conditions needed to achieve this are more complex than tossing them into the standard compost heap and allowing nature take it's course.

Heat and moisture are needed to break down the polymer chains. These smaller polymer chains are then broken down into lactic acid, a readily abundant substance that plays a vital role in the biosphere. The appropriate degrees of heat and moisture may be difficult to achieve in a home composting heap, you can bring your failed prints to a professional composting enterprise to complete the recycling process.

(3) Auto Ignition Risk.

The auto ignition temperature of PLA is 388°C, far above hazardous levels.

While this would ensure that autoignition is unlikely during your 3D printer's normal operation, a faulty controller can allow temperatures to reach 388°C and above. We therefore recommend that prints be monitered intermittently, a smoke alarm is positioned within close proximity of the 3D printer and that a fire extinguisher is readily available. For more details about the most appropriate fire extinguisher medium, please consult the safety precautions section below.

PLA Safety Concerns:

(1) Acrylic Acid Production.

While acrylic acid is produced when PLA is thermally decomposed or melted, this only happens at temperatures greater than 250°C. The new formulation of Ink3D.ie PLA only requires the filament to be heated to between 170°C and 200°C. The older formulation only required the filament to be heated to between 190°C and 210°C. This discrepancy allows for a significant margin of error on the part of the user or 3D printer itself before hazardous acrylic acid is produced.

(2) The Presence of Tin.

While tin is used as a catalyst in the production of PLA, the residual trace amounts that may be present are orders of magnitude less than would be ingested when eating canned food. Even if 100% of residual tin present in the PLA filament was inhaled, the quantities are so insignificant that they are not of any danger to human health.

(3) The Production of Ultrafine Particles (UFPs).

While the production of UFPs is far more prevalent in the extrusion of ABS, PLA does produce a moderate amount of UTP's too. PLA UTPss differ from ABS UFPs in composition due to the nature of the material themselves.

PLA UTP's are demonstrably safer than ABS UTP's and are even used in some instances as a bioavailable drug delivery system for certain medicines. (Lassalle, 2007).

While PLA UFPs can act as a substrate for drug delivery, the diameter of the nano particles is an important factor. The aforementioned study refers to nano particles ranging from 6.6 nm to 1402 nm. The UTPs produced during 3D printing filament extrusion range from 10-100nm. While this is within the range above and does indicate that the size of UTPs produced by 3D printing are similar to PLA UTPs used as drug delivery vehicles, the inherent nature of the UTPs may be different and as a result we would advise you to read the safety precautions section at the bottom of this article.

PLA UFPs 3D Filament

While PLA produces UTP's at an order of magnitude less than ABS (Stephens, 2013), and the nature of these UFP's are different, safety precautions are outlined below to limit their environmental presence.

(4) Carbon Monoxide Production.

Because PLA is an organic compound, small amounts of CO are produced when it is combusted. Extrusion of PLA does not require combustion nor does it produce quantities of CO large enough to warrant concern. CO is also produced by household fires and barbeques, adequate ventilation should alleviate any concerns.

(5) Evacuation of Molten Plastic from Extrusion Nozzle.

Some low quality PLA is made from recycled bead stock. This bead stock can become contaminated with foreign materials during the recycling process, the volatility and behaviour of which is not accounted for in the above points.

Contaminated PLA may also contain dust and water particles.

Because of the hydrophilic nature of PLA, it has a tendency to absorb water over time. Water particles, if present in the filament, are exposed to temperatures greater than 100°C. They then boil and create pockets of steam. These pockets of steam are prone to exploding causing the print to fail, filament to warp and molten plastic to evacuate the machine onto the surrounding surfaces.

Mitigating the Aforementioned Health Concerns of PLA Extrusion.

(1) Use high quality PLA.

By using high quality PLA you can be sure of the chemical content of the material you are extruding.

Ink3D.ie PLA is made from 100% virgin material polymer bead stock, never recycled material. Our PLA is vacuum sealed with desiccant immediately upon spooling to ensure no contamination or water absorption occurs.

(2) Ensure Good Ventilation.

While the presence of PLA UTP's should not be a concern to those exposed to it, ensuring good ventilation of the room in which the 3D printers are operating is a good insurance policy and can provide peace of mind. It should be noted that ventilation should facilitate a consistent temperature within the room in question so as to not affect the 3D printer settings.

Good ventilation also ensures that the small amounts of carbon monoxide that may be produced are evacuated from the environment.

(3) Install an Activated Carbon Filter.

Activated carbon filters provide another layer of insurance against the presence of UTP's. Run a fan aimed at an activated carbon filter to achieve the desired result. Activated carbon is a widely used and competent medium for the filtration of air and liquids. Once the filter is saturated with filtrate it can be replenished by exposure to UV light. This makes activated carbon filters a cost effective solution (Weber, 1995).

(4) Irritation response.

Irritation may occur in rare circumstances. Please consult the following list if needed:

Eye Contact: Rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes. Call a physician immediately.

Skin Contact: Rinse immediately with water for at least 15 minutes. If irritation persists, call a physician. Cool skin under cold water immediately upon the exposure to melted polymer.

Inhalation of large quantity of material causing nausea or dizziness: Move to a well ventilated area, call a physician immediately.

(5) Unintended or uncontrolled combustion.

While the combustion temperature of PLA in 388°C, should you need to extinguish it the following methods will suffice:

Foam, water, C02 or dry chemical. Alcohol resistant foams are preferred if available. General purpose synthetic foams will work to a lesser degree.

Conclusion.

In summary, while we at Ink3D.ie believe the current scientific literature indicates that the use of PLA as a 3D printing filament is relatively safe when compared to other materials, more specific and long term studies need to be completed before an absolute statement can be made. While we have no ethical hesitations in selling or recommending our products to the public, we would advise that the aforementioned precautions are put in place to mitigate unforeseen problems in the future.

It should be noted that we have taken care to include all the possible health problems of PLA, even though many of them are rare and unlikely to occur.

While there are some safety concerns, many of which can be avoided by using premium quality material such as ours, we believe the mitigating factors outlined above should more than compensate for any future revelations regarding potential health risks.