Toxicity Investigations on Liquid Crystals
Liquid crystals are constantly subjected to toxicity and eco-toxicity testing for any hazard potential. The result:
- are not acutely toxic,
- but may have an irritant, corrosive or sensitizing effect in rare cases. Any effects can be avoided by using a limited concentration in mixtures.
- are not mutagenic – neither in bacteria (Ames test) nor in mammalian cells (mouse lymphoma assay or chromosome aberration test),
- are not suspected of being carcinogenic,
- are not hazardous to aquatic organisms (bacteria, algae, daphnia, fish),
- do not possess any significant bioaccumulation potential,
- are not easily biodegradable.
The statements are applicable to EMD Performance Materials as well as its competitors JNC Corporation (formerly Chisso Corporation) and DIC (formerly Dainippon Ink & Chemicals). All three manufacturers have agreed not to introduce any acutely toxic or mutagenic liquid crystals to the market. They cover more than 90 percent of the global liquid crystal market. The remaining market share of liquid crystals, produced primarily in China, consists of older, patent-free substances from the three leading world producers and have already been tested for toxicity by them. As a result, they can also be considered non-toxic.
Liquid crystals are characterized by high chemical stability – this is a requirement for use in liquid crystal displays. Since they are not acutely toxic and do not accumulate in organisms, they do not fulfill the criteria of PBT (persistent, bioaccumulative and toxic), vPvB (very persistent and very bioaccumulative) or POPs (persistent organic pollutants).
Just 0.1% of the total weight of an LCD
Any possible effects of liquid crystal materials on humans or the environment should always be assessed from the viewpoint that the extremely low volume of liquid crystals – on average 0.4 to 0.5 mg per cm2 of an LCD screen – only adds up to about 0.1% of the total weight of a liquid crystal display. In addition, the materials are hermetically sealed from the outside since the glass plates are adhered together. Even if the glass breaks, the strong adhesive forces of the liquid crystals to the inner orientation surface prevent them from escaping. Any glass fragments including liquid crystals that may be stuck to them would remain stuck to the polarization film on the outside. Even the possibility of being cut or injured from broken shards of glass is therefore extremely low. It can therefore practically be ruled out that consumers will come into direct contact with liquid crystals in LCDs.
LCDs recycled eco-efficiently
The results of investigations and findings on the construction of LCDs ensure that any hazard to users or environmental pollution due to liquid crystal materials are minor. However, this requires the proper handling and recovery of LCDs – as in all chemical and technical products. Liquid crystal displays are easily recovered eco-efficiently in metallurgical extraction processes or through incineration in a waste incineration plant, in accordance with the WEEE Directive. In accordance with the EU Waste Code 2000/532/EC, LCDs are considered non hazardous waste with the waste code number 160216.
- Simon-Hettich B., Becker W.: "Toxicological Investigations of Liquid Crystals",
28th Freiburger Arbeitstagung "Flüssigkristalle", March 24 – 26, 1999, Freiburg;
- Takatsu H. et al.: "Investigation Activity and Data on Safety of Liquid Crystal Materials",
18th International Liquid Crystal Conference, July 24 – 28, 2000, Sendai, Japan
- Simon-Hettich B., Broschard T. H., Becker W. et al: Exotoxicological properties of liquid-crystal compounds, Journal of the SID 9/4, 2001, pages 307 - 312;
- Martin R., Simon-Hettich B., Becker W.: New EU Legislation (WEEE) Compliant Recovery Processes for LCDs, IDW '04, Proc. of the 11th IDW, pages 583 - 586;
- Becker W., Itzel H., Martin R.: Verwertungslösungen für Flüssigkristall-Displays (LCDs), Expertenforum Fraunhofer-Institut IPA Stuttgart, 18.04.2007
- Becker W.: Liquid Crystals in Liquid Crystal Displays (LCDs), Basics, Safety and End-of-Life Aspects, Take-Back Conference in Prague, Czech Republic, 03.05.2011
Statement on Safety of Liquid Crystal Materials
We, the three liquid crystal material suppliers: EMD Performance Materials, JNC and DIC maintain the safety of our products, both towards the users and the environment.
Therefore, we carry out intensive toxicological investigations and do not introduce the acutely toxic, mutagenic or otherwise seriously hazardous liquid crystal materials into the market.
Moreover, we investigate the eco-toxicological properties of our liquid crystal materials in compliance with legal regulations and as precautionary measures according to the principles of "Responsible Care" and "Product Stewardship".
- EMD Performance Materials:
President Performance Materials,
Business Unit Liquid Crystals
- JNC Corporation:
Dr. Yasuyuki Gotoh,
Director, Managing Executive Officer,
Liquid Crystals Division
- DIC Corporation:
Executive Officer & Division President,
Liquid Crystals Division
Recycling Liquid Crystal Displays
Liquid crystal displays with a surface area greater than 100 cm2 and those containing mercury in electric gas discharge lamps (CCFLs) as backlight must be dismantled and disposed of separately. This is specified by the European WEEE (Waste Electrical and Electronic Equipment) Directive 2002/96/EC of January 27, 2003. Liquid crystal displays without backlight – in accordance with the EU Directive 2000/532/EC with the waste code number 160216 – can be declared as non hazardous waste.
EMD Performance Materials patents contribute to reducing environmental pollution
In addition, the electrical waste directive 2002/95/EC and its amendments (expected mid 2012) prescribe recycling and recovery quotas for dismantled liquid crystal displays. LCDs without electronic components and lighting comprise about 85 percent glass, 15 percent plastic film and only about 0.1 percent liquid crystals. In order to fulfill legal requirements, glass and plastics must be recycled. In a patented process developed by EMD Performance Materials, the LCD glass replaces silica sand. Plastic films replace the carbon in metallurgical extraction processes. In another process, industrial waste incineration, the LCD glass replaces normal glass or quartz sand to protect the stone encasing around the rotary kiln from aggressive by-products of incineration.
This allows the materials from all LCDs to be recovered by almost 100 percent eco-efficiently in a few plants globally. The result: less waste and a sustainable reduction of environmental pollution.