What are plasticisers?
A plasticiser is a substance which when added to a material, usually a plastic, produces a product which is flexible, resilient and easier to handle. Since the dawn of civilisation, water has been used to plasticise clay for the production of pottery and clay tablets. Also, lime has been used to promote the easier working of cements. Other early examples of plasticisers include the oils to plasticise pitch for caulking prehistoric boats and neatsfoot oil and sperm oil to soften leather.
In modern applications plasticisers are produced by reacting an alcohol (such as methanol or ethanol) with an acid such as phthalic anhydride, adipic acid, etc. These plasticisers must satisfy more demanding technical and economic requirements which are best met by esters such as phthalates, adipates, trimellitates, etc. Phthalates, due to their technical performance, versatility and cost effectiveness, are the most widely used.
What are phthalates?
Phthalates are a group of colourless, odourless liquids which are used as plasticisers (or softeners). They are produced by the simple reaction of alcohols with phthalic anhydride and the elimination of water. Both alcohols and phthalic anhydride are well known substances derived from petroleum, which have been in use for a long time. Phthalates have very low volatility, do not readily dissolve in water and are not persistent in the environment. Their principal use is to soften polyvinyl chloride (PVC), also known as vinyl. Plasticised PVC is used in a wide range of durable applications such as flooring and wall-coverings, roofing membranes, electrical cable insulation, automotive applications, medical tubing and blood-bags.
What is the difference between high and low phthalates?
Phthalate esters are manufactured from alcohols ranging from methanol and ethanol (C1/C2) up to iso-tridecanol (C13), either as a straight chain or with some branching. They are divided into two distinct groups, with very different applications, toxicological properties and classification, based on the number of Carbon molecules in their alcohol backbone. High molecular weight (HMW) phthalates, more simply known as high phthalates, include those with 7-13 Carbons in their backbone, which gives them more permanency and durability. Low molecular weight phthalates (LMW), or low phthalates, are those with only 3-7 Carbon molecules in their chemical backbone.
What other products, apart from PVC, are phthalates used in?
Around 90% of all plasticisers are used in the production of flexible PVC. Phthalates are one of the most versatile types of plasticisers and they are used mainly in PVC. However, Low phthalates BBP, DIBP, DBP are also used in rubber products, paints, printing inks, adhesives and sealants.
How many phthalates are used in Europe, and what are the principal ones?
In Western Europe, about one million tonnes of phthalates are produced each year. More than 900,000 tonnes are used in the plasticisation of PVC. High phthalates represent around 85% of all the phthalates currently being produced in Western Europe. Currently, the most commonly used high phthalates are diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) and di(2-Propyl Heptyl) phthalate (DPHP).
Low phthalates account for less than 11% of the total production, with di-2ethylhexyl phthalate (DEHP, also known as DOP) being the most commonly used.
Are phthalates safe?
Because phthalates are so widely used, they have undergone extensive testing for possible health and environmental effects and are among the most widely researched of all chemical substances. In Europe, the European Commission, the European Chemicals Bureau (ECHA) and EU Member States have undertaken 10-year-long comprehensive scientific assessments of both high and low phthalates under the EU Risk Assessment Regulation.
High phthalates (DINP, DIDP, DPHP, DIUP, and DTDP): Risk assessments showed positive results regarding the safe use of this group of substances. They have all been registered under REACH and do not require any classification for health and environmental effects, nor are they on the Candidate List for Authorisation.
Low phthalates (DEHP, DBP, DIBP and BBP): Risk assessments have led to their classification and labelling as Category 1B Reproductive agents and these four phthalates are now on the REACH Candidate List for Authorisation. They have all been registered under REACH.
Phthalates are found in many household items and some of these items contain more than 50% phthalates. Should this be a cause for concern?
The amount of phthalates found in a finished product has little to do with potential exposure. There are many misconceptions about phthalates leaching out and easily dispersing from PVC products. This is actually quite a difficult process and would only happen if very abrasive detergents or solvents are used or if the articles are exposed to adverse conditions for an exceptionally long time.
If DEHP is a low phthalate of very high concern, shouldn’t it be banned in medical applications?
DEHP has been registered under the EU’s new Chemicals Legislation REACH and this registration enables the continued manufacturing and use of DEHP. However, because it is classified in as a Substance of Very High Concern (SVHC), its uses beyond January 2015 is subject to an Authorisation.
The use of DEHP in some medical applications is allowed in Europe, but upon an evaluation of possible alternatives, four new plasticisers have been added to the European Pharmacopoeia:
- (Hexamoll® DINCH (cyclohexane 1,2-dicarboxylic acid, diisononyl ester)
- BTHC (butyryl tri-n-hexyl citrate)
- TOTM (tris(2-ethylhexyl) trimellitate)
- DEHT (bis(2-ethylhexyl) terephthalate)
These plasticisers can be used in the production of containers for human blood and blood components; tubing used in sets for the transfusion of blood and blood components; and empty sterile containers of plasticised PVC for human blood and blood components.
Is it true that phthalates can leach out of plastic water and soda bottles?
This is definitely not true. Phthalates do not leach out of water or soda bottles because bottles do not contain any phthalates. Such bottles are made from polyethylene terephthalate, a plastic material also known as PET or polyester. Despite the similarity in name, PET and phthalates are very different.
Isn't the plasticiser industry being complacent and insufficiently responsive in view of all of these issues it faces?
The European plasticiser industry is very conscious of the genuine public concern which now exists concerning the use of phthalates. The Industry welcomes a responsible public debate, and accepts that it has a responsibility to respond to public concern by ensuring that there is an open exchange of information about the performance of its products. Clearly, if there was evidence that any single product presented a serious risk to human health, the plasticiser industry would have no hesitation in withdrawing it.
The industry is also fully committed to supporting and, where appropriate, commissioning further scientific research about the potential hazards that phthalates may pose to our health and the environment.
Some plasticisers and classified low molecular weight ortho-phthalates in particular, have been under the spotlight in media and public debates due to their health effects. However, it is crucial to keep in mind that there are lots of different plasticisers with very different composition, effects, applications and regulatory status. Using all-encompassing, generic terms such as “plasticisers” or “phthalates” in referring to health and environmental hazards and risks is simply not correct. Some of the conditions most commonly cited in association with plasticisers include:
It is very important to emphasize that the presence of flexible PVC particles in house dust does not pose any risks to human health. Plasticisers do not readily migrate or leach into the environment from articles because they are physically bound within the PVC matrix. Even in abraded particles that may be collected in the form of dust, plasticisers would remain tightly bound within the PVC matrix. If this was not the case, flexible PVC would not remain flexible and perform as intended. Essential applications such as wire and cable, where electrical safety is paramount, would crack and break rendering them unusable and potentially unsafe for consumers.
Reports linking exposure to phthalates and asthma are often based on finding a correlation, which does not mean causation.
In addition, recent scientific studies have concluded that household dust does not correlate to human exposure levels, and is not an indicator of indoor air quality1. It is therefore not scientifically sound to conclude that levels in dust equate to exposure and therefore exceed safe limits.
1 H. Fromme et al., “Occurrence of phthalates and musk fragrances in indoor air and dust from apartments and kindergartens in Berlin (Germany), Indoor Air 2003, 1-8. Kerstin Becker et al. “DEHP metabolites in urine of children and DEHP in house dust”. International Journal of Hygiene and Environmental Health 207 (2004); 409-417. Tobias Schripp et al. “Chamber studies on mass-transfer of di(2-ethylhexyl)phthalate (DEHP) and di-n-butylphthalate (DnBP) from emission sources into house dust”, Atmospheric Environment 44 (2010) ECPI Scientific Working Group Report 110301 – “Endocrine Data Evaluation Report” – March 2011
In today’s flexible PVC, there is not a single plasticiser being used which has been found to be carcinogenic for humans. Extensive research has shown that cancers seen in animal studies with orthophthlates are not relevant to humans. This research has been reviewed by regulators in Europe who confirmed this conclusion of lack of human relevance. In addition, it should also be noted that plasticisers – including phthalates – bind tightly within the plastic material and do not readily migrate. They are not absorbed via the skin or saliva as. Even if placed in the mouth, it requires prolonged chewing for the plasticisers to be released.
There have been studies and media reports claiming that obesity could be linked to exposure to phthalate plasticisers used in cosmetics. Today, only the non-classified DMP and DEP are used in cosmetics in the EU because they have not been classified or restricted because they do not pose any risks for our health or the environment.
In the past, EU classified low phthalates DBP and DIBP were employed in cosmetics and body care products but are no longer found in articles produced and commercialised in the European Union due to provisions of the European Cosmetics legislation, which prohibits the use of substances classified as carcinogenic, mutagenic or repro-toxic (CMR). Non-classified phthalates are not used in this type of applications.
There is no good evidence that exposure to phthalates or other chemicals contributes to obesity – this is simply scaremongering. Lifestyle factors including diet, exercise, smoking, and alcohol consumption are major factors in determining the health of human populations. There is no robust evidence that the very low levels of exposure to chemicals which typically occurs in consumers is contributing to the disease burden of human populations. In fact the contrary is true and chemicals make a positive contribution to health via the myriad benefits they bring to society such as for example safe and hygienic food as well as in healthcare. Occupational Health and Safety controls are of course very important for people working in the chemical industry where there is potential for significant exposure.