| Epoxidized soybean oil | |
|---|---|
|
Other names
ESBO; Epoxidized soya bean oil; ESO |
|
| Identifiers | |
| CAS number | 8013-07-8 |
| Properties | |
| Appearance | Light yellow viscous liquid[1] |
| Density | 0.994 g/cm3[1] |
| Melting point |
0 °C, 273 K, 32 °F ([1]) |
| Solubility in water | Insoluble[1] |
| Hazards | |
| R-phrases | R36 R37 R38 R43 |
| S-phrases | S24 S26 S37 |
| NFPA 704 |
0
3
0
|
| Flash point | 227 °C (441 °F) |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Epoxidized soybean oil, better known by its acronym, ESBO, is a plasticizer used in polyvinyl chloride (PVC) plastics. It serves as a plasticizer and as a scavenger for hydrochloric acid liberated from PVC when the PVC undergoes heat treatment.[2]
A few EU surveys have shown fairly high levels of ESBO in foods, in which about 4% were above the current specific migration limit (SML) for ESBO of 60 mg/kg and about 15% of the samples were above 30 mg ESBO/kg food. High migration levels might lead to an intake that exceeds the existing Tolerable Daily Intake of 1 mg/kg body weight/day.
Contents |
ESBO is manufactured from soybean oil through the process of epoxidation. The reason why vegetable oils are widely used as plasticizers is because the high numbers of carbon-carbon double bonds present in vegetable oils make them a good target for manipulation into some other useful products like in this case - from soybean oil into epoxidized soybean oil.[3] The epoxide group is more reactive than double bond, thus providing a more energetically favorable site for reaction and making the oil a good hydrochloric acid scavenger and plasticizer. Usually a peroxide or a peracid is used to add an atom of oxygen and convert the -C=C- bond to an epoxide group.
Metal closures incorporate a ring-shaped gasket formed from a bead of liquid plastisol containing up to 40% ESBO which is moulded into the correct profile in the closure shell using a hot punch, then fused by passing through an oven at 200°C for 90 seconds. PVC starts to break down at this high temperature and releases hydrogen chloride. ESBO functions as a stabilizer to scavenge this hydrogen chloride to prevent the autocatalytic breakdown of the polymer. It also functions as a plasticizer.
A Swiss survey done in June 2005 had shown that migration of ESBO into foods could reach up to 1,170 mg/kg.[4]
Rapid Alert System in Food and Feed (RASFF) had also reported cases of food product rejection in EU for exceeding SML under EU Legislation (EC/2002/72).[5]
In Europe, plastics are regulated by the Commission Directive 2002/72/EC which consolidates Commission Directive 90/128/EEC and its seven amendments (Directives 92/39/EEC, 93/9/EEC, 95/3/EEC, 96/11/EEC, 1999/91/EC, 2001/62/EC and 2002/17/EC). These amendments mainly modified the lists of authorized substances such as monomers and additives.
Directive 2002/72/EC establishes a specific migration limit for ESBO of 60 mg/kg.[5] However in the case of infant formula and follow-on formula as defined by Directive 91/321/EEC[6] or products containing processed cereal-based foods and baby foods for infants and young children as defined by Directive 96/5/EC,[7] the SML is lowered to 30 mg/kg. This is because babies have higher ratio of food consumption per body weight.
Food products that are stored in glass jars with metal lids need a gasket to make a good seal and the gasket is usually made from PVC. It forms an airtight seal preventing microbiological and other contamination. ESBO is one of the additives used in the PVC gasket. It serves as a plasticizer and a scavenger for hydrochloric acid released from PVC when the food product undergoes sterilization.[8]
The tolerable daily intake (TDI) of ESBO defined by the Scientific Committee on Food (SCF) of the EU is 1 mg/kg body weight. This value is based on a toxicological assessment performed by the British Industrial Biological Research Association (BIBRA) in the late 1997. Repearted oral administration had been shown to affect the liver, kidney, testis and uterus.[9] According to the conventional European rules for food packaging materials, the TDI became a basis for the SML of 60 mg/kg.