What Is DEHP?
The term DEHP stands for di(2-ethylhexyl)phthalate.
It is a softener used in PVC or polyvinyl chloride. PVC is a plastic polymer, and it is used in several products like toys, food packaging materials, medical devices, etc. Usually, PVC is quite brittle and hard at room temperature, so a softener like DEHP is added to plasticize it. DEHP helps in softening by increasing the flexibility of PVC. The tubing material softens and flexes more as the amount of plasticizer or softener is increased. The plasticizer allows free movement for polymer chains by interfering with the rigid bonds.
In the majority of medical products made of PVC, the aim of plasticization is met by the use of DEHP or other phthalate softeners. Despite how commonly it has been used, DEHP has recently been proven to leach out of the materials and into the solutions.
DEHP PVC is utilized in the following devices:
- IV tubing and bags
- Blood bags
- Blood infusion tubing
- Peritoneal dialysis tubing and bags
- Tubing used in ECMO
- Tubing used in hemodialysis
- Umbilical artery catheters
- Tubing used for CPB procedures
- Nasogastric tubes
- Enteral nutrition feeding bags
Some people may be exposed to high-leached DEHP levels in some of these medical procedures, making it very dangerous. And when a patient requires more than one of such medical procedures, the health risks increase. Depending upon the duration of contact of liquid with the plastic, lipid content, and temperature, the amount of leaching can vary.
For this reason, even the use of PVC altogether has been under debate. Therefore, the FDA has banned the use of DEHP. As an alternative, DHEP-free PVC or PVC-free devices have been introduced by many companies, which are a bit less economical but worth it for health purposes. These plasticizers or softeners include DEHT or di-2-Ethylhexyl-terephthalate, ATBC or acetyl tributyl citrate, DINCH 1,2-cyclohexane dicarboxylic acid diisononyl ester, and TOTM or tri octyl trimellitate.
Difference between DEHP and non-DEHP PVC
There are two alternatives to DEHP PVC:
- Either some other flexible polymer replaces the PVC, OR
- A DEHP-free plasticizer replaces the current plasticizer
The study on alternative polymers is still limited, and because of that, there are many data gaps. Therefore, a more preferred and well-understood option at present is the use of alternative softeners or plasticizers.
Non-DEHP PVC can be made from many alternative materials. These include aliphatic dibasic esters, citrates, phosphates, carboxylates, adipates, benzoates, trimellitates, and other phthalates for making medical devices. Among these, the most studied and understood alternative is the DEHA or di(Ethylhexyl) adipate.
Some commonly used alternatives to DEHP-PVC are below:
DEHA vs. DEHP
The two have similar structures and metabolism, but DEHA has three times more potential to leak. Among all DEHP-free PVC alternatives, DEHA has the highest migration potential. Despite such facts, DEHA is still excessively used in household plastic products. Furthermore, there are plans to use it in medical devices and packaging now as well. The reason is that it has not shown any of the adverse effects, unlike DEHP. The toxicological profile of DEHA has demonstrated that it has no genotoxicity, carcinogenicity, or endocrine effects, unlike DEHP. It does not lead to skin sensitization effects either, and about acute toxicity, DEHA has a very mild level. When talking about reproductive toxicity, no anti-androgenic activity was reported.
DINCH vs. DEHP
DINCH has been developed very recently for sensitive applications and is named the ‘sensitive alternative.’ As compared to DEHP, the difference in the structure of DINCH allows less interaction with PVC, despite having almost the same molecular weight as DEHP. The migration of DINCH is eight times less than DEHP. The toxicological profile of DINCH is excellent, as it shows no evidence of carcinogenicity, reproductive hazards, or environmental hazards. Prolonged use may affect the kidneys, liver, or thyroid, but that has not been proven to be only because of DINCH, as other factors were excluded in such studies. DINCH has been used to manufacture respiratory tubes, hemodialysis, and enteral tubing, bags, catheters, breathing masks, and gloves.
TETM vs. DEHP
Compared to other plasticizers, TETM has a higher molecular weight and the lowest potential of migration in aqueous solutions. Its toxicological report shows that TETM has low dermal and oral toxicity and is neither carcinogenic nor mutagenic. Also, TETM does not cause skin sensitization. The degree of liver toxicity was much less as compared to that caused by DEHA. TETM has thus far proved to be the safest option, but still, researchers are trying to make it even safer for the public. The main area that needs improvement is the developmental and reproductive toxicity of TETM, which is currently much lower than DEHP but still not zero.
ATBC vs. DEHP
ATBC is much less lipophilic when compared to other plasticizers, even less than phthalates. It is a non-volatile compound and is highly soluble in water. ATBC can leach into the solutions in some devices, like enteral feeding solutions, in quite prominent amounts. Despite its excessive use in cosmetics, toys, and food products as a flavoring agent, ink, and adhesive, ATBC has limited uses in the medical field. It is mainly used in blood bags and tubing only. The toxicological report of ATBC shows that it has almost no genotoxicity, and its acute oral toxicity is quite low as well. Despite mild eye irritation in animals, ATBC shows no skin sensitization or irritation.
These are only a few of the many alternatives to DEHP used in medical devices and other industries. Some other alternatives include PVC-free compounds that use other flexible polymers to do the same or even better job than the PVC. These include the following materials:
- Polyolefins – the most widely used plastics in the world
- Silicone – Widely used in medical devices and breast implants
- Polyurethane – thermoset plastics that are more durable than PVC
- Ethylene vinyl acetate – non-carcinogenic plastic used as a drug delivery device and as a laminate