Toxicology

Alternatives for significant uses of DEHP in Massachusetts

Introduction

In July 2005, the Commonwealth of Massachusetts requested that the Toxics Use Reduction Institute perform an alternatives assessment for five chemicals. For each chemical, the Institute was charged with identifying significant uses in manufacturing, consumer products, and other applications; reviewing health and environmental effects; and evaluating possible alternatives. The results of this study will serve as a guide for those seeking safer substitutes to the chemicals studied.

Presented here is an executive summary of the findings for high priority uses of Di (2-ethylhexyl) phthalate (DEHP) in Massachusetts. The full report, the Five Chemicals Alternatives Assessment Study available from the link below, presents extensive factual information on each alternative

DEHP is a synthetic organic chemical that is used primarily as a plasticizer to impart flexibility to rigid plastics such as PVC. It belongs to the class of chemicals known as phthalates, which are used primarily as plasticizers in PVC plastics in a range of applications. DEHP is used in a wide variety of flexible plastic products.

DEHP is classified by the U.S. EPA as a probable human carcinogen (Class B2). In 2000, the International Agency for Research on Cancer (IARC) changed its classification for DEHP from Group 2A ("possibly carcinogenic to humans") to Group 3 ("cannot be classified as to its carcinogenicity to humans”). Animal studies have found that DEHP is toxic to the male reproductive system. When DEHP is metabolized in the human body, it produces compounds that are likely to be reproductive toxicants.

DEHP can be released to the environment during its production, distribution and incorporation into PVC. DEHP is also released when PVC material is heated or comes into contact with certain media. DEHP is not chemically bound into the polymer matrix and therefore can migrate out of the polymer. It is especially likely to migrate out of the polymer in the presence of fatty solutions. Indoor releases of DEHP to the air from plastic materials, coatings, and flooring in home and work environments can lead to higher indoor levels than are found in the outdoor air.

Use of DEHP in flexible PVC medical devices is a significant source of exposure, especially in neonatal care. The National Toxicology Program (NTP) has expressed serious concern about reproductive toxicity in male infants who are exposed to DEHP in medical care. The Food and Drug Administration has recommended that health providers consider using alternatives to DEHP-containing medical devices when high-risk procedures are to be performed on male neonates, pregnant women who are carrying male fetuses, and peripubertal males.

The Institute assessed alternatives to DEHP in PVC in three categories: medical devices for neonatal care; resilient flooring; and wall coverings. Because DEHP is used primarily as a plasticizer in PVC plastics, two types of substitutions may be relevant: substitution of an alternative plasticizer for use with PVC, or use of a different material that does not require addition of a plasticizer. For each application, the Institute examined alternatives in both categories.

Resilient flooring

Resilient flooring is defined as tile and sheet materials that have the ability to return to their original form after compacting. The Institute assessed alternative plasticizers for use in PVC flooring, as well as alternative flooring materials.

Alternative plasticizers

The Institute assessed four alternative plasticizers for use in resilient flooring: di (2-ethylhexyl) terephthalate (DEHT), di isononyl phthalate (DINP), dipropylene glycol dibenzoate (DGD), and di (2-ethylhexyl) adipate (DEHA).

  • Health. All the alternatives appear to be superior to DEHP from the perspective of reproductive toxicity, although some evidence exists that DEHA may be toxic to the developing fetus. None of the alternatives has been classified as to carcinogenicity in humans, but there is evidence that DINP is carcinogenic in rodents.
  • Environment. All of the alternatives are less bioaccumulative than DEHP. DEHA is less persistent in sediment and less toxic to fish than DEHP; the other plasticizers are similar to DEHP for these parameters.
  • Technical criteria. Technical parameters of interest for alternative plasticizers in resilient flooring include volatility, ease in compounding, tensile elongation, compatibility with PVC, and loss of plasticizer during manufacture and use. All the alternatives are comparable with DEHP from the perspective of volatility and tensile elongation. All except DEHT are comparable to DEHP with regard to compounding, and all except DEHA are comparable to DEHP with regard to PVC compatibility. DINP has greater emissions during use, DEHA is inferior with regard to emissions during both manufacturing and use, and DGD has unknown properties on this metric.
  • Cost. All the alternative plasticizers are comparable in cost to DEHP for resilient flooring applications on a functional equivalence basis.

Alternative materials

The Institute assessed three alternative flooring materials: natural linoleum, cork, and polyolefin.

  • Health. Many studies have examined the human health and environmental implications of choice of flooring materials. Most of these studies examine the entire life-cycle of the product, from production to disposal. In general, these analyses favor the alternatives over DEHP/PVC flooring. Polyolefin flooring has the advantage of very low VOC emissions during use.
  • Environment. Linoleum and cork are derived from sustainable materials and are biodegradable, making them superior to DEHP/PVC on these metrics. Cork offers the additional advantage that it can be installed without the use of adhesives. Linoleum has less impact on energy use from a life cycle perspective than DEHP/PVC flooring.
  • Technical criteria. Technical criteria of interest for flooring applications include the availability of a range of colors and patterns; ease of maintenance; and recyclability. Linoleum and polyolefin flooring materials offer a range of colors and patterns that make them similar to DEHP/PVC in this regard, while cork is more limited in this respect. Ease of maintenance is generally similar across all the options. Polyolefin flooring is recyclable; linoleum and cork are not.
  • Cost. The alternatives are generally similar to DEHP/PVC in purchase and installation cost, although costs vary depending on application. All the alternative materials have a longer expected life span than DEHP/PVC, further decreasing the overall cost.

Medical devices for neonatal care: sheet and tubing applications

Two distinct categories of medical devices used for infants in neonatal intensive care facilities were the focus of this study: bag/sheet devices, and tubing. The Institute investigated both alternative plasticizers and alternative materials for this application.

Alternative plasticizers

The Institute assessed five alternative plasticizers for use in medical devices.

  • Trioctyl trimellitate (TOTM) is a clear, oily liquid that is a high production volume plasticizer in the US. In the medical device industry, TOTM is currently used primarily in blood and bag infusion sets.
  • Di (2-ethylhexyl) adipate (DEHA) has properties that make it a useful plasticizer for materials used to store medical solutions that must be kept cold.
  • Butyryl trihexyl citrate (BTHC) is a plasticizer specifically designed for use in medical articles, especially blood storage bags.
  • Di (isononyl) cyclohexane-1,2-dicarboxylate (DINCH) is the hydrogenated product of the corresponding di C9 phthalate ester (DINP).
  • Di isononyl phthalate (DINP) is currently used as a plasticizer in medical tubing devices.

TOTM, DEHA, BTHC, and DINCH are applicable for use in bag/sheet devices. Based on their elastic recovery properties, DEHA is also applicable for use in tubing, and DINP was assessed for use in tubing only. For each of these alternatives, the Institute assessed health, environmental, technical, and cost criteria.

  • Health. All the alternatives are superior from the perspective of carcinogenicity and reproductive toxicity, although there are grounds for concern about DINP and DEHA, as noted above. The alternatives are generally superior with regard to skin, eye, and respiratory irritation, with some exceptions.
    A key issue associated with potential health effects is the ability of a plasticizer to exude from the polymer matrix as well as its potential to produce metabolites of concern. DEHP is lipid soluble and therefore is likely to exude out of the polymer when exposed to a lipid-soluble solution. TOTM, BTHC and DINCH appear to be less likely to migrate out of the polymer in the presence of lipid-soluble medical solutions. DINP appears to be similar to DEHP in this regard, and the potential for DEHA to migrate is not well defined.
    Little information is available on the health effects of metabolites associated with the alternatives assessed. The exception is BTHC, which can be metabolized to butyric acid, a chemical that is associated with negative impacts on the GI tract, liver and skin.
  • Environment. All the alternatives are equally or less persistent in sediment compared to DEHP (DINCH persistence is unknown). The alternative plasticizers studied are all superior from the bioaccumulative and aquatic toxicity perspectives, with the exception of DINP, which has aquatic toxicity similar to that of DEHP. The aquatic toxicity of BTHC is not known.
  • Technical criteria. Important criteria for both sheet/bag and tubing applications include flexibility when cold, clarity, compatibility with PVC, sterilizability, and plasticizer loss during manufacture and use. In addition, elastic recovery is an important parameter for tubing applications. Some important differences between DEHP and alternatives are noted below:
    • TOTM is inferior on measures of cold flexibility; DEHA is similar; and the other three alternatives are superior to DEHP on this measure.
    • DEHA is less compatible with PVC than DEHP.
    • BTHC is not steam sterilizable, while DINP tolerates steam sterilization better than DEHP. The sterilizability of DINCH is not known.
    • TOTM, BTHC, and DINCH are superior to DEHP on measures of plasticizer loss during use. DEHA and BTHC are inferior to DEHP on measure of plasticizer use during manufacture.
  • Cost. Costs of DEHA and DINP are similar to those of DEHP, while the other alternatives are more expensive.

Alternative materials

The Institute evaluated five alternative materials for medical devices: ethyl vinyl acetate (EVA), polyolefins (polyethylene and polypropylene), glass, silicone, and polyurethane. Some of these could replace DEHP/PVC sheets, while others could replace DEHP/PVC tubing.

  • Ethyl vinyl acetate (EVA) is a copolymer blend of vinyl acetate, ethylene, and ethyl acetate that has been used for many years in medical sheet applications. EVA bags are also used for custom mixing of drugs by pharmacies.
  • The polyolefins polyethyelene (PE) and polypropylene (PP) are widely used compounds that are valued for their flexibility, transparency and toughness.
  • Glass was commonly used to store medical solutions prior to the extensive use of plastics.
  • Silicone is a synthetic rubber that can be used in medical tubing. Silicone tubing is translucent, biologically inert, and inherently flexible.
  • Thermoplastic polyurethane (TPU) is used in tubing applications.

The Institute assessed health, environmental, technical and cost criteria for each alternative.

  • Health. All the alternative materials are superior to DEHP/PVC from the perspective of leaching plasticizers with known health concerns, since none of the alternatives utilize plasticizers. While rigid and more difficult to handle due to the potential for breakage, glass is the most inert material available on the market today for health care.
  • Environment. All the alternative materials are superior to DEHP/PVC materials plasticized with DEHP in the sense that they do not generate hazardous chlorinated organic compounds when incinerated. However, there is significant variation among the alternatives in level of toxicity over the life cycle of the product. Manufacture of TPU involves use of diisocyanates that are listed on the Massachusetts Science Advisory Board’s list of more hazardous chemicals. Incineration of TPU also releases hazardous chemicals including isocyanates and hydrogen cyanide. On measures of recyclability, glass is far superior to PVC containing DEHP; other alternatives are equally or more difficult to recycle compared with DEHP/PVC.
  • Technical criteria. Using materials that are inherently flexible eliminates one of the key problems with DEHP/PVC, the potential for the material to become brittle due to loss of plasticizer. Therefore, the alternatives may have longer shelf lives than their DEHP/PVC counterparts and the possibility of leached plasticizer entering the body is eliminated. Other performance criteria of interest for these uses include elastic recovery, cold flexibility, sterilizability, gas permeability, and manufacturability. Some key differences between the alternative materials and DEHP/PVC are noted below.
    • TPU exhibits inferior elastic recovery.
    • Only silicone is superior to DEHP/PVC from the perspective of cold flexibility. Glass is not flexible.
    • Neither EVA nor polyolefin is appropriate for steam sterilization.
    • Manufacturability (i.e., the ease with which the material can be transformed into the finished product) is superior for glass, and inferior for EVA, silicone and TPU.
  • Cost. Currently raw material prices and relative use costs for the alternatives vary relative to DEHP/PVC. However, costs of the alternatives are changing in response to increasing demand for and supply of DEHP- and PVC-free medical devices. Technical differences among materials can also be a source of cost savings. For example, EVA film can be manufactured at a thinner gauge than similar PVC film, thus reducing the per-item cost. For tubing applications, silicone and TPU can be used for longer periods of time than PVC/DEHP, thereby reducing the cost differential. Large hospital chains are also driving market changes, and cost reductions, by specifying PVC- or DEHP-free materials in their purchasing contracts.

Wall coverings

DEHP/PVC (vinyl) wall coverings are used in both commercial and residential settings for decorative and protective purposes. Vinyl wall coverings are popular because they are available in a wide array of patterns and colors and are both durable and scrubbable.

It is worth noting that there are viable process alternatives to vinyl wall coverings, including painted wall surfaces or using different wall materials (such as wood paneling). They differ significantly from wall coverings in terms of aesthetics, but can be functionally equivalent. These process alternatives were not included in the assessment.

Alternative plasticizers

The Institute assessed two plasticizer alternatives for use in wall coverings: DEHA and DINP.

  • Health. As previously discussed, DEHA is potentially toxic to the developing fetus and DINP has been found to cause cancer in laboratory animals. The potential for exposure to DEHA is greater than for DEHP.
  • Environment. DEHA is less persistent in sediment than DEHP, and DINP is similar to DEHP on this parameter. Both are less bioaccumulative than DEHP. DEHA is less toxic to fish than either DEHP or DINP.
  • Technical criteria. Criteria of interest for wall coverings include volatility, compounding, tensile elongation (life of product), compatibility with PVC, and emissions (during manufacture and use). DINP is similar to DEHP on all measures. DEHA is inferior on measures of volatility, PVC compatibility, and emissions during manufacture and use. Compared with DEHP, DINP has better high-temperature performance and extraction resistance, which improves is processability.
  • Cost. Both plasticizers are similar to DEHP in cost per pound applied. Compared with DEHP, DINP processing emits lower levels of plasticizer mist from process equipment. As a result, less plasticizer is lost to the air and more retained in the product, yielding overall cost savings.

Alternative materials

The Institute assessed five categories of alternative materials: glass woven textiles, cellulose/polyester blends, wood fiber/polyester blends, biofibers, and polyolefins.

The Institute evaluated health, environmental, technical, and cost criteria for each of these alternative materials.

  • Health. The primary concern with DEHP in wall coverings is exposure during manufacture and use. No plasticizer is emitted during manufacture or use of the alternative materials, but there may be other volatile organic emissions. In particular, the glass textile and polyolefin alternatives have similar potential VOC exposures compared to DEHP/PVC. Little information on exposure associated with the other materials was available.
  • Environment. All the alternative materials except the polyolefins are derived from more sustainable materials than DEHP/PVC. Some offer the advantage of being recyclable and one alternative material (wood pulp/recycled paper) is compostable. Two of the alternative materials (BioFibers and polyolefins) are routinely coated with Teflon® finish, which may pose occupational and other hazards.
  • Technical criteria. All the alternatives are similar to DEHP/PVC in ease of maintenance. Wood fiber/polyester and cellulose/polyester alternatives offer a range of colors and patterns similar to those available with DEHP/PVC.
  • Cost. Most of the alternatives are comparable in price to high-end DEHP/PVC wall covering products, but are much more expensive than low-end vinyl.

Additional Information

Further reading

Editor's Notes

Glossary

Citation

Institute, T., Harriman, E., Civie, P., & Ellenbecker, M. (2013). Alternatives for significant uses of DEHP in Massachusetts. Retrieved from http://www.eoearth.org/view/article/51cbece77896bb431f68e5de