An MD&DI September 1997 Column
The industrial sterilization market will grow in the next few years and will see the emergence of low-temperature oxidative technologies.
Industrial sterilization is a dynamic field. In addition to the two most common techniques, EtO and gamma radiation, electron-beam (E-beam) and steam processes also are used by some medical device manufacturers and contract sterilizers. Several emerging low-temperature oxidative technologies are also generating a lot of interest these days. (See Table I for a comparison of primary industrial sterilization methods.)
|Ethylene Oxide (EtO)||Gamma Radiation||Electron Beam (E-beam)|
|Process Type||Batch (complex)||Batch (simple)||Continuous (simple)|
|Efficacy||Requires biological indicators to verify sterility assurance level (SAL)||SAL verification is dosimetric||SAL verification is dosimetric|
|Penetration||Requires gas-permeable packaging||Complete penetration||Near-complete penetration|
|Material||Certain cellulosic materials||Acetal, PTFE; marginally compatible with polypropylene, certain rubbers, PC, and acrylics||No significant difference from gamma radiation|
|Safety||Considered a known carcinogen/mutagen||Little concern regarding in-use process safety||Virtually no safety concerns|
|Turnaround||In-house: 69 days
Contract: 812 days
|In-house: 3 days
Contract: 5 days
|In-house: 3 days
Contract: 10+ days
Table I. Comparison of primary industrial sterilization methods.
According to a research study conducted by DuPont Co. (Wilmington, DE), the market for industrial sterilization will grow steadily through 1999, with EtO and gamma radiation technologies continuing to lead the field. The purpose of the study, which included 44 in-depth interviews with leading contract sterilizers, medical device manufacturers, and equipment suppliers, was threefold:
- To estimate the volume of medical devices being sterilized by both traditional and emerging technologies.
- To analyze the driving forces behind selection or rejection of each sterilization method.
- To identify current and future trends in sterilization methods.
SIZING UP THE MARKET
The study indicates that the market for industrial sterilization is expected to grow from approximately 250 million cu ft of sterilized product in 1994 to approximately 310 million cu ft in 1999--an increase of more than 25% (Figure 1). Although overall volume is expected to increase significantly, the breakdown among the various methods of sterilization should remain relatively unchanged. Respondents believe that EtO's share of total sterilization volume will drop slightly (from 49 to 47%), while sterilization by radiation will see a slight increase (from 44 to 46%). E-beam and steam sterilization will continue to capture approximately 7% of the total market.
Figure 1. Projected numbers for the 1999 industrial sterilization market compared with actual figures from the 1994 market (in million cubic feet of sterilized product).
THE CHANGING FACE OF ETO
Despite the slight decrease anticipated in EtO's market share, its position as a significant sterilization method is not in jeopardy for several reasons. First, popular materials such as PTFE and acetal are not radiation compatible. Second, the costs of validating a switch from EtO to gamma radiation can be prohibitive. Third, the movement of nonmedical sterilization applications (such as spices) away from EtO toward gamma radiation could tax gamma capacities and lead to higher costs for this form of sterilization. Finally, continued growth in custom medical kits should help offset any decline in market share of EtO, because custom kits are likely to contain drugs or devices that are not compatible with radiation sterilization.
The projected decline in EtO's market share is due primarily to the impact of regulations--specifically the 1997 emissions standards in the Clean Air Act. Medical device manufacturers that currently rely on in-house EtO sterilization are facing a tough decision whether to invest in costly facility upgrades to meet new emissions requirements or switch to a contract sterilizer that may use 100% EtO or another form of sterilization.
In addition to its uncertain regulatory future, there are other reasons why EtO use may be threatened. Concerns about worker safety were first raised in 1977 when the National Institute for Occupational Safety and Health (NIOSH) reported that EtO was a possible carcinogen/mutagen. Additionally, the final phaseout of chlorofluorocarbon (CFC)-12 at the end of 1995 eliminated its use as a diluent in 12/88 EtO, forcing some medical device manufacturers and contract sterilizers to convert to 100% EtO to avoid increased taxes and escalating costs associated with emissions recovery and regulatory documentation. But the bottom line, according to the study, is that if medical device manufacturers are able to switch away from EtO easily, they've already done it.
Gamma radiation enjoys a reputation as an environmentally safe, nontoxic sterilization technique. But since 1992 its overall market share has remained relatively unchanged. Although it has suffered a slight share loss to E-beam sterilization, gamma has offset this by capturing part of EtO's market share.
Continued growth in radiation sterilization will be due mainly to economics. The number of low-cost, radiation-compatible resins is on the rise, and most new devices are now being designed for both radiation and EtO sterilization techniques. In addition, the trend toward just-in-time inventory systems is causing many medical device manufacturers to consider gamma radiation, which can sterilize devices in 5 days or less, compared with 8 to 12 days for EtO.
NICHE MARKETS ARE KEY FOR E-BEAM
E-beam sterilization is expected to hold a steady market share over the next several years by maintaining its niche with high-volume, low-value products, such as syringes, as well as with high-value, low-volume products such as cardiothoracic devices. Any further market penetration by this technology will most likely be offset by the inclusion of high-volume goods in custom kits, which are generally sterilized by EtO. Also, although E-beam boasts faster turnaround times than either gamma or EtO, most facilities are in the Northeast, leading to longer shipping times for some medical device manufacturers.
According to the study, emerging low-temperature oxidative sterilization methods will have little effect on the industrial sterilization market in the next few years. Although some adoption of these methods is taking place throughout the industry, the study contends that in the near term, they will be unable to handle large-volume requirements. Low-temperature oxidative sterilization methods are expected to have their largest impact on in-hospital sterilization, where volumes are smaller.
In the long run, emerging sterilization methods can look forward to significant market shares in specific niche markets, such as orthopedic implants. Recently, companies that manufacture low-temperature oxidative systems have begun to introduce larger units that better meet industrial sterilization requirements. As these larger systems continue to come on-line, their potential for growth will increase.
THE PACKAGING MATERIAL CONNECTION
A particular sterilization method is selected because of a combination of factors including worker and environmental safety, cycle time, and packaging and device compatibility and long-term stability. The device manufacturer must evaluate packaging materials with all of these factors in mind.
Today, the most commonly used materials for medical device packaging are films, rigid trays, medical-grade papers, and spunbonded olefin. Each of these materials exhibits specific performance characteristics that make it more or less suitable for any given sterilization method.
For example, before using irradiation technology to sterilize a medical device, the following three questions concerning the packaging material should be considered.
- Does the material maintain its stability and integrity following exposure to radiation?
- Does the material discolor after exposure?
- Does the material produce offensive odors after exposure (i.e., off-gas) that could be negatively associated with the device when the package is opened?
Packaging material for a medical device must include a porous component to be compatible with either gaseous or oxidative sterilization methods. This is because the relative porosity of a material facilitates the ingress and egress of the sterilant and directly affects sterilization cycle time. Also, the device itself must be compatible with oxidative sterilization methods. For example, cellulosic materials will absorb the sterilant, often leading to incomplete sterilization of the device.
The information gathered from this research study provides a current, quantitative look at the industrial sterilization market and is intended to provide valuable insights for suppliers to the health-care industry. While the current market shares for EtO, gamma and E-beam radiation, and steam sterilization methods will remain about the same in the near future, emerging technologies are becoming better equipped to meet the needs of industrial sterilization. This will benefit medical device manufacturers, allowing them broader sterilization choices.
Michael H. Scholla is the medical packaging segment leader at DuPont Tyvek. Mary E. Wells is the senior programs manager at DuPont Marketing and Business Research.