Chapter 5: Standards, Specifications and TestsThe Latex Condom: Recent Advances, Future Directions
Chapter 5: Standards, Specifications and Tests
The emergence of the AIDS pandemic focused high-level scientific attention on condoms for the first time. When the U.S. Surgeon General recommended condoms to the U.S. public, for example, government officials and scientists went into libraries and laboratories to see what data supported such recommendations. Were there any tests that proved its reliability?
In the late 1980s, research began to yield more reliable guidance on condom performance. The most informed scientific debate often took place in the forum of standards organizations, involving research institutions, major buyers of condoms, the manufacturers and academics. Standards organizations provide technical definition for products manufactured in their respective jurisdiction.
Until these debates, standards for manufacturing condoms were determined almost exclusively by industry practices. Manufacturers relied on their own tests, on consumer demand and on specifications from large buyers such as the military. The manufacturers tested for uniformity in condom dimensions, holes and variations in the strength of the product. However, regulatory bodies did little monitoring of condom production, and no worldwide standards on quality assurance existed.
As better understanding of condom tests emerged, regulatory bodies carried out a more thorough examination of manufacturing practices, and test data received more scrutiny by major condom procurement agencies such as USAID. Gradually over the last 20 years, standards for condom production have been tightened and refined, with some countries establishing rules regarding condom quality. Also, greater uniformity among standards has evolved throughout the world.
Currently, six primary laboratory tests are used to assure the quality of new latex condoms at the factory: condom dimensions, package integrity, lubricant quantity, leakage, tensile properties and air burst properties. Some of these are also used to test the quality of condoms after being transported, stored in the field or artificially aged in laboratories.
Tests are able to measure directly condom dimensions, package integrity, lubricant quantity and leakage. The tensile and air burst tests measure various strength properties of latex film. In addition, an oven-conditioning process is used to simulate the aging of condoms. Air burst and/or tensile tests are then used to assess the changes in various strength properties of these artificially aged condoms.
This chapter first discusses the major standard-setting agencies, procurement specifications and regulatory actions. It then summarizes the function of the major laboratory tests and concludes with proposed changes to the standards.
Worldwide, there are three major agencies that have established condom manufacturing standards: the International Organization for Standardization (ISO), the Comité Européen de Normalisation (CEN) and the American Society for Testing and Materials (ASTM). Standards set by these agencies are key benchmarks for manufacturers, government regulators and large purchasers.
The standards published by these authorities are concerned primarily with safety and the integrity of manufactured products. Standards establish minimum acceptable quality levels for a product, in this case, the latex condom. In some circumstances, standards are required by law. In other situations, standards serve as guidelines for the manufacturers. If random samples from a batch of condoms pass a standard, the batch is considered acceptable for the market.
|Currently, six primary laboratory tests are used to assure the quality of new latex condoms at the factory.|
The ISO is a worldwide federation of national standards bodies, called "member bodies." Each member body has one vote. Representatives of manufacturers, regulators and research institutions from a single country must reach a consensus among themselves regarding how they will cast their single vote. Countries can choose to be represented on the ISO technical committee that develops standards. Proposed changes in standards are circulated to member bodies for discussion. Adoption of an international standard requires approval by at least 75 percent of member bodies casting a vote; currently 20 to 25 countries cast votes on condom issues. A slow, deliberative body, the ISO sometimes takes years to make a change in standards.
The CEN establishes the standards for the 18 member national bodies in the European community. In theory, the CEN has the same standards as the ISO. However, the condom standard currently includes some requirements that are different from those in the ISO condom standard.
The ASTM sets standards for a broad range of products manufactured in the United States, including condoms. It is a voluntary, membership body, composed of manufacturers, purchasing agents, raw material suppliers, research institutes, individuals and other groups. Each member has one vote regarding changes in condom standards.
The ASTM, ISO and CEN standards all affect condom quality worldwide because many of the condoms distributed in developing countries are manufactured in the United States, Europe and Asia.
Procurement Specifications and Regulatory Actions
Procurement specifications are established by the major condom buyers. While standards focus on the manufactured product, specifications stipulate requirements for condoms that reach the consumer. Specifications are designed to ensure that condoms are safe, effective and acceptable to a particular set of users. They specify such issues as shape, color and packaging, and include details on quantity and delivery schedules. Major purchasers of condoms develop their own specifications, guided primarily by the ISO and ASTM standards. Two major condom procurement specifications are used as models by countries throughout the world, those of WHO and of USAID.
Government regulatory agencies have still another emphasis: to ensure that various laws and regulations are being met and that the condom is safe. If a condom is faulty, it could result in an unintended pregnancy or transmission of a sexually transmitted infection. Regulators therefore monitor the accuracy of claims made by manufacturers on consumer labeling, inspect manufacturing facilities, test domestically manufactured and imported condoms for quality, and test condoms already on the market. Regulatory agencies include the FDA, comparable agencies in other countries, and government agencies regulating imports and exports.
The FDA currently uses the ASTM standard for condoms as a basis for audits of manufacturers, product recalls and injunctions against manufacturers, but is considering using some elements of the ISO standard. Many developing countries rely on the ISO standard and WHO specifications for testing condoms that are entering their countries. For example, India and Indonesia have adopted the WHO specifications as their basis for regulating imports.
While latex condom standards among the major standards and specifications are becoming more uniform, there are still significant differences (see Table 5-1). The most significant differences are discussed below.
Traditional Laboratory Tests
The traditional laboratory tests measure dimensions, leakage ("freedom from holes") and tensile properties.
Dimensions. This group of tests measures condom width, thickness and length. The major difference among the international authorities concerns thickness. Procurement agencies emphasize thickness more than the standard-setting agencies, believing this to be important for consumer safety. USAID specifications require a minimum thickness of .05 mm, and the condoms they buy have a typical thickness of about .06 mm. WHO requires a thickness range of .04 mm to .08 mm. The ASTM standard calls for a minimum of .03 mm, while both ISO and CEN have no thickness requirement, allowing "ultra-thin" condoms manufactured in Japan to comply with those standards.
The minimum length requirement, which does not include the reservoir tip, ranges from 160 mm to 180 mm. The width requirement is generally 50 mm to 54 mm. WHO and USAID specifications have two range requirements, for standard width and for smaller-width condoms, which are designed for targeted markets, primarily in Asia.
Leakage ("Freedom from Holes"). Leakage tests are used both during the manufacturing process and by independent laboratories testing the finished product for quality assurance purposes.
Manufacturers screen every condom during the manufacturing process for tiny pinholes or weak spots, using either a "dry" or "wet" screening method. The dry method involves placing the condom on a metal mandrel and inducing an electrical charge across the condom; a hole allows the current to pass, indicating a faulty condom. The wet approach immerses the condom in an electrolyte, saline solution, with an electric current signal indicating if any holes are present.
Independent laboratories testing selected condoms from batches for quality assurance use either the "hang" or the "hang/roll" method, described on page 50. (Some manufacturers also use these methods.) ISO, CEN and WHO require the hang/roll method. ASTM and USAID require only the hang method. The hang/roll method is more capable of detecting holes that leak tiny amounts of water undetected by the human eye. Even so, both tests are limited to visual detection.
While experts consider the visual test acceptable, they would like to find a more reliable and reproducible test that is independent of the technician's judgment. An electronic detection approach could be used, but would require complex apparatus. In monitoring condom imports, a few countries currently use an electronic wet test similar to the one used during the manufacturing process.
Tensile Properties. Used in many industries, tensile tests measure the extent to which a material changes shape in relation to an applied force. The condom tensile test stretches a cross-sectional piece of latex film, a ring cut from the mid-section of the condom, until it breaks. It measures three properties of the latex: the force it takes to break the ring of latex, the maximum amount of extension before breaking (called percent elongation), and the tensile breaking strength. The tensile measurements were designed to monitor quality and uniformity of manufacturing a latex product.
The tensile test has limitations in terms of predicting how well condoms function in human use; it was not designed for this purpose. The portion of the condom being tested is enclosed within the roll of the packaged condom and is therefore partially if not completely protected from exposure to oxygen and ozone. Thus, the sample used for tensile testing would not be expected to deteriorate as much as the condom tip, which is not protected within the roll.
Also, the tensile test measures the condom in an area and direction that are not the most critical to condom performance during use. The middle section of the condom is not subjected to forces as strong as those either at the base (open end) or tip (closed end) of a condom. During condom donning, the tip-end of the rolled condom is stretched or forced until it fits over the penis. After unrolling the condom its entire length, it is the base of the condom that is manipulated to place it properly. In removing the condom, the tip and/or base again receive the most pressure.
In the 1980s, USAID began more rigorous testing of condoms that it purchased for distribution in developing countries, including investigating more closely complaints about condom breakage from developing countries that received USAID commodities. The condoms from apparently defective batches continued to pass the standards for the tensile test. When using the air burst test and the hang water leak test, however, the tip of the condom broke easily, which suggested that these tests might be more predictive of breakage in human use.
Most experts gradually agreed that the tensile test did not adequately measure deterioration or other factors that could lead to breakage in human use. In 1996, both the ASTM and the ISO dropped the tensile test from their standards. WHO also dropped the tensile test. As of 1997, USAID and CEN still require it because the test does provide valuable information on the quality of condoms at the point of production. The tensile test gives direct evidence that the latex has been formulated and vulcanized correctly. It has also been a useful guide in the development of alternative condom materials.
Air Burst Test
In the late 1970s, researchers began to use the air burst test, believing it might be more predictive of condom performance in human use than the tensile test. The air burst test inflates the entire condom like a balloon, stretching all of the latex until it bursts. Hence, it tests the strength of the entire product, not just a portion of the condom. The test measures the maximum amount of air the condom can hold before breaking as well as the air pressure level inside the condom when it breaks.
.By 1986, two published scientific articles (discussed in Chapter 6) suggested that the results of the air burst test did correlate with breakage in human use. (Free 1980, 1986) In 1990, after some 15 years of deliberation, ISO issued its first condom standard, which included both the air burst and tensile tests. A central reason for the long delay was the debate over testing methodology and acceptance limits of the air burst test. In 1990 USAID adopted the ISO air burst test into its procurement specifications
The U.S.-based ASTM was slower to adopt the air burst test, apparently because of the limited research data correlating it with human breakage. In 1992, however, two published studies pointed out weaknesses in the ASTM standard. One found breakage rates ranging from 7 percent to 13 percent in three countries using batches of condoms that had passed the ASTM standard. The study concluded that the laboratory tests used in the ASTM standard could not reliably predict condom performance during human use. (Russell-Brown) The other study found that measurements from the air burst test, as well as the percent elongation measurement from the tensile test, were highly predictive of condom breakage in human use. (Steiner)
In 1993, ASTM included the air burst test in the standard but did not establish minimum acceptance criteria. In 1996, after further studies by manufacturers and research groups, the ASTM adopted acceptance criteria.
The current air burst criteria in the international standards and specifications vary primarily on minimum air volume. CEN and WHO minimums are 18 liters (L), with ISO, ASTM and USAID at 16 L. When USAID reviewed its specifications prior to soliciting bids for 1996-98, it considered raising its minimum to 18 L. In discussions with manufacturers, concerns arose that making this change could result in other changes, such as a slightly thinner condom that would also be more expensive. In the absence of compelling data indicating that 18 L would ensure a product with improved performance, such as reduced breakage, and given the additional concerns, USAID retained the 16 L requirement.
The air burst test has several drawbacks. First, because it inflates the entire condom, the condom breaks when its weakest point gives way to the air pressure. If this is in the thinnest part of the condom, the test is not sensitive to defects in the thicker regions of the condom, which might receive more pressure during intercourse. For example, for condoms that are manufactured with thicker latex at the closed end, the air burst test may not be sensitive to weaknesses there and hence, not predictive of breakage in human use. Several unpublished studies have found that while a batch of condoms can have very low breakage rates in use, the batch may have a relatively poor air burst performance.
The air burst test protocols exempt the portion of the condom very close to the open end, but the air burst test might be more predictive of breakage if it focused more directly on the closed end. A better test might be the so-called "short-stem" air burst test, which blows air into a smaller part of the condom near the closed end.
Another limitation of air burst testing is that variations occur among laboratory testing facilities. Hence, unless condoms are tested at the same laboratory using the same method, personnel and equipment, test results may not be comparable. To address this concern, in 1993 USAID began sponsoring an international collaborative effort among condom testing laboratories called the Condom Inflation Test Network (CITNET), with PATH coordinating the project. CITNET provides a continuing mechanism whereby condom air burst test systems at manufacturing sites, government agencies and independent laboratories can be checked against one another to minimize inter-laboratory and inter-system variation.
CITNET participants include labs in the United States (Alabama, Massachusetts, North Carolina, Ohio and Washington), Australia, England, Malaysia, Sweden and Zimbabwe. CITNET participation is voluntary and all data are available to all participants. Condoms from the same lot are sent to participating labs with precisely the same testing protocol. The labs test the condoms and return results to the CITNET coordinator. This monitoring process has resulted in a significant reduction in air burst volume variation among test systems over time and has led to suggestions for system re-engineering to further decrease testing variations.
Testing for Deterioration
In the late 1980s, researchers began to test condoms stored in warehouses to assess the importance of condom deterioration. Manufacturers knew that latex deteriorated or "aged" gradually over time and that certain storage conditions, such as intense heat, humidity or moisture, could accelerate the aging process.
One way to slow the aging process of condoms and to ensure product stability was to increase attention to packaging. Concerned that consumers have confidence in receiving a condom in good condition, major buyers including WHO and USAID added a package integrity test to their specifications. This test subjects the package seal to stress under a vacuum seal. ASTM also added this test to its standard, although ISO and CEN have not.
The amount of lubricant in the package can also affect oxidation and thus slow deterioration. (Free 1996) Only the procurement agencies, WHO and USAID, have required this test. USAID requires a minimum of 250 milligrams (mg), and the average is generally about 400 mg. WHO requires 350 mg to 550 mg.
As attention to storage conditions increased, a method of artificially aging condoms assumed more importance. A so-called "oven test" was designed to mimic natural deterioration. Current standards and specifications differ substantially regarding the length of the aging period, the temperatures at which the product is conditioned, which tests to use in measuring the aged condom, and minimum acceptance requirements.
ISO and USAID require a condom aged for two days at 70° C to undergo the air burst test and meet the same minimum requirements as before aging, 16 L of volume and 1.0 kilopascals of pressure. Normally, the mean volume for a batch of new condoms is much higher than the minimum, from 25 L to 40 L. WHO requires 27 L minimum mean burst volume for the batch after seven days of oven conditioning at 70° C, with the same 1.0 kilopascals of pressure.
USAID also includes a tensile test after seven days at 70° C. The ASTM is currently considering an oven conditioning standard but does not have clear data for developing a protocol. Experts are debating whether aging time periods and temperature ranges in the oven test have any correlation to real-time aging, calling into question the aging protocols now in use. Research is continuing to find better ways to predict accurately the stability of the product as it ages.
Proposed Changes in Standards
Among the changes under discussion are: tightening the acceptance criteria for the leakage test, improving the package integrity test and adjusting the air burst test.
Tightening Acceptance Criteria for Leakage Test. Authorities are concerned about limiting the number and size of pinholes that could allow sperm, bacteria or viruses to escape through the condom. Water molecules are smaller than even HIV molecules, so using a water test can address the concern -- if the test is tight enough. There are several ways to tighten the current protocols: to require the hang/roll method rather than the hang approach alone, and to set more stringent acceptable quality levels (AQL). The AQL indicates a calculation that allows a certain number of defective condoms in a given batch; the AQL is not a percentage measurement.
For the leakage test, ISO, CEN and WHO have a tighter AQL, a limit of 0.25, compared to the ASTM and USAID, which have an AQL of 0.40. ASTM and USAID are considering tightening their AQL to 0.25 as well.
The AQL level and number of allowable defects depends on the sample size tested. For example, in the leakage test, in a group of 315 condoms selected for testing from a batch of 150,001 to 500,000 manufactured condoms (a standard test size), a 0.40 AQL allows acceptance of the entire batch if three condoms fail the test; if four fail, the entire batch is rejected. Tightening the AQL for leakage to 0.25 would bring the acceptable number of failures for this batch down from three condoms to two in the sample tested -- i.e., the whole batch is rejected if there are three defective condoms in the sample.
Theoretically, either change may tighten the standard. But no research has been done to show that such a tighter standard would result in less condom failure in use.
Improving Package Integrity Test. Recent research has found that condoms with no packaging or with plastic film packaging deteriorate at a faster rate than do those packaged in foil. (Free 1996; PATH) WHO and USAID specifications now require that all condoms be packaged with aluminum-foil laminate. Other standards and specifications may also move to more specific packaging requirements.
Adjusting Air Burst Test. Various adjustments to the volume level are under consideration. Some proposals would raise the current limit while others would take a new approach, using allowable deviations rather than limits. Still others would adjust the air burst criteria used with the accelerated aging measurements. The current standards for new condoms rely on minimum limits, ranging from 16 L to 18 L. For the accelerated aging test, ISO and USAID require a minimum of 16 L volume, but the mean for a batch of condoms is usually much higher, 25 L to 40 L; WHO requires a minimum mean of 27 L.
Recent research recommended that in the accelerated aging measurements, the mean burst volume be no less than 30 L. (Free 1996) The limit might be slightly higher for condoms intended for use in hot climates and slightly lower for smaller condoms, the study recommended. Experts do not agree on whether and how high to raise the minimum burst volume. Although intuition suggests the higher the minimum, the better the product, most experts agree that there is not enough clinical data to justify raising the limit at this point. Several small studies are underway to test this hypothesis.
by William P. Schellstede, Eli J. Carter and William R. Finger
- Free MJ, Hutchings J, Lubis F, et al. An assessment of burst strength distribution data for monitoring quality of condom stocks in developing countries. Contraception 1986;33:285-99.
- Free MJ, Skiens EW, Morrow MM. Relationship between condom strength and failure during use. Contraception 1980;22:31-37.
- Free MJ, Srisamang V, Vail J, et al. Latex rubber condoms: predicting and extending shelf life. Contraception 1996;53:221-29.
- PATH. Final Report -- Package Integrity Study. Seattle, WA: Program for Appropriate Technology in Health, 1996.
- Russell-Brown P, Piedrahita C, Foldesy R et al. Comparison of condom breakage during human use with performance in laboratory testing. Contraception 1992;45:429-37.
- Steiner M, Foldesy R, Cole D, et al. Study to determine the correlation between condom breakage in human use and laboratory test results. Contraception 1992;46: 279-88.
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Related DocumentsNetwork Vol. 16, No. 3, Spring 1996: Barrier Methods