The Product Safety Label: A Critical Component of Compliance

The essential function of a product safety label is to communicate hazard information that allows a person to safely use or service a product. Product safety labels also play an integral role in preventing product liability loss exposure and helping manufacturers obtain CE certification, and improve product safety. Safety labels are now viewed as a critical component of the product's overall design.

Since the safety label is such a visible part of a product, using the wrong label format broadcasts the fact that a manufacturer is not in compliance with the appropriate standards. This article gives product manufacturers practical information about safety labels pertinent to global marketing, discussing the importance of symbols on product warnings, reviewing the primary international and U.S. standards in use, and examining the issues relevant to harmonizing those standards.

An International Perspective: Symbols, CE Compliance, and ISO Standards

The first thing to understand is that symbols are the essential ingredient of international product safety labels. The terms pictogram, pictorial, and symbol—with reference to safety labels—each describe the same thing: an illustration that defines a hazard or an action to be taken to avoid a hazard. Well-designed symbols communicate information quickly and do so across language barriers. Text-message-only safety labels are practically meaningless to product users who are illiterate or do not speak the language of the label text. This is why symbols are state-of-the-art for communicating hazard information.

Symbols are preferred to text-based warnings because there are huge practical problems involved with conveying safety information in multiple languages. The ability of symbols to communicate across language barriers is an important benefit in Europe, where many languages are spoken and products often cross borders.

The citation from the annex to the directive brings up the question of which hazards require warnings. Presumably, the product manufacturer has performed a risk assessment (see EN 1050) before deciding to apply warning labels. This process involves eliminating or reducing risks stepwise. If the hazard cannot be designed out of the product, use safeguarding. If the hazard cannot be guarded, warn about it. The prioritized three-tier approach to protecting users from hazards is well-known and widely used throughout the United States. But even if the hazard is guarded, a warning on the outside of the guard may be necessary because the hazard may not be evident (ref. MD Annex 1.7.2); that is, the guard may block the hazard from view. It is becoming more common to place safety labels both on a guard and in a location underneath it in case the guard is removed (see Figure 1).

Figure 1. Labels affixed to equipment beneath guards remind users that a guard has been removed.

European norms (ENs) are standards that give specific guidance. They are used to ensure that the requirements set forth in European directives are fulfilled. A more exacting European perspective on the issue of warnings and text appears in EN 292-2, Safety of Machinery—Basic Concepts, General Principles for Design, which states: "Markings, signs and written warnings shall be readily understandable and unambiguous, especially as regards the function(s) of the machine which they are related to. Readily understandable signs (pictograms) shall be used in preference to written warnings" (Paragraph 5.4(c)). This norm clearly indicates that CEN (the European Committee for Standardization, the body responsible for EN 292-2) prefers symbol-based safety signs. Its vocabulary shows that, to the Europeans, signs and pictograms are the same thing. A safety sign is a symbol.

Problems arise from the statements concerning safety labeling found in the MD and EN 292-2. The qualification that the pictograms be readily understandable makes sense but can be difficult to achieve in practice. Several factors are involved. First, it is preferable to use an existing symbol if one can be found for the hazard in question. Yet no single standard illustrates a large number of the available safety-related graphics. Finding the appropriate graphic for a specific hazard can be a daunting task. Next, because standardized graphic design leads to higher symbol recognition, it is essential that, if a new symbol must be developed, the right graphic design principles be employed to properly depict the hazard or hazard avoidance information. Again, the problem lies in the fact that no general ISO standard exists that defines a method for designing safety-related graphics. Third, the quoted documents state that symbols must be readily understandable, but they describe no method for ensuring that the symbols will be comprehended. And is comprehension testing mandatory? If so, then the national standards of many European countries are questionable, because the vast majority of symbols appearing in them have never been tested for comprehensibility.

The MD and EN 292-2 set the mandatory legal requirements machinery must meet to be sold in Europe. Individual national standards and CEN have agreed to give ISO and IEC authority over the realm of safety signs and symbols. Work currently under way in ISO Technical Committee (TC) 145 is of critical importance to the quest for standardization in this area. ISO/TC 145, unsurprisingly, is dominated by a European perspective; of 13 members, 9 are European. Thus, the concerns of U.S. manufacturers must often struggle to be understood.

ISO/TC 145 and ISO 3864

ISO/TC 145 is in charge of several standards involving graphical symbols, including ISO 3864, Safety Colours and Safety Signs, the principal international standard concerned with the appearance of safety signs. This standard was last published in 1984. The technical committee has been working on its revision since 1996.

Formats. ISO 3864 defines four basic formats for safety signs, which are illustrated in Figure 2. Through a vocabulary of shape, color, and symbol, each format communicates a particular type of safety message. The blue mandatory-action and yellow-and-black triangular warning sign formats are unfamiliar to many people in the United States, although more and more manufacturers are using them or considering them for use in the near future. The one ISO 3864 sign format that does have a high comprehension value in the United States is the prohibition symbol. However, it is now used to indicate many types of activities prohibited for reasons having little or nothing to do with product or equipment safety.

Figure 2. ISO 3864 safety sign formats (clockwise from top left): warning sign, prohibition sign, mandatory action sign, and safety information sign.

At the ISO/TC 145 plenary meeting in Lisbon, Portugal, in March 2000, production of a guideline for the development of safety symbols was discussed at length. The need for such guidance was illustrated with the example of how the prohibition sign is used to indicate prohibitions that are not safety messages: Does the No Smoking sign serve to secure the comfort of nonsmokers, to indicate a long-term health risk, or to indicate an immediate hazard, such as a possible explosion at a gas station? Other ways to signify negation or prohibition include placing an X or a single diagonal bar over the symbol. Might these design elements be more appropriate for the No Smoking symbol than the prohibition circle with slash when a nonsafety message needs to be conveyed in symbolic form? Committee members at the Lisbon meeting decided to proceed with the development of a guideline that would cross the boundaries of several standards to assist those who design and apply safety signs and labels.

Revision of ISO 3864. To better define its application, ISO 3864 is divided into three parts in the proposed revision:

Parts One and Two are intended for signs found on walls in buildings. The U.S. technical advisory group (TAG) has taken the initiative of informing the other country delegations about the special signage requirements of products. Understanding that providing safety information on products raises distinct issues, TC 145 decided to expand upon the principles defined in ISO 3864 Part One in a separate part of the standard covering the requirements for product safety labeling.

Importantly, the United States is in charge of drafting Part Three of ISO 3864. One of the significant accomplishments of TAG has been the acceptance for ISO 3864 Part Three of the ANSI Z535 formats, which are discussed later in this article. This will enable U.S. manufacturers to use identical formats for both their domestic and international safety labels.

The decision to create a catalog of symbols for inclusion in ISO 3864 Part Two is a major step forward in the attempt to standardize symbols across many industries. At the March 2000 Lisbon meeting, TC 145 resolved to develop standardization procedures and design guidelines for safety symbols in the same way that function and control symbols are standardized in ISO 7000, Graphical Symbols for Use on Equipment, another of TC 145's standards. Comprehension testing will most likely be a step in the procedure that qualifies a symbol for inclusion in ISO 3864 Part Two. Having a set of standards that collects the symbols, provides design guidelines, and uses comprehension-testing procedures will help alleviate the problems relating to compliance with the Machinery Directive and EN 292 noted earlier.

One major point of contention has been the European ISO/TC 145 delegation's insistence that the standard surround shape and color be maintained for the symbols to be used on product safety signs. The delegation's concern is rooted in the fact that the European visual vocabulary of signage defines a safety sign in terms of shape, color, and symbol combined in a single unit. Most U.S. symbols now have no surround shape and color. A compromise has been incorporated into the ISO 3864 Part Three draft to the effect that any symbols standardized in Part Two will maintain their surround shape and color if they are used on product safety labels. For example, the lightning bolt that symbolizes an electrical hazard would always appear on a product label within a yellow-triangle-with-black-band surround shape.

Another ongoing debate within ISO/TC 145 concerns the need for comprehension testing and education to ensure that standardized safety symbols are understood by people. The considerable cost of undertaking symbol-comprehension testing programs cannot be borne by the ISO committee; industries must come forward to sponsor the work. It is quite possible that a core group of cross-industry symbols will be standardized initially, and that subsequent sets of symbols will be included in ISO 3864 as specific industries come forward to sponsor symbol development and comprehension testing.

A fourth part may be added to ISO 3864 to collect product-related safety symbols, or Part Two's scope may be revised to include such symbols. The issue of the necessity for surround shape and color will probably be a contentious element of this decision, too, if ISO/TC 145 accepts the responsibility for standardizing all product safety symbols.

A side note: IEC standard 1310-1, Safety of Machinery—Indication, Marking, and Actuation (1995), sets forth the requirements for visual, auditory, and tactile signals for machinery. The section of this standard that contains safety sign formats gives some examples of ISO 3864–formatted signs, several of which would never actually be considered for machinery. That is because this section of IEC 1310-1 was copied from an early draft revision proposal for ISO 3864. After ISO/TC 145 completes its revision of ISO 3864, IEC 1310 probably will be revised accordingly and its presentation of symbols reduced to those pertaining to machinery. The symbols that remain will also be in accordance with the new ISO 3864.

A U.S. Perspective: The ANSI Z535 Standards

Safety label standardization in the United States dates largely to the creation of the American National Standards Institute's (ANSI's) Z535.4 standard in 1991. Before that, no existing standard was relevant to the format and design of safety signs for use on products. Most manufacturers developed their own safety sign designs, or borrowed the OSHA designs for environmental and facility safety signs, or purchased generic signage from inventory-based safety sign companies. The result was a proliferation of product-safety sign designs, colors, and messages. The 1991 publication of the ANSI product safety sign and label standard was of significance to manufacturers. For the first time, a single cohesive standard covered the majority of product warnings.

ANSI Z535.4 defined its purpose in Subsection 2.2:

In the United States, warning labels are essential because manufacturers have a legal duty to warn users about hazards associated with their products. The Z535 standards are important to product manufacturers for reasons involving user protection and product liability.

ANSI Z535 brings a degree of standardization to safety sign formats, colors, signal words, and symbols. The theory goes that standardizing the components of safety signs leads to better comprehension, and that better comprehension should lead to fewer accidents. Standard formats, colors, and symbols appearing on highway signs have improved their comprehension by U.S. motorists. Applying this same standardization process to safety labels should enable people to recognize and better understand hazard information so that they can avoid possible injury.

A by-product of the standardization of product safety signs is that the ANSI Z535 standards now offer U.S. manufacturers an officially recognized state of the art for product warnings and thus a defense against product liability. Prior to the ANSI Z535.4 standard, many warnings could be challenged in court as inadequate. In fact, inadequate warnings and failure to warn are leading allegations in product liability lawsuits in the United States. A decision to apply the ANSI Z535 standards can do much to reduce product liability exposure.

The ANSI Z535.4 Format

Figure 3. A typical three-panel ANSI Z535.4 product-safety sign.

The ANSI Z535.4 format for a product safety sign is relatively simple. It consists of a signal-word panel, a word message panel, and an optional symbol panel in either a vertical or a horizontal configuration. Figure 3 illustrates a vertical version.The Z535.4 standard names four items of content that should be communicated by a product safety sign:

Of the four key components that make up an ANSI Z535.4 product safety sign or label, the first is the signal word, the large word in capital letters on a colored background appearing at the top of the sign. The second component is the colored background behind the signal word. danger appears as white letters on a red background, warning as black letters on an orange background, and caution as black letters on a yellow background. Each signal word with its corresponding background color communicates a different level of hazard seriousness. danger indicates an imminently hazardous situation that, if not avoided, will result in death or serious injury. This signal word is to be reserved for the most extreme situations. warning indicates a potentially hazardous situation that, if not avoided, could result in death or serious injury. And caution indicates a potentially hazardous situation that, if not avoided, may result in minor or moderate injury. This word may also be used to alert against unsafe practices.

Two determinations underlie the choice of the appropriate signal word for a product's safety sign. First, what is the severity of the hazard? If serious injury or death could result, then the choice is between danger and warning. Then, what is the likelihood that injury will occur if the safety sign's message is ignored? A sense of certainty that serious injury or death will be the result of interaction with the hazard, and that this outcome will occur if the hazard is not avoided, calls for the signal word danger. If injury or death is only a possibility, then the signal word choice should be warning.

Note that, in the 1998 revision of ANSI Z535.4, caution without the safety alert symbol (the triangle containing an exclamation mark placed to the left of the signal word) is used to indicate hazards that might result in property damage only. This change was made because the safety alert symbol is by definition used to indicate a potential personal injury hazard. The revision now properly limits use of the symbol to safety labels concerned with alerting people to hazards involving personal injury. The expected 2001 revision of Z535.4 will maintain this distinction for the use of caution for safety signs and labels.

The symbol and the word message are the third and fourth key components of an ANSI Z535.4 safety label, communicating the nature of the hazard, its consequences, and how to avoid it.

The ANSI Z535.4 standard makes the use of symbols optional. However, the ability of symbols to communicate across language barriers and the attention-getting speed with which they convey hazard information make them an integral part of a product-safety labeling program. As the state of the art in safety communication, symbols are tools not only for promoting product safety but also for winning product liability lawsuits. Viewed in this light, symbols become virtually mandatory on ANSI Z535 labels.

In combination with the symbol, the word message conveys the hazard description and consequence and avoidance information. ANSI Z535.4 says that the word message should be "concise and readily understood." To help accomplish this task, the manufacturer may refer the product user to other sources of information such as operator's manuals. This is an important allowance. The manufacturer need place only the most essential hazard information on the product's safety labels. The manuals can be relied on to offer a more complete picture of the safe use and servicing of the product. Such a label design is shown in Figure 4.

Figure 4. A typical read-and-understand-manual label refers the user to a source of more-complete safety information.

The ANSI Z535 standards seem to work extremely well. They are firm in their definitions and yet flexible enough to accommodate the great majority of product safety label applications manufacturers confront. Since 1991, many industry-specific safety sign standards have been revised to conform to the Z535.4 format. Recognition is spreading that well-designed ANSI Z535.4 safety labels communicate hazard information far better than the old generic-style safety signs and labels once in common usage.

Both the Z535.2 environmental and facility safety sign standard and the Z535.5 standard for accident prevention tags were revised in 1998 to express preference for the use of the Z535.4 format over the old OSHA-style formats. The 2001 revision of Z535.2 and Z535.5 will permit use of only the Z535.4 format for safety signs, labels, and tags. Thus, the danger in an oval, overall-orange warning sign format and the caution in an overall-yellow sign format that were included in the original Z35 standard will no longer exist in the Z535 standards. (The Z35 standard was the precursor to the Z535 standards and was the basis document for the OSHA regulations on safety sign formats. OSHA encourages compliance with the latest version of the basis document for an OSHA regulation.) The effect of this change is that the United States is definitely moving closer to the realization of a single national uniform standard for hazard recognition.

Harmonization of Product Safety Label Standards

Harmonization of U.S. and international safety sign design standards is proving to be complicated. Back in 1995, the U.S. delegation to the standardization activities of the ISO felt that all it could achieve was possible harmonization of the colors and symbols stipulated in the ANSI Z535 and ISO 3864 standards. But as the revision process for both standards nears completion, both ANSI and ISO committees will likely accept a degree of flexibility. Final publication of the next revision of the ANSI Z535 standards is scheduled for December 2001. The various parts of ISO 3864 are also expected to be published in 2001.

The Z535 committee is considering revising the Z535.4 product safety label standard to allow the use of graphic-only (nonword) formats that are identical to those defined by ISO 3864. A proposed addition to the foreword, after noting the international precedent, points out that whether to convey some part of the necessary hazard communication with words and whether to include a signal word panel are choices based on many factors. Such factors include, but are not limited to, the product's anticipated market, the movement of the product from country to country during its expected life, the target audience's characteristics, the severity and risk of engaging the hazard, the difficulty of providing for translations, space limitations on the product, and common industry practices. It should be noted that as of this time, nonword product safety labels have not been tested in litigation.

If the proposal to include symbol-only label formats passes, it will break a 20-year tradition in the development of this standard. Because of the important role product safety labels play in fulfilling manufacturers' legal duty to warn, legal precedent to a large degree has governed the course of ANSI Z535. Symbol-only formats have not been subjected to this litmus test.

Symbol-only labels may prove to be more effective in their ability to warn than labels with words in some situations. Permitting symbol-only formats in revised Z535.4 would allow manufacturers to determine the best labeling approach for any product. A key issue is the question of how manufacturers will choose to enhance or verify the comprehensibility of their symbol-only labels. Possibilities include comprehension-testing safety symbols prior to using them on safety labels, providing training materials to a product's users, and reinforcing the meaning of safety symbols in product manuals.

The revision of the SEMI S1 semiconductor equipment industry guideline for product safety labels will probably be completed this fall, ushering in a new era of safety labeling for this industry. This document will incorporate many of the features included in or now under consideration for ISO 3864 and ANSI Z535. The S1 guideline wholly adopts the harmonized approach illustrated in Figure 5 as the preferred format for communicating safety information on equipment intended for use both in the United States and abroad.

Figure 5. A harmonized ISO 3864/ANSI Z535.4 label provides a single format for communicating hazard information in both U.S. and international applications.

The harmonized safety sign format raises the question of whether translation of the label text is necessary when equipment manufactured in the United States ships to a non-English-speaking country. Many CE compliance services argue that the symbols on the sign constitute the international safety sign and that the text portion, being a supplementary sign, does not have to be translated on the label. (Because the label message is safety related, it would have to be translated in the product manual.) This seems like a workable solution; however, any manufacturer's decision concerning translation will ultimately depend on satisfying the desires of the customer and the market, as well as the CE-compliance consultant.

Conclusion

The U.S. and international product safety label standards are converging as efforts to standardize safety symbols continue. The United States is playing a major role in these developments because of its identification of safety labels as a critical component part of a product. And in an increasingly global economy, using symbols to communicate safety information is practically essential.

For products now intended for use in the United States, it is highly advisable that safety labels comply with ANSI Z535.4, even though the standard is voluntary. Reasons of both product safety and product liability support using its state-of-the-art guidance.

Most capital equipment manufacturers seem to use ANSI Z535.4 warnings for equipment sold in the United States and ISO 3864 symbol-only safety labels on equipment for export. Such an approach supports compliance with existing U.S. and international standards.

The harmonized format of the future will provide manufacturers with a single-formatted safety label to meet both U.S. and international requirements, though translation may still have to be considered. This single-formatted label will be used widely in the semiconductor manufacturing industry in the very near future. The degree to which translation is an issue will soon be apparent.

Another option for a manufacturer who can manage the logistical problems of inventory and assembly is to produce translated versions of its Z535 labels for each country it sells to. This approach allows for a consistent use of formats, words, and symbols throughout a product line, though anticipating inventory requirements would be a challenge.

All these scenarios meet the Z535 and CE compliance requirements. The challenge for engineering staff is deciding which approach is most appropriate for a particular product and market while keeping informed of ongoing developments regarding the ANSI and ISO standards.

Geoffrey Peckham is president of Hazard Communication Systems Inc. (Milford, PA). He is chairman of the U.S. technical advisory group to ISO/TC 45, and chairman of the ANSI Z535.1 committee.