Medical Device Link.

Originally Published MDDI April 2004

Product Development Insight

Are Your Product Safety Labels State-of-the-Art?

Designers need to be aware of two different standards for safety labels, one for the U.S. market, the other for international markets. Fortunately, there is a format that harmonizes the two.

David Warburton

Devid Warburton

How much thought do you give to the design of the safety labels on your products? In a product liability lawsuit, could you defend the design of the product’s safety label as meeting the latest U.S. and international standards? You may have to some day. Failure to warn users of a product’s nonapparent hazards is a common allegation in product liability litigation. 

To defend against “failure to warn” allegations in a product liability lawsuit, you should take two steps. The first, risk analysis, is already required by the design controls portion of FDA’s quality system regulation. This analysis identifies the inherent and nonapparent hazards in the product. 

But what happens if the residual hazards identified in the risk analysis either cannot be designed out of the product or cannot be avoided by other means? This is where the second step comes in. You must ensure that the product’s label copy adequately warns of these hazards. For such hazards, state-of-the-art warning labels—meaning the best labels that are technically and economically achievable—are essential.

But what is the state of the art in a warning label? How can a manufacturer know that its safety labels will stand up to legal scrutiny?
Fortunately, and not too surprisingly, there are two existing standards devoted to product safety labeling. The first is ANSI Z535.4, the Product Safety Sign and Label Standard. The ANSI standard is a voluntary standard for products sold in the United States, but it is recognized by the U.S. courts as state of the art, and is the standard against which a product’s safety labels will be judged in a U.S. product liability lawsuit. 

The second standard is ISO 3864 part 2, Safety Colours, Safety Signs—Product Safety Labeling. This is a mandatory EU standard for CE- marked products. Products sold in Europe must have safety labeling that complies with it.

Each of these two standards has different requirements for label design. Recently, however, both have been revised, and both standards committees worked toward harmonization. Owing in large part to their efforts, it is now possible to create a single product safety label that complies with both standards.

Rather than discuss the differences in the ANSI and ISO formats for product safety labels here, I will instead focus on what has become known as the harmonized format. This format is considered to be state of the art and meets both ANSI Z535.4 and ISO 3864. The harmonized format originated from the SEMI standards developed for the semiconductor equipment industry, but is gaining wide acceptance in all industries.

The Harmonized Format

According to ANSI Z535.4 section 2.1, a product safety label should “alert persons to a specific hazard, the degree or level of hazard seriousness, the probable consequence of involvement with the hazard, and how the hazard can be avoided.” This is a succinct definition and makes three important points:

• The label should be specific to a single hazard and should clearly illustrate the nature of the hazard. This is most often done with a symbol.
• The label should alert the user to the seriousness of the hazard. On an ANSI standard label, this is accomplished by using signal words, which are all defined in the sidebar on page 42.
• The label should warn the user about what could happen if the label is ignored and, most importantly, how the hazard can be avoided. If the hazard is simple to understand, this part of the label may simply state, “Do not operate without guard in place.” If complicated, it may direct the user to the instruction manual, where more detailed instructions on avoiding the hazard are given: “Read instruction manual before operating.”

Figure 1. An ANSI Z535.4 label showing the three-panel horizontal format.

The format of an ANSI Z535.4 label is designed to ensure that each of these points is addressed. A safety label that complies with the format consists of three panels:

• A signal word panel. 
• A word message panel.
• An optional pictorial panel. 

Each panel on the label provides a key part of the information required to fully meet the definition of a product safety label. The first part of the label is the signal word. This word, in conjunction with its symbol and background color, defines the hazard and its level of seriousness. The sidebar on page 42 identifies and defines each of the signal words.

The word message describes the specific hazard, the consequences of ignoring the hazard, and how the hazard can be avoided. All three of these elements should be contained in the word message panel.

The last panel, the pictorial panel, illustrates the specific hazard. The pictorial panel is considered optional by ANSI Z535.4 and is sometimes eliminated in very small product safety labels. However, the pictorial panel is essential to creating a harmonized label format that is compliant to EU standard ISO 3864. This is because in the view of ISO, the safety symbol is the warning label; both the signal word and message panels are considered optional by the EU standard. A three-panel label is shown in Figure 1.

Safety Symbols Essential to ISO Compliance

If a product safety label is to be ISO 3864 compliant, the symbol in the pictorial panel of the harmonized label must follow the graphic design format outlined in the ISO standard. The black-on-white graphics sometimes seen on an ANSI Z535.4 three-panel safety labels are not recognized by ISO. ISO 3864-2 defines three graphic formats appropriate for product safety labels:

• The warning sign, warning the user of a hazard.
• The prohibition sign, warning the user against a specific action.
• The mandatory action sign, directing the user to perform a specific action.

Figure 2. Warning signs are identified by yellow triangles with a black border.

Figure 3. Prohibition signs use white circles with a red circle and slash.

Figure 4. A mandatory action is indicated by blue circles with white graphics.

These symbols are defined by both their shape and their color. 

Warning signs must be yellow triangles with a black border. The graphic must be black. Figure 2 illustrates a strong magnetic field hazard.

Prohibition signs are white circles with the familiar red circle and slash. Again, the graphic must be black. Each prohibition sign illustrates a prohibited activity; in the case of Figure 3, the sign indicates “no pacemakers.”

The mandatory action signs are blue circles with white graphics and no border. Each sign illustrates an action that must be performed for the safe use of the product. In Figure 4, the mandatory action is to lock out the machine before servicing.

In order for a label to comply with ISO 3864-2, the graphic in the pictorial panel of the harmonized product safety label must be in one of these three formats. 

ISO 7010 is a standard that provides a catalog of safety symbols that are in wide use and have gained broad acceptance. These existing symbols, such as the familiar lightning bolt warning of electrical hazards shown in Figure 5, should be used whenever possible to aid the user in quickly understanding the hazard. Safety label suppliers have hundreds of stock labels using standard symbols for all kinds of hazards. It is acceptable to create custom graphics to describe a hazard unique to a specific product, but such labels should be validated with users to make sure the graphic clearly communicates the hazard message.

The Role of the User Manual

In the United States, English is the only language ANSI Z535.4 requires on the product safety label. But what happens if the product is exported? CE compliance experts’ opinions may differ on this issue, depending on the product and the specific hazards being warned against. But the prevailing opinion is that safety labels incorporating ISO symbols do not need to have the message panel translated into the language of each country where the device is sold. The reasoning is that ISO 3864-2 considers the symbol on the label to be the safety sign. The text contained in the message panel is supplementary, and therefore does not require translation. 

Figure 5: An ANSI Z535.4 vertical-format sign with an ISO 7010 electrical hazard warning symbol.

However, the notified body performing the CE certification on the product will generally require that all safety labels (with ISO safety symbol) appear in the user instructions (and the service manual as well), along with a more detailed explanation of each hazard and the proper way to avoid it. The notified body will usually require that this detailed explanation be translated into the appropriate language or languages. The reasoning is that when users see a warning symbol on a product, they can refer to the user instructions, find the matching warning symbol in the instructions, and then read the detailed safety information in their own language.

Product safety labeling often does not receive the attention it deserves in the overall product design process. Yet product safety labels play a key role in the overall risk mitigation strategy for the product, and can be critical in defending a product in a liability lawsuit. Thus, it is important for the project team to understand and comply with the latest ANSI and ISO product safety standards. 

Copyright ©2004 Medical Device & Diagnostic Industry