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Child-Resistant Closures
Learning of the Month
Learning Objectives
Discuss the history of child-resistant closures
Analyze child-resistant closure testing
Discuss common child-resistant closures
Examine a real-world example of a child “opening” these closures

Ever tried to open a bottle of pills or a cleaning product only to feel like you’re solving a Rubik's Cube? While this may be frustrating, child-resistant closures (CRC) are the superheroes of packaging, keeping curious little fingers away from potentially harmful substances and remaining accessible to adults. They're like tiny fortresses, designed to thwart the most determined of tiny hands and give peace of mind to parents everywhere. So, let’s take a closer look at how child resistant closures have evolved and their current testing methods.

Child-resistant closures have a fascinating history, marked by concerns over child safety and regulatory efforts to mitigate accidental poisonings. Here’s a condensed timeline1,2,3,4:

Early 20th Century: As household products became more common, so did accidental poisonings, particularly among children. Bottles often had simple screw caps that were easy for children to open.

1936: A significant event occurred when the American Medical Association (AMA) published a study highlighting the dangers of accidental poisonings, especially among children. This spurred discussions on the need for safer packaging.

1957: The first child-resistant packaging, known as the "Palm 'n Turn" closure, was invented by Dr. Henri Breault, a Canadian pediatrician. It required a combination of squeezing and turning to open, making it difficult for young children to access its contents.

1970: The Poison Prevention Packaging Act (PPPA) was passed in the United States, mandating child-resistant packaging for various household substances, including prescription drugs, over-the-counter medications, and household chemicals. This legislation significantly boosted the development and adoption of CRC.

1973: The Consumer Product Safety Commission (CPSC) was established in the US, further emphasizing the importance of product safety, including child-resistant packaging standards.

1984: The International Organization for Standardization (ISO) published ISO 8317, a standard for child-resistant packaging, providing guidelines for manufacturers worldwide.

2002: The European Union implemented regulations requiring child-resistant packaging for certain pharmaceutical products, aligning with existing standards in the US and other regions.

Modern Innovations: Over the years, CRC technology has continued to evolve, with advancements such as push-and-turn caps, squeeze-and-turn caps, blister packs, and other innovative designs aimed at balancing safety with accessibility for adults.

Now let’s take a look at the testing component of child-resistant closures. 

Child-resistant closures (CRC) undergo rigorous testing to ensure they meet specified safety standards. Two prominent organizations, ASTM International and the International Organization for Standardization (ISO), have established testing protocols for CRC. Here's an overview of the testing methods commonly used:

ASTM Standards5,6,7

  • ASTM D3475: This standard outlines the test method for measuring the torque required to open and close child-resistant packages. It involves applying a specific torque to the closure and measuring the force required to open it.

  • ASTM D7860: This standard specifies the test method for determining the force required to remove or disengage child-resistant caps from bottles or containers. It evaluates the strength of the closure's engagement mechanism.

  • ASTM F2097: This standard focuses on the testing of blister packaging to determine its effectiveness as child-resistant packaging. It involves testing the force required to push the product through the blister and into the container.

ISO Standards1,8,9:

  • ISO 8317: This standard specifies requirements and test methods for child-resistant packaging. It outlines procedures for evaluating the effectiveness of closures in preventing access by young children while allowing easy access for adults.

  • ISO 13127: This standard provides guidelines for the testing of reclosable child-resistant packaging. It includes methods for assessing the ease of opening and reclosing the packaging while maintaining child resistance.

  • ISO 17480: This standard specifies test methods for the assessment of the ease of opening and reclosing child-resistant packaging for pharmaceutical products. It covers various closure types, including push-and-turn caps and squeeze-and-turn caps.

These testing standards ensure that child-resistant closures are effective in preventing access by children while remaining accessible to adults. Manufacturers typically conduct these tests during the development and production phases to certify compliance with regulatory requirements. Additionally, regulatory agencies such as the U.S. Consumer Product Safety Commission (CPSC) and the European Medicines Agency (EMA)  . Also of note—each state has specific requirements for child-resistant closures, but most of these rules fall under the jurisdiction of the Poison Prevention Act (PPPA) standards created decades ago.3

Interestingly and maybe obviously, for packaging to meet the CPSC’s child-resistant standard, it must be subjected to real-world testing with children and adults. Packaging must be tested under normal conditions by a panel of children in three different age groups: 42–44 months,  45–48 months, and 49–51 months.10 For the packaging to successfully pass child-resistant testing, at least 80% of the children involved in the test should not be able to open the package throughout the entire ten-minute testing period. Within these ten minutes, the children are instructed on how to open the package and that they may use their teeth (like real life, huh?).11

Child-resistant testing often involves statistical analysis to determine the effectiveness of the packaging. The number of children who can open the packaging within a specified time frame, such as the first five minutes, is a crucial factor in determining the effectiveness of the packaging. By setting thresholds for the number of children who can open the packaging before it is deemed a failure, regulators can ensure that the packaging provides a reasonable level of protection against accidental ingestion by children.12

As with most packaging, child-resistant closures come in a variety of designs—each carefully crafted and tested. Let’s take a look at some common closure styles and their typical applications: 13,14,15

  • Push-and-Turn (Twist) Closure: This style requires the user to simultaneously push down and twist the cap to open the container. It often features a safety lock mechanism that engages when the cap is closed, requiring deliberate action to unlock it. Push-and-turn closures are commonly used for pharmaceuticals, over-the-counter medications, personal care products, and household chemical products.

  • Squeeze-and-Turn Closure: Similar to push-and-turn closures, squeeze-and-turn closures require the user to squeeze the sides of the cap while twisting to open the container. This design offers an additional level of child resistance by incorporating a squeezing action. Squeeze-and-turn closures are frequently found on pharmaceutical bottles, containers for liquid medications, and household chemicals.

  • Flip-Top Closure: These closures typically involve a mechanism that requires a specific combination of actions to open, which can be challenging for young children to figure out but manageable for adults. These mechanisms often include pressing down and simultaneously flipping a cap or pushing and twisting motions. 

And there are some hacks out there as well. For folks that have no need for these child-resistant measures or have increased loss of dexterity in their hands, the traditional Rx bottle closure can be flipped and put on backwards. This action makes the pill bottle no longer childproof and a whole lot easier to open. While this is not a universal action (from our research), we have found that pharmacies will provide snap-off/on caps as well when requested. 

CRCs are typically made from a variety of materials, each chosen for its suitability in providing both child resistance and functionality. Some common materials used for CRCs include:16,17,18,19

  • Polypropylene (PP): PP is a widely used thermoplastic polymer known for its durability, chemical resistance, and versatility. It's commonly used in CRC closures due to its ability to withstand repeated opening and closing cycles without deforming or losing its child-resistant properties. PP closures are often used for pharmaceutical packaging, household chemical products, and food containers.

  • High-Density Polyethylene (HDPE): HDPE is a strong, rigid plastic known for its resistance to chemicals and impact. It's commonly used in CRC closures for its durability and ability to maintain child-resistant features over time. HDPE closures are often used for products such as prescription medication bottles, household chemicals, and industrial containers. 

  • Metal: Some CRC closures utilize metal components, such as aluminum or steel, to provide additional strength and security. Metal closures are often used in combination with plastic components to create a child-resistant locking mechanism. Metal closures are commonly found on products such as prescription medication vials, aerosol cans, and certain types of food packaging.

  • Blends and Composites: Manufacturers may also use blends of different polymers or composite materials to achieve specific performance requirements for CRC closures. These blends may offer enhanced durability, chemical resistance, or aesthetic properties compared to single-material closures.

  • Flexible Packaging Materials with Zipper Mechanisms: Child-safe zippers and flexible packaging are essential components in ensuring the safety of children around potentially hazardous products. These are typically made from high-barrier films, mult-layer structures, and some companies have been testing the use of PCR in both the film and the zipper closures.

In summary, child-resistant closures are indispensable safeguards, designed to protect children from accidental ingestion of harmful substances while allowing easy access for adults. Through innovative designs and rigorous testing, CRCs ensure safety without compromising convenience. These closures, along with child-safe zippers and flexible packaging, represent a vital aspect of product safety, promoting peace of mind for caregivers and manufacturers alike.

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