Exposure to hazardous substances in a laboratory environment is a significant concern because of the impact on human health. A 2021 study indicated that exposure to toxic and hazardous substances is a laboratory’s third most prominent cause of injury. For this reason, personal protective equipment (PPE) is a requirement in any health care or testing environment. It protects researchers from harmful substances like infectious materials, toxic and corrosive materials, particulate matter, and more. Ultimately, it ensures they work in a safe environment while protecting themselves from life-altering injuries.
Even though using PPE is a requirement, the efficacy of protective clothing remains an issue. Strengthening manufacturing processes can impact their effectiveness, but product testing is the only way to assess their efficacy accurately. PPE like gloves, lab coats, and shoes need to undergo rigorous physical testing to ensure that the product can truly protect researchers from the dangers of such substances. There are several regulatory requirements analysts need to consider, such as EN ISO 374-1 (contact via gloves), EN 9431-1 (airtight suits), and EN 14605 (liquid tight suits). In addition, organizations like the American Society of Testing and Materials (ASTM), the International Organization for Standardization (ISO), and the European Center for Standardization (CEN) have their own handbooks on testing. The UL Mark is widely recognized and respected as a symbol of certification to the highest standards of safety and can provide a competitive edge within the PPE market. To receive the UL mark of approval, they need to be certified as per different standards—requiring systems that can offer such flexibility.
Approaches to evaluating the efficacy of protective clothing against chemicals
There are two common approaches to test if PPE is chemically protective: penetration and permeation testing. Penetration testing focuses on how a chemical penetrates through a material without changing its properties. It can happen through larger than normal pores in the materials, leading to a lack of chemical barrier—acting as a defect test.
On the other hand, permeation testing focuses on how a chemical passes through the material by changing its inherent properties. This possibility is far more dangerous as it's difficult to detect and can lead to severe consequences if researchers work with chemicals that the skin can easily absorb. The chemical gets absorbed into the material from one end, diffuses through the material, and gets desorbed on the other end.
In addition to these approaches, degradation testing is also used to determine efficacy against chemicals. In this case, the material is tested with the challenge chemical to observe whether the material’s properties undergo any change in physical properties such as composition, elasticity, texture, and more. When we combine the results from all these tests, we get an accurate picture of its efficacy.
Yet, there are several challenges associated with testing, such as:
- Differences in testing parameters for separate regulatory standards
- Testing only for specific contact duration, whereas real-life scenarios might differ
- Only a tiny portion of the material is tested but not when it's flexed or abrased
- Non-standardized testing methods available in the market
- Errors in manual testing due to non-standardized testing methods
Due to such challenges, it's difficult to understand the protective material's actual resistance to hazardous chemicals. This is why manufacturing companies must use permeation analyzers that can assess the efficacy of such materials using standardized and automated processes to ensure testing accuracy, material resiliency, and product safety.
Using automated permeation testing for chemical protection
Permeation testing is based on a diffusion cell experiment prescribed by standards such as the American ASTM F739 and the European EN16523-1. In this experiment, a cutout of the material is placed between two halves of the analysis cell. The challenge chemical is placed in the donor chamber, and the rate at which it passes through the material to the receiver chamber is measured at specific time intervals (specified by the regulatory body). The time it takes for the quantity of the chemical to exceed 1μg min-1 cm-2 in the receiver chamber is called the breakthrough time. The minimum time interval differs based on the type and protection class of the test material.
Currently, newer versions of this approach are available with slight modifications to make it more accurate and efficient. For example, a 2021 study discussed using an indicator of activated charcoal cloth (ACC) that can be used to test the material's efficacy under different working conditions—although it only applies to selective conditions. However, when such methods are used, it's challenging to conduct such thorough analysis quickly at scale. This is where automated systems can fill the gap. There’s an increasing need for automated and flexible testing systems, in part due to the COVID-19 pandemic and supply chain issues.
Automated permeation analyzers offer analysts and manufacturers the advantage of simultaneous testing and the ability to test under different conditions. Such analyzers have multiple permeation cells where several test samples can be tested simultaneously. Once the sample is placed, the challenge chemical can be automatically introduced as required so it is in contact with it on one face of the material. The breakthrough time is plotted automatically via custom software with regular results automatically derived from a gas chromatograph that detects the chemical in the headspace on the other side of the analysis cell.
Depending on the regulatory requirements, the analyst can monitor the temperature, conduct analysis in triplicates, control the gas flow, automate the introduction of the challenge chemical, and even initiate the shutdown process once the breakthrough point is reached. Moreover, they can also automate the plotting process by connecting to custom analysis software that does the reporting for them. Such systems allow the analyst to alter the speed of the testing process, which helps them avoid waiting for longer tests to complete before getting the full report.
Automating the entire process means they don't have to wait for one sample to finish before getting to the next one—making it highly efficient.
Permeation testing plays a huge role in the chemical resistance testing process as it gives users of PPE products a comprehensive overview of whether the product is suited for their workflows. As PPEs play a significant role in any research environment, manufacturers must get their products tested per the required regulatory standards. We can protect countless lives with the right products, as working with chemicals requires a high degree of caution. It also helps manufacturers sell their products confidently as it becomes easier to test and get the mark of approval in a shorter period. Automated permeation testing can hasten the process through simultaneous testing and make it more efficient by avoiding frequent manual intervention.