What is a Manufacturing Restricted Substances List (MRSL)?

Why MRSLs matter

MRSLs play a vital role in improving chemical safety across global manufacturing supply chains. They control chemicals at the process level, and cover raw materials such as dyes, inks, coatings, adhesives, and process chemicals like detergents, catalysts and lubricants. By preventing problematic substances from entering production upstream, MRSLs make it easier to meet regulatory requirements and support safer chemistry goals. 

MRSLs also support both worker safety and consumer safety. Workers in factories, textile mills, or tanneries are often the first to be exposed to hazardous substances, and MRSLs help remove these hazards from the working environment. For consumers, controlling chemicals early in production reduces the likelihood of harmful residues remaining in finished products. 

The ZDHC MRSL is a widely adopted example in the textile, leather, and footwear industries. It sets global limits for hazardous substances such as certain azo dyes, perfluorinated chemicals (PFCs), and heavy metals, helping to reduce them in production processes. Brands including Adidas, Levi Strauss & Co., and H&M have adopted the ZDHC MRSL to align their supply chains with best practices in safer chemistry and environmental stewardship. 

From a compliance standpoint, MRSLs are particularly powerful in complex, multi-tier global supply chains. Manufacturers often source materials from multiple countries with varying regulations. A single MRSL standard allows brands to set consistent chemical requirements for all suppliers, regardless of geography, simplifying audits and reducing compliance risk. 

In global supply chains, the biggest risk is not only what ends up in the finished product — it’s what happens during production. MRSLs shift the focus from end-of-line testing to process control, creating a proactive barrier against chemical hazards. This protects workers and the environment and helps brands avoid costly recalls and reputational damage. 

MRSLs are therefore an essential tool for responsible manufacturing. They help brands, suppliers, and chemical producers move towards safer chemistry, prevent harmful substances from entering the production process in the first place, and create a unified compliance framework that supports both sustainability and safety goals. 

MRSLs vs RSLs vs Regulatory Lists

In supply chain chemical management, three main types of lists guide compliance and industry efforts to reduce the use of known, harmful substances: MRSLs, RSLs, and regulatory lists. Watch lists and voluntary frameworks add an extra layer. Understanding the scope and purpose of each helps companies decide when and how to apply them effectively. 

MRSLs set limits for hazardous chemicals used in manufacturing processes.  

They apply to all process chemicals, including dyes, adhesives, coatings, and cleaning agents, and are designed to ensure that problematic substances do not enter production in the first place. MRSLs are proactive by nature: they reduce the use of hazardous substances at the process level, protecting workers, reducing environmental impact, and making downstream compliance easier.  

RSLs specify chemical limits in finished products.  

They are used for product testing before market release to verify compliance with regulations or brand standards. RSLs are reactive in the sense that they confirm outcomes rather than control how a product was made. While they are essential for consumer safety, they do not guarantee that hazardous substances were avoided during manufacturing. 

Regulatory lists are legal requirements, such as EU REACH Annex XVII, US TSCA restrictions, or China’s GB standards.  

These lists may apply to substances in products, manufacturing, or emissions and discharges. Regulatory lists are mandatory within their jurisdiction, and non-compliance can result in fines, legal actions, lack of market access, and damage to reputation. Companies operating global supply chains must comply with all applicable regulatory lists.

Watch lists and voluntary frameworks flag potential substances of concern. 

These lists typically highlight substances that may be regulated in the future or that brands may wish to avoid voluntarily. They are often based on hazard profiles rather than legal thresholds. Examples include the ZDHC Candidate List and the International Living Future Institute (ILFI) Living Building Challenge Watch List. Watch lists and voluntary frameworks flag substances where emerging evidence suggest potential concern, help companies anticipate possible regulatory changes, and demonstrate leadership in sustainability. 

In practice, responsible brands use all four approaches: MRSLs to prevent, RSLs to ensure compliance, regulatory lists to comply, and watch lists to stay ahead of change. 

Challenges of using MRSLs

MRSLs are powerful tools towards safer manufacturing, but implementing them across a global supply chain has its challenges. 

One major issue is supplier data quality and disclosure. Many suppliers, especially at lower tiers, lack detailed chemical inventories or the capacity to provide complete and accurate information. This can make it difficult to verify whether all process chemicals meet MRSL requirements. Differences in data formats and reporting systems further complicate consolidation across multiple suppliers and regions. 

Gaps in supply chain visibility are another challenge. Brands often have good oversight of tier-1 suppliers but far less visibility into chemical use at sub-suppliers, contract manufacturers, or upstream processors. Without direct engagement, hazardous substances can enter into production unnoticed. 

Adding complexity, MRSL requirements are not always harmonized. Standards may vary by industry, brand, or initiative, meaning suppliers may need to use multiple, slightly different MRSLs for different customers. This raises the risk of confusion or unintentional non-compliance. 

A further issue is the presence of “hidden” chemicals in auxiliaries, cleaning agents, and other process chemicals. These substances may not be intentionally added to product and are not always captured in standard disclosures, yet they can still contaminate the supply chain or pose health and environmental risks. 

Ultimately, MRSL effectiveness depends on clear communication, consistent requirements, training for suppliers, and robust verification systems, combined with a willingness to look beyond surface-level compliance. 

What’s next for MRSLs?

MRSLs are increasingly used as part of broader chemical management programs, helping brands and suppliers improve visibility into the substances used during manufacturing and strengthen upstream controls. As expectations for chemical transparency grow, MRSL implementation is likely to expand beyond basic compliance checks toward more consistent data collection, verification, and supplier engagement across multi-tier supply chains. 

 Future trends point toward broader substance scopes, with some MRSLs moving toward restrictions on chemical groups, such as per and polyfluoroalkyl substances (PFAS), known as “forever chemicals”, certain solvents, emerging contaminants, and other hazardous classes.  

There is also growing alignment with regulatory initiatives such as EU REACH, the US Toxic Substances Control Act (TSCA), and the UN’s Strategic Approach to International Chemicals Management (SAICM). Greater alignment will make it easier for global brands to harmonize requirements. At the same time, digital chemical management platforms are improving real-time visibility into compliance across multi-tier supply chains. 

However, MRSLs have some limitations. Restricting listed substances does not guarantee that substitutes are safer, and MRSLs alone cannot prevent regrettable substitution. They work best alongside chemical assessment, strong supplier transparency, and ongoing review as lists evolve.  

Key takeaways

MRSLs are more than a set of rules; they are tools to support a proactive approach to chemical management. By restricting substances based on hazard and applying those controls within manufacturing processes.  MRSLs help companies move away from inherently hazardous chemistry, and reduce the likelihood of harmful residues in finished products.