## 4 Discussion
### Cost Analysis  
This approach to blockchain-based traceability includes some aspects that have an impact in both initial and recurring expenses [59]. First, the implementation of blockchain technology typically involves significant upfront costs to cover the hardware, software, and network resources necessary to deploy a blockchain environment. Additionally, organisations may need to invest in specialised development skills to create and deploy efficient and secure smart contracts, which can further increase initial costs. Note that, in many cases, traceability organisations or consortia deploy their own blockchain infrastructure due to the significant benefits that it offers in terms of data integrity, transparency, and control. By utilising a private blockchain, companies can ensure that all transactions and data entries are immutable and verifiable, which in turn promotes trust among stakeholders and facilitates compliance with regulatory requirements [60]. In addition, keeping control on blockchain infrastructure allows one to tailor the system to specific needs, including the ability to manage access permissions and integrate with existing supply chain processes. Furthermore, having a dedicated blockchain enhances operational efficiency by streamlining data sharing and reducing the risk of fraud or errors associated with traditional record-keeping methods. Ultimately, this investment can lead to improved accountability, better quality assurance, and increased consumer confidence in the products being traced. Note that, in any case, a private-operated blockchain infrastructure can still meet the public open access requirements to guarantee accountability.  
Using an existing blockchain also incurs relevant ongoing operational costs. For example, transaction fees depend on demand, and can be especially high during periods of network congestion, which can impact operational budgets. These include transaction fees associated with executing smart contracts and recording data on the blockchain. Depending on the volume of transactions, these fees can accumulate quickly, particularly if the solution relies heavily on on-chain data storage. To mitigate these costs, the proposed solution suggests a hybrid model that combines on-chain and off-chain storage, which helps to limit the amount of data stored directly on the blockchain, thereby lowering transaction fees.  
Moreover, maintenance costs must be considered independently of the nature of the underlying blockchain, as it will require regular updates and security audits to ensure the integrity and functionality of the smart contracts, and also of the overall blockchain infrastructure in the case of private blockchains. This ongoing maintenance is critical to protect against vulnerabilities and to adapt to evolving regulatory requirements, which in turn adds to the total cost.  
On the other side, the potential for cost savings should also be included in the analysis [61]. By improving accountability and transparency, a blockchain-based traceability solution can help organisations reduce losses associated with fraud, recalls, and compliance failures. Enhanced consumer trust and operational efficiencies will eventually lead to increased sales and reduced operational costs over time, providing a return on investment. Overall, while the initial and ongoing costs of implementing a blockchain-based traceability solution can be substantial, the long-term benefits and potential savings will justify in many cases the investment required.