*2.1. Control Banding: ISO/TS 12901-2:2014*

The control banding approach was originally developed by the pharmaceutical industry to safely handle new chemicals with limited or no toxicity data. This practical method can also be utilized to manage the risk of exposure to possibly hazardous agents in the workplace that have unknown or uncertain toxicological properties, such as nanomaterials, where quantitative exposure estimations are not available.

Developing a control banding approach for nanomaterials presents a significant challenge, as it is necessary to determine which parameters and criteria are relevant to assign a nano-object to a control band and which operational strategies to implement. Producers or importers are responsible for identifying whether their product contains nanomaterials and must provide relevant information in safety data sheets, labels, etc., in accordance with existing regulations. By utilizing this information, companies and employees can recognize potential hazards and implement appropriate controls [4,6,11,12,16].

ISO/TS 12901-2:2014 mentioned above is a Technical Specification developed by the ISO that presents a guide to the use of control banding in managing occupational risks associated with engineered nanomaterials. Given the level of uncertainty in assessing potential work-related health risks from nano-objects, including aggregates and agglomerates larger than 100 nm, control banding is a valuable tool for risk assessment and management of nanomaterials. The control banding process outlined in this standard includes several elements, which are well-summarized in the infographic presented in the standard and briefly described below.

First, information must be gathered, and if there are limited or no data available, "reasonable worst-case assumptions" should be used along with management practices appropriate for those options. Then, hazard banding is used to assign a hazard band to nano-objects based on a comprehensive evaluation of available data, taking into account parameters such as toxicity, in vivo biopersistence, and respiratory tract deposition. Exposure banding is used to assign an exposure scenario to an exposure band, taking into account the physical form and amount of the nano-object, dust generation potential, and actual exposure measurement data. Next, control banding is implemented proactively or retroactively to define recommended work environments and handling practices based on hazard banding and fundamental factors mitigating anticipated exposure potential. Finally, periodic and as-needed reviews are conducted to ensure that the information, evaluations, decisions, and actions from the previous steps are kept up to date [4,7,11,12].

ISO/TS 12901-2:2014 describes five hazard bands, as summarized in Table 1 [7].


**Table 1.** Hazard bands.

Details of the allocation of the different hazard bands can be found in Table 1 in the standard.

In terms of exposure banding, the standard proposes four levels from EB 1 to EB 4 corresponding to increased levels of exposure to nanomaterials. In the case of production processes where nanomaterials are handled in liquid form, exposure banding using the levels EB1 or EB2 is normally suggested. When nano-objects are in suspension in a liquid, the choice depends on the amount of liquid and number of nano-objects involved, as well as the potential for aerosol generation [12].

Table 2 presents the control measures proposed in the standard.

**Table 2.** Specific control measures for risk mitigation bands.


Control banding can be determined by combining the hazard bands and the potential exposure band. The corresponding matrix included in ISO/TS 12901-2:2014 is presented in Table 3 [7].


**Table 3.** Control band matrix as a result of hazard and exposure potential bands.

#### *2.2. Case Study*

In a case study conducted by Ramos et al. [11], the methodology of control banding was applied in a Portuguese textile finishing company specialized in producing knitted fabrics. The study focused on the use of nanomaterials in two chemical finishes—namely, mosquito repellent and antibacterial finish—which were applied to specific customers' textile products. The risk analysis was mainly focused on four workers who were involved in preparing the finishing baths and operating the stenter frame for knitted fabric finishing [4,7,11,12].

The safety data sheets for the two chemicals, in accordance with the CLP regulation (Regulation EC No 1272/2008), present the hazard statements (H) and precautionary statements (P) shown in Tables 4 and 5.

**Table 4.** Product A (mosquito repellent).


**Table 5.** Product B (antibacterial finish).


The two chemicals, delivered in cans in an aqueous suspension, are applied to cotton knitted fabrics through padding and heat setting in a stenter frame. It should be noted that neither the product information nor the safety data sheets explicitly mention that these chemicals contain nanomaterials, although this information is indirectly provided by the suppliers. In one case, the information just states that the remaining composition of the product is kept secret by the company.

The risk analysis primarily focused on the four workers involved in the preparation of the finishing baths, starting in the chemical warehouse, and in the operation of the stenter frame. The workers' tasks included opening the cans, weighing the required amount for each batch, transporting the chemicals to the production process, transferring the chemicals to the stenter frame (via automatic dispenser), mixing and preparing the chemicals (with the addition of water), and, finally, developing the finishing process in the stenter.
