Based on all available information in the scenario and supporting documents, what are the considerations when carrying out a hazardous substance risk assessment for the handling of vitamin C powder by workers at Nutripex??????

Mixing

The vitamins and supplements are made within the production department, which consists of three main areas: mixing, tableting and packaging. The production manager (PM) is responsible for all the workers in these areas. The mixing area is particularly busy and noisy, as it has five mixing machines (designated by the letters A to E) often operating simultaneously. At the start of the production of a batch of product, raw materials are emptied into the mixing vessels at the charging point above the mixer. Most of the raw materials are usually in the form of powders, in 25kg sacks. There are typically 30 sacks of raw materials added to each batch. To empty the contents of one of these sacks into the mixing vessel the rip and tip method is used. This involves the worker standing on a platform that provides access to the charging point, holding the sack, while cutting the end open with a knife. The sack contents are then poured into the mixing vessel. The empty sacks are then flattened and stacked nearby. It takes around an hour to add all the raw materials to the mixing vessel at the start of each batch. Workers often complain about getting too hot while carrying out this work. During the production, dust can be seen in the air, even though there is local exhaust ventilation (LEV) at the charging point. There have been complaints from some of the workers about the dust, especially when handling vitamin C (ascorbic acid) powder. Workers also point out that there is a thin layer of dust on most surfaces, not just at the charging point, but throughout the production department. As a result of this, the PM has reviewed the raw material safety data sheet (SDS) for vitamin C powder. The vitamin C powder is described as non-hazardous and there is no occupational exposure limit assigned. Therefore, the PM has concluded that a hazardous substance risk assessment for the handling of this raw material is not required. On any given day, any one of the mixing machines may be mixing a different product from any of the other machines. However, the weekly production schedule for a specific mixing vessel is often the same, with certain days allocated to the production of a particular product. For example, if one product is being manufactured all day in one mixing vessel, it is likely that up to three batches of that product will be made in one day. Usually, two batches in the morning (starting at 09.00 and 11.00) and one batch in the afternoon (starting at 14.00). When all of the raw materials are sufficiently blended in the mixing machine, the product is moved to the tableting machine. When manufacturing vitamin tablets, the particle size is extremely important in determining how well the product will run through the tableting machine. When the raw materials such as vitamin C powder are delivered, information about the particle size distribution is provided by the supplier, LEV ducting runs throughout the whole production department. This ducting is often fixed high above the machines, with branch ducts to the charging points for each of the five mixing machines A to E, and tableting machines 1 and 2. There are a number of joints in the ducting; not all of them are sealed well and dust can be seen escaping in some places. The mixing machines and surfaces that workers can reach are cleaned down regularly as part of the weekly production schedule.

Tableting

In the tableting area the product makes its way through several processes, including a punch press; here, pressure is applied to the product by dies to form the completed tablet. The tablets are ejected onto a vibrating belt to shake off any loose dust. The two tableting machines are particularly noisy. In this area, there is a long run of LEV ducting that branches to two hoods, one for each tableting machine. Some of this ducting is sagging in places and has adhesive tape wrapped around the joints. In most cases this has made the sagging worse. Nearby is the LEV dust-collector and air-cleaner unit. Workers in this area are responsible for changing the collection bags and have commented on how, recently, the bags are taking much longer to fill up. Also located here is the fan for the LEV system. When the fan is running it is very difficult to have a conversation in this area. Workers are supplied with earplugs, that are not used regularly. When questioned, workers frequently say that they have lost one or both of their earplugs.

Workers remain concerned about the levels of dust, so Nutripex have decided to engage an Occupational Hygienist (OH) to help review exposure of workers to vitamin C powder and other raw materials. Some initial results of the OHs work are given in supporting document 1. In the last couple of weeks there have been frequent alarms on the LEV control panel. As a result of this, the PM arranged for a thorough inspection and test (TExT) of the LEV, which has just been completed by a competent external contractor, AirTest. The PM is looking through the results and recommendations in AirTests report. One of the recommendations is to change the current design of the LEV at the charging point where raw materials are added to the mixing machines. The PM and HR manager have now met with the OH to go through the dust exposure measurements and decide what to do next. The OH agrees that the LEV design change recommended by AirTest would be helpful, but understands that this will take some time. In the meantime, the OH is concerned about the levels of dust exposure and recommends that workers handling vitamin C powder should wear tight-fitting respiratory protective equipment (RPE). The OH has made recommendations about the specific type of RPE and the PM says that they will help ensure that it is used, just as soon as it arrives from the supplie