Laboratory $1($Lab $1)$

In this lab, workers are testing water samples and working on water treatment plans. The treatment plans often require sodium hypochlorite to be added to water systems at an appropriate dose, and the lab workers carry out tests to determine the dosing regime required. These tests involve adding measured amounts of sodium hypochlorite to water samples. The sodium hypochlorite is supplied in $5$ litre containers that are a manageable size to handle in the lab, and allow relatively small amounts of sodium hypochlorite $($typically $100-200$mls$)$ to be dispensed safely into measuring cylinders.

Today, worker B finds that the $5$ litre container that is kept in the lab$$s cupboard is empty, and visits the stores to collect another. At the stores, worker B is informed that sodium hypochlorite is now being purchased in a $20$ litre container which is better value for money. The stores$$ manager shows worker B the advert in the supplier$$s catalogue $($see supporting document $1),$ and seems pleased that they have managed to save the organisation money. They tell worker B that, in future, the $20$ litre container will be delivered straight to the lab, so fewer trips to the stores will be needed.

Worker B$,$ who is now running late on the day$$s work schedule, returns to Lab $1$ with this much larger container. They feel quite hot after carrying the $20$ litre container, so push up the sleeves on their lab coat before putting on their PPE. Remembering their induction training worker B does not want to decant any of the sodium hypochlorite into an unlabelled container, as this is not good practice. Instead, they lift up the container and start to pour the required amount directly into the measuring cylinder on the workbench. Unfortunately, the sodium hypochlorite comes out of the container very quickly, spilling down the side of the measuring cylinder and onto the workbench. Worker B tries to stop the measuring cylinder from falling over, and in doing this partly loses their grip on the large container of sodium hypochlorite. There is now sodium hypochlorite all over the workbench, the equipment, and on the forearms of worker B$.$ Their colleagues grab the spill kit and rush to assist worker B$,$ and deal with the spillage.

The next day when Lab $1$s manager returns from annual leave, they see the accident report on their desk. They are concerned that there will be lots of questions raised about the safe working methods in Lab $1.$ They quickly look at the existing hazardous substance risk assessment for this task, and the safety data sheet $($SDS$)$ for sodium hypochlorite $($see supporting document $2).$ The lab manager is thankful that the company$-$wide control system is now in place for hazardous substances. This also means that they can confirm that all workers at WWA received training in the safe handling of chemical and biological agents earlier in the year. However, that makes it more surprising to the manager that this accident happened.

Supporting document $1$

Task $1$: Use of sodium hypochlorite

$1$

At WWA, the way in which sodium hypochlorite is supplied has changed, as described in the scenario and shown in supporting document $1.$

$($a$)$ Discuss what difference, if any, this has made to the risks associated with the use of sodium hypochlorite at WWA.

Note: You should support your answer, where applicable, using relevant information from the scenario and supporting documents $1$ and $2.$

$($b$)$ What additional control measures could be introduced in Lab $1$ if it is decided that the use of $20$ litre containers of sodium hypochlorite is to be continued?

$(15)$

Note: You should support your answer, where applicable, using relevant information from the scenario and supporting documents $1$ and $2.$

$(20)$