Both are fine for handwashing. HTH leaves a sediment when it is made in solution. Therefore, it is preferable to use NaDCC in the sprayers to avoid clogging. But there is no difference in the disinfection. And HTH is easier to procure than NaDCC, so if stocks are low NaDCC should be prioritized for the sprayers and HTH used for other tasks.
NaDCC also known as Sodium troclesene or Sodium dichloroisocyanurate has the "same" pH as human skin whereas Hypochlorite ( bleach) and HTH have elevated pH scores. NaDCC has been found to have act as an emollient on hands and on milking cow's teats ( where it is used extensively for disinfection)
The current consensus I am hearing on the email chains and from the meetings at UNC Water and Health Conference and guidance from WHO is to recommend soap or hand sanitizer as they are more effective than chlorine solutions for hand washing because of the chlorine demand of the organic material in your hands that exerts chlorine demand and degrades the chlorine concentration, and chlorine can damage hands and cause breaks in skin, which can lead to increased transmission. There is also the risk of Ebola in the water that has been used for hand washing (particularly if this is in an open bucket). The general consensus I am hearing is:
- Use soap/hand sanitizer preferentially
- Use chlorine solution for hand washing only when it’s culturally demanded at a 0.05% solution
- Think about treating the hand washing water with chlorine if stored in an open bucket to reduce transmission risk.
If you are using chlorine solution for handwashing (because it is socially accepted, or for whatever reason) it is recommended 0.05%. This can be made with sodium hypochlorite (liquid) - there is liquid available in Liberia from Manco and Operation Blessing. It can also be diluted from HTH or NaDCC powder. 0.05% sodium hypochlorite / HTH solution degrades 50% in 4-6 weeks at temps in the affected countries at unstabilized pH (generally around 7 if unstabilized); if stabilized to pH>11 with sodium hydroxide then 0.05% solution lasts 24 months. It appears that NaDCC degrades faster (within a few days if unstabilized) in aqueous solution, although more research is needed on this.
In any case, due to the degradation issue of chlorine, it is safest to make solution fresh every day for handwashing.
From fresh experience in the field:
Both are acceptable to make 0,5% (disinfection of PPE, material and facilities and gloved hands washing) and 0,05% (bare hands washing).
HTH is generaly found with a higher Chlorine concentration (65-70%) that NaDCC (50-55%). With the amount needed to run properly a Treatment Centre with several tens of beds, you will need in any case a reliable supply chain and sometimes you will have to change the product you are using.
The main problem with HTH is the calcium sediment (still with a high chlorine content): 1) You have to prepare the mother solution in a specific additional recipient to allow the sedimentation to take place
2) You will have to deal with the remaining "mud" and to dispose it somewhere. It can quickly represent an important enough volume to become a problem (infiltration pit clogging) and so you have to consider where to dispose it properly. Consider that evacuating any kind of waste from an Ebola Treatment Centre can have a negative impact on the image of the centre in the population and for authorities (even powder milk tin can used for coffee break can be considered as "a waste from the ebola yard
3) If you use a small gravity distribution system (which is a very convenient to distribute chlorine solution in high risk zone), the remaining calcium sediment will eventually clog pipes and taps.
4) For all the sprayers, it will also be quickly a problem (easy to counter with a weekly maintenance with chlorine, but again, any activity run in high risk zone is an additional load of work and risk)
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