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Disinfecting Coronavirus from Jewellery

A study into what is effective in killing the virus, and what is wishful thinking.

Coronavirus
Coronavirus - Perfectly designed for rapid transmission

Issues to be considered regarding the protection of the workforce and the general public through the disinfection and sterilisation of jewellery and other products used and sold within the jewellery and giftware industry environment during the Covid-19 pandemic.

Consider our current knowledge

As the jewellery industry plans the resumption of business the question of protection for both work colleagues and the general public becomes an important issue for the industry. This article attempts to highlight and discuss the issue of infection risks to colleagues and the general public from handling jewellery products and the control of the risk of cross contamination.

Many research projects around the world are underway and as they report and publish findings knowledge and understanding of the virus will improve modifying our current understanding. This means that what we understand to be ‘best practice’ now will most likely evolve and be modified over time. It will be important for all members of the industry to be proactive in keeping up to date with developments and best practice as we go forward.

Just over 6 months ago the virus known as covid19 or (SARS-Cov-2) was unknown, Corona viruses of which covid 19 is a new strain, was first characterised in the 1960's. So much research has been completed into coronavirus over the last 40 years, unfortunately much of this knowledge gained does not apply to this new strain. The limited length of time since covid 19 was discovered means the amount of research completed into this particular strain is incomplete leaving questions and gaps in our understanding of the virus and its transmission.

It must also be emphasised this article is not meant to be exhaustive; it has been created to be informative but cannot address the hazards and risks associated with any individual business. It should be used only to assist in the process of risk assessment every business is required to complete. Some of the examples given can be used as a template but it should not be used as an alternative to a business completing their own risk assessments.

A Route Map for Assessment

 

Indentify hazards

 

 

 

Identify who is at risk

Evaluate risks and devise control mechanisms

Record findings

Review regularly

For example:

Existing stock hazards?

Contracting covid 19 through contact with contaminated stock

Who is at risk?

Visitors to workplace, clients, staff and colleagues

Evaluate risks and mitigation / controls

Risk is negligible to non-existent if stock has been out of circulation human contact since lockdown started

Record findings

~ ~

Review regularly

~ ~

Risks could be identified as:

Risk

Who

Severity

Removal

Mitigation

Handling existing potentially contaminated stock

Visitor

 

Insignificant

Stock has been untouched since beginning of lockdown.

N/a

N/a

Staff

Insignificant

Stock has been untouched since beginning of lockdown.

N/a

N/a

Customer / general public

Insignificant

Stock has been untouched since beginning of lockdown.

N/a

N/a

 

Risk

Who

Severity

Removal

Mitigation

Handling potentially contaminated new stock deliveries

Visitor

Insignificant

Visitors have limited exposure to stock

N/a

N/a

Staff

Significant

N/a

Wear protective gloves

Disinfect stock following handing

Limit handling of stock

Customer/ general public

Significant

N/a

Disinfect stock following handing

Limit handling of stock

Disinfect purchases

Inward postal clerk

Significant

Wear protective gloves

Disinfect stock on delivery

Disinfect stock following handing

 

Risk

Who

Severity

Removal

Mitigation

Handling of stock potentially previously handled by a work colleague

Visitor

Insignificant

N/a

N/a

Staff

Significant

N/a

Wear protective gloves

Disinfect stock following handing

Limit handling of stock

Customer / general public

Significant

N/a

Disinfect stock following handing

Limit handling of stock

Disinfect purchases

 

Risk

Who

Severity

Removal

Mitigation

Handling of potentially contaminated stock previously
handled by a member of the general public

Visitor

Insignificant

N/a

N/a

Staff

Significant

N/a

Wear protective gloves

Disinfect stock following handing

Limit handling of stock

Customer / general public

Significant

N/a

Disinfect stock following handing

Limit handling of stock

Disinfect purchases

Methods of Sterilisation and Disinfection

What are common methods of sterilisation and disinfection in other industries/environments?

1. Chemical
2. Heat
3. Radiation
4. Quarantine
5. Steam Cleaners

1 - Chemicals

toxic stamp
Follow instructions to the letter

What chemicals kill the covid 19 Virus?
There are a number of recognised national databases around the world that have details of chemicals that will kill viruses including encapsulated coronavirus's and some have detailed the results of tests for effectiveness on covid 19.

Some of the most effective chemicals listed are harmful or poisonous that potentially can cause harm or have the potential to kill anyone having contact, so the chemicals that are of most interest in this situation are chemicals that are harmless or with mild contra indications to health. It would also be prudent to limiting any selection to chemicals with appropriate approval for use. In the UK we are currently aligned with the European Approvals legislation.

All chemicals are tested to determine the required concentration to ensure complete sterilisation, another issue that is addressed is the length of exposure that is required for complete sterilisation. Finally, a further issue tested is the potential of the virus to gain increased resilience from dilution with other biological material. These issues should be considered when considering chemical sterilisation.

As general advice when using chemicals:

Always read and follow the directions on the label to ensure safe and effective use.

  • Wear skin protection and consider eye protection for potential splash hazards
  • Ensure adequate ventilation
  • Use no more than the amount recommended on the label
  • Use water at room temperature for dilution (unless stated otherwise on the label)
  • Avoid mixing chemical products
  • Label diluted cleaning solutions
  • Store and use chemicals out of the reach of children and pets

Possible suitable chemicals include:

Chemical

Concentration

Exposure time

Comment 1

Comment 2

Soap

Foam

Minimum 20 seconds

Readily available

Not commonly recommended for sterilisation

Household bleach (sodium hypochlorite)

Typical concentration 5 tablespoons bleach per gallon water at room temperature. Bleach only remains active for 24 hours

Minimum 1 minute

Readily available

Smell, bleach effectiveness reduces over time, potential reactions, discolouration

Alcohol (ethanol)

Over 70% concentration

30 seconds

Limited resources due to pandemic

fire risk, flammable

Isopropyl alcohol

Over 70% concentration

30 seconds

Limited resources due to pandemic

Fire risk, flammable, avoid breathing fumes

Quaternary Ammonia

Follow directions

30 seconds

Applications with ongoing testing. Safety concerns over use including lung irritant, asthma & sterility

Has a cumulative effect with prolonged / repeated exposure

Hypochlorous acid

Not tested or approved in UK or Europe for covid 19 use.

Tested in USA on another corona virus >99.9% effective

USA approved in certain food prep environments

60 seconds

Due to lack of approval any use in UK questionable if safe to use

Products are however available in the UK market.

Quaternary ammonium includes any of the following compounds:

  • Benzalkonium chloride
  • Benzethonium chloride
  • Alkyl dimethyl benzyl ammonium chlorides (C12-16)
  • Alkyl dimethyl benzyl ammonium chloride (C14 60%, C16 30%, C12 5%, C18 5%)
  • Alkyl dimethyl ethylbenzyl ammonium chloride (C12-14)
  • Alkyl dimethyl ethylbenzyl ammonium chlorides (C12-18)
  • Didecyldimethylammonium chloride
  • Dioctyldimethylammonium chloride

Chemicals could be combined within ultrasonic cleaning systems but as far as sterilisation is concerned the chemical present alone would be the method of sterilisation. Most ultrasonic tanks are heated that may be inappropriate with certain chemicals, certain chemicals could create noxious vapours, certain chemicals could evaporate diminishing their sterilisation properties.

2 - Heat

Heat can be used in a number of ways to sterilise and disinfect items including:

Dry Heat

With dry heat viruses and bacteria are burned to death or oxidised. Dry, hot air is much less effective in transferring heat than moist heat. This is why microorganisms are much more able to withstand heat in a dry state. The dry heat sterilisation process therefore takes a long long time and is done at a high temperature (2 hours at 160oC). The total cycle time, including heating up and cooling down to 80oC can take about 10-11 hours, not the greatest solution for an active environment that needs access. With forced cooling the time may be reduced to five hours. Requires capital purchase and safety issues regarding use serious risk of burns.

Moist Heat Sterilisation

Of all the methods available for sterilisation (killing or removal of all microorganisms, including bacterial spores), moist heat in the form of saturated steam under pressure is the most widely used and the most dependable method. Steam sterilisation is nontoxic, inexpensive, rapidly microbicidal, and sporicidal. It rapidly heats and penetrates fabrics. Moist heat sterilisation using autoclave is commonly used for the sterilisation of biohazardous trash, heat and moisture resistant materials such as aqueous preparation (culture media). This method is also used for the sterilisation of surgical dressings and medical devices. Requires capital purchase and safety issues regarding use has serious risk of burns.

Boiling

Use boiling to sterilise metal, rubber or plastic boil for 20 minutes. Start counting the 20 minutes when the water starts boiling.

3 - Radiation (Ultraviolet)

Ring under SW UV light
Ring under SW UV light

There are a number of ionising radiations that can be used to sterilise and disinfect but the only realistic viable possibility for the jewellery industry is UV radiation. High energy UV radiation can be very efficient at sterilisation although its speed and efficiency are controlled by 4 factors.

This means for effective sterilisation including viruses as well as bacteria the exposure required needs to reach a certain minimum. The minimum is calculated as the sum of the four factors detailed below.

Type - The first of the four factors are the type of UV light used the wavelength/type of UV used is very important as some types have very limited/ weak effects. UV light can be described as UVA (315-400nm), UVB (280-315nm) and UVC (200- 280 nm) there is also vacuum UV (VUV) (100 - 200 nm) but it's strongly absorbed by air so difficult to use in normal environments. UVA and UVB are not effective at sterilisation UVC and VUV are recognised for their sterilisation properties.

Distance - The distance of the item being sterilised from the UV light source is governed by the 'inverse square rule' this means ‘the radiation exposure from a point source (with no shielding) gets smaller very quickly the farther away it is’. So, the distance between the item being sterilised and the light source is a very important factor.

Time - The length of exposure time is the third factor so increasing exposure time can partially offset limitations from the other two factors described.

Intensity - The final factor is the intensity of the radiation emitter, that will control the intensity of incident light in combination with the distance although the intensity being a linear relationship would have less significance than distance between source and object being irradiated unless at very close proximities.

It must also be remembered that it is 'light' that is doing the sterilisation so for '3D' objects all surfaces must be directly exposed to the light to be effective this may require many different treatments at different orientations to be utilised for each item to ensure complete coverage of the entire '3D' surface.

Other considerations are the health and safety of your staff in working with high energy UVC. Exposure can cause burns, and increase the risk of skin cancer, and damage the eyes. I think careful research into both the safety of the system and its operation and also the efficiency of the system would be essential to ensure safety for all retailers intending to purchase or use a system.

Further, UVC and VUV are both ionising radiations which means they can change the properties and/or appearance of items exposed: colours can change textures and properties can be modified. Certain gemstones could be affected, leathers, plastics and fabric materials could also be affected. Metals should not be affected, watch glasses? possibly in some cases dependant on the material they are composed of also glues and adhesives that could have been used in manufacture could be affected.

The compromise in the design of any system will be in general the shorter the wavelength of UV used the more effective and quicker the sterilisation process, but the shorter the wavelength of UV the more inherently dangerous and potentially damaging the radiation is.

Finally, UV light sources are generally not single-wavelength sources they can emit over a range of wavelengths creating an additional complexity to any evaluation.

4 - Quarantine

Many organisations have used quarantine as the mechanism to mitigate contamination risks, obviously, handling of items going into quarantine must be risk assessed and controlled as well as the length of time as research is limited although 72 hours is a frequently used period.

Jewellery steam cleaner
Commercial steam cleaner for jewellery - Steriliser? or virus aerosol?

5 - Steam Cleaners

Many workshops and retailers have steam cleaners three issues that should be considered are when completing a risk assessment are:

  • The length of time the item requires to be held in the steam jet to ensure sterilisation, no research exists, so the risk assessment must include this issue and decide on an exposure time that will robust under scrutiny.
  • The possibility certain items will be damaged by the process
  • The implication that the process creates by nature creates an aerosol that may carry the virus some of which may not have been killed. This risk would have to be assessed in relation to risks for both the operator and anyone in the vicinity of the equipment.

It may be considered that the risks could be mitigated with appropriate PPE. It could also be assessments consider that the risks are too great and such that can't be mitigated with PPE.

The article has been based on extensive research from both international government sources and peer-reviewed publications undertaken by the author. It is correct at the time of writing but Covid 19 is a continuously developing situation and the reader should be aware knowledge and advice will inevitably change over time. The author has the links and references to all the resources accessed available to the reader on request.

Richard Taylor - Diamond Valuer

Author

  • Dr Richard P. Taylor PhD
  • Jewellery Valuer
  • Shrewsbury, UK
  • Taylor & Co. Ltd.

Topics

  • Coronavirus (primary)
  • Jewellery
  • Gems / Gemmology

Intended Audience

  • Retailers (primary)
  • Appraisers/Valuers
  • Academics
  • Consumers

Content

  • June 2020
  • 10 mins reading time
  • Dale-Chall readability level:
    Easily understood by an average College Graduate
  • 13.5 mins speaking time
  • 1 Comment

About the Author

Jewellery and Diamond Appraiser - Richard Taylor

Dr Richard P. Taylor PhD

Dr. Taylor is an active researcher with numerous peer-reviewed internationally published scientific articles and is an experienced lecturer in gem sciences, forensic science and mineral physics. I am also the MD of Taylor & Co Ltd, an internationally recognised consultancy specialising in the gem and jewellery industry.

 
Richard Taylor - Jewellery Appraiser

Taylor & Co Ltd

London & Shewsbury, England

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Comments

Comments (1)
Leave a Comment

avatarAdrian Smith. UKJun 2020

Excellent article, thank you Richard. I have changed by disinfecting process as a result (extended immersion in alcohol and not now using steam blast as 2nd line defense).

 

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Consumer advice can be found in the Consumer Resources section, this contains information to assist the jewellery-buying public, for example: Types of Jewelry Appraisals and Jewelry Trade Asociations etc.