3: TOXICITY AND SOLUBILITY OF DIFFERENT FLUORIDES

[1] Professor Kaj Roholm's three categories of inorganic fluorine compounds. It should be noted that Prof. Roholm is the author of the first and most comprehensive monograph on fluorine toxicity.


EXTREMELY TOXIC VERY TOXIC (Easily soluble fluorides and fluorosilicates) MODERATELY TOXIC (Poorly soluble fluorides)


Hydrogen Fluoride (anhydrous) Sodium Fluoride Cryolite
Silicon Tetrafluoride Potassium Fluoride Calcium Fluoride
Hydrofluoric Acid Ammonium Fluoride
Hydrofluorosilicic Acid (used for fluoridation) Sodium Fluorosilicate
Potassium Fluorosilicate
Ammonium Fluorosilicate

 

[2] Former Aston University chemist Malcolm Harris' table of solubility ( "... a critical aspect of toxicity" ) of 1971;-
Calcium fluoride natural Solubility = 16 ppm at 18ºC and 17 ppm at 26ºC
Sodium Fluoride (used in the USA) artificial 42,200 ppm at 18ºC
Sodium fluosilicate artificial 6,520 ppm at 17ºC
Hydrofluorosilic acid (commonly used in UK) artificial miscible liquid

 

[3] Advice on Hydrofluoric Acid from the Health & Safety Executive (UK) in 2001.
Hydrofluoric acid poisoning

 

Recommendations on first aid procedures

 

Health & Safety Executive

 

http://www.hse.gov.uk
_____________________

 

Information contained within this document is accurate as of 1/1/2001

 

IMPORTANT.

 

ALWAYS contact the HSE for advice. See Disclaimer (below).

 

_____________________

 

This leaflet is aimed at employers and employees in industries where hydrofluoric acid is used. It provides information on:

 

* health effects;



* precautions to be taken when working with hydrofluoric acid;



* first aid procedures to be followed in cases of hydrofluoric acid poisoning;



* first aid training.

 

DISCLAIMER

 

[1] THE INFORMATION PROVIDED ON THIS WEB-PAGE IS PURELY FOR THE PURPOSE OF HIGHLIGHTING THE DANGERS OF HYDROFLUORIC ACID.

 

[2] ANYONE WHO WORKS WITH HYDROFLUORIC ACID SHOULD ENSURE THAT THEIR EMPLOYER HAS THE APPROPRIATE MEASURES TO DEAL WITH ANY INCIDENT RELATING TO THE USE OF THIS CHEMICAL.

 


Health Effects

 

Hydrofluoric acid is corrosive. It can cause severe burns to the skin and eyes. If it comes into contact with skin, you may not feel pain at once. Hydrofluoric acid is also highly irritating to the respiratory system and very toxic if swallowed.


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Precautions

 

The Control of Substances Hazardous to Health Regulations 1999 (COSHH) apply. A COSHH assessment should be completed. Consider the use of safer alternatives. If there are no suitable alternatives, the assessment should detail appropriate precautions to be taken when using hydrofluoric acid, which include using a safe system of work. Employers should ensure that employees are given adequate information and training on the hazards to health posed by hydrofluoric acid, and the precautions to take to avoid them.

 

Employers should:

 

* always use the protections provided;



* always wash gloves and other impervious clothing before removing them;



* test gloves for pinholes using a method advised by the manufacturers (this might be done by filling them with water, before drying and putting them away for use again), discarding gloves that are not sound;



* always wash their hands before leaving the work area

 

First aid

 

Urgent action is required. Obtain immediate medical attention.

 

When giving first aid, protect yourself and the casualty from further exposure.

 

Casualties should be sent to hospital as soon as possible (see opposite). In all cases, the hospital should be informed of the cause of injury.


Skin contact

 

* Remove contaminated clothing while protecting your hands with suitable gloves.



* Flood the skin with plenty of water for at least 5-10 minutes.



* Apply calcium gluconate gel on and around the affected area and continuously massage into the skin for at least 15 minutes after pain is relieved. Cover the area with a dressing soaked in the gel and lightly bandage. these procedures can be continued during transit to hospital.



* Send to the Accident and Emergency Department.

 

Eye contact

 

* Flush the eye with water for at least 20 minutes. This can be continued during transit to the hospital.


* Send the casualty to the Accident & Emergency Department or local Eye Casualty Department.

 

Gassing

 

* Remove the casualty from the contaminated area and place in fresh air.



* If necessary, resuscitate the casualty.


* If suitably trained, give oxygen.



* Send to the Accident & Emergency Department.

 

Swallowing

 

* Never attempt to induce vomiting.



* If the casualty is conscious, rinse out their mouth with water.



* Send to Accident & Emergency Department.


The Truth About Fluoride