Hydrofluoric acid

7664-39-3

Metal trades; glass; polish; chemical industry. 
HF is used in
metal industry; in manufacturing of fluorine containing plastic
and polymers (teflon) and freons.

Anhydrous HF and hydrofluoric acid is used for the production 
of organoflour compounds and inorganic fluorides, as well as 
catalyst of alkylation reactions in the petrochemical industry. 

It is also used for etching of glass and pickling of stainless 
steel (EU RA Report 2001).

Colourless.

20.01

Soil can bind fluorides tightly if pH is > 6.5; high calcium
content will also immobilize fluorides (Sax 1986).

In fresh water at pH above 5, the free ion is main fluoride     
species. 
At lower pH the proportion of fluoride ion decreases,  
while HF2- (hydrogen difluoride ion) and non-dissociated HF
increase. 
In the presence of phosphate insoluble fluorapatite   
is formed, a large part of which is transferred to the bottom   
sediments (EU RA Report 2001).

In seawater fluoride belongs to the macrocomponents; the total 
fluoride content is divided in 51% F-, 47% MgF+, 2% CaF+ and 
traces of HF and HF2- (EU RA Report 2001).

Solubility: misciple.

Natural alkalinity slowly dissipates acidity (Sax 1986).

In aquatic organisms fluoride accumulates primarily in the 
exoskeleton of crustacea and in the bones of fish. 
No F 
accumulation was reported in edible tissues. 
In fish BCF-values 
of 53-58 (d.w.) and <2 (w.w) were found. 
In crustacea 
BCF-values based on whole body fluoride content are found to be 
<1 (based on dry weight). 
The highest reported BCF-values for 
mollusca and aquatic macrophyta were 3.2 and 7.5 (w.w.), 
respectively (EU RA Report 2001).

Earthworma collected from F-polluted sites reflected F 
contamination very well. 
At highest polluted sites the F 
content in worms reached values of up to 135 mg/kg (without 
gut), whereas worms from umpolluted sites showed contents of 
6-14 mg/kg. 
The F content in the whole worm from unpolluted 
sites was found to be much higher and reached values up to 150 
mg/kg. 
This was due to the fluoride content of soil contained 
in the gut (EU RA Report 001).

The most important F exposure route of F for plants in uptake 
from the atmosphere. 
Grass species have in comparison to other 
plant species a relatively high uptake rate. 
The equilibrim 
between the concentration in the atmosphere and in the grass is 
generally reached within 24 hours. 
In a period without rainfall 
the half-life of fluoride in grass is circa 4 days in the 
summer and circa 12 days in the winter (EURA Report 2001). 

Direct contact: highly irritable; severe and painful injury on
contact. 
Skin, eyes; gangrene of affected areas may follow.

General sensation: Severe irritation to eyes resulting in
visual defects. 
Skin contact results in pungent irritating
odour. 
Severe burns. 
Recognition odour 0.03 mg/m3. 
Dose effect
relations: 3 ppm = good warning properties; MAC 8 hr, 10 ppm,
MAC 0.5 - 1 hr, 30 ppm sour taste smarting eyes; 60 ppm, burn
pain may be delayed up to 1 hr; apparent irritation of nose and
eyes; 120 ppm irritation of skin, respiratory system; vapors
can cause ulcers of respiratory tract; 50 - 250 ppm dangerous
with short exposure; 1500 ppm fatal to animals in tract. 5 min
concentration of 50 - 250 ppm can be dangerous even for brief
exposures (Sax 1986).

dnd, dmg, ihl, 1300 ppb, 6 w;
sln, dmg, ihl, 2900 ppb (Sax 1986).

cyt, rat, ihl, 1 mg/m3, 6 hr (Sweet 1987).

Exposure to hydrogen fluoride induces increased frequence of
lethal and sterile mutations both in plants and in banana flies
(Borg 1976).

LDLo, 112 mg/kg, scu, frog (Sax 1986).

Fluorides can be damaging to plants when present in acid soils
(Sax 1986).

60 mg/l, fish, lethal;
40 mg/l, fish, harmful (Sax 1986).

0.9 - 4.5 mg/l NaF, lobster, not toxic;
100 mg/l NaF, mullet, ambasis, safgha, terapon, prawn, jaruba,
no effect, 96hr;
7.2 mg/l NaF, 108 hr, brown mussels, toxic effect;
52 mg/l NaF, 72 d, mullet, crab, physical deterioration;
52 mg/l NaF, 72 d, shrimp, affects reproduction (Sax 1986).

Strong irritant. 
Highly toxic via ingestion or inhalation.

Moderately toxic with chronic exposure. 
Emits toxic vapors when
heated to decomposition (Sax 1986).

Air pollution high (Sax 1986).