4.1 This guide includes chromates that are not readily soluble in water and that have water solubilities (Chromate ION) within the range of the more soluble calcium chromate and the much less soluble lead chromate. The major occupations involving potential exposure to insoluble chromates are in roasting of chromite ore, the manufacture of chromate pigments, the manufacture of coatings containing chromate pigments, and spray painting with these coatings. There is insufficient evidence to conclude that trivalent chromium compounds are carcinogenic.

1.1 This guide covers control procedures for the safe production, storage, transportation, and handling of only the hexavalent chromium compounds found in Table 1 and their various hydrates, and mixtures of coprecipitates of the same regardless of crystalline form.

Chemical Name

Formula

Color Index Name^A

Barium chromate

BaCrO₄

Pigment Yellow 31

Barium potassium chromate

BaK₃(CrO₄)₂

Pigment Yellow 31

Basic copper chromate

CuCrO₄
 xCu(OH) ₂

Not listed

Basic cadmium chromate

Cd₂(OH)₂CrO₄

Pigment Yellow 44

Basic lead chromate

PbCrO₄PbO

Pigment Orange 21

Bismuth basic dichromate

Bi₂O₃CrO₃

Pigment Red 103

Calcium chromate

CaCrO₄

None assigned

“Chromic chromate”
 (calcium chromate sinter)

xCaO yCr₂O ₃
 zCrO ₃

Pigment Yellow 33
Not listed

Ferric chromate

Fe₂(CrO₄)₃

Pigment Yellow 45

Basic ferric chromate

Fe(OH)CrO₄

Pigment Yellow 45

Lead chromate

PbCrO₄

Pigment Yellow 34

Lead molybdochromate

PbCrO₄PbMoO₄

Pigment Red 104

Potassium zinc chromate

K₂O 4ano·4Cr4O₃

Pigment Yellow 36

Strontium chromate

SrCrO₄

Pigment Yellow 32

Zinc chromate

ZnCrO₄

Pigment Yellow 36

1.2 This guide is not intended to cover ( a) such “soluble” chromates as chromates of sodium, potassium, magnesium, or ammonium; (b) soluble bichromates; (c) chromic acid; (d) volatile chromyl compounds; (e) any trivalent chromium compound; or (f) elemental chromium. Omission of said compounds or classes of compounds should not be construed to mean that they may be handled without due regard to their particular physical, chemical, and toxicological hazards (9, 10, 11).

1.3 The chromate ion, CrO₄⁻² , depending upon the acidity, complexes to form di-, tri-, and higher polychromates; hence, the chromates listed in Table 1 may contain mixtures of polychromates, depending on the method of isolation and end use.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (For more specific precautionary information see Section 5.)