Chromium VI, in the form of Zinc Chromate in paint, is a hazard on ships and industrial metal structures. Chromium compounds occur mainly in two valency states, trivalent Cr III and hexavalent Cr VI. Chromium III is less toxic than Cr VI. The respiratory tract is the major target organ for Cr VI toxicity for acute and chronic inhalation exposures.
Apart from use as zinc chromate on ships, Chromium and its compounds are used for making steel, electroplating, the manufacture of dyes and pigments, leather and wood preservation, and in cooling tower water. Chromium is a naturally occurring essential nutrient involved in glucose, protein and fat metabolism. Exposure to excess Chromium is ranked as in the worst 10% of compounds hazardous to ecosystems and human health.
Zinc Chromate dust is distinctively yellow. As a dry film, it is inert and presents no risks provided it is not disturbed by sanding, grinding and welding activities. Zinc Chromate dust can cause short term skin irritations, rashes, ulcers and irritation of the eyes, ears, nose and throat.
The method for dealing with Zinc Chromate and leaded paints is the same, and work should be conducted in accordance with Australian Standard for removal of lead based paints, AS 4361.2- 1998.
A Hazardous Materials Register should be prepared for each ship or structure. The register should be updated whenever there is a change in the situation, eg some Zinc Chromate paint is removed. If hazardous materials are present and are not to be removed immediately, then a Management Plan should be put in place to ensure people are not exposed to those materials without taking proper precautions.
In preparing the Register for Chromium VI, it is necessary to survey painted surfaces, usually conducting scratch tests combined with tests using spot test kits, although laboratory analysis of samples is also needed. Such surveys typically cover large areas and may not be adequate on a localised scale. Further detailed testing may be called for before any work which involves disturbing paint in a specific area is undertaken. Wet removal techniques and stripers are the preferred methods.
Workers removing paint containing Cr VI must wear Personal Protective Equipment (PPE) and follow personal hygiene procedures. The importance of paying full attention to rigorous personal hygiene procedures is often overlooked. Getex have found that the importance of this aspect should not be underestimated and should be reinforced with personnel working with Chromium VI on a regular basis.
Removed paint dust, rags and any wash down water must be handled appropriately so that no contamination of the environment occurs. Spill cleanup procedures and equipment should be available, with personnel trained in their use, prior to work commencing on areas where Zinc Chromate is present.