Graham Lampard was right in his comments in Leather, February 2001; the perception that chromium in leather and its manufacture is hazardous must be counteracted. Results of risk assessments must be communicated to the legislators and the public.
Risk assessment is increasingly being used in evaluating environmental issues, especially in the USA. For example, an expert panel investigated chromium-contaminated soils in a residential area and concluded that soil concentrations of 2,800 mg/kg CrIII and 180 mg/kg CrVI do not pose a health hazard following acute or chronic exposure for residents living on or near the contaminated sites1. These findings and recent reports of Health-Based Soil Action Levels2 and case studies involving human exposure to CrVI in soil and ground water3 put the relative toxicity of CrIII and VI into perspective. CrVI is more toxic than CrIII but human studies have shown that the gastrointestinal tract can reduce ingested CrVI to CrIII at concentrations up to 10 mg CrVI/L and soil concentrations of 1240 ppm CrVI do not elicit allergic contact dermatitis in over 99.9% of the general population.
An assessment of a waste site which had contaminated groundwater with CrVI concluded that 0.37 mg/l of CrVI in drinking water for a lifetime is not a significant risk to health, and neither CrIII nor CrVI is a cancer risk following ingestion4.
Based on risk assessment, the US EPA has recently revised their limit for total chromium in sewage sludge applied to agricultural land to 100,000 mg/kg (ie 10%) of dry solids5.
The limits will never be reached but show that there is no environmental issue with CrIII application to land.
There is no evidence that the chrome tanned leathers which we have been using for over 100 years have caused any health problems except allergic contact dermatitis in sensitive people which is well documented. Despite this, low levels of CrVI in leathers are at present a concern in parts of Europe.
The issue is that German regulations require that any carcinogen should not be present at higher than detectable levels. However, low levels of CrVI in leather are not carcinogenic. It is inhaled CrVI that causes cancer. Although measures can be taken to meet the stringent German requirements for CrVI in leathers, the cost has not been justified.
As has been stated in Leather many times, chrome tanning can be environmentally friendly. We must not let unsubstantiated perceptions continue to damage the world tanning industry.
Catherine A Money
Leather Research Centre
CSIRO Textile and Fibre
Technology
Australia
