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Expert Panel on Air Quality Standards 296. The measurements made in this study were of ‘Cr(VI) as CrO 3 ’. Expressed as Cr(VI) the guideline value above must be multiplied by a factor of 0.52, producing a figure of 0.2 ng/m 3 . 5.5.1 Sensitivity to method of derivation 297. Unit risk approach. There are three choices of exposure response for determining an acceptable level for public protection: 1) USEPA, based on the Ohio chromate production workers; 2) WHO based on a hybrid of Baltimore chromate production workers and Norwegian ferrochrome workers; and 3) Park et al. (2004) analysis of Baltimore chromate production workers. Our opinion is that we should use the last of these since it appears to use the best data and to be best analysed. 298. Park et al. (2004) estimated that 1mg/m 3 .year of cumulative exposure to Cr(VI) (as CrO 3 ) with a lag of five years had a relative rate of 2.44 (95% CI 1.54 to 3.83). This was used to estimate the unit risk for lung cancer per µg/m 3 over a life-time using the formula in WHO (2000): • UR = P 0 (RR-1)/life time exposure • P 0 = 0.04 (as in WHO 2000) • RR-1 per mg/m 3 = 1.44 (from Park et al., 2004) • Life-time average exposure = 8/24x240/365x1/70 = 0.003131 • Unit risk = (0.04x1.44)/(8/24x240/365x1/70) = 18.40 per mg/m 3 • = 0.0184 per µg/m 3 (1.8 x 10 -2 ) 299. This is close to the unit risks estimated by the USEPA from different data, and WHO using a combination of Baltimore and Norwegian data (see earlier). 300. The risks of lung cancer associated with life-time exposures to different levels are: 0.05 ng/m 3 =1 in 10 -6 (10 -6 /1.84 x 10 -5 ); 0.5 ng/m 3 = I in 10 -5 ; 5.0 ng/m 3 = 1 in 10 -4 . 301. The guideline value of 0.35 ng/m 3 as CrO 3 derived using the customary EPAQS method above equates to a lifetime risk of 7 in one million people. This gives confidence that the EPAQS procedure yields a guideline value consistent with that that would be generated by other procedures such as the unit risk method. 302. At current upper UK urban levels of chromium of around 15 ng/m 3 containing an estimated 4 ng/m 3 of Cr(VI), the increased risk of lung cancer would amount to a little under 1 in 10,000 which is comparable to the rate of death from lung cancer in non-smokers derived from a 20 year follow-up of male British doctors. 303. Particulate matter may be more potent as any effect may be extended in time and effectively localised. However, particulate matter will be largely Cr(III) and a standard must take account of this. 98
Chromium 5.6. Recommendation 304. 0.2 ng/m 3 chromium in the Cr(VI) oxidation state in the PM 10 size fraction as an annual mean. 305. The Panel believes that the recommended guideline for Cr(VI) should offer a high level of protection against the risk of lung cancer and of other adverse health effects. However, for this as for other carcinogens, the Panel advocates a progressive reduction in airborne concentrations below this guideline. References Alloway, B.J. (1995). (Editor). Heavy Metals in Soils. Blackie Academic and Professional, London. Anderson, R.A. (1981). Nutritional role of chromium. Sci Total Environ 17:13-29. Anderson, R.A. (1997). Chromium as an essential nutrient for humans. Regul. Toxicol. Pharmacol 26: S35-S41. ATSDR (2000). Toxicological profile: chromium. Agency for Toxic Substances and Disease Registry. http://www.atsdr.cdc.gov/toxprofiles/tp7.pdf. Axelsson, G. and Rylander, R. (1980). Environmental chromium dust and lung cancer mortality. Environ Res. 23:469-476. Baetjer, A.M., Lowney, J.F., Steffee, H. and Budacz, V. (1959). Effect of chromium on incidence of lung tumours in mice and rats. Arch Ind Health 20: 124-135. Bonde, J.P., Olsen, J.H. and Hansen, K.S. (1992). Adverse pregnancy outcome and childhood malignancy with reference to paternal welding exposure. Scand J Work Environ Health. Jun;18(3):169-77. Cawse, P.A. (1987). Trace and major elements in the atmosphere at rural locations in Great Britain, 1972-1981. In: Pollutant Transport and Fate in Ecosystems. Special Publication Number 6 of The British Ecological Society. Blackwell Scientific Publications, Oxford. CEH (2006). Heavy Metal Monitoring Network. The Centre for Ecology & Hydrology. www.heavymetals.ceh.ac.uk CEPA (1994) Priority Substances List Assessment Report. Chromium and its 99
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Department for Environment, Food an
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Department for Environment, Food an
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Contents Contents Terms of Referenc
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3.5 Justification for air quality g
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Terms of Reference The Expert Panel
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Dr Alison Searl BSc, MSc, PhD Insti
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Acknowledgments We thank the follow
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Expert Panel on Air Quality Standar
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Page 99 and 100: Chapter 5 Chromium 5.1 Background 5
Page 101 and 102: Chromium stations, industry and for
Page 103 and 104: Chromium 245. Occupational exposure
Page 105 and 106: Chromium 5.2.3 Tissue distribution
Page 107 and 108: Chromium occasionally reached level
Page 109 and 110: Chromium 5.3.4.2 Human studies 272.
Page 111 and 112: Chromium 282. The WHO (2000) classi
Page 113: Chromium 5.5. Justification for air
Page 117 and 118: Chromium HSE (2002). EH64 Summary C
Page 119 and 120: Chromium Nethercott, J., Paustenbac
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Page 127 and 128: Glossary Epidemiology Epithelium Fe
Page 129 and 130: Glossary Metalloid Mucocilliary tra
Page 131 and 132: Glossary Threshold Limit Values (TL
Page 133 and 134: Appendix 1 Setting air quality stan
Page 135 and 136: Appendix 1 hours per week for a 40
Page 137 and 138: Appendix 1 arrive at a single conce
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