Guidelines for Metals and Metalloids in Ambient ... - ARCHIVE: Defra

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Expert Panel on Air Quality Standards 5.1.4 Human exposures 240. Non-occupational human exposures to chromium are difficult to quantify. Exposure is widespread due to occurrence in air, water and soil. It is present in essentially all biological materials that have been examined, and thus is also consumed in food, although the trend to consumption of highly processed foods has led to a reduced intake by this route. This, coupled with the consumption of relatively high levels of sugar (which stimulates excretion of chromium) may lead to potentially serious dietary deficiency of chromium (Anderson, 1981). 241. Intake of chromium in the diet accounts for most of the nonoccupational exposure. The wide variation in chromium content of food is the main reason for the difficulty in estimating intakes overall. Foods rich in chromium include meat, vegetables and unrefined sugar while fish, vegetable oils and fruit contain smaller amounts. The most available form of chromium in the diet is found in yeast, liver and meats (Langård and Norseth, 1979). 242. Chromium concentrations in drinking water have been measured in several countries and are almost always below (often well below) 0.005 mg/l. Thus an adult consuming 2 l/day would derive no more than 0.01 mg/day of chromium from this source. Dietary chromium is normally considered to be in the Cr(III) form as Cr(VI) is reduced in the presence of organic material. The speciation in drinking water is less certain; at least some of the intake from this source could be in the form of Cr(VI). 243. Wind blown soils and dusts provide a source of chromium in the atmosphere, but based on typical concentrations of chromium in surface soils, these are unlikely to generate annual concentrations as high as 1 ng/m 3 except in areas of significant industrial contamination. 244. Although chromium is present in cigarettes at up to 390 µg/kg (Schroeder et al., 1962) there are no published estimates of total intake from this source. However assuming complete absorption from 25 g tobacco daily, this would account for 10 µg/day, so it is unlikely that this will contribute significantly to the overall intake. However, it should be noted that this is possibly in the Cr(VI) form and in this context may be significant. Other potential sources such as wood preservatives, pica and residence in neighbourhoods with industrial contamination are only minor contributors to exposure. In the UK average daily intakes from ambient air are estimated to range from 0.0001 to 0.0006 µg/day, (based on values from DETR, 1997), but this may include a proportion of Cr(VI). 86
Chromium 245. Occupational exposures to chromium and chromates have been measured during chromate and chrome pigment production, chrome plating, ferrochromium and chrome alloy production, leather tanning and gold mining. Average exposures measured range from 0.04 to 0.5 mg/m 3 . 246. Rowbotham et al. (2000) estimated the daily intake of total chromium for adults and children by inhalation and compared these with ingested chromium (Table 5.1). The assumptions made were that: • adults breathe 20 m 3 , and children 8.7 m 3 , of air per day. • mean airborne particulate total chromium concentration for rural sites are 0.9 to 12 ng/m 3 and for urban sites 4.1 to 17.2 ng/m 3 . Table 5.1: Estimated range of daily intakes of chromium by inhalation, adults and children UK. State Daily intake (µg) by inhalation urban adult rural adult urban adult (smoker) urban adult (passive smoker) urban child rural child 0.08-0.34 0.02-0.24 0.14-0.6 0.14-0.6 0.04-0.15 0.01-0.1 247. Rowbotham et al. (2000) also estimated the daily intake of Cr(VI) from inhalation, assuming that Cr(VI) constitutes between 3 and 8% of total airborne chromium. Inhaled intake of Cr(VI) for an urban child was between 0.001 and 0.01 µg/day. These figures compare with 0.002 and 0.03 µg/day for an adult. 5.2 Toxicology 5.2.1 Pulmonary absorption 248. Pulmonary absorption of chromium is influenced by a number of factors including size, oxidation state and solubility of the chromium particulate matter. Absorption of inhaled chromium is demonstrated by its presence in other compartments such as blood and urine. 249. Hexavalent chromium compounds penetrate the alveoli more readily than trivalent compounds (CEPA, 1994). This process is described in detail in Figure 5.2. 87
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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 52 and 53: Expert Panel on Air Quality Standar
Page 99 and 100: Chapter 5 Chromium 5.1 Background 5
Page 101: Chromium stations, industry and for
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 and 114: Chromium 5.5. Justification for air
Page 115 and 116: Chromium 5.6. Recommendation 304. 0
Page 117 and 118: Chromium HSE (2002). EH64 Summary C
Page 119 and 120: Chromium Nethercott, J., Paustenbac
Page 121 and 122: Chromium Von Burg, R. and Liu, D. (
Page 123 and 124: Abbreviations ACGIH American Confer
Page 125 and 126: Glossary Acute toxicity / effects A
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
Page 139: ISBN 978-0-85521-185-1 £10.00 Prod
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