Will We Heed the Canary in the Mine?

Paul Torrence is a world-class research chemist with expertise in biochemistry and medicinal chemistry. I met him in 1999, when he came to Northern Arizona University to chair the Chemistry Department. Before that he had had a full, thirty-year career at the National Institutes of Health in Washington, D.C., where he was Chief of the Section on Biomedical Chemistry and oversaw research teams working on cures for life-threatening human diseases, including cancer and HIV.

As a member of a Sierra Club study group in Bellingham, Wash., I turned to Paul for help in assessing the potential impact on public health and the environment from the proposed coal export terminal at Cherry Point near Bellingham and the transport of coal by rail from Wyoming’s Powder River Basin across the United States and along the Washington coast.

I told him I was interested in the impact on aquatic life in general and shellfish in particular, since our attention to these smaller species might be diminished by our concern for larger animals such as salmon and marine mammals. Oysters, clams, Dungeness crab, and other shellfish have significant commercial and recreational value in Washington, in addition to their intrinsic value as part of Puget Sound’s unique marine environment.

Paul’s focus on cadmium was a different angle than I expected, because we’ve been much more aware of the dangers from coal and diesel particulate matter and from heavy metals such as lead and mercury. Cadmium is found in coal and coal dust in smaller quantities than lead and mercury, but its toxicity is such that it may actually pose an even greater danger.

At my asking, Paul has kept his statement brief and accessible to non-experts. He has provided the references below for those who would like to look more deeply into the scientific research behind his statement. All I can say is that I sincerely hope we will follow his urging and “heed the canary in the mine.”

(Robert M. Johnston, Bellingham, Wash., Northern Arizona University – Emeritus.)

by Paul F. Torrence, Ph. D.

Coal in general, and Powder River Basin coal in particular, contains numerous heavy metals that are toxic to humans and other creatures. These include, among others, lead, mercury, nickel, cadmium, selenium, manganese, antimony, and arsenic. Coal also contains the radioactive elements thorium and strontium.

Transporting coal by train or truck and creating stockpiles for shipping sends coal dust into the air, which diminishes air quality and subjects nearby populations to dust inhalation. Health effects from exposure to coal dust include increased asthma, wheezing and cough, especially in children and the elderly. A wide range of serious health problems accompanies exposure to the heavy metals present in coal dust. Coal dust may also be carcinogenic due to the presence of polycyclic aromatic hydrocarbons (PAH).

Each of these metals as well as the spectrum of carcinogenic polycyclic hydrocarbons presents hazards to many species including humans. As may be expected, there is more scientific literature on the effects of these contaminants on humans than on other species; however, by the precautionary principle, it is reasonable to extrapolate data from other organisms to humans and vice versa.

Based upon a literature examination, I believe we must be wary of additional cadmium introduction to natural ecosystems because of established adverse effects on both humans and wildlife. That is not to imply that the other metals and chemicals should not be matters of concern. For example, mercury is certainly a huge hazard also.

Several facts provide a platform for understanding the hazards of cadmium contamination of the environment. First, cadmium occurs in many soils and rocks. It is easily mobilized by various anthropogenic activities such as agriculture, forestry operations and mining. There can, therefore, be levels of cadmium present in soils, waters and sediments that provide a “background” of cadmium that may allow little leeway for added accumulation before toxic concentrations result.

Second, certain organisms, such as shellfish, are able to actively sequester cadmium in their bodies due to the presence of a metal-binding protein. This “bioaccumulation” can greatly magnify the concentrations of cadmium in the environment by astounding factors as high as 40,000-fold. As a result, any organism that consumes these shellfish will obtain a dose of cadmium that is much greater than ambient environment levels.

Third, the human kidney also accumulates cadmium, leading to renal toxicity and, if not controlled, kidney failure. Women, especially those with low iron levels, as well as smokers of both sexes, are particularly at risk from cadmium toxicity. This has become a serious issue in European countries. Cadmium burdens have also been linked to osteoporosis and breast cancer.

Fourth, cadmium is toxic at part-per-billion concentrations to shellfish and is even more toxic to their juvenile forms.

Fifth, organisms at higher trophic levels that consume shellfish (as an example) can suffer adverse consequences from consumption of cadmium-containing tissues. This has been well documented for avian species.

Based on these facts from the scientific literature, we can predict that increased environmental cadmium burdens may cause:

1. increase in shellfish mortality;

2. decrease in shellfish reproduction and population levels;

3. increased cadmium burdens in shellfish tissue with resultant accumulation in wildlife with consequent adverse effects on terrestrial, freshwater, and marine wildlife populations;

4. increased cadmium burdens in shellfish with the potential of shutdown of recreational and commercial harvests and/or increased human body burdens with resultant kidney damage and other pathogenic effects.

Thus the externalized cost of coal has to include (among a panoply of other costs) the negative economic, ecological and human health effects (including healthcare costs) of cadmium toxicities.

References Provided by Paul F. Torrence, Ph.D

• “Chapter PQ: Coal Quality and Geochemistry, Powder River Basin, Wyoming and Montana.” G. D. Stricker and M. S. Ellis. In US Geological Survey Professional Paper 1625-A. http://pubs.usgs.gov/pp/p1625a/Chapters/PQ.pdf.

• “Hazards of Heavy Metal Contamination.” Järup, Lars (Department of Epidemiology and Public Health, Imperial College, London, UK). British Medical Bulletin, Vol. 68 (2003). Pp. 167-82.

• “Cadmium Exposure and Breast Cancer Risk.” McElroy, Jane, Martin M. Shafer, Amy Trentham-Dietz, John M. Hampton, and Polly A. Newcomb. Journal of the National Cancer Institute, June 21, 2006. Pp. 869-73.

• “Health effects of cadmium exposure--a review of the literature and a risk estimate.” Järup L, Berglund M, Elinder CG, Nordberg G, Vahter M. Scand J Work Environ Health. 1998; 24 Suppl 1:1-51. Source: Department of Environmental Health, Norrbacka, Karolinska Hospital, Stockholm, Sweden. PMID: 9569444.

• Cadmium Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review. Eisler, Ronald. Biological Report 85(1.2), July 1985. Contaminant Hazard Reviews Report No. 2. Patuxent Wildlife Research Center, US Fish and Wildlife Service, Laurel, MD, 1985.

• The Toll from Coal: An Updated Assessment of Death and Disease from America’s Dirtiest Energy Source. Schneider, Conrad and Jonathan Banks. Boston, MA. Clean Air Task Force. September 2010.

• “Exploring spatial and temporal variations of cadmium concentrations in Pacific oysters from British Columbia.” Feng CX, Cao J, Bendell L. Source: Department of Statistics and Actuarial Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada. © 2010, The International Biometric Society.

• “Cadmium in shellfish: the British Columbia, Canada experience--a mini-review.” Bendell LI. Toxicol Lett. 2010 Sep 15; 198(1): 7-12. Epub 2010 Apr 24. Source: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada. PMID: 20417697

• “Current status of cadmium as an environmental health problem.” Järup L, Akesson A. Toxicol Appl Pharmacol. 2009 Aug. 1; 238(3): 201-8. Epub 2009 May 3. Source: Department of Epidemiology and Public Health, Imperial College London, London, UK. PMID: 19409405

• “Cadmium exposure in the population: from health risks to strategies of prevention.” Nawrot TS, Staessen JA, Roels HA, Munters E, Cuypers A, Richart T, Ruttens A, Smeets K, Clijsters H, Vangronsveld J. Biometals. 2010 Oct; 23(5): 769-82. Epub 2010 Jun 3. Source: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium. PMID: 20517707.

• “Geochemical survey and metal bioaccumulation of three bivalve species (Crassostrea gigas, Cerastoderma edule and Ruditapes philippinarum) in the Nord Medoc salt marshes (Gironde estuary, France).” Baudrimont M, Schäfer J, Marie V, Maury-Brachet R, Bossy C, Boudou A, Blanc G. Sci Total Environ. 2005 Jan 20; 337(1-3): 265-80. Source: Laboratoire d’Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, LEESA, University Bordeaux 1/UMR CNRS 5805 EPOC, Place du Dr B. Peyneau, 33120 Arcachon, France. PMID: 15626396

• “Cadmium toxicity among wildlife in the Colorado Rocky Mountains.” James R. Larison, Gene E. Likens, John W. Fitzpatrick & J. G. Crock. Nature 406, 181-183 (13 July 2000). PMID: 10910356

• “Cadmium toxicity to three species of estuarine invertebrates.” Gerald G. Pesch, Nelson E. Stewart. Marine Environmental Research, Vol. 3, Issue 2, April-June 1980, Pages 145-156.

• “Acute Toxicity of Copper, Cadmium, and zinc to Larvae of the Crab Paragrapus quadridentatus (H. Milne Edwards), and Implications for Water Quality Criteria.” M. Ahsanullah and G.H. Arnott. Australian Journal of Marine and Freshwater Research 29 (1) 1 – 8.

• “Bioaccumulation of cadmium in marine organisms.” Frazier JM. Environ Health Perspect. 1979 Feb; 28:75-9. PMID: 488051.

• “Bioaccumulation of cadmium in marine organisms.” Ray S. Experientia Suppl. 1986; 50:65-75. PMID: 3525217

• “Critical soil concentrations of cadmium, lead, and mercury in view of health effects on humans and animals.” de Vries W, Römkens PF, Schütze G. Rev Environ Contam Toxicol. 2007; 191:91-130. Source: Alterra, Wageningen University and Research Centre, Droevendaalse steeg 4, Atlas 104, P.O. Box 47, NL-6700 AA Wageningen, The Netherlands. PMID: 17708073

• “Sea ducks and aquaculture: the cadmium connection.” Bendell LI. Ecotoxicology. 2011 Mar; 20(2): 474-8. Epub 2010 Dec 12. Source: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada. PMID: 21153700

• “Health concerns of consuming cockles (Cerastoderma edule L.) from a low contaminated coastal system.” Figueira E, Lima A, Branco D, Quintino V, Rodrigues AM, Freitas R. Environ Int. 2011 Jul;37(5):965-72. Epub 2011 Apr 20. Source: CBC (Centre for Cell Biology), Departmento de Biologia, Universidade de Aveiro, 3810-193 Aveiro, Portugal. PMID: 21507485.

• “The comparison of heavy metal accumulation ratios of some fish species in Enne Dame Lake (Kütahya/Turkey).” Uysal K, Köse E, Bülbül M, Dönmez M, Erdogan Y, Koyun M, Omeroglu C, Ozmal F. Environ Monit Assess. 2009 Oct;157(1-4):355-62. Epub 2008 Oct 9. Source: Department of Biology, Faculty of Arts and Sciences, Dumlupinar University, 43100, Kütahya, Turkey. PMID: 18843546.

• “Toxicity of cadmium to six species in two genera of crayfish and the effect of cadmium on molting success.” Wigginton AJ, Birge WJ. Environ Toxicol Chem. 2007 Mar;26(3):548-54. Source: University of Kentucky, 101 TH Morgan Building, 675 Rose Street, Lexington, Kentucky 40506-0225, USA. PMID: 17373521

(Note: These resources are accessible via the Internet using a browser to search for the PMID number or the title. As Paul suggests, a Google search for “cadmium is the new lead,” will produce an astonishing number of additional sources on the toxicity of cadmium and its presence in commercial products and the environment. R. J.)