Abstract
The concept of hormesis has been receiving greater interest in the biomedical and toxicological research communities over the past decade. Of particular importance has been how the hormesis concept may affect risk assessment practices, litigation, and regulation. This paper identifies and discusses what may be the first application of the hormesis concept in environmental assessment and litigation. This occurred in California within the context of an assessment of alleged continuing smelter contamination nearly a century ago.
Hormesis is a dose-response phenomenon that is characterized by a low-dose stimulation and a high-dose inhibition (Calabrese and Baldwin 2002 Calabrese and Baldwin 2003a). Although the concept of hormesis has been vastly overshadowed by the threshold and linear at low-dose models, especially by public health and environmental regulatory agencies in risk assessment, the hormetic model has received much attention recently because it appears to occur more frequently than other dose-response models based on substantial head-to-head comparisons using objective a priori criteria (Calabrese and Baldwin 2001 Calabrese and Baldwin 2003ba; Calabrese et al. 2006). These findings have led to the suggestion that the hormesis model be considered as the default model in risk assessment (Calabrese 2004; Calabrese and Cook 2005; Cook and Calabrese 2006).
Despite the recent interest in the hormesis concept and its risk assessment implications, the readership may be surprised to learn that the first application of the hormesis concept in a major environmental litigation is believed to have involved an assessment of the environmental impact of the Selby Smelter in California over 90 years ago (Holmes et al. 1915).
In March 1905, the State of California filed for an injunction in the Superior Court of Solano County to restrain and enjoin the Selby Smelting and Lead Company from allowing smoke from their smelter to pollute the air and soil near Vallejo Junction, California, 5 miles west of Benicia, a small city north of San Francisco.
After much legal maneuvering, the case was brought to trial on August 7, 1906, before the court with a jury trial being waived by both parties. The case was quite involved, taking considerable lay and expert testimonies. In late October 1906 the Court’s opinion was filed; findings of fact and conclusions of law were filed on April 22, 1907. Finally, on July 16, 1908, judgment was issued in favor of the plaintiffs and required the Selby Smelting and Lead Co. to take specific actions to significantly reduce emissions. More legal action followed with other motions and their evaluation, until the original judgment of the trial court was affirmed by the State Supreme Court on July 12, 1912. During the prolonged period between the initial complaint and the final judgment offered by the State’s Supreme Court, the farmers continued to complain that the injunction to abate the pollution was being violated, while at the same time, the smelter company argued that it was significantly reducing the amount of smoke released into the atmosphere.
In order to avoid the cost of more litigation dealing with contempt of court, both sides agreed to submit the question of whether there was a violation of the injunction to a board of technically qualified individuals to render such a decision. On May 22, 1913, the court created the Selby Smelter Commission. It consisted of three members (J. A. Holmes, Chair, Director of the US Bureau of Mines; Edward C. Franklin, Professor of Organic Chemistry, Stanford University; Ralph A. Gould, a chemical engineer from San Francisco). The Commission was advised by a number of researchers from the University of California, Stanford University, and various federal agencies and initiated numerous research projects with these technical experts. Amongst the many specific studies authorized by the Commission was an evaluation of the relationship of Selby Smelter smoke and soil quality by Professor Charles F. Shaw of the University of California and his colleague, E. E. Free. Within their capacity as researchers supporting the activities of the Selby Smelter Commission, Shaw and Free invited a colleague, Professor Charles B. Lipman, to offer a commentary on the capacity of metals released from smelters, such as the Selby smelter, to cause toxicity to vegetation. The apparent reason for the invitation was that Lipman published a paper in 1913 (Lipman and Wilson 1913) and was undertaking subsequent research (see Lipman and Gericke 1917) addressing the effects of toxic inorganic salts and acids emitted from smelters on the growth of several species of plants. This research had revealed that toxic substances such as copper, lead, and zinc stimulated plant growth at low doses but also over a broader than expected dose range. Lipman (1915) opined that there was no likely potential adverse effect on plants grown in the vicinity of the Selby smelter from these metals. Immediately below is the invited commentary by Professor Lipman that was published in the Holmes et al (1915) report of the Selby Smelter Commission.
LETTER OF PROF. C.B. LIPMAN CONCERNING INJURIES BY METALS IN THE SOIL
Below is presented a letter by Prof. C.B. Lipman regarding injuries to vegetation caused by salts of the heavy metals in the soil:
SELBY SMELTER COMMISSION, San Francisco, Cal.
GENTLEMEN: In accordance with the request of Messrs. Shaw and Free, I beg to submit a statement with reference to the results obtained in experimental work carried out in my laboratories and greenhouses on the effects of salts of the heavy metals on barley, wheat, and vetch.
Of interest particularly in connection with the investigations of Messrs. Shaw and Free are the figures obtained on the effect of lead on the growth of barley. In growing two successive crops on soil treated with lead sulphate we have found that no damage to crops occurs unless the plants be put in immediately after the lead sulphate is incorporated into the soil. Amounts as at high as 1,000 parts of lead sulphate per million have been used in a soil plentifully supplied with organic matter, without any damage whatever to the crop. Indeed, stimulation of the crop has been obtained with very considerable concentrations of lead sulphate (in excess of 1,200 parts per million).
Similar results were also obtained with copper sulphate, which shows that the amount of organic matter or of colloidal material in the soil regulates the point of stimulation or toxicity of the salt in question. Thus, for example, in a very sandy soil barley growth was much stimulated by the presence of 100 parts per million of copper sulphate, and amounts higher than that in the same soil showed a gradual toxicity as the concentration became greater.
In an adobe soil the point of highest stimulation was between 300 and 400 parts per million of copper sulphate, and in the same kind of soil to which much organic matter had been added the point of highest stimulation was 700 parts per million. In any case, however, stimulation by the use of copper sulphate at some point had been shown to obtain so far as barley is concerned.
It is particularly to be noted also that the copper compounds used are not such insoluble ones as are likely to occur in smelter wastes, but is the copper sulphate, which is an easily soluble salt.
Similar results, differing only in degree but not in kind, were obtained with zinc sulphate and iron sulphate, the latter having been used in very much larger quantities than even the zinc or the copper.
Considering that the largest amount of lead found in the soils by Messrs. Shaw and Free was equal to 25 parts per million, it would seem that lead as a factor in the destruction of plants, through its content in soil, or through the latter’s contamination from smelter wastes, would seem to be absolutely a negligible one. None of the amounts of lead which we used in our investigations was as low even as 25 parts per million on the basis of the weight of the soil, lead sulphate being used, and yet no toxic effect, but actually stimulating effects, from quantities far in excess of 25 parts per million parts of lead were obtained.
So far as arsenic is concerned, I cannot make any statement based on our own experiments, because, although we have some work started along that line, it is not completed, and therefore we are unable to make definite statements. It would appear, however, from the experiments of Greaves at the Utah Experiment Station, that the bacterial flora at least, upon which crops depend for their available plant-food supply are very active, and may be stimulated by quantities of arsenic which are certainly not smaller than those which have been found by Messrs. Shaw and Free in the soil about the Selby smelter.
I wish to offer it, therefore, as my opinion, based on extensive experimental work with the so-called poisonous metals that are likely to be thrown down in the smelter wastes and thus introduced into the soil, that no damage can possibly come to any appreciable area of land around the smelter from the deposition of poisonous metals through the fumes of the smelter. No content of these materials in the soil as yet determined has shown itself to be great enough in our experiments to give anything but a stimulating effect to the growth of the plant, and although the smelter problem may be a serious one as regards sulphur dioxide gas and its effects on crops, it has no significance at all so far as the solid smelter wastes are concerned which are introduced into agricultural soil areas through the smelter fumes.
Very truly yours,
(Signed.) Chas. B. Lipman,
Professor of Soil Chemistry and Bacteriology,
University of California
In their report, the Commission summarized the data presented by Lipman. Holmes, Franklin, and Gould (1915) stated “Prof. Lipman states emphatically, and bases his statement on the results of his own investigations, that such quantities of arsenic and lead have no adverse influence on the growth of plants, that indeed such small quantities seem rather to stimulate their growth.” Although the Commission did not explicitly address the issue of the stimulatory or hormetic response, in their “conclusions and findings” section, they stated “. . . that the quantity of these metals so deposited was of no economic importance and did not poison the soil or in any way produce a loss or reduction of crops,” a clear impact of the Lipman (1915) commentary.
Although it appears that the Selby Smelter Commission (Holmes, Franklin, and Gould 1915) gave serious consideration to the research findings and expert opinion of Professor Lipman (1915), the broader scientific community never cited his historic paper (Lipman and Wilson 1913), based on the Web of Science database, until 1999 (see Calabrese and Baldwin 1999).