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Abstract
Introduction
Traditional chemical analysis of contaminated land has its drawbacks both in cost and scientific limitations. Increasingly sophisticated and expensive analytical techniques such as GC/MS and ICP-OES add to the analytical arsenal available to site investigators. But in addition to confusing the investigator with an overload of data and effectively limiting the number of samples to be analyzed with increasing analysis bills per sample (within the constraints of a finite budget), until instrumental techniques based on the as yet undiscovered "unifying principle" are available, all chemical analytical techniques will only be able to detect a finite number of chemical contaminants. Neither will they take account of the "chemical cocktail" or additive toxicity (synergic) effect of combined contaminants. The use of biological indicating organisms (BIOs) brings a more holistic approach to site investigation that complements traditional chemical analytical techniques.
Use of biological organisms for toxicological testing has been widespread, particularly in the areas of product testing, and is well documented. Rachel Carson's seminal book Silent Spring [1] gave voice to the environmental chattering classes and damned the chemical industry, particularly the producers of organochlorines for the devastating effects they wreaked on U.S. wildlife. However, measurement of the very effect these chemicals have on organisms can now be used to protect the environment. Simple biological organisms have recently been harnessed in environmental testing, e.g. the naturally luminescent marine bacterium Photobacterium phosphoreum and small invertebrates such as Daphnia. However, most of these techniques so far have been somewhat limited to the testing of aqueous systems. The thornier problem of biological testing of the soil matrix encountered in contaminated land was, until very recently, largely unresolved.
The use of so-called "sentinel" animals as indicators of the bioavailability of the toxin TCDD in contaminated areas was described in 1984 [7]. A contaminated site in Missouri resulted in the deaths of 48 horses; several hundred birds; and several cats, dogs, and chickens as a result of exposure to the soil [2,8]. Tragically, the high mortality of guinea pigs reared close to a disused solvent recovery site in England [3] bears testimony to the contamination later proved by chemical analysis.
It was these findings that prompted the study described below.
The GUPPY Project
The decommissioning of an ex-ammunitions production facility presented logistical problems, not least of which was how to determine the scale and type of soil contamination present without subjecting site investigation personnel to as yet unknown hazards (such as explosions) and toxins.
For this reason it was decided to use the domestic guinea pig (Cavia porcellus) as a biological indicator of contamination in a controlled investigation, and so the "GUPPY" project was born. All normal controls used in toxicological investigations were used as far as were practicable and achievable by the supplier (see acknowledgment). The area of land to be investigated was penned out in 2.5 meter grids on the herringbone design recommended by Ferguson et al. [4], and randomly selected pairs (of attested fecundity and opposite sex) were put into each pen and fed on identical nutritionally balanced and chemically screened diets, but of minimal bulk to encourage the pica habit and uptake of any toxins. An identically mapped-out control greenfield site was also populated and tested identically (see acknowledgment).
Findings by expert clinical diagnosticians were pooled and biopsies of mortalities performed, including chemical analysis of target organs such as livers, kidneys, and spleens. This chemical analysis identified probable "culprit contaminants" for the toxicological symptoms suffered by the BIOs and will form the subject of a separate paper. Traditional statistical techniques were used for the rejection of rogue rodent outliers.
The confidential nature of the project unfortunately precludes the detailed discussion of findings but examples of diagnostic clinical symptoms included:
(i) Chloracne indicative of dioxin contamination
(ii) Luminescent guinea pigs indicative of radioactivity
Mutagenic and teratogenic effects on the population are perhaps rather too distressing to describe here but the project was a success in that:
(i) No human lives were lost
(ii) A hazard ranking of each area was achieved allowing subsequent amelioration techniques (the site was capped and is now a gypsy transit camp)
(iii) The heterogeneous nature of the surface contamination was to some extent homogenized within each penned area by rodent defecation, demonstrating the "dilute and disperse" pollution solution. Soil condition was also improved.
(iv) This is an in situ investigation technique mirroring the current preference for such techniques over alternative ex situ methods that could have transported the hazards to other areas and thus compounded the problem
Problems encountered during the three-month investigation included:
(i) Unexpected press interest following the reporting of "glow-in-the-dark furry monsters" (sic) in the area surrounding the test area. (Unfortunately, the adrenaline-enhancing effects of ingested toxins was not foreseen accounting for a loss of several BIOs prior to reinforcing of the pen barriers). Luckily, their unplanned release coincided with the launch of the latest Steven Spielberg movie so incorrect conclusions were drawn (as is usual on matters scientific). All were later recaptured.
(ii) Disposal of the carcases
Subsurface Investigation: The Future
The author acknowledges the limitations of the above technique in that it does not and did not determine the extent of subsurface contamination. However, it was a pragmatic method based on the U.S. "learn as you go" principle, and the means justifies the end and horses for courses (or moles for holes, as will be shown shortly). On the receipt of adequate funding, the author proposes the logical extension of the GUPPY project by the use of burrowing mammals or moles.The common mole (Talpa europaea) whose anthropomorphic qualities (eloquently described by Grahame, [5]) make it particularly suitable for such studies has been shown to be very effective in initial blind trials. Avogadro first propounded the principles of molar concentrations as long ago as the early nineteenth century although there was little appreciation of the enormity of the environmental damage that would be wreaked on the landscape by the burgeoning industrial revolution at this time, let alone the use of moles to measure it.
Possible advantages over the guinea-pig trials (apart from the sub-surface investigation) are:
(i) Lower profile and increased security (no possibility of exciting the interest of local press, animal rights activists, or personnel working or inhabitants living on the site)
(ii) Possibility of use under existing development
(iii) "Dilute and disperse" activities underground
(iv) Moleskin trousers
Possible disadvantages might include:
(i) Unsuitability for golf-course developments (unless mortality was 100%)
(ii) Lack of respect for boundaries. Definition of a non-cost-prohibitive three-dimensional grid system that would be obeyed by the subsurface BIOs has yet to be formulated. (Psychological training to enhance the existing spatial awareness and territorial defensive instinct of the species using Pavlovian techniques is being considered).
(iii) Recovery of the moles (dead or alive)
(iv) Lack of foodstuffs (earthworms, beetles, etc.) in heavily contaminated areas
(v) Formal quality accreditation of this technique might prove difficult
Conclusion
The author is the first to admit that there are ethical and scientific questions raised by this (and the proposed) study. However, contaminated site investigation requires a multidisciplinary approach if it is to be successful and ultimately fit for purpose. He is unlikely to repeat the GUPPY experiment.
Paul Board, the author, has been under a lot of stress recently.
Cary Barnhard grew up in New Jersey, where his senior class voted him "most unique." He maintains that honor is a polite way of being voted "most likely to need therapy." After a few misadventures in the music industry, he started pretending to be a graphic artist. Eventually it became the truth.
