Terrestrial species

Our knowledge of effects on terrestrial species is largely derived from the use of methyl chloride, methyl bromide, chloroform, carbon tetrachloride, ethylene dichloride, ethylene dibromide, dibromo-chloropropane and dibromobutane as fumigants, for the control of pests of stored grain, and of soil nematodes [11, 40]. A typical fumigant dose is of the order of 50 mg/1, which is similar to the measured action levels against aquatic organisms shown in Table 9. 

Chloroform, methyl chloroform, and to some extent carbon tetrachloride, trichloroethylene and perchloroethylene inhibit the anaerobic sludge digestion stage of biological sewage treatment, at levels as low as 5 mg/kg on dry sludge solids [8] but there are no reports of any inhibition or aerobic microbial activity at realistic levels of occurrence. 

---

The major routes of uptake of xenobiotics by animals and plants are discussed in Chapter 4, Section 4.1. With animals, there is an important distinction between terrestrial species, on the one hand, and aquatic invertebrates and fish on the other. The latter readily absorb many xenobiotics directly from ambient water or sediment across permeable respiratory surfaces (e.g., gills). Some amphibia (e.g., frogs) readily absorb such compounds across permeable skin. By contrast, many aquatic vertebrates, such as whales and seabirds, absorb little by this route. In lung-breathing organisms, direct absorption from water across exposed respiratory membranes is not an important route of uptake. 

The lateral diverticulum cells in semi-terrestrial species such as toads can still detect a wide range of amino acids, comparable to the properties of fish neuroepithelium. Both water-soluble and volatile odourants are discriminated by the olfactory neurones of the Clawed toad (Xenopus) (Iida and Kashiwayanagi, 1999). When single olfactory neurones were tested with acidic, neutral and basic amino acids, over 50% of the receptors gave some excitatory response. 

No evidence of copper deficiency exists in terrestrial species of invertebrates examined. However, relatively low concentrations of copper stimulated growth and reproduction. Reproduction in mites (Platynothrus peltifer) increases when fed diets containing 28 mg Cu/kg DW (vs. 13 mg/kg in controls) for 3 months (Denneman and van Straalen 1991). Also, juveniles of earthworms (Eisenia andrei) show increased growth at 18 mg Cu/kg DW soil after 12 weeks (van Gestel et al. 1991). 

Among the requirements for registration of pesticides in the United States, the 1978 guidelines proposed by the U.S. Environmental Protection Agency (3) list general metabolism studies "in at least one mammalian species, preferably the laboratory rat. .." Although similar tests have been conducted on other terrestrial species with increasing frequency, the small rodents have remained the principal source of metabolism data from intact animals. 

To aid in assessing the risks associated with large numbers of environmental contaminants, quantitative-structure-activity relationships (QSARs) have been developed covering nearly all biological effects or other endpoints in both aquatic and terrestrial species (Connell, 1990). QSARs relate chemical structural... 

The EMEA Committee for Medicinal Products for Veterinary Use (CVMP) established similar guidelines to those for human pharmaceuticals, to assess the potential for veterinary medicines to affect nontarget species in the environment, including both aquatic and terrestrial species [123]. 

Another salamander courtship pheromone, identified in 1999, is a protein. During courtship, males of the Appalachian woodland salamander, Plethodon jordani, (Plethodontidae), a terrestrial species, actively deliver a pheromone to the female. In the mating season, males develop a mental gland, located... 

Environmental release estimates are critical inputs for models that calculate indirect human exposures via the environment such as through ambient air or drinking water. They are also critical to modeling exposures to nonhuman aquatic and terrestrial species. Release estimates may be site-specific or they may be generic for a particular industrial process or industrial use. Releases from consumer and commercial products should also be estimated if applicable. 

Pietra, F. (1995) Structurally similar natural products in phylogenetically distant marine organisms, and a com parison with terrestrial species. Chan. Soc. Rev., 24, 65-71. 

Of course, the discovery of new structures is very important. Marine microbes are relatively new targets for such research. Bacteria and fungi isolated from marine environments, i.e., seawater, sediments, and marine organisms, often produce metabolites identical or similar to those from terrestrial species. 

What properties of the matrix could act as (additional) stressors to the exposed biota For example, acid soil both influences the speciation of metals (increasing bioavailability) and may cause stress in terrestrial species such as earthworms. 

TerraBase Inc. (www.terrabase-inc.com) is a Canadian company specializing in databases for QSAR-type research. It provides the data in a normalized, logarithmic fashion for direct use in QSAR development. It has several CD-ROM products specialized to the endpoint of interest and the application of chemicals. These databases can be searched by a variety of means, including chemical structure fragments. Information includes use, physicochemical properties, and over 100 types of toxicity data to aquatic and terrestrial species. A complete list of the types of data covered is available on the company s website. 

Such simple procedures, however, cost a lot of money. To obtain a single toxicity figure, for example, many tests need to be conducted to answer questions of interest such as Does this chemical cause cancer Does this chemical cause malformation and so forth. In fact, more than 20 animal toxicity tests are needed to answer such questions and obtain a toxicity figure. This could cost approximately USD 15 million. Similarly, to obtain a single exposure figure, the tests on residue analysis and environmental behaviour can cost up to USD 5 million. To examine the toxicity of natural organisms usually three aquatic species are tested as representatives of the water environment fish, water flea, and algae. For terrestrial species, earthworms, honey bees, and birds are tested. For these tests, approximately USD 1 million is needed. 

Because olfactory receptors can detect a wide array of structural types (in principle, any), the evolution of pheromones has been influenced primarily by ecological factors. First, certain types of chemical compounds can travel great distances and convey information in complex environments, including those that lack light. These compounds can be adapted, through evolution, to the medium within which the animal functions (e.g., water or air). Second, other types of chemicals are sufficiently stable that they can convey information for extended periods terrestrial species benefit most from these. Third, complex structures and/or mixtures of smaller structures can be information-rich and highly specific (i.e., immune to eavesdropping by other species because of the selective nature of olfactory receptors). Finally, products that are readily and naturally produced by... 

A polyclad flatworm (planocerid sp. 1) collected in Guam was found to contain the neurotoxin tetrodotoxin (TTX 225 and ll-nortetrodotoxin-6(5)-ol 226 which it uses to kill mobile prey such as gastropod mollusks. Consistent with a role in prey capture, levels of TTX in the flatworm decreased after they were fed on cowries. Although an antipredation role has been implied for TTX in some terrestrial species, its presence does not prevent flatworms from being consumed by reef fish.259... 

Magoski NS, Bulloch AG (1999) Dopamine Activates two Different Receptors to Produce Variability in Sign at an Identified Synapse. J Neurophysiol 81 1330 Pietra F (1995) Structurally Similar Natural Products in Phylogenetically Distant Marine Organisms, and a Comparison with Terrestrial Species. Chem Soc Rev 24 65... 

---