Sensitivity of test species

Is the sensitivity of test species associated with their geographical home ranges In other words, are sensitivities the same for... 

Table 1 on toxicities is a broad-brush treatment of the toxicity data and does not consider the effects on toxicity values due to AES structure, differential sensitivity of test species within taxonomic groups or the variables of the test methods. The Dutch government surveyed the complex toxicity literature and developed rules for determining a risk-based, maximum permissible concentration (MFC) for AES in their country s surface waters. In 1995 they established the MFC at 0.4 mg/L [7]. 

LAS Toxicity. The ranges in toxicity can be explained by (a) the differential sensitivity of test species marine organisms tend to be more... 

Acute oral toxicity of mirex to warm-blooded organisms was low, except for rats and mice, which died 60 to 90 days after treatment with 6 to 10 mg mirex/kg body weight (Table 21.1). Birds were comparatively resistant. The red-winged blackbird (Agelaius phoeniceus) was unaffected at 100 mg mirex/kg body weight, although it was considered the most sensitive of 68 species of birds tested with 998 chemicals for acute oral toxicity, repellency, and hazard potential (Schafer et al. 1983). 

Maltby L, Blake N, Brock TCM et al (2005) Insecticide species sensitivity distributions the importance of test species selection and relevance to aquatic ecosystems. Environ Toxicol Chem 24 379-388... 

In many studies on solid waste in which ecotoxicological tests have been used, little attention has been given to such aspects as the selection of test species, sensitivity of the tests, and the... 

The applicability of CE-ICP-MS for fast screening of weak metal interactions of Cd2+ with several test proteins (such as carbonic anhydrase from bovine erythrocytes, bovine serum albumin, human holotransferrin, ceruloplasmin and superoxide dismutase) has been studied by Cahmoun and Hagege.74 The sensitivity of element species and their detection limits in CE-ICP-MS have been improved by introducing a preconcentration step involving large volume stacking with polarity... 

By far the most comprehensive research into AHR-related effects of PCDD/Fs on fish was a retrospective analysis of Lake Ontario lake trout reproductive impairment due to AHR-mediated early life stage mortality [16]. This includes blue sac disease as well as sublethal effects, which may increase susceptibility of sac fry and alevins to increased mortality and predation during swim-up. Lake trout are more susceptible to AHR-mediated toxic effects than any other Great Lakes species, with the possible exception of mink. WHO TEFs for fish were used to calculate the 2378-TCDD equivalent (TECegg or TEQ) concentrations in lake trout eggs. The validity of the additive toxicity equivalence model was established through early life stage trout toxicity tests. The WHO fish TEFs are likely to be fairly robust for lake trout, since they were determined primarily from relative potency values for effects in embryos of a related salmonid, rainbow trout, even if the relative sensitivity of the species to 2378-TeCDD toxicity may be different. 

Taxa. Although many species show the classic inverse relationship between stomatal frequency and C02, not all species do so. Therefore, the sensitivity of the species of fossil leaves needs to be tested when selecting fossil species to work with. Moreover, since plants have morphological and physiological constraints that do not allow adjustment of stomatal numbers to infinitely high or low C02, plant species have species-specific response limits to C02 (Kiirschner et al. 1997). For instance, the nonlinearity of the stomatal index-elevation... 

Because plants and mammals differ in organization and physiology, it might be expected that herbicides would constitute only a slight chemical hazard to mammals. Whereas some herbicides have very low toxicides in mammals, others have considerable. A number of test species are used to appraise toxicity, and their sensitivities are graded as acute (short-term) LD50 values. 

An analysis of regularities observed in species sensitivity distributions (SSD) fitted on acute and chronic aquatic toxicity data for a large number of organic and inorganic toxicants is provided by De Zwart (2002). The log-logistic sensitivity model he used is characterized by the parameter a, which is the mean of the observed loglO-transformed L(E)C50 or NOEC values over a variety of test species, and /3, a scale parameter proportional to the standard deviation of the loglO-transformed... 

Biological activity can be evaluated by using in vitro techniques to determine which effects of the product are related to clinical activity. Due to species specificity of biotechnology derived products, it is necessary to select relevant species for testing. Mammalian cell lines can be used to predict in vivo activity and the relative sensitivity of various species including man. Such studies are useful to determine receptor occupancy, receptor affinity pharmacological aspects, and for the selection of adequate animal species for toxicity testing. 

No chronic animal toxicity studies have been conducted on VX however, there are two subchronic studies which can be used for developing an RfD. In one study, rats were dosed by s.c. injection 5 days per week for 90 days (Goldman et al., 1988). In the second study, sheep received daily doses of VX in feed for 56 days (Rice et al., 1971). Both of these studies identify blood cholinesterase as the most sensitive endpoint. Data are available indicating that sheep are more sensitive than rats to the toxic effects of VX. Ivanov et al. (1993) reported that the oral LD50 in sheep is 6 figfkg whereas that for rats is 66 //g/kg. In addition, Ivanov et al. (1993) suggested that this increased susceptibihty in sheep may be due, in part, to the lower concentration of catalytic sites for serum ChE in sheep (7.098 x lO mol/L vs. 1.704 x 10 mol/L in rats). The Rice et al. (1971) study is selected here for deriving an oral RfD because it utilized an exposure route that is more relevant for an oral RfD, and also because the experimental evidence indicates that sheep are the more sensitive of the species tested. 

Sensitivity is a criterion that is used in the choice of a test species. The sensitivity of the species in Table 3 relative to one another as well as to indigenous flora and fauna in the ecosystem is a matter of contention. There is no single test species and no group of test species consistently most sensitive to toxicants or most reliable for extrapolation to all other organisms. Most toxic effects reported for a variety of test substances have been species-specific. Therefore, acute toxicity tests are conducted first with a variety of freshwater and marine test species to determine the most sensitive plant and animal. These sensitive species then are used in all subsequent chronic testing. 

Known species sensitivities of test animal dermis compared to that of the human skin from earlier experience Application of different concentrations of test agent and the need for comparable control sites where the dermis is similar Application of the test agent to intact and abraded dermis, the latter having slight damage to the stratum corneum (dead cell layer) by mechanical means to mimic the loss of the protective barrier through abrasions and cuts... 

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