Sensitivity to sodium fluoroacetate (1080) of native animals from north-western Australia

The sensitivity to sodium monofluoroacetate (1080) of 9 species of native animals from north-western Australia was assessed using the increasing dose procedure to determine the Approximate Lethal Dose for each species. Granivorous birds from this region (e.g. ducks, corellas) were generally more sensitive to 1080 than their counterparts from southern Australia, and would be theoretically at risk from primary poisoning during 1080 grainbased baiting programs. However, the tolerance to 1080 of birds of prey from these areas is sufficient that these species face little risk of secondary poisoning during pest-control programs aimed at rodents or rabbits. The risk of primary poisoning to raptors from meat baits containing 6 mg 1080 per bait or less also appears to be low. The coexistence of brown falcons and barn owls with fluoroacetate-bearing vegetation over parts of their range has probably contributed to their development of tolerance to fluoroacetate.

Virulence of Listeria monocytogenes Propagated in NaCl Containing Media at 4, 25 and 37°C

Virulence, as determined in a mouse model, and virulence factor activities of catalase (CA), superoxide dismutase (SOD) and listeriolysin O (LLO), was examined in Listeria monocytogenes 10403S. Cells were propagated in media containing various concentrations of sodium chloride (NaCl) at 4, 25 and 37°C. Strain 10403S exhibited significant increases in CA activity and LLO when grown in media containing 428 mM of NaCl at 37°C. The CA activities at 4 and 25°C were significantly less, and the cells exhibited similar increases and decreases as cells grown at 37°C. When comparing the growth temperatures, the CA activity decreased as the growth temperature decreased. The SOD activity was significantly increased only when cells were propagated in media containing either 428 or 1,112 mM of NaCl. The SOD activity increased as the growth temperature decreased. No LLO activity was detected when cells were grown at 4 and 25°C. The production of these enzymes appeared to be thermoregulated. In addition, approximate lethal dose (ALD50) values were determined after intragastric (i.g.) and intraperitoneal (i.p.) infection. Each method of infection indicated that LLO was required for virulence, while growth in salt containing media, growth at 4°C, or the production of higher levels of CA, SOD and LLO did not appear to influence the virulence of L. monocytogenes.

Acute Toxicity in Rats of Chlorinated Hydrocarbons Given via the Intratracheal Route

1 The approximate lethal dose (ALD) of six chlorinated hydrocarbons via the intratracheal route has been determined in rats and compared with published oral LD50 values. 2 The compounds tested in this study were dichloromethane, perchloroethylene, trichloroethylene, carbon tetrachloride, chloroform and ethylene dichloride. 3 A method of administering the materials intratracheally to unanaesthetized animals was developed. 4 The intratracheal ALD of the chlorinated hydrocarbons ranged from 3.1 to 17.5% of the oral LD 50 and death was peracute. 5 Aspiration of chlorinated hydrocarbons may present more of a hazard than oral toxicity and should be considered when rendering first aid or emergency medical treatment.

Assessment of an Approximate Lethal Dose Technique for Determining the Relative Susceptibility of Non-Target Species to 1080-Toxin

The susceptibility of eight species of dasyurid marsupials and five species of murid rodents from the pastoral areas of Western Australia to the toxin sodium monofluoroacetate (Compound 1080) was assessed. Both LD*5O tests and an increasing dose procedure to determine the approximate lethal dose (ALD) were used. The results ranged from a low ALD of 1.6 mg kg-1 for an island population of Pseudomys hermannsburgensis to a high of 20 mg kg-1 for a mainland population of Notomys mitchelli. Intraspecific and regional variation in sensitivity was evident: three populations of P. hermannsburgensis showed widely different ALDS, and high ALDS were found in the Millstream area relative to elsewhere in the pastoral regions. Where both ALD and LD*5O were available, the dose response curve was steep; all LDSOS were less than a factor of 1.5 above the ALD. LD*5O values and ALDS were significantly correlated for selected dasyurids and murids, using published data. A computer simulation based on sampling a standard number of animals from 10 theoretical populations differing only in their LD~O confirmed that ALD and LD*5O gave similar rankings of sensitivity, although high variance on the LD~O reduced the strength of the correlation. Actual dosing data from eight populations of Rattus fuscipes were also analysed; both LD*5O and ALD gave similar rankings of population sensitivity. Subject to assumptions about the variability of sensitivity within a population, the ALD offers an alternative to LD~O testing that requires fewer animals, and need not cause more than one death per population tested.

An Assessment of the Potential Target Specificity of 1080 Predator Baiting in Western-Australia

The potential hazard of 1080 baiting for predators to 14 species of non-target mammals in the pastoral areas of Western Australia and a further six from Western Australia's Fitzgerald River National Park, was assessed by comparing projected doses of 1080 (based on consumption of non-toxic bait by captive animals in the absence of alternative food) with the approximate lethal dose of 1080 for each species. These figures suggested that individuals from 12 species were potentially at risk from crackle baits, while only individuals from Dasyurus hallucatus, Ningaui spp., Sminthopsis crassicaudata, Planigale maculata, one population of Leggadina forresti and one population of Sminthopsis ooldea were potentially endangered by meat baits. Tests using the native mammals Zyzomys argurus and Pseudomys hermannsbergensis and laboratory mice (Mus musculus) and laboratory rats (Rattus norvegicus) showed that individuals of all species reduced their consumption of toxic bait relative to non-toxic bait, although this did not prevent three of five rats and one of three P. hermannsbergensis from being killed.