13th Meeting of the Scientific Group on Methodologies for the Safety Evaluation of Chemicals (SGOMSEC): alternative testing methodologies for ecotoxicity.

There is growing public pressure to minimize the use of vertebrates in ecotoxicity testing; therefore, effective alternatives to toxicity tests causing suffering are being sought. This report discusses alternatives and differs in some respects from the reports of the other three groups because the primary concern is with harmful effects of chemicals at the level of population and above rather than with harmful effects upon individuals. It is concluded that progress toward the objective of minimizing testing that causes suffering would be served by the following initiatives--a clearer definition of goals and strategies when undertaking testing procedures; development of alternative assays, including in vitro test systems, that are based on new technology; development of nondestructive assays for vertebrates (e.g., biomarkers) that do not cause suffering; selection of most appropriate species, strains, and developmental stages for testing procedures (but no additional species for basic testing); better integrated and more flexible testing procedures incorporating biomarker responses, ecophysiological concepts, and ecological end points (progress in this direction depends upon expert judgment). In general, testing procedures could be made more realistic, taking into account problems with mixtures, and with volatile or insoluble chemicals.

Passive transfer of humoral resistance against adults of the tsetse fly, Glossina palpalis palpalis (Diptera, Glossinidae), in rabbits.

The possibility of passive transfer of rabbit humoral immunity against tsetse fly bites was investigated for the first time. Partial immunity of recipient animals was achieved after two intravenous injections of 15 ml of serum from immunized (donor) rabbits during 48 hrs. This treatment induced an apparent increase of resistance in the passively immunized group of rabbits expressed as direct mortality ("killing effect") of sucking flies within the following 72 hr period. The immunological state of immune sera of both donors and recipients was examined by ELISA, using the water-soluble proteins of tsetse salivary glands as antigen. No direct correlation between the titre of antibodies and the killing of Glossina was detected. These results indicate that these antibodies were not the only humoral factor responsible for tsetse mortality since their titre did not substantially change in the course of 7 days while the "killing effect" had disappeared from the recipient's blood within 72 hrs.