title: Immunotoxicity of the pyrethroid insecticides deltametrin and alpha-cypermetrin.
abstract: The synthetic pyrethroids deltametrin and alpha-cypermetrin were studied for effects on the immune system in 28-day studies in F344 male rats. Sixteen rats per group were dosed with either deltametrin 0, 1, 5, or 10 mg/kg body wt./day or alpha-cypermertin 0, 4, 8, or 12 mg/kg body wt./day in soy bean oil by gavage. Haematology, bone marrow cell counts, tests for natural killer (NK) cell activity and mitogen response (Con A and STM) as well as quantitation of lymphocyte subpopulations were performed. Spleen cells from immunized animals (six animals/group) were tested for antibody production (SRBC-PFC). Volumes of lymphoid compartments of mesenteric lymph nodes and thymus were estimated using stereological methods. In the deltametrin study an effect was found in the groups receiving 5 or 10 mg/kg body wt. The effects were: increased weight of mesenterial lymph nodes, decreased thymus weight in immunized animals and an increase in numbers of SRBC-PFC and splenic NK cell activity. An effect on relative adrenal weight was seen in the 10 mg/kg body wt. group. No severe effects on the immune system was found. The lowest effect level of alpha-cypermetrin was 12 mg/kg body wt./day based on increased relative adrenal weight.
authors.affiliation: Institute of Toxicology, National Food Agency, Soeberg, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Madsen
authors.forename: M H
authors.initials: MH
authors.lastname: Claesson
authors.forename: C
authors.initials: C
authors.lastname: Röpke
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects; D000818:Animals; D000921:Antibody-Producing Cells / Q000187:drug effects / Q000276:immunology; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D007107:Immune System / Q000187:drug effects* / Q000276:immunology; D007306:Insecticides / Q000008:administration & dosage / Q000633:toxicity*; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology; D008198:Lymph Nodes / Q000187:drug effects; D008213:Lymphocyte Activation / Q000187:drug effects; D016131:Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology; D008297:Male; D009570:Nitriles; D009929:Organ Size / Q000187:drug effects; D011722:Pyrethrins / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D011916:Rats, Inbred F344; D013950:Thymus Gland / Q000187:drug effects / Q000276:immunology
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017160:cypermethrin; C017180:decamethrin