The effectiveness and residual activities of permethrin-impregnated military battle dress uniforms were evaluated by comparing a new company-manufactured ready-to-use polymer-coating method with two "dipping methods" that are currently used to treat uniforms. Residual permethrin amounts and remaining contact toxicities on treated fabrics before and after up to 100 launderings were tested against Aedes aegypti (L.), Ixodes ricinus (L.), and Lepisma saccharina (L.). The residual amount of permethrin was considerably higher with the polymer-coating method: 280 mg a.i./m2 after 100 launderings, compared with 16 and 11 mg a.i./m2, respectively, obtained when using the two dipping methods. Hard ticks were most susceptible to the new polymer-coating method, resulting in prelaundering 100% knockdown times of 7.0 +/- 0.9 min, whereas equivalent times for the dipping methods were 7.9 +/- 0.35 min and 8.0 +/- 0.54 min, respectively. After 100 launderings, 100% knockdown of I. ricinus nymphs was reached at 15.2 +/- 1.04 min using the polymer-coating method, compared with 178.8 +/- 24.7 min and 231 +/- 53.6 min, respectively, using the dipping methods. Similar results were obtained for Ae. aegypti and L. saccharina, indicating that the polymer-coating method is more effective and efficient when compared with the dipping methods.

Iodolactone (6-iodo-8,11,14-eicosatrienoic-delta-lactone), an iodinated derivative of arachidonic acid, was found to be synthesized in rat thyroid slices; however, the physiological role of this compound is still unknown. We tried to detect iodolactone in isolated porcine thyroid follicles and investigated the effects of in vitro synthesized iodolactone on epidermal growth factor-induced thyroid cell proliferation and TSH-induced cAMP formation. In vitro synthesis of iodolactone was performed with lactoperoxidase-catalyzed iodination of arachidonic acid in the presence of trace amounts of [125I]- and [3H]arachidonic acid. After purification by silica gel chromatography, HPLC of the reaction products revealed one main peak containing trace amounts of both [125I]- and [3H]arachidonic acid. With gas chromatography-mass spectrometry (GC-MS) a molecular mass of 391 m/z, corresponding to the derivatization product of iodolactone, was found. An ethanol-chloroform extract of isolated thyroid follicles preincubated with KI (10 microM) and arachidonic acid (1 microM) revealed peaks in HPLC and GC comparable with those of in vitro synthesized iodolactone. This indicates the ability of thyroid follicles to form iodolactone. Iodolactone (0.1-1.0 microM) dose-dependently inhibited epidermal growth factor-induced thyroid cell growth. This growth-inhibiting effect of iodolactone was 50-fold more pronounced than the inhibitory effect of KI (4 X 10(-5) microM) on thyroid cell proliferation. In contrast to the effect of iodide, the inhibitory effect of iodolactone on thyroid cell growth could not be abolished by methimazole (1 mM). Basal as well as TSH (0.5 U/liter)-induced cAMP formation were not changed by iodolactone. These experiments suggest a physiological role of iodolactone as a mediator of the known inhibitory effect of iodide on thyroid growth.

No abstract

The factory-based permethrin coating technique has only recently been developed. Consequently, no data are available on residual activity, laundering, and weathering resistance in impregnated battle dress uniforms (BDUs) worn under military deployment conditions, or on the cross-contamination potential of such uniforms. Herein, factory-impregnated BDUs worn-out during military deployment to Afghanistan were investigated for residual permethrin concentration, residual efficacy against arthropod vectors, and cross-contamination during laundering and storage. When compared with BDUs subjected to 50 defined washings using the U.S. Insect/Arthropod Repellent Fabric Treatment method, no significant differences in efficacy were observed against Aedes mosquitoes, but remaining knockdown activity in Ixodes ticks was significantly better in polymer-coated BDUs. BDUs impregnated by the polymer-coating method were found to be effective for the life of the uniform, ensuring protection of soldiers in the field from arthropod vectors, while causing less cross-contamination than those treated by the Insect/Arthropod Repellent Fabric Treatment method.

Personal protective measures against hematophagous vectors constitute the first line of defense against arthropod-borne diseases. In this regard, a major advance has been the development of residual insecticides that can be impregnated into clothing. Currently, however, information on specific treatment procedures, initial insecticide concentrations, arthropod toxicity, residual activity, and laundering resistance is either fragmentary or non-existent, and no World Health Organization Pesticides Evaluation Scheme or other guidelines exist for the standardized testing and licensing of insecticide-treated clothing. The aim of this study was to analyze the insecticide content, contact toxicity, laundering resistance, and residual activity of five commercially available and commonly used permethrin-treated fabrics-Insect Shield, ExOfficio, Sol's Monarch T-shirts, battle dress uniforms (BDUs), and Labonal socks-against vector-competent Aedes aegypti, Anopheles stephensi, and Culex pipiens mosquitoes under laboratory conditions. Prior to laundering, permethrin concentrations ranged from 4300 to 870 mg/m(2) whereas, after 100 defined machine launderings, the remaining permethrin content fell to between 1800 and 20 mg/m(2), a percentage permethrin loss of 58.1 to 98.5 %. The highest 99 % knockdown (KD99) efficacy of permethrin was detected in Ae. aegypti, followed by An. stephensi and Cx. pipiens demonstrating that Ae. aegypti is the most sensitive species and Cx. pipiens the least sensitive. After 100 launderings, the remaining biocidal efficacy differed markedly among the five brands, with KD99 times varying from 38.8 ± 2.9 to >360 min for Ae. aegypti, from 44 ± 3.5 to >360 min for An. stephensi, and from 98 ± 10.6 to >360 min for Cx. pipiens. Overall, the ranking of the residual biocidal efficacies within the five brands tested was as follows: BDU ≈ Labonal > Sol's Monarch > ExOfficio > Insect Shield. When applying German Armed Forces licensing conditions, none of the four products available in the civilian market would completely meet all the necessary efficacy and safety requirements fulfilled by BDUs. Therefore, we strongly recommend standardized testing and licensing procedures for insecticide-treated clothing, with defined cutoff values for initial maximum and post-laundering minimum concentrations of permethrin as well as figures for permethrin migration rates, arthropod toxicity, homogeneity on fabrics, residual activity, and laundering resistance.