Hecken und Flurgehölze - Struktur, Funktion und Bewertung

Symposium Bayreuth, 17.-19.5.198

Unexpected brain lesions in lactating Sprague-Dawley rats in a two-generation inhalation reproductive toxicity study with pentafluoropropane (HFC-245fa)

The study presented was conducted following the reproductive study guideline OECD Guideline 416 Two-Generation Reproduction Toxicity Study. Sprague-Dawley rats were exposed to 2000, 10,000 and 50,000ppm of HFC-245fa. There was an unexpected mortality of lactating dams in the medium and high dose group beginning at day 10 of lactation. Statistically significant histopathological alterations were observed in the cerebellum of a total of 9/30 females of the high dose group of the F0-generation and in 10/27 females of the high dose group of the F1-generation. In contrast there were no brain lesions found in males or non-pregnant females of all dose groups. Neuronal necrosis and degeneration in the cerebellar cortex were observed as the most severe finding. Furthermore vacuolation of the neuropil in different degrees was diagnosed in 7/30 females of the F0-generation and in 9/30 females of the F1-generation. Acute hemorrhages - in particular perivascular - occurred in 5/30 f emales of the F0- and in 5/30 females of the F1-generation indicating a disturbed vascular integrity. The main lesions found in the cerebrum were glial scars in the corpus callosum and restricted to 2/30 females of the F0-generation of the high dose group. The increased incidence of myocardial fibrosis and mononuclear cell infiltration in males - indicating myocarditis - was only seen in the F0-generation of the high dose group. Females of the F1-generation of the high dose group showed an increased incidence of minimal myocardial fibrosis. In summary, histopathology revealed that the brain, particularly the cerebellum, and to a minor degree the heart turned out to be the toxicological target organs of the substance. Presumably substance-related energy deprivation may be responsible for the observed changes. One of the metabolites, 3,3,3-trifluoropropanoic acid has been shown to be capable of causing this effect

Measurements in aircrafts during application of biocides for aircraft disinsection

Pest control operations in aircrafts are necessary to prevent the spreading of insect-transmitted infectious diseases. However, if pesticides are used in flight as sprays health disorders in passengers and crew members cannot be excluded. Measurements were taken during application of different disinsection sprays using the "top-of-descent" technique simulated at ground level in parked aircrafts. Concentrations in the air (during spraying and 40 minutes afterwards) were 21µg/m3/285 µg/m3 for pyrethrins/piperonyl butoxide (median values with SRA spray) and 133µg/m3 (224µg/m3) for d-phenothrin after use on Aircraft Disinsectant Denka ( Arrow Aircraft Disinsection Spray). Maximum amounts inhaled were calculated to be 17-200µg. Concentrations found on interior surfaces differed widely. On vertical surfaces (walls, folding tables, overhead bins) median values varied between <= 2 ng/cm2 and <= 17 ng/cm2 . Concentrations (median values) on seats, headrests and floor were 24-39 ng/cm² (pyrethrins), 144-233 ng/cm2 (piperonyl butoxide) and 219-1005 ng/cm2 (d-phenothrin)

Pyrethroids used indoors: Biological monitoring of exposure to pyrethroids following an indoor pest control operation

A prospective epidemiological study with respect to pyrethroid exposure was carried out combining clinical examination, indoor monitoring and biological monitoring. The results of the biological monitoring are presented. Biological monitoring was performed in 57 persons before (T1) as well as 1 day (T2), 3 days (T3), 4-6 months (T4), and 10-12 months (T5) following a pest control operation (PCO) with pyrethroid containing products such as cyfluthrin, cypermethrin, deltamethrin or permethrin. Pyrethroids in blood were measured by GC-ECD. The respective metabolities cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA), 3-phenoxybenzoic acid (3-PBA) and fluorophenoxybenzoic acid (FPBA) were measured in urine using GC/MS. For all cases the concentrations of pyrethroids in blood were found to be below the detection limit of 5 micrograms/l before and after the PCO. With a detection limit of 0.2 microgram/l of the investigated metabolites, the percentage of positive samples were 7% for cis-DCCA, 3.5% for trans-DCCA and 5.3% for 3-PBA before PCO. One day after PCO (T2) the percentage of positive samples increased remarkably for cis-DCCA (21.5%), trans-DCCA (32.1%) and 3-PBA (25%) showing significantly increased internal doses as compared to pre-existing values. This holds also true for T3, whereas at T4 and T5 the significant increase was no more present. FPBA and DBCA concentrations were below the respective detection limit before PCO and also in most cases after PCO. In 72% of the subjects the route of pyrethroid uptake (measured by determining the DCCA isomeric ratio) was oral/inhalative and in 28% it was dermal. Based on the biological monitoring data it could be shown that appropriately performed pest control operations lead to a significant increase of pyrethroid metabolite concentration in the early phase (1 and 3 days) after pyrethroid application as compared to the pre-exposure values. However, evaluated metabolite concentrations 4-6 months after PCO did not exceed values of published background levels

Even-electron ions: A systematic study of the neutral species lost in the dissociation of quasi-molecular ions

The collision-induced dissociations of the even-electron [M + H](+) and/or [M - H](-) ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap, instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH3, SO3H in the negative ion mode, or NO2 in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH2 in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H](+) and [M - H](-) ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even-electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data and ab initio calculations at the CBS-QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even-electron [M + H](+) and/or [M - H](-) ions (generated by ESI or APCI) with that of the corresponding odd-electron [M](+) ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common production