Samples of vapor obtained in May 1994 from the headspace of the Hanford single-shell waste storage tank 24 1-C-103 were analyzed for selected inorganic compounds at Pacific Northwest Laboratory. The work was performed to provide concentration information supporting safety and toxicological evaluations. The vapor samples were passed through analyte-specific solid sorbent traps which held the compounds by chernisorption until analysis. Samples were analyzed to determine the concentrations of ammonia, nitric oxide, nitrogen dioxide, sulfur oxides, and hydrogen cyanide. Samples were also analyzed to provide information on the total mass concentration of vapors in the headspace. A summary of results is shown in Table 1. Throughout the multi-week sample job, average ammonia concentrations were uniform and ranged between 296 and 3 10 ppmv. The actual ammonia concentrations were more than 10-fold greater than the recommended exposure limit (REL) of 25 ppmv. The results of nitric oxide, sulfur oxides, and hydrogen cyanide samples were-2,10.02, and 10.04 ppmv, respectively, and were less or much less than the recommended exposure levels. The concentration of nitrogen dioxide was subject to potential sampling and analytical errors, but was estimated to be less than or much less than 0.4 ppmv. Only the nitrogen dioxide results failed to meet the target analytical detection limit of one-tenth of the REL. Fifty of 55 inorganic samples yielded an average mass concentration of 42.1 f 2.7 mg/L. A series of 10 ammonia samples, also supported by gravimetric analyses, showed no sampling bias occurred between samples obtained from different sample ports. Company (WHC) provided technical guidance by issuing Letters of Instruction and Sampling and

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Ingestion of contaminated food is considered the primary route of exposure in birds to agricultural chemicals. Routes of exposure other than ingestion are not often considered in risk assessments of agricultural chemicals to avian wildlife. However, recent studies demonstrated anorexic or avoidance behaviors in birds exposed to organophosphate (OP) insecticides. These behaviors would tend to limit exposure if ingestion alone were considered. The contribution, if any, of dermal, preening, and respiratory pathways to the exposure of birds to pesticides under field conditions is unknown. In addition, oral exposures are currently assessed in artificial environments that do not reflect real‐life exposure scenarios. To determine the relative contribution of these pathways and to assess exposures under ecological conditions, 270 northern bobwhite (Colinus virginianus) were exposed to simulated aerial crop applications of methyl parathion in an environmentally controlled wind tunnel. The wind tunnel environment consisted of a 25‐cm cotton plant canopy, a 5‐cm‐thick floor of silt‐loam, a temperature of 25°C, 50% RH, UV intensity similar to summer sunlight, and a wind speed of 3.2 km/h. Inhalation, preening, and dermal routes were isolated in groups of birds exposed to each application. Five birds from each group were collected at 1, 4, 8, 24, and 48 h post‐spray to determine cholinesterase (ChE) response to the exposures. Contaminated and uncontaminated darkling beetle (Tenebrio molitar) larvae were presented to free‐ranging sprayed birds in the wind tunnel to assess oral uptake. ChE response was determined at 4, 8, 24, and 48 h postspray. All exposures were replicated. All four routes contributed to the inhibition of brain ChE at different post‐spray periods. Dermal uptake and preening were major contributors to the overall dose and toxic response of birds to methyl parathion. Inhalation was the major route of exposure at 1 h post‐spray. At 4 h post‐spray, uptake through preening caused the greatest inhibition of brain ChE activity. Oral ingestion resulted in less than 20% inhibition of brain ChE during the test. Routes of uptake in order of contribution to toxicologic response from 8 to 48 h post‐spray were dermal > preening ≥ oral > inhalation.

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This report was prepared as an account of work SJXlnsmed hy an agency of the United States Government. Neither the United States Government nor any agency ther!'.'O(nor Battelle Memorial lnstitu~e. nor any of their em• ployees, mpkf's any warranty, (>):pressed or implied, or assumes any legal liability or rnpoosibtlity for tOe accuracy, completeml'H,. or usefulness of any lnfonnation, apparnlus, product,. or process disclosed, or r~ts that its. UR would not infri~ privately own£d rights. Reference herein to any spocific CQt't'lfr'!effial prOOuct, proces.s. or service by trade name, trademark, manuf.:tcturef, or otherNise, does 1101: necesianly COOst11ute or impfy its en-recommendation, or favoOng by the United States. Gow:fnmeot ot any agency thetrof, or 6,;!ttelle Memorial Institute, The views and opinions of authors e)(pre>Jled herein do not necessarily state ill reflect 1~ of the United States ('..ovemment or .wy agency thereof.

In Fiscal Year (FY) 1995, staff at the Vapor Analytical Laboratory (VAL) at Pacific Northwest National Laboratory (PNL) performed work in support of characterizing the vapor composition of the headspaces of radioactive waste tanks at the Hanford Site in Southeastern Washington. The work was supported by the Westinghouse Hanford Company (WHC) Tank Waste Remediation System ("WRS) Characterization Program and the U.S. Department of Energy's Richland Operations Office (DOEM.,). Work performed included support for technical issues and sampling methodologies, upgrades for analytical equipment, analytical method development, preparation of unexposed samples, dnalyses of tank headspace samples, preparation of data reports, preparation of input for WHC tank characterization reports, and operation of the tank vapor database. Work performed in FY 1995 was a continuation of work initiated with the first vapor sample job, which was performed in December 1993. Progress made in F Y 1995 included completion of sample analyses from all 40 jobs performed during the year, plus back-logged sample sets from jobs performed in F T 1994. Of the