{'fraction_non_alphanumeric': 0.01891965999451604, 'fraction_numerical': 0.004112969564025226, 'mean_word_length': 5.278829604130809, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
PLUTONIUM: ASSESSMENT OF THE OCCUPATIONAL ENVIRONMENT

In evaluating the occupational environment to assess its hazard potential from the presence of plutonium, measurements must be made on the physical environment and on the worker. The most significant of the former are measurements of plutonium air concentration supplemented by particle size and duration of exposure estimates. These can only be very approximately estimated because of various compromises which must be made and are most useful as indicators of the effectiveness of the containment. Measurements on the worker such as urine assay and chest counting for plutonium also involve compromises and their interpretation involves assumptions based on limited and variable data. Information from analysis of tissue samples shows only a rough correlation with calculations based on urine assay data. Nevertheless, assemblage of all pertinent information from these measurements does permit real control of potential health hazards from work with plutonium. THERE are two basic types of measurements that are made to assess the hazard potential of the occupational environment; those made on the physical environment itself and those made on the exposed worker. Of the first type, the most significant for plutonium are those involving measurements on plutonium suspended in air as an aerosol. One would like to be able to estimate the dosage given to the exposed worker as a result of his inhalation of the workroom air. Classically, there are four kinds of information needed to make this assessment; (1) the concentration of plutonium in the breathing zone of the worker, (2) the duration of exposure of the worker to this concentration, (3) the particle size of the suspended plutonium and, (4) pertinent knowledge of such particle properties as solubility, reactivity or chemical composition. These are the factors defined for this purpose for many years beginning with the earliest studies on silica dust exposure. Given this information one can, as noted in ICRP Publication No. 12, “assess the probable upper limit of the inhalation of radioactive materials by workers.” (ICRP, 1969). In practice, i t is extremely difficult to accomplish this except in very exceptional cases. Reports of studies on airborne plutonium are very scanty in the literature with the most complete inforination being reported from Harwell and Los Alamos and more limited data from Hanford, Winfrith, Windscale and Rocky Flats. Unfortunately, the data that have been reported are based on a wide variety of sampling techniques and instruments and are expressed in many different ways. It is impossible to summarize this in any compact fashion but a study of the collected data leads to a number of tentative conclusions. (1) The air concentrations of plutonium around most routine activities are well below established maximum permissible concentration (MPC) values. (2) Unanticipated concentrations in excess of MPC values occur as a result of containment breakdowns such as glove failures or excessive opening of containment entrances. Resulting excessive concentrations are usually short in duration but may be very high. (3) Longer term high concentrations usually occur under planned conditions such as changing gloves, bagging-out operations, maintenance work, decontamination or filter changing. (4) Significant gains in exposure or dosage reduction can be made by minimizing the time between the initial occurrence of an unexpected high concentration and its discovery so that protective action can be taken. (5) Concentrations at a given point are usually distributed in time in a logarithmic