Streib R, Botzenhart K, Drysch K, Rettenmeier A W
Abteilung Allgemeine Hygiene und Umwelthygiene, Universität Tübingen.
Zentralbl Hyg Umweltmed. 1996 Jul;198(6):531-51.
The exposure of employees to airborne dust and microorganisms was assessed in a waste processing plant established to recover reusable materials from unsorted domestic and industrial waste. Exposure criteria considered relevant were the quantity of the individual size-selected particle fractions, the morphological properties of the particles, their heavy metal content, and the degree of their contamination with various microorganisms and mold. In addition, separate microbiological analyses to determine potential pathogen concentrations in the air were made. The highest concentrations of total and fine dust were measured in the waste delivery area. A close correlation between the frequency of deliveries and the level of dust exposure was observed. In this area, fine dust concentrations exceeded the threshold limit value of 6 mg/m3 repeatedly for shorter periods. The average fine dust concentration during an entire work-shift, however, was considerably lower than this value. Particles with an aerodynamic diameter of 2 to 7 microns predominated both in the waste delivery and the processing areas. Fibrous dust particles were present in smaller numbers than spherical particles and consisted mainly of organic materials. Natural and artificial inorganic fibers were found only occasionally. The concentrations of lead, cadmium, nickel and mercury were considerably lower than the corresponding MAK and TRK values, and were--with the exception of lead--in the range of the respective metal concentrations in the atmosphere of urban areas. Microscopical examinations of used protective masks (protection category P2) revealed that dust particles were deposited even on the inner side of the masks. Most of the particles on this side were very small and carried nickel or titanium. Microorganism concentrations measured in air from the highly dust-exposed areas of the plant showed values up to 6.9 x 10(5) cfu/m3, with a mold content of 6.6 x 10(4) cfu/m3. Approximately 90% of the microorganisms were deposited on particles of the fine dust fraction (particle size < 7 microns), and more than 50% contaminated particles with an aerodynamic diameter of 2 to 4.7 microns. In the compost facility, mold concentrations of up to 8.4 x 10(5) cfu/m3 were measured. In contrast, the level of microbial contamination in the filtered air from the compost facility did not exceed the concentration measured in air outside the plant. The data which were obtained during the winter months are probably at the lower end of the average exposure range over the entire year. In regard to exposure assessment, it should be mentioned that particles with a size of 4 to 7 microns are not really "inert" particles, since they are preferential carriers for heavy metals and microorganisms. More studies in the future should be performed to establish, whether the level of exposure to microorganisms can be estimated indirectly by the determination of dust exposure.
在一家旨在从未经分类的生活垃圾和工业垃圾中回收可再利用材料的废物处理厂，对员工接触空气中灰尘和微生物的情况进行了评估。所考虑的相关接触标准包括按粒径选择的各个颗粒组分的数量、颗粒的形态特性、其重金属含量以及它们被各种微生物和霉菌污染的程度。此外，还进行了单独的微生物分析以确定空气中潜在病原体的浓度。在垃圾输送区域测得的总灰尘和细灰尘浓度最高。观察到垃圾输送频率与灰尘接触水平之间存在密切相关性。在该区域，细灰尘浓度在较短时间内多次超过6毫克/立方米的阈限值。然而，整个工作班次期间的平均细灰尘浓度远低于该值。在垃圾输送区和处理区，空气动力学直径为2至7微米的颗粒占主导地位。纤维状灰尘颗粒的数量少于球形颗粒，主要由有机材料组成。仅偶尔发现天然和人造无机纤维。铅、镉、镍和汞的浓度远低于相应的职业接触限值（MAK）和技术指导值（TRK），并且除铅之外，均处于城市地区大气中各自金属浓度的范围内。对使用过的防护口罩（P2防护等级）进行显微镜检查发现，即使在口罩内侧也有灰尘颗粒沉积。这一侧的大多数颗粒非常小，且含有镍或钛。在该厂高灰尘暴露区域空气中测得的微生物浓度高达6.9×10⁵ 菌落形成单位/立方米，霉菌含量为6.6×10⁴ 菌落形成单位/立方米。约90%的微生物沉积在细灰尘组分（粒径<7微米）的颗粒上，超过50%的污染颗粒空气动力学直径为2至4.7微米。在堆肥设施中，测得的霉菌浓度高达8.4×10⁵ 菌落形成单位/立方米。相比之下，堆肥设施过滤空气中的微生物污染水平未超过该厂外空气中测得的浓度。冬季获得的数据可能处于全年平均接触范围的下限。关于接触评估，应该提到，粒径为4至7微米的颗粒并非真正的“惰性”颗粒，因为它们是重金属和微生物的优先载体。未来应开展更多研究，以确定是否可以通过测定灰尘接触情况来间接估算微生物接触水平。
