Bioaerosol Composition and Associated Hazards in a Prominent Fruit Beverage Production Facility

Abstract

Bioaerosols are defined as aerosols that comprise particles of biological origin or activity that may affect living organisms through infectivity, allergenicity, toxicity, or through pharmacological or other processes. Interest in bioaerosol exposure has increased over the last few decades. This is mainly due to the association of bioaerosols with a wide variety of adverse health effects that have a major public health impact such as contagious infectious diseases, acute toxic effects, allergies, and cancer. Exposure to bioaerosols may cause three major problems in the food industry, namely: (i) contamination of food (spoilage); (ii) allergic reactions in individual consumers; or (iii) infection by means of pathogenic microorganisms present in the aerosol. Unfortunately, there is limited information available with regards to the specific organisms/biological agents involved in these processes and how exactly these processes occur. This deficiency in knowledge can be attributed to a lack of research on these processes, possibly because the importance of bioaerosols has not been considered. Furthermore, international standards on acceptable maximum bioaerosol loads are not uniform, which creates confusion as to what the acceptable limit of microorganisms in bioaerosols should be. There is also a lack of standardised methods for the collection and analysis of bacterial and fungal bioaerosols, making it difficult to compare the data released by various researchers. According to the literature, controversy exists regarding: (i) the effect of the environment and season on bioaerosols; (ii) types of sampling procedures; (iii) whether the detection of the culturable fraction of bioaerosols is efficient; and (iv) whether these bioaerosols can in actual fact affect the product or cause occupational health problems. The aim of this study was therefore to address the above-mentioned questions by means of an investigation in a selected fruit juice production facility. The culturable and non-culturable fraction of bioaerosols were collected in this facility by active sampling using SAMPL’AIR LITE (AES Chemunex), a standard bioaerosol sampler, in different areas of the facility during the peak and off-peak seasons. It is noteworthy that the microbial counts observed during this study were high, with high total microbial counts detected during both sampling periods. This indicates that the air in the selected facility created ideal conditions for all types of bioaerosols. Traces of presumptive positive pathogens as well as yeast and mould were observed in the samples collected from five designated areas. Several environmental factors were analysed, but temperature was the only concrete environmental factor observed in the facility during this study. However, statistical analyses indicated that temperature had no statistically significant effect on the presence of bioaerosols in the facility. More than 380 bioaerosols were detected during culturable identification, with 92 different species confirmed. A unique group of controversial bioaerosols was identified, ranging from highly probable pathogens such as Bacillus spp., Staphylococcus spp. and even Candida spp. Not only were harmful microorganisms identified in the bioaerosols, but microorganisms that are capable of bio-diesel production, that possess anti-tumour activities and that are capable of post-harvest control were also detected. Data obtained by PCR-DGGE analysis were used to determine the similarity, richness and diversity of the bacterial composition in the different areas of the facility during the two sampling seasons. The highest microbial diversity and richness was obtained in the air of the area where the bottles were filled with the final product and where a large number of personnel was present. Data obtained during this study indicated high microbial counts and species diversity in the air of this specific production facility. Even though this does raise concern, it is important to note that the dose-relationship of microorganisms, even for pathogenic agents, has not yet been established. This is mainly due to a lack of valid methods to qualitatively assess exposure. It is therefore clear that there is still a need for the development of an environment/sample/facility sampler for bioaerosols in order to facilitate the immediate evaluation of the specific health risks associated with a specific industry. The information obtained by means of this study will be useful to address this gap in knowledge and will aid the fruit juice industry to better understand and control bioaerosols in their facilities. This may also relate to other industries where it is necessary for more specific, valid risk assessments and control of bioaerosols in order to ensure product and occupational health safety.