Assessment of the Level of Organic Dust and Mould Spores in the Work Environment of Baker.

AIM: This study was conducted to determine the level of fungal contamination of the air in bakeries to assess health hazards for workers.
MATERIALS AND METHODS: Six bakeries producing traditionally baked goods were selected for the study. After a background survey, samples of exhaled air were collected to test for fungal aerosols. The inhalable and respirable fraction in the bakery air environment was measured by the gravimetric method. STATISTICAL ANALYSIS USED: All data analyses were performed using Statistica software (v 8.0).
RESULTS: The mean concentration of fungi and particles in the bakeries did not exceed the recommended levels. The air in the bakeries had a low level of microbial contamination. The identified fungi included biological agents from hazard group 2.
CONCLUSIONS: Proper employee training and the introduction of preventive measures (including both individual and group protection) can significantly reduce employees' exposure and thus their occupational risk. Copyright:

INTRODUCTION

Allergy prevention in the workplace is a difficult challenge for industrial hygiene practitioners. In small traditional bakeries, regular monitoring of the work environment is not carried out, as minimizing production costs plays a significant role. Therefore, it is recommended to include them in occupational health studies and employee training programs. The incidence of allergic diseases in the work environment has been increasing for many years. Statistics do not accurately reflect the health status of the active working population. Research conducted at workplaces in Poland has shown that 58% of people are exposed to occupational hazards.[1] Among people of working age, one in 10 cases of asthma is caused by exposure to occupational factors. Over 300 substances responsible for occupational asthma have been identified in the work environment.[23] Numerous studies indicate that bakers are an occupational group in which this problem is widespread on a global scale.[2478] The incidence of occupational diseases and allergies depends on the type of exposure, and among bakers, it may be as high as 50%. During bread baking, numerous dust particles are formed, which together with the microorganisms contained in the air form bioaerosols. Exposure to flour dust and microbial contaminants can cause asthma, allergic reactions, and immunotoxicity. Flour dust contains a-amylases (FAA), which are fungal enzymes produced by Aspergillus oryzae. They are highly allergenic substances with a high molecular weight and they can be monitored when dust concentrations in the work environment are high.[910] Bakers and confectioners are also included among those with the highest incidence of contact dermatitis.[11] The occurrence of this occupational dermatosis has not been precisely estimated, because many workers do not seek medical advice.[12] Allergy symptoms are not manifested until repeated exposure to individual allergens. During this process, a specific IgE antigen is produced and binds to receptors on mast cells, which are concentrated on the mucous membrane of the stomach and airways. The main fungal allergens are cell wall components – (1,3) b-glucans or water-soluble glycoproteins.[1314] Allergy symptoms are mainly associated with direct irritation of mucous membranes and induction of IgE-mediated hypersensitivity reactions. The strongest manifestations are nasal and upper respiratory tract congestion, eye irritation, and sinusitis, which are characteristic of allergic reactions.[15] Long-term exposure leads to the development of diseases such as allergic asthma, allergic rhinitis, bronchopulmonary mycosis, and hypersensitivity pneumonitis. In people with impaired immunity, long-term exposure to fungal infectious agents may lead to the development of allergic bronchopulmonary aspergillosis, invasive or semi-invasive pulmonary aspergillosis, or pulmonary aspergilloma.

The last decade has seen significant changes in the bakery industry due to a significant decline in bread consumption. There are some small bakeries left on the market, supplying only local stores. These places usually do not have mechanical ventilation systems and therefore there is restricted air exchange. Therefore, research is needed to identify risks in the work environment of bakers. The aim of this study was to evaluate workers’ exposure in bakeries to inhalable and respirable fractions of dust and fungal aerosol.

MATERIALS AND METHODS

Six bakeries were selected for the study by the snowball sampling method from a group of small, traditional enterprises located in south-eastern Poland. These bakeries are often family-run, with a self-employed owner and a few (one to six) employees. All bakeries in the study were located in the same province within a 50 km radius of Lublin, which enabled more precise standardization of the facilities. Natural ventilation without forced airflow was used in each of the studied bakeries. Each bakery produced traditional bakery products (bread and rolls), and the employees had several years of work experience. The flour used was about 80–90% light wheat and about 10% dark rye flour. Production did not exceed using 40 tonnes of flour per year. In the first stage of the study, employees were interviewed regarding hazards and symptoms arising during their work and the use of preventive measures. In the second stage, while the bakers were working, fungal aerosols were measured using a MicroBio MB1 sampler from De Ville Biotechnology (UK). The results were expressed as the number of colony-forming units (CFU) per cubic meter of air. Filamentous fungi were cultured on Sabouraud Chloramphenicol Agar (Oxoid, France) and then identified to the species level using keys.[16171819] Identification of molds was entirely based on the structures bearing spores and on the spores themselves. The process of identification involved using keys to species containing specialized flowcharts leading to the name of the organism at hand. The dust concentration in the air was measured by the gravimetric method. The inhalable and respirable fractions of dust were measured using filters and a previously calibrated personal air sampling pump. At least four samples were taken at all facilities. Each sample was taken twice and the average value of two measurements taken was treated as the result. Personal and stationary samples of inhaled dust were collected after — of the work shift. Employees wore portable pumps at their waists (SKC Ltd. 224-44XR), within airflow rate of 4.2 l/min through a Whatman Glass 25 mm (no. 1820-025) filter by GE Healthcare United Kingdom, Ltd. The collected samples were transported to the Department of Hygiene and Environmental Hazards of the University of Life Sciences in Lublin, where they were conditioned and weighed in accordance with Polish Standards.[1718] All data analyses were performed using Statistica software (v 8.0). The distribution of all exposure variables differed significantly from the normal distribution, and therefore the following descriptive measures of exposure are presented: geometric mean, geometric standard deviation, and minimum and maximum range. Statistical significance was verified at P ≤ 0.05.

Ethical Clearance

Ethical approval for this study was provided by the University of Life Sciences, Lublin, Polland on 13th Nov 2020.

RESULTS

The results obtained for fungal aerosols in the air of the bakeries are presented in Tables 1 and 2. The microclimatic conditions in the bakeries were typical for this type of facility. The concentrations of mold fungi in the air ranged from 400 to 5880 CFU/m3. The highest level was found in bakery no. 2 (3181.2 CFU/m3), and the lowest in bakery no. 5 (711.782 CFU/m3), [Table 1]. The average concentration of mold fungi in the air of all the bakeries was 1116.18 CFU/m3, which was four times higher than that in the background air (257.52 CFU/m3) [Figure 1]. According to Polish standard N–Z–04111–03:1989,[20] the degree of fungal contamination indicates that the air samples should be classified as contaminated. According to recommendations by Krzysztofik (1992), the level of air pollution for production facilities should not exceed 1000 CFU/m3.[21] The literature currently suggests that in rooms with high concentrations of organic dust, mycological contamination should not exceed 5.0 × 104 CFU/m3.[2223] Among the filamentous fungi identified, the most common were Paecilomyces sp. (P2 69.44%), Penicillium expansum (P1 58.31%), and Aspergillus sp. (P5 54.17% and P6 35.10%), [Table 2]. The geometric mean of inhalable dust particles in the bakeries was 0.41 mg/m3, and that of respirable dust was 0.08 mg/m3 [Figure 2]. The autumn-winter period (when internal heating is on) was the most critical because the ventilation openings were shielded to prevent heat loss, which led to an increase in the concentration of air pollutants.

Table 1

The mean concentration of fungal aerosol in the air of the studied object (cfu·m-3)

Sample collection site / Bakery	GM	GSD	Range	Background GM
Bakery 1	1407.10	28.10	1100.00-1800.00	360.00
Bakery 2	3181.20	33.74	2200.00-4600.00	318.00
Bakery 3	1076.60	55.12	400.00-5880.00	318.00
Bakery 4	864.60	51.73	828.00-1056.00	200.00
Bakery 5	711.78	48.86	580.00-960.00	200.00
Bakery 6	871.03	51.84	720.00-950.00	280.00

GM: Geometric mean; GSD: Geometric standard deviation

Table 2

Percentage of mold fungi in air samples from the bakery

Identified mold fungus	B1	B2	B3	B4	B5	B6
Aspergillus fumigatus	ni	2.78	ni	4.17	ni	ni
Aspergillus niger	ni	ni	5.88	1.30	3.33	8.33
Aspergillus versicolor	8.33	ni	ni	ni	3.33	ni
Aspergillus sp.	ni	ni	29.41	31.49	35.10	54.17
Cladosporium sp.	ni	ni	5.88	8.10	10.82	8.33
Fusarium sp.	ni	ni	5.88	12.32	13.33	8.33
Mucor sp.	ni	2.78	ni	8.29	6.67	4.17
Paecilomyces sp.	ni	69.44	11.76	ni	ni	ni
Penicillium expansum	58.31	11.11	ni	ni	ni	ni
Penicillium sp.	ni	ni	ni	15.67	3.33	ni
Rhizopus sp.	ni	2.78	11.76	4.17	3.33	4.17
Sclerotium sp.	ni	ni	5.88	ni	6.67	ni
Ulocladium sp.	ni	2.78	5.88	ni	10.82	8.33
Unidentified	33.36	8.33	17.60	14.52	3.33	4.33

ni: Not isolated

Figure 1

The geometric mean concentration of fungi in bakeries in relation to the background (CFU/m3)

Figure 2

The geometric mean concentration of particulates in the bakery air (mg/m3)

DISCUSSION

The American Conference of Governmental Industrial Hygienists (ACGIH) introduced hygiene standards for solid particles in bakeries, specifying a level of 0.5 mg/m3 as the occupational exposure limit (OEL). This suggests that allergies do not occur below this level. Research shows a linear relationship between the level of allergens in the air and the concentration of flour dust, which means that the latter can be used as an indicator of allergen exposure. These values were not exceeded in our study. Bulat et al. (2004), in a comparison of traditional and industrial bakeries in Belgium, showed that employees of traditional bakeries were significantly more exposed to dust (0.30–13.30 mg/m3), and the results were statistically significant (P < 0.001).[24] The results of our own research were in the lower range of values given by the above authors.

Measures taken in the bakery industry in the Netherlands have clearly reduced exposure to wheat dust and allergens. The behavior of employees while performing tasks has been observed to have a significant impact on their exposure. However, it should be remembered that the promotion of such safe practices in the handling of dusty material will not necessarily prevent injury and disease.[325] Research conducted by Tagiyeva et al. (2012) in Scotland indicates that allergens can be conveyed over long distances. According to the author, in small bakeries, which are often family-run, pollutants and allergens are transported from the work environment (on clothing or skin), leading to an increase in these factors in the air inside homes.[26] Analyses conducted in the bakery industry have shown impairment of respiratory function in employees after just three years. The authors also point out the socio-economic aspects of such early health dysfunction.[252728] Research on bakeries belonging to a supermarket chain in South Africa indicates that as many as 25% of employees are allergic to both rye and wheat flour allergens, while 13% suffer from asthma. The fraction of inhalable dust in these bakeries was 0.11–7.29 mg/m3; it was highest for bakers (0.25–7.29 mg/m3) and lowest for bread sellers (0.11–1.95 mg/m3).[4]

Dust contamination is strictly correlated with fungal contamination in the air of bakeries. Saad-Hussein et al. (2016) reported that the fungi most frequently isolated from suspended dust particles in bakery air were Aspergillus sp. The concentrations of Aspergillus flavus and Aspergillus niger were highest in samples from the milling department. In the workers exposed to these contaminants, serum activity of alkaline phosphatase (ALP) was significantly higher and significantly correlated with the serum level of aflatoxin B1 (AFB1) in bakers.[8] Fungi of the genus Aspergillus are a source of numerous aflatoxins, and the level of their release is associated with the microclimatic conditions of the environment. One of the most important respiratory diseases caused by Aspergillus fumigatus is allergic bronchopulmonary aspergillosis (ABPA). Aspergillus flavus, on the other hand, is used to assess the risk of microbial contamination in determining critical control points on the production line of bread made from a mixture of wheat and rye flour. An analysis by Czerwińska and Piotrowski (2009) showed a low level of air contamination in bakeries which is consistent with the results of own research. The concentration of isolated microorganisms was at a safe level and did not exceed the recommended values for production facilities (7.5·102–1.0·107 CFU/m3). The number of fungi varied depending on when the measurement was taken (1.0·101–5.41 CFU/m3) and was lower than in our research. Among mold fungi, the authors identified mainly Rhizopus sp. and Penicillium sp.[29] In our research, fungi of the genus Rhizopus were identified in five bakeries and Penicillium sp. in two. The species Penicillium expansum was identified in 58.31% of samples, which meant that their metabolites were present as well, including the neurotoxic compound patulin. The average fungal concentration in the air of the bakeries did not exceed the values recommended by the Biological Factors Expert Group (5.0 × 104 CFU/m3).

CONCLUSIONS

In the light of research and scientific data, allergy prevention in the workplace is a new, difficult, and urgent challenge for industrial hygiene. In small traditional bakeries, which are often family-run, regular monitoring of the work environment is not carried out, as minimizing production costs plays a significant role. Therefore, it is recommended to include them in occupational health studies and employee training programs. The identification of fungal hazards in bakeries makes it possible to maintain optimal sanitary and hygiene conditions, which ensures the high quality and safety of the product as well as the health of the workers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.