If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Tingting Liu
Footnotes
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Affiliations
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Zhifeng Huang
Footnotes
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Affiliations
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Huiqing Zhu
Footnotes
1 Tingting Liu, Zhifeng Huang and Huiqing Zhu contributed equally as co-first authors.
Affiliations
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
Department of Clinical Laboratory, National Center for Respiratory Medicine, National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
The prevalence of allergic diseases has increased significantly in China over the last few decades, and there have been very few reports of allergic diseases in certain occupational specialties, with almost no reports among sanitation workers.
Objective
Our objective was to investigate the prevalence of allergic diseases and the prevalence of common allergen sensitization in the population engaged in sanitation, and to try to answer the connection between urban garbage waste exposure and the development of allergic diseases.
Methods
We conducted a cross-sectional survey of people working in sanitation-related jobs in Liwan District, Guangzhou, China. A total of 893 people completed the questionnaire for this study, and 500 of them were further screened and tested for allergens specific IgE and IgG4. Combining the questionnaire and test results, we investigated the incidence of allergy disorders and patterns of sensitization to allergens in this community, and evaluated the presence of occupational-related risk factors in this particular population.
Results
Of the 893 sanitation workers, 166 (18.59%) self-reported allergic diseases, predominantly suffering from allergic rhinitis (AR) (n = 98, 10.97%), followed by drug allergy (n = 31, 3.47%), atopic dermatitis (n = 27, 3.02%), food allergy (n = 21, 2.35%), and asthma (n = 9, 1.00%), in that order. In addition to dust mites (32.20%), which had the highest sensitization rate, the subject population had relatively high sensitization rates to ragweed (7.00%) and moulds mixture (8.20%) when compared with the rates of sensitization to moulds and ragweed in the general population; the top 3 sIgG4 positivity rates were egg (50.00%), milk (10.20%), and soybean (9.40%). The prevalence of self-reported AR was higher in office managers (the control group) than in cleaning staff (the exposed group), but there was no difference in sIgE positivity for serum allergens between the 2 groups. The chance of having AR may increase with management positions (crude OR 2.20, 95% CI 1.38–3.50), P = 0.001).
Conclusion
This is the first study to investigate the prevalence of allergy illnesses in the sanitation workforce in mainland China. We identified a community of real sanitation workers with high ragweed and mycobacterial sensitization rates. Urban cleaning may be protective factor against AR at the symptom level, but the serological results did not show this to be the case.
Genetic and environmental factors are the key factors affecting the occurrence and development of allergy disorders. People with atopic constitution can induce allergic diseases due to exposure to environmental allergens.
Prevalence patterns of allergen sensitization by region, gender, age, and season among patients with allergic symptoms in mainland China: a four-year multicenter study.
Several studies have also reported occupational inhalation of food allergens leading to sensitization, rhinitis, and asthma in people working in food processing industries, such as baking and seafood.
However, there are not many reports on allergic diseases and sensitization caused by occupational exposure to allergens in urban sanitation workers. Sanitation workers are inevitably exposed to various allergens, such as dust, tree pollen, and microbial aerosols produced by various household waste residues, over a long period of time
and other environmental factors such as automobile exhaust and industrial harmful gas. The association between occupational exposure and chances of the occurrence of lung disease in sanitation workers has been confirmed in several studies reporting numerous cases of respiratory disease and dysfunction in employees at composting plants and waste sorting plants.
However, these studies were only performed on workers at waste sorting or disposal plants and did not assess allergic reactions serologically.
Immunoglobulin E (IgE) is the main substance that mediates allergic reactions. Even if exposed to a very small number of allergens, it will cause atopic individuals to produce allergen specific IgE (sIgE), that is, allergic sensitization, so high level of IgE tend to mean a higher risk of developing allergies.
In addition, naturally occurring allergen-specific immunoglobulins G (sIgG), which usually recognize different epitopes on allergens, cannot effectively interfere with allergen-induced inflammatory responses. It has been shown that allergen-specific immunotherapy can induce the production of IgG4 targeting IgE epitopes, thereby blocking IgE binding to allergens to prevent allergic reactions from occurring.
The role of IgG4 in allergy is still unclear and the prevalence of the allergen sIgG4 in the general population is uncertain.
In this cross-sectional study, 893 sanitation workers in Liwan District, Guangzhou City, China, were analyzed using an allergic disease questionnaire, and 500 of them were screened for 12 inhalation-food allergen-specific IgE tests and 10 food allergen-specific IgG4 tests, and statistical variables such as demographic characteristics, job characteristics, serum-specific IgE sensitization, and IgG4 levels of this occupational group were recorded.
Experimental details
Research population
This is a cross-sectional study of an epidemiological investigation project of allergic diseases among sanitation practitioners, from January 2022 to May 2022 in Guangdong Province, Mainland China Guangzhou City. According to statistics, a total of 1538 people were engaged in urban sanitation work in Liwan District, Guangzhou, of which 893 were willing to participate in the project and signed informed consent. All of these participated subjects were asked to fill out a questionnaire first. According to the questionnaire information, People who reported a history of current allergic disease (Allergic rhinitis, Bronchial asthma, Allergic conjunctivitis, Skin allergy, and drug allergy) and those who give positive answers to questions about related symptoms，were defined as Self-reporting allergy, otherwise were defined as No allergy. Thus these 893 subjects were divided into reporting allergy (N = 166) and non-allergic (N = 727) groups. Among these people, 148 are in the sanitation management position and 745 are in the sanitation cleaning position. Based on allergy and position information, all these 893 subjects can be divided into 4 subgroups [(Persons in management position and reporting allergy, N = 55); (Persons in cleaning position and reporting allergy, N = 111); (Persons in management position and reporting no-allergy, N = 93); and (Persons in cleaning position and reporting no-allergy, N = 634)]. Due to the research purpose as we mentioned previously, we included all the subjects who reported allergy and all the subjects who are in management positions. To balance the sample size of different groups, another 241 people were randomly selected from the population who reported no allergy and were in sanitation cleaning positions. Finally, 500 cases were included for serological allergen sIgE testing. The enrollment process is shown in Fig. 1.
Fig. 1The process of enrollment. Previous allergic disease is defined as having had at least one previous allergic skin reaction (eg, hives, eczema) and/or having asthma as a child that resolved spontaneously after growing up, and/or having a food allergy at a certain stage
The questionnaire (see supplementary material) was designed by a team of allergy experts and was reviewed and evaluated by several experts in the field. Trained researchers instruct subjects face-to-face to complete the questionnaires, due to the low level of knowledge of some sanitation workers, ensuring that all subjects had a consistent understanding of the questions. The questionnaires included demographic characteristics, education level, job characteristics, work environment characteristics, history of allergic diseases, family history of allergies, cigarette exposure, and level of exposure to municipal waste. The questionnaire questions to investigate the exposure of cigarettes involve active smoking history and amount of smoking, as well as passive smoking; the questions about urban waste exposure are specifically reflected in asking whether the participant was a managerial worker or an out-of-home municipal waste cleaner, the number of years in the job, and whether the participant used protective measures such as a mask while on duty. The researcher first introduced the research background, research purpose, and possible risks and benefits of participating in the project to the subjects, and the subjects themselves (all adults) signed the project informed consent. Finally, the researcher checked the questionnaire again, and the researcher guided the subjects to fill in the unfilled or missed filling.
Definition
Considering that management staff and cleaning staff are sanitation employees, but in fact management staff are not involved in garbage cleaning, we graded the urban waste exposure levels as following rules: people in management positions are defined as exposure level 0 (control group), sanitation populations with cumulative working experience of less than 5 years are classified as exposure level 1, and sanitation populations with cumulative working experience of 5–10 years are classified as exposure level 2. The sanitation population over 10 years is classified as exposure level 3.
Severity of cigarette exposure: People who do not smoke and are less exposed to secondhand smoke are defined as the low-light exposure group; as mildly exposed. Those who meet any of the following criteria are defined as moderately exposed: (a) The average number of cigarettes smoked does not exceed 10 cigarettes per day and the cumulative smoking for no more than 10 years. (b) The average smoking volume exceeds 10 cigarettes per day but the cumulative smoking time does not exceed 5 years. The heavy exposure group is defined as meeting any of the following conditions: (a) People who do not smoke but have been exposed to second-hand smoke; (b) The average smoking volume does not exceed 10 cigarettes per day but accumulated smoking for more than 10 years; (c) average smoking more than 10 cigarettes per day and cumulative smoking time for more than 5 years.
Samples collection and serological testing
Serum samples from the selected patients were obtained by 10-minute centrifugation at 3000g of peripheral blood collected with a yellow-headed tube (separation gel promoting coagulation tube), Aliquots of serum were stored at −80 °C. Serological testing to allergens-Including the test of sIgE to dust mite mixture (Dermatophagoides pteronyssinus/Dermatophagoides farinae, d1/d2), cat hair (e1), dog hair (e5), ragweed (w1), mugwort (w6), moulds mixture (Penicillium/Alternaria/Aspergillus/Cladosporium, mx1), egg white (f1), milk (f2), shrimp (f24), crab (f23), peanut (f13), soybean (f14); and sIgG4 to cod (f3), egg (f1), milk (f2), beef (f27), shrimp (f24), soybean (f14), wheat (f4), chicken (f83), crab (f23), and mushroom (f212) - was performed on all subjects using a fully automated western blotting instrument of DX-Blot 45 II (Hangzhou Zheda Dixun Biological Gene Engineering Co., Ltd., Hangzhou, China). sIgE and sIgG4 levels were expressed in international units per milliliter (IU/mL). Tests with sIgE level less than 0.35 IU/mL were defined as sIgE-negative, and tests with sIgE levels greater than or equal to 0.35 IU/mL were defined as sIgE-positive. SIgE-positive tests were categorized into the following 6 classes: class 1 (≥0.35 to <0.70 IU/mL), class 2 (≥0.70 to <3.50 IU/mL), class 3 (≥3.50 to <17.50 IU/mL), class 4 (≥17.50 to <50 IU/mL), class 5 (≥50 to <100 IU/mL), and class 6 (≥100 IU/mL). Tests with sIgG4 level less than 250 IU/mL were defined as sIgG4-negative, and tests with sIgG4 levels greater than or equal to 250 IU/mL were defined as sIgG4-positive. SIgG4-positive tests were categorized into the following 3 classes: weak (≥250 to <500 IU/mL), medium (≥500 to <1000 IU/mL), and strong (≥1000 IU/mL).
Fig. 2 summarizes the reported history of or current allergic disease in the sanitation practitioner population. A total of 893 questionnaires from sanitation practitioners were included, and 100% were valid questionnaires. One hundred sixty-six cases (18.59%) reported having or suffering from allergic diseases, including 139 cases with a single allergic disease alone and 27 cases with 2 or more allergic diseases at the same time. Among the 166 people who reported allergies, allergic rhinitis (AR) was the most common (98/166, 59.04%), with only 3 subjects having allergic conjunctivitis (AC). This was followed by drug allergy (DA, 18.67%), atopic dermatitis (AD, 16.27%), food allergy (FA, 12.65%), and asthma (AS, 5.42%) (Fig. 2A).
Fig. 2Allergic disease reporting. (A) Distribution of allergic diseases among people who have suffered or are currently suffering from allergic diseases. (B) Distribution of drugs causing allergies in people reporting drug allergy. (C). Distribution of foods causing allergies in people reporting food allergies. The word unclear in the B and C means people who self-reported drug allergy or food allergy actually didn't know or remember which one they were allergic to. Abbreviation: AC, allergic conjunctivitis; FA, food allergy; AD, atopic dermatitis; DA, drug allergy; AR, allergic rhinitis. AS, asthma
The questionnaire delved deeper into specific drug and food allergens for people with drug allergy and food allergy. According to the findings, 22.58% of those who reported drug allergy thought they were allergic to a drug but were not sure which one exactly. Furthermore, penicillin allergy was reported by 41.94% of subjects with clear drug allergens, followed by cephalosporins (16.13%). (Fig. 2B). Seafood allergies were the most common (28.75%) among those who reported food allergies (Fig. 2C).
Five hundred 500 enrolled participants were examined for sIgE and sIgG4 to allergens as previously mentioned. Among them, 314 (62.80%) were male and 186 (37.20%) were female. The median age (P25, P75) was 47 (42, 51) years old. Most of the patients were Han nationality (98.20%). The highest educational level of 63.20% of the participants was junior high school, and 61.60% of the participants reported moderate-to-severe cigarette exposure. According to whether or not allergic disease had been reported and the type of allergic disease, subjects were classified, and demographic differences between groups were summarized (Table 1) There was no statistical difference in the composition ratio of different positions between the reporting allergy and no allergy groups (P = 0.223), but in the AR reporting group and the no allergy group, the AR group had a higher proportion of sanitation management staff (45.92%), compared with the non-allergic group (27.84%), it was statistically significant (P = 0.001). At the same time, the AR report rate of the sanitation management group was significantly higher than that of the sanitation cleaning group (30.41% vs. 15.06%, P < 0.001). Similarly, there was no statistical difference in the composition ratio of educational level between the reporting allergy group and the no allergy group, but in the reporting AR group and the no allergy group, the AR group had a higher proportion of high education levels (high school and above) than the no allergy group (31.63% vs. 16.47%, P = 0.002). Both in the allergy group and AR group, the proportion of people with a family history of allergic disease was significantly higher than that in the no-allergy group, 9.64% vs. 0.90% (p < 0.001) and 7.14% vs. 0.90% (P = 0.001), respectively.
Table 1Demographic characteristic of the self-reported Allergic group and Nonallergic group.
Allergic groups
Nonallergic
P∗ value
P# value
AR with or without AC
Food allergy
Drug allergy
Atopic dermatitis
Asthma
Allergy
Sample size
98
21
31
27
9
166
334
–
–
Gender, n (%)
Male
60 (61.22)
13 (61.9)
15 (48.39)
13 (48.15)
6 (66.67)
99 (59.64)
215 (64.37)
0.302
0.569
Female
38 (38.78)
8 (38.1)
16 (51.61)
14 (51.85)
3 (33.33)
67 (40.36)
119 (35.63)
Position, n (%)
Administrator
45 (45.92)
7 (33.33)
5 (16.13)
5 (18.52)
1 (11.11)
55 (33.13)
93 (27.84)
0.223
0.001
Sanitary worker
53 (54.08)
14 (66.67)
26 (83.87)
22 (81.48)
8 (88.89)
111 (66.87)
241 (72.16)
Education, n (%)
Primary school and below
10 (10.2)
3 (14.29)
6 (19.35)
5 (18.52)
5 (55.56)
26 (15.66)
61 (18.26)
0.062
0.002
Junior high school
57 (58.16)
14 (66.67)
20 (64.52)
17 (62.96)
1 (11.11)
98 (59.04)
218 (65.27)
Senior high school and above
31 (31.63)
4 (19.05)
5 (16.13)
5 (18.52)
3 (33.33)
42 (25.3)
55 (16.47)
Cigarette exposure, n (%)
Mild
37 (37.76)
7 (33.33)
15 (48.39)
11 (40.74)
2 (22.22)
64 (38.55)
128 (38.32)
0.887
0.664
Moderate
38 (38.78)
8 (38.1)
11 (35.48)
14 (51.85)
5 (55.56)
67 (40.36)
141 (42.22)
Severe
23 (23.47)
6 (28.57)
5 (16.13)
2 (7.41)
2 (22.22)
35 (21.08)
65 (19.46)
Family history of allergy, n (%)
No
91 (92.86)
20 (95.24)
29 (93.55)
24 (88.89)
4 (44.44)
150 (90.36)
331 (99.10)
<0.001
0.001
Yes
7 (7.14)
1 (4.76)
2 (6.45)
3 (11.11)
5 (55.56)
16 (9.64)
3 (0.90)
Note: ∗-Difference comparison between self-reported allergic group and nonallergic group. #-Difference comparison between AR group and nonallergic group
Sensitization spectrum and difference analysis of common allergens among urban sanitation practitioners
Five hundred included sanitation practitioners were tested for 12 common allergen serum sIgE and 10 food allergen serum sIgG4; the results showed that the dust mite allergen sIgE positive rate was the highest, 32.20%, followed by mx1 (8.20%) and Ragweed (7.00%), the other 9 allergens all had lower sensitization rates, ranging from 0.60% to 2.40% (Figure, 3A). Class analysis showed that allergen sIgE positive results detected were mainly concentrated at low classes (ie, class 1–3). In the positive results of dust mites, fungi mixture, and ragweed allergens, classes 1–3 cumulatively accounted for 42.60% of the positive results. Among the results of food sIgG4 positive rate detection, chicken protein (50.00%) had the highest positive rate, followed by milk (10.20%) and soybean (9.40%). The sIgG4 positivity rates for the other 7 food allergens ranged from 0.20% to 2.20% (Figure, 3B). The positive results of sIgG4 were mainly in the middle and high grade.
The positive rates of sIgE to dust mite in the reporting allergy group and AR group were higher than that in the no-allergy group (42.77% and 39.80% vs. 26.95%, all P < 0.05). There were no statistical differences of the positive rates of ragweed and mx1 between these groups. The sensitization rate of ragweed in the self-reported allergy group and AR group was slightly higher than that in the no-allergy group (7.83% and 8.16% vs. 6.59%, all P > 0.05), (Figure, 4A). For sIgG4 to food allergens, it was only observed that the positive rate of milk in the self-reported allergy group and AR group was higher than that in the no-allergy group (16.27% and 15.31% vs. 7.19%, all P < 0.05) (Figure, 4B).
Fig. 4Analysis of differences in allergen sensitization between different groups. 500 participants were divided into reporting allergy (N = 166) and no-allergy (N = 334) groups. AR was also used as the main allergic disease type, so the reported AR population was used as one of the subgroups to analyze the differences in the positive rates of allergen serum sIgE and sIgG4 between different groups. Due to the very low positive rates of other allergens (sIgE: 0.60%–2.40%; sIgG4: 0.20%–2.20%) except for dust mites, ragweed and moulds mixture, these allergens were excluded from the analysis of differences between groups. (A). Positive rate of allergen sIgE and classes distribution of self-reported allergic disease group, self-reported allergic rhinitis group and self-reported non-allergic disease group. (B) Positive rate of allergen sIgG4 and classes distribution of self-reported allergy group, self-reported allergic rhinitis group and self-reported no-allergy group. d1/d2, Dermatophagoides pteronyssinus/Dermatophagoides farinae; w1, Ragweed; mx1, moulds mixture (Penicillium/Alternaria/Aspergillus/Cladosporium); f1, egg white; f2, milk; f14, soybean
Analysis of risk factors for allergic rhinitis in sanitation practitioners
AR is the most predominant allergic disease among sanitation workers, and further study of the factors influencing the development of AR in this population is necessary. Fig. 5A summarizes the risk coefficients for several indicators using univariate binary logistic regression analysis. The results showed that sanitation management position (OR 2.20, (95% CI 1.38–3.50), P = 0.001), higher education level (OR 3.44, (95% CI 1.54–7.66), P = 0.002), and family history of allergy (OR 8.49, (95% CI 2.15–33.48), P = 0.002) were considered as risk factors for AR. Further multivariate binary logistic regression analysis was used to calibrate confounding factors, and the results still showed that having a family history of allergies was an independent risk factor for AR [OR 8.62 (2.03–36.64), P = 0.004], and the urban waste exposure level 0 population was higher than that of the level 3 population. Higher risk of AR [OR 3.10 (1.27–7.58), P = 0.013] (Fig. 5B).
Fig. 5Risk factors for AR. (A) Unadjusted OR for AR. (B) Adjusted OR for AR. Gender, family history of allergic diseases and city waste exposure degrees were included in the logistic regression analysis. AR, self-reported allergic rhinitis; OR, Odds Ratio; 95% CI, 95% confidence intervals
Analysis of the sensitization characteristics of inhaled allergens based on classification of urban waste exposure levels
The previous data (Table 1) showed that the proportion of self-reported AR is higher for the management post population than for the cleaning post population. Therefore, in this part of analysis, we only included people who self-reported AR and self-reported no allergy. And we divided them into 4 groups, the control group and 3 urban waste exposure groups. The details of classification rules are in the definition section. We analyzed the sensitization characteristics of dust mites, common ragweed, and moulds mixture among people with different exposure levels. The results showed (Table 2) that there was no statistical difference in the sensitization rates of these 3 allergens between the control group and the exposure group, the control group and the exposure level 3 group, and the control group and the 3 different exposure level groups. The sensitization rates of mites in the control group and the exposure group were 31.16% and 29.25%, respectively (P > 0.05); the sensitization rates of the mold combination in the control group and the exposure group were 6.52% and 7.48%, respectively (P > 0.05). It is worth noting that although there was no statistical difference, in absolute terms, the sensitization rate to ragweed in the exposed group appeared to be significantly higher than that in the non-exposed group (8.50% vs. 3.62%), and each subgroup of exposure groups, has higher sensitization rate of w1 (10.59%, 6.92% and 10.00%, respectively) than that in the control group, and perhaps the phenomenon would have been statistically significant if a larger amount of data had been available.
Table 2Analysis of differences of sensitization to mite mixture, ragweed and moulds mixture between the control group and city waste exposure groups, from people who reported AR and No-allergy.
Allergen
Sanitation management post (class 0), n = 138
Sanitation cleaning post, Urban waste exposure
P∗ value
P# value
P$ value
Class 1, N = 85
Class 2, N = 159
Class 3, N = 50
Total, N = 294
Mite mixture, (n, %)
–
–
–
sIgE class 1
10 (7.25)
10 (11.76)
16 (10.06)
5 (10.00)
31 (10.54)
–
–
–
sIgE class 2
17 (12.32)
6 (7.06)
11 (6.92)
11 (22.00)
28 (9.52)
–
–
–
sIgE class 3
12 (8.70)
6 (7.06)
13 (8.18)
2 (4.00)
21 (7.14)
–
–
–
sIgE class 4
4 (2.90)
2 (2.35)
2 (1.26)
0 (0.00)
4 (1.36)
–
–
–
sIgE class 5
0 (0.00)
1 (1.18)
1 (0.63)
0 (0.00)
2 (0.68)
–
–
–
sIgE class 6
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
–
–
–
Total
43 (31.16)
25 (29.41)
43 (27.04)
18 (36.00)
86 (29.25)
0.686
0.531
0.655
Common ragweed, (n, %)
–
–
–
sIgE class 1
2 (1.45)
4 (4.71)
5 (3.14)
4 (8.00)
13 (4.42)
–
–
–
sIgE class 2
2 (1.45)
2 (2.35)
5 (3.14)
1 (2.00)
8 (2.72)
–
–
–
sIgE class 3
0 (0.00)
2 (2.35)
0 (0.00)
0 (0.00)
2 (0.68)
–
–
–
sIgE class 4
1 (0.72)
1 (1.18)
1 (0.63)
0 (0.00)
2 (0.68)
–
–
–
sIgE class 5
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
–
–
–
sIgE class 6
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
–
–
–
Total
5 (3.62)
9 (10.59)
11 (6.92)
5 (10.00)
25 (8.50)
0.063
0.176
0.185
Moulds mixture, (n, %)
–
–
–
sIgE class 1
5 (3.62)
3 (3.53)
3 (1.89)
0 (0.00)
6 (2.04)
–
–
–
sIgE class 2
3 (2.17)
1 (1.18)
3 (1.89)
2 (4.00)
6 (2.04)
–
–
–
sIgE class 3
0 (0.00)
1 (1.18)
2 (1.26)
0 (0.00)
3 (1.02)
–
–
–
sIgE class 4
0 (0.00)
1 (1.18)
4 (2.52)
1 (2.00)
6 (2.04)
–
–
–
sIgE class 5
0 (0.00)
1 (1.18)
0 (0.00)
0 (0.00)
1 (0.34)
–
–
–
sIgE class 6
1 (0.72)
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
–
–
–
Total
9 (6.52)
7 (8.24)
12 (7.55)
3 (6.00)
22 (7.48)
0.718
1.000
0.947
Note: ∗class 0 vs. total, #Class 0 vs. Class 3, $Class 0 vs. Class 1 vs. Class 2 vs. Class 3
At present, there are no relevant reports on the prevalence of allergic diseases and allergen sensitization rates in this special group engaged in sanitation work in China. The novelty of this study is that it is the first time to conduct epidemiological studies on the sanitation workers in Liwan District, Guangzhou, and we believe that the epidemiological data from this study may provide a data base for future epidemiological studies investigating allergic diseases in the Chinese sanitation worker population. The results show that in this occupational group, the proportion of men is larger than that of women (62.80% vs 37.20%), which is similar to the proportion of men and women in waste management in other developed and developing countries,
The overall education level of this occupational group is not high, 80.06% are junior high school or below, and 63.20% of them are concentrated in the junior high school education level. According to their different positions, the sanitation practitioners can be divided into management positions and those who actually collect and clean garbage outside. And the results of the questionnaire analysis showed that most of the participants had a long history of smoking, and even if they did not smoke, they were often exposed to secondhand smoke from colleagues.
Of the 893 people who participated in the questionnaire, 18.59% reported having had or currently suffering from allergic diseases, and more than half (59.04%) of these populations reported having AR. Allergic rhinitis is estimated to affect 10%–40% of the population.
In this cross-sectional study of sanitation workers, the proportion of self-reported AR was 10.97%, which is due to the fact that the prevalence of AR is related to a variety of factors, such as age and geography, and the age of our survey population was concentrated after the age of 40 and the location was limited to Guangzhou City. The second highest prevalence was drug allergy, and the majority of the drug-allergic population (58.06%) had allergic reactions to penicillin and cephalosporins. The most common class of antibiotics reported to cause hypersensitivity reactions are β-lactam antibiotics, including penicillins, cephalosporins, carbapenems and monobactams, L. Zhou et al reported a decrease in penicillin allergic reactions in recent years, but penicillin is still the drug with the highest incidence of allergic reactions.
Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys.
In developed countries, the prevalence of FA in adults is 0.2%–4.1%, and in China, reports on the prevalence of food allergy in adults are still very limited. The survey data of Wang et al on the prevalence of self-reported food allergy in 6 regions of Inner Mongolia showed that by age group, the lowest prevalence of self-reported food allergy was in people over 60 years old (6.7%).
In contrast, a lower incidence of food allergy (2.45%) was reported in this study, and this difference may be due to different geographic locations, leading to differences in lifestyle and eating habits.
Data from several studies show that men consistently show higher positive rates of inhalant and food allergen-specific IgE levels.
Prevalence patterns of allergen sensitization by region, gender, age, and season among patients with allergic symptoms in mainland China: a four-year multicenter study.
The data from this study showed a higher percentage of males in the reported allergy group than in the healthy group, but there was no difference in the male to female composition ratio, probably because the number of our participants was not large enough. The data showed that management position and senior high school and above, these 2 factors were not statistically different between the group of reporting allergy and the no-allergy group, but differed between the group of reporting having AR and the group of reporting no allergy. And there was a significant correlation between the management position and the higher education level of senior high school and above (χ2 = 99.26, P = 2.79E-22). In addition, we assume that people who actually clean garbage outside may be more often exposed to some inhaled allergens (such as various pollens, moulds, etc.), which will help the immune system to develop tolerance to these inhaled allergens. In contrast, the management staff who work indoors are exposed to fewer inhaled allergens and exposure time than the real sanitation workers, and may be more prone to allergic reactions in the respiratory tract. Therefore, the proportion of the management position population in the AR group was significantly higher than that of the non-allergy-reporting group. Allergic diseases are known to be genetically predisposed, and the data reaffirmed this, with a significantly higher proportion of people with a family history of allergic disease in both the reported allergy and AR groups than in the reported no-allergy group. People with a history of allergic disease were 8.62 times more likely to have AR than people without a family history of allergic disease (95% CI: 2.03–36.64).
Serological results showed that the highest sensitization rates to dust mites were found in the sanitation workforce. Studies have reported that dust mites are the most important inhalant allergen in many Asian countries.
Prevalence patterns of allergen sensitization by region, gender, age, and season among patients with allergic symptoms in mainland China: a four-year multicenter study.
Guangzhou is located in a subtropical region, with high temperature and humidity all year round, making it suitable for dust mites to survive Interestingly, compared with the previous multicenter study data in China,
Prevalence patterns of allergen sensitization by region, gender, age, and season among patients with allergic symptoms in mainland China: a four-year multicenter study.
the data here showed that the mold combination and ragweed allergy rates of this particular group were higher, reaching 8.20% and 7.00%, respectively. This is presumably because those who clean the roads and parks are often exposed to ragweed powder and various moulds, or poor housing conditions may also be responsible for the high mold sensitization rate.
Unlike IgE, the role of allergen sIgG4 antibodies in allergic reactions remains controversial. On the one hand, allergen-related IgG4 antibodies are thought to be involved in the development of clinical tolerance, and the mechanism of its immunoprotective effect is that IgG4 can compete with IgE for binding to allergen epitopes, thereby blocking IgE-mediated allergic reactions.
It is known that the incidence of food allergies such as egg and milk allergy in adults is much lower than that in children, and the serum IgG4 test results in this study showed that up to 50% of the individuals were positive for egg IgG4. Since few of these individuals reported any previous or current egg allergy and the egg sensitization rate is extremely low, the IgG4 in their serum should be due to recent or ongoing egg intake. However, we do not exclude that this is a protective effect for adults because of high IgG4/IgE in their serum. This explanation also applies to the phenomenon of higher positive rates of milk and soybean IgG4. In addition, our data here show that there is no difference in the IgG4 positive rate of eggs and soybeans between groups, but there is a difference in milk sIgG4, which may be due to the fact that the management staff in the reporting allergy group accounts for a large proportion, and the IgG4 positive rate of the management group was significantly higher than that in the waste removal group (16.89% vs. 7.34%, p = 0.001), thus pulling up the overall difference between the reporting allergy group and the reporting no allergy group. For these data, we are more inclined to interpret IgG4 in this way, that is, people in management positions consume milk more frequently than people in cleaning positions due to better economic conditions and more attention to nutritional intake.
Univariate analysis data showed that management positions, high school education or above, and family history of allergies were risk factors for AR. It is very clear that allergic diseases have familial inheritance, and we discussed previously that the educational level is related to the position. Therefore, we excluded the educational background factor and directly based on the characteristics of the position and the length of service, divides the subjects who reported AR and reported no allergy into groups by level of garbage exposure. The idea for this grouping comes from the “hygiene hypothesis” developed in the twentieth century, which states that the increase in the prevalence of allergic diseases is due to a decrease in the prevalence of infection at an early age.
The garbage removal population is exposed to various allergens, especially inhaled allergens, much more than the management post population, then according to the principle of the hygiene hypothesis, it is possible that the garbage removal population is exposed to inhaled allergens from time to time while working outdoors to stimulate the body's immune system and gradually build up the body's immune tolerance to allergic rhinitis or bronchial asthma. Data from the current univariate analysis showed that the control group (management post population) was 2.20 times (95% CI: 1.38–3.50) more likely to report AR than the municipal waste exposure group (waste removal population) and 3.10 times (95% CI: 1.27–7.58) more likely than the level 3 municipal waste exposure group, a figure that appears to support the hygiene hypothesis.
However, there are 2 main limitations of this study. First, the sample size is not large enough, especially the random number of garbage cleaning people seems to be insufficient. Second, we did not do prick tests to further diagnose patients who self-reported allergic diseases, and there are no skin prick test (SPT) data.
Conclusion
In conclusion, we believe this is the first study conducted in mainland China on investigating the prevalence of allergic diseases in a specific group of sanitation workers. It should be noted that the group of sanitation workers in this study is mainly divided into two categories, the management post population and the real outside cleaning and sanitation population. We found that sanitation practitioners, especially true sanitation workers, had higher levels of ragweed and mold sIgE; the proportion of self-reported AR among management workers (here also the general population) was higher than that of cleaning workers. At the symptom level, urban cleaning may be a protective factor against AR, but serological data do not provide favorable evidence in this regard. Our findings may help clinicians diagnose and treat allergic diseases in sanitation practitioner groups, and provide guidance for researchers to further epidemiological studies of allergic diseases in this special population.
This study was supported by Guangdong Zhongnanshan Medical Foundation (ZNSXS-20220011).
Funding
This study was supported by Guangdong Zhongnanshan Medical Foundation (ZNSXS-20220011).
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author (Email: [email protected]) on reasonable request.
Author contributions
Peiyan Zheng, Zhifeng Huang and Baoqing Sun designed the study. Tingting Liu, Zhifeng Huang, Huiqing Zhu and Nairui An collected questionnaire information and serum samples. Tingting Liu, Huiqing Zhu, Hui Gan and Mingshan Xue performed the detection of allergen-specific IgE for all samples. Tingting Liu, Zhifeng Huang and Huiqing Zhu analyzed the data. Peiyan Zheng, Zhifeng Huang, Tingting Liu and Baoqing Sun wrote the manuscript. All authors gave final approval of the version to be published, agreed to the submitted journal, and agree to be accountable for all aspects of the work.
Ethics approval
This project and the use of serum samples from patients involved in this study were approved by the Ethics Committee of the First Hospital of Guangzhou Medical University (Medical Research Lun Review 2021 No. 67). All patients signed a paper version of informed consent.
Consent for publication
All the authors give the consent for publication in the journal.
Declaration of competing interest
The author reports no conflicts of interest in this work.
Appendix A. Supplementary data
The following is the Supplementary data to this article.
Prevalence patterns of allergen sensitization by region, gender, age, and season among patients with allergic symptoms in mainland China: a four-year multicenter study.
Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys.
00014-5&id=gr1.jpg){kind=link}
00014-5&id=gr2.jpg){kind=link}
00014-5&id=gr3.jpg){kind=link}
00014-5&id=gr4.jpg){kind=link}
00014-5&id=gr5.jpg){kind=link}