An Assessment of Dust, Endotoxin, and Microorganism Exposure during Waste Collection and Sorting

Figures & data

Table 1. Categorization of variables related to waste collection and sorting activities

Variable	Classification
Sex	Male
	Female
Job title	Street cleaner to collect street waste
	Handlers of residential waste including driver of waste
	vehicle
Type of company	Private
	Government
Day during waste collection	Weekday
	Weekend
Temperature	≤20 °C
	>20 °C
Humidity	<50%
	>50%
Region	Seoul
	Other cities in Korea

Table 2. Inhalation exposure level to dust, endotoxin, and microorganisms during waste collection and sorting

Hazardous Agent	n	Mean	SD	GM	Median	Range
Dust, mg/m^3	48	0.9	0.9	0.6	0.5	LOD–4.5
Endotoxin, ×10^2 EU/m^3	48	11.2	15.1	2.2	4.2	0.04–68.7
Viable total bacteria, ×10^5 CFU/m^3	49	1.9	4.8	0.2	0.2	0.13–23.5
Viable GNB, ×10^4 CFU/m^3	49	7	15.4	0.4	0.4	0.4–58.3
Viable fungi, ×10^4 CFU/m^3	49	2.2	2.8	0.9	0.9	2.4–0.8
Notes: n = Number of waste handlers, SD = standard deviation, GM = geometric mean.

Table 3. Comparison of inhalation exposure to dust, endotoxin, and microbes during waste collection and sorting according to the categorization of work characteristics

	Dust, mg/m^3			Endotoxin, EU/m^3			Bacteria, CFU/m^3			GNB, CFU/m^3			Fungi, CFU/m^3
Categorization of Variables	n	Mean (SD)	ANOVA	n	Mean (SD)	ANOVA	n	Mean (SD)	ANOVA	n	Mean (SD)	ANOVA	n	Mean (SD)	ANOVA
Sex			P = 0.242			P = 0.236			P < 0.001			P = 0.214			P = 0.024
Male	44	0.7 (1.0)		44	1.0 × 10^3 (1.5 × 10^3)		45	1.2 × 10^5 (3.6 × 10^5)		45	4.0 × 10^4 (1.2 × 10^5)		45	1.9 × 10^4 (2.6 × 10^4)
Female	4	2.6 (1.0)		4	2.0 × 10^3 (1.1 × 10^3)		4	1.0 × 10^6 (8.9 × 10^5)		4	4.1 × 10^5 (1.2 × 10^5)		4	5.1 × 10^4 (3.5 × 10^4)
Job title			NS			NS			NS			P = 0.248			P = 0.186
Driver	6	0.6 (0.4)		6	1.1 × 10^3 (1.2 × 10^3)		7	1.8 × 10^4 (1.8 × 10^4)		7	7.2 × 10^3 (8.6 × 10^3)		7	8.7 × 10^3 (1.3 × 10^4)
Waste handler	42	0.9 (1.0)		42	1.1 × 10^3 (1.6 × 10^3)		42	2.2 × 10^5 (5.2 × 10^5)		42	8.1 × 10^4 (1.6 × 10^4)		42	2.4 × 10^4 (3.0 × 10^4)
Company type			P = 0.228			NS			NS			NS			P = 0.157
Private	42	0.8 (1.0)		42	1.2 × 10^3 (1.6 × 10^3)		43	2.1 × 10^5 (5.1 × 10^5)		43	7.8 × 10^4 (1.6 × 10^5)		43	2.4 × 10^4 (2.9 × 10^4)
Government	6	1.3 (1.0)		6	7.0 × 10^2 (8.9 × 10^2)		6	8.0 × 10^4 (7.6 × 10^4)		6	1.2 × 10^4 (1.6 × 10^4)		6	6.5 × 10^3 (4.8 × 10^3)
Day			P = 0.011			P = 0.008			P = 0.214			P = 0.089			P = 0.188
Weekday	38	1.1 (1.0)		38	1.4 × 10^3 (1.6 × 10^3)		38	2.4 × 10^5 (5.4 × 10^5)		38	9.0 × 10^4 (1.7 × 10^5)		38	2.4 × 10^4 (3.0 × 10^4)
Weekend	10	0.2 (0.2)		10	2.5 × 10 (3.0 × 10)		11	3.3 × 10^4 (8.6 × 10^4)		11	3.3 × 102 (2.3 × 102)		11	1.2 × 10^4 (1.3 × 10^4)
Temperature			NS			P = 0.027			NS			P = 0.187			P = 0.079
≤20 °C	8	0.6 (0.5)		8	5.6 × 10 (6.3 × 10)		8	2.5 × 10^4 (2.8 × 10^4)		8	3.8 × 10^3 (6.4 × 10^3)		8	5.8 × 10^3 (3.8 × 10^3)
>20 °C	40	0.9 (1.1)		40	2.4 × 10^3 (1.4 × 10^3)		41	2.2 × 10^5 (5.2 × 10^5)		41	4.5 × 10^5 (1.2 × 10^5)		41	2.5 × 10^4 (2.9 × 10^4)
Humidity			P = 0.019			P < 0.001			P = 0.001			P < 0.001			P = 0.001
≤50%	16	1.4 (1.4)		16	2.6 × 10^3 (1.6 × 10^3)		16	5.1 × 10^5 (7.6 × 10^5)		16	2.0 × 10^5 (2.2 × 10^5)		16	4.8 × 10^4 (3.2 × 10^4)
>50%	32	0.7 (0.6)		32	3.8 × 10^2 (7.7 × 10^2)		33	3.7 × 10^4 (6.3 × 10^4)		33	8.8 × 10^3 (1.7 × 10^4)		33	9.0 × 10^3 (1.3 × 10^4)
Region			P = 0.021			P = 0.018			P = 0.014			P = 0.091			P = 0.188
Seoul	10	0.2 (0.2)		10	2.5 × 10 (3.0 × 10)		11	3.3 × 10^4 (8.6 × 10^4)		11	3.3 × 10^2 (2.3 × 10^2)		11	1.2 × 10^4 (1.3 × 10^4)
Other cities in Korea	38	1.1 (1.0)		38	1.4 × 10^3 (1.5 × 10^3)		38	2.4 × 10^5 (5.4 × 10^5)		38	9.0 × 10^4 (1.7 × 10^5)		38	2.4 × 10^4 (3.1 × 10^4)
Notes: n = number of samples, NS = nostatistically significant differences with any other groups (P ≤ 0.25).

Table 4. Correlation matrix among dust, endotoxin, bacteria, GNB, and fungi level (P value)

	Dust	Endotoxin	Bacteria	GNB	Fungi
Dust	1
Endotoxin	0.38 (P = 0.0071)	1
Bacteria	0.69 (P ≤ 0.0001)	0.43 (P = 0.0026)	1
GNB	0.76 (P ≤ 0.0001)	0.52 (P = 0.0001)	0.74 (P ≤ 0.0001)	1
Fungi	0.40 (P = 0.0047)	0.59 (P ≤ 0.0001)	0.62 (P ≤ 0.0001)	0.55 (P ≤ 0.0001)	1

Table 5. Factors significantly affecting inhalation exposure to dust, endotoxin, and microorganisms during waste collection and sorting

	Coefficient (95% confidence limit)
Independent Variables	Dust	Endotoxin	Bacteria	GNB	Fungi
Full model adjusted R ^2, % (P)	31.8 (P = 0.0034)	71.8 (P ≤ 0.0001)	39.2 (P ≤ 0.0001)	64.2 (P ≤ 0.0001)	49.6 (P ≤ 0.0001)
Constant	−0.24 (−1.35 to 0.87)	2.42 (0.50–4.34)	10.98 (10.08–11.88)	5.99 (3.74–8.25)	9.26 (7.46–11.07)
Sex
Male (reference)
Female	1.70 (0.55–2.85)	−0.34 (−1.77 to 1.10)	2.62 (0.82–4.42)	2.47 (0.58–4.36)	−0.02 (−1.26 to 1.21)
Job title
Driver (reference)
Waste collector	NS	NS	NS	1.99 (0.57–3.42)	1.39 (0.45–2.34)
Company type
Government (reference)
Private	−0.54 (−1.49 to 0.42)	NS	NS	NS	−0.03 (−1.07 to 1.00)
Day
Weekday (reference)
Weekend	−0.98 (−1.88 to −0.08)	NS*	−1.28 (−2.43 to −0.13)	−3.78 (−5.14 to −2.42)	0.31 (−0.61 to 1.24)
Temperature
<20 °C (reference)
>20 °C	NS	2.35 (1.25–3.46)	NS	2.42 (0.94–3.91)	0.10 (−0.88 to 1.08)
Humidity
<50% (reference)
>50%	0.17 (−0.59 to 0.93)	−2.02 (−3.00 to −1.04)	−1.04 (−4.59 to −1.89)	−1.01 (−2.27–0.26)	−2.21 (−3.07 to −1.35)
Region
Seoul (reference)
Other cities in Korea	NS	3.02 (1.99–4.05)	NS*	NS*	NS*
Notes: NS = not statistically significant factor (P > 0.25), which was already removed through ANOVA test (Table 3). NS* = not statistically significant factor in final model (P > 0.05). P value (dependent variables = log-transformed value, independent variables = categorical).

Table 6. Level of microorganisms collected from faces and from several parts of clothing of waste collectors

			Bacteria, CFU/cm^2		GNB, CFU/cm^2		Fungi, CFU/cm^2
Type of Worker	Part Exposed/Wiped	n	Mean	SD	Mean	SD	Mean	SD
Waste collector ^a
Before work	Face	49	1.3 × 10^2	1.9 × 10^2	3.5 × 10^1	1.2 × 10^2	1.4 × 10^2	2.9 × 10^2
After work	Face	49	3.1 ×10^4	5.6 × 10^4	5.5 × 10^4	1.9 × 10^5	2.7 × 10^5	6.5 × 10^5
Street cleaner	Face	6	9.2 × 10^3	9.1 × 10^3	3.6 × 10^4	8.4 × 10^4	8.2 × 10^3	1.0 × 10^4
Driver	Face	7	5.1 × 10^4	9.3 × 10^4	8.9 × 10^3	1.8 × 10^4	3.2 ×10^5	8.1 × 10^5
Waste separator	Face	6	1.4 × 10^4	3.1 × 10^4	5.5 × 10^4	8.6 × 10^4	1.6 × 10^4	1.3 ×10^4
Waste collector	Face	30	3.3 × 10^4	5.4 × 10^4	6.9 × 10^4	2.3 × 10^5	3.7 × 10^5	7.3 × 10^5
ANOVA P value	–	–	NS	–	NS	–	NS	–
Office worker
Before work	Face	10	3.8 × 10^1	7.3 × 10^1	ND	ND	4.4 × 10^1	8.6 × 10^1
After work	Face	10	1.0 × 10^2	1.6 × 10^2	ND	ND	9.3 ×10^1	1.0 × 10^2
Waste collector/after work	Pants	24	5.4 × 10^6	9.3 × 10^6	3.2 × 10^6	7.1 × 10^6	4.2 × 10^6	8.8 × 10^6
	Gloves	7	2.4 × 10^6	3.0 × 10^6	1.5 × 10^6	2.2 × 10^6	6.5 × 10^6	8.4 × 10^6
	Palm	3	1.4 × 10^7	6.9 × 10^6	1.4 × 10^7	6.9 × 10^6	6.4 ×10^6	2.1 × 10^6
	Back of hand	4	2.3 × 10^6	2.9 × 10^6	3.4 × 10^5	7.4 × 10^4	2.6 ×10^6	2.8 × 10^6
	Sleeve	8	3.5 × 10^7	6.7 × 10^7	2.3 × 10^7	2.8 × 10^7	3.2 × 10^6	3.6 × 10^6
	Shoulder	8	1.4 × 10^6	2.7 × 10^6	6.7 × 10^4	1.2 × 10^5	1.6 ×10^5	2.1 × 10^5
	Handkerchief	1	1.3 × 10^5	NA	1.2 × 10^6	NA	3.3 ×10^5	NA
	Navel	2	3.7 × 10^5	2.6 × 10^5	7.7 × 10^4	5.8 × 10^4	7.9 ×10^4	6.3 × 10^4
Notes: n = number of samples, NS = not statistically significant (P > 0.05), ND = 50 CFU/sample, P value = multiple comparison mean test among job titles (dependent variables = log-transformed value).
^aIncludes driver.