Biocidal spray product exposure: Measured gas, particle, and surface concentrations compared with spray model simulations

Figures & data

Figure 1. Climate chamber schematic. Sampling positions for chemical analysis is marked as Tenax TA and XAD-2. Aerosol measurements were performed in the middle and in the right side of the chamber. For wiping surfaces fields were drawn on the wall in the sprayed corner and the opposite corner and on the steel plate on the floor in the sprayed corner.

Table 1. Spray characterization of the three biocidal spray products.

Product	Amount, g	Mean spray time / pressure, sec/bar	# of chamber experiments	Mass generation rate, g/sec [# of tests^$]	Geometrical particle diameter, µm [GSD*]
Biocide 1	11.2–11.8	10 / n.a.	2	1.1 [2]	5.5 [1.8]
Biocide 2 (2% disper-sion in water)	53–95	4.7 / 5.5	2	21 [3]	4.3 [1.9]
Biocide 3 (2% solution in water)	116–126	5.8 / 5.5	3	21 [4]	4.8 [1.7]

n.a. not available.

^$ Separate experiments.

^* GSD = geometrical standard deviation

Table 2. Parameters and settings in the ConsExpo Web simulations and selected results for the active substances. Experimental values inserted in place of default values are underlined.

	Biocide 1		Biocide 2		Biocide 3
	Few parameters	Many parameters	Few parameters	Many parameters	Few parameters	Many parameters
Fact sheet information	Pest control products	Pest control products	Pest control products	Pest control products	Disinfectants	Disinfectants
Product category	Sprays	Sprays	Sprays	Sprays	Disinfectant for use indoors	Disinfectant for use indoors
Product	Air space	Air space	General surface	General surface	Disinfectant for use indoors	Disinfectant for use indoors
Scenario	Application	Application	Application (trigger spray^§)	Application (trigger spray^§)	Spraying	Spraying
Frequency (day^−1)	1	1	1	1	1	1
Simulation model	Exposure to spray	Exposure to spray	Exposure to spray	Exposure to spray	Exposure to spray	Exposure to spray
Simulation model settings
Mode of release	Spraying	Spraying	Spraying	Spraying	Spraying	Spraying
Spray duration (s)	10	10	5	5	6	6
Exposure duration (min)	240	240	240	240	240	240
Weight fraction substance (%)
Piperonyl butoxide	1.22	1.22
Pyrethrum extract	0.25	0.25
Permethrin	0.216	0.216
λ-cyhalothrin			0.194	0.194
Benzalkonium chloride					0.17	0.17
Room volume (m^3)	20.3	20.3	20.3	20.3	20.3	20.3
Room height (m)	2.29	2.29	2.29	2.29	2.29	2.29
Ventilation rate (h^−1)	0.5	0.5	0.5	0.5	2.5	0.5
Inhalation rate (l/min)	24.1	24.1	24.1	24.1	24.1	24.1
Mass generation rate (g/s)*	1.1	1.1	0.8	21	0.8	21
Airborne fraction^$	0.3	0.7	0.008	<0.002	0.008	0.001
Density non-volatile (g/cm^3)	1.8	1.8	1.8	1.8	1.8	1.8
Inhalation cut off diameter (µm)	15	15	15	15	15	15
Aerosol diameter distribution type	Log-normal	Log-normal	Log-normal	Log-normal	Log-normal	Log-normal
Median diameter (µm)^£	28.2	5.5	7.7	4.3	7.7	4.8
Arithmic coefficient of variation^£	1.6	1.8	1.9	1.9	1.9	1.7
Maximum diameter (µm)	50	50	50	50	50	50
Simulation Results
Peak conc. (TWA 15 min) (mg/m^3)
Piperonyl butoxide	0.31	2.7
Pyrethrum extract	0.063	0.56
Permethrin	0.042	0.48
λ-cyhalothrin			0.0015	<0.013
Benzalkonium chloride					0.0013	0.0066

^§ Pumped spray could not be chosen in ConsExpo Web.

* The experimental mass generation rate for Biocide 1 was equal to the default value (Table 1).

^$ Airborne fractions were calculated from the maximum measured concentrations divided by the theoretical maximum concentration based on sprayed amount of product, content of substance and no ventilation in the climate chamber.

^£ The aerosol distribution parameters were estimated in separate spray experiments (Table 1).

Figure 2. Concentration vs. time data for active substances and alkanes after spraying Biocide 1 in the chamber (data from one experiment). The lines are the fitted first-order decay functions (see Table 3). The black dotted line shows a decay following the air exchange rate. The ConsExpo Web curve is based on the many parameter scenario.

Table 3. Measured maximum air concentrations (out of 2–3 experiments) emitted during application of the biocidal spray products, parameters of fitted first-order decay model (k₁ and C₀ in Equation (1)(1) $$\mathrm{C}\left(\mathrm{t}\right)={\mathrm{C}}_0·\hspace{0.17em}\text{exp}\hspace{0.17em}(-{\mathrm{k}}_1·\mathrm{t})$$(1) ) with two-sided confidence limits, and available occupational exposure limit values.

Biocide Spraying time, sec	Substance	Max measured air conc. (mg/m^3)	Max air conc. at time (min)	C0, max theoretical air conc. (95% conf. limit) at t = 0 (mg/m^3)	k1, first-order decay constant (95% conf. limit) (h^−1)	OEL value (mg/m^3)	OEL source
Biocide 1 10	Alkanes	13	10	13(1)	0.5(0.1)
	Dimethoxy methane	0.05		0.068(0.009)	2.1(0.3)	–
	Phenylethyl alcohol	0.24		0.24(0.03)	0.8(0.2)	–
	Lilial	<0.05		0.060(0.006)	1.7(0.2)	–
	Nopyl acetate	<0.05		0.043(0.005)	1.1(0.2)	–
	Piperonyl butoxide*	7		10(1)	2.5(0.3)	–
	Pyrethrum extract*	1		1.6(0.3)	3.2(0.7)	–
	Permethrin (cis/trans)*	0.4		0.55(0.05)	2.8(0.3)	–
Biocide 2 2.5-4.5	1,2-propanediol	0.5	45-302
	1,2,4-Trimethylbenzene	0.4	9-57			100	SCOEL 1994
	Propylbenzene	0.009	19-45
	Indane	0.003	9-34			45	Danish OEL
	λ-cyhalothrin*	<LOD = 0.022 mg/m^3				0.04 mg/m^3	Syngenta OEL MSDS
	1,2-Benzisothiazol-3(2H)-one	<LOD = 0.014 mg/m^3				- 25 mg/kg bw/d	Scientific Committee on Consumer Safety SCCS/1482/12
Biocide 3 5.5-6	Benzyldimethyldodecyl-ammonium chloride (C12-benzalkonium chloride)*	0.01	9	0.014(0.004)	3.5(1.3)	0.005	Danish EPA^(26)
	Benzyldimethyltetradecyl-ammonium chloride (C14-benzalkonium chloride)*	0.001		0.0015(0.0005)	4.6(1.9)	0.005	Danish EPA^(26)

* Active substance. - = No information about inhalation.

Figure 3. Total particle number and mass concentrations measured by the OPS vs. time in the chamber after spraying Biocide 1 (A), Biocide 2 (B), and Biocide 3 (C) (data from one experiment).

Table 4. Mean surface and dermal exposure concentrations of substances emitted during application of biocidal spray products.

Biocide Spraying time, sec	Substance	Sampling site and medium	Mean Surface conc. ± std. (mg/m^2)
Biocide 1 10	Piperonyl butoxide*	Wipe (Day 1, n = 3):
		Floor	10.4 ± 4.6
		Wall, adult height	0.3 ± 0.04
		Wall, child height	<LOD
	Pyrethrum extract*	Wipe (Day 1, n = 3):
		Floor	2.2 ± 2.0
		Wall, adult height	<LOD
		Wall, child height	<LOD
	Permethrin (cis/trans)*	Wipe (Day 1, n = 3):
		Floor	1.0 ± 0.3
		Wall, adult height	0.3 ± 0.3
		Wall, child height	<LOD
Biocide 2 2.5–4.5	λ-cyhalothrin*	Wipe (Day 1, n = 4):
		Floor	3.8 ± 3.9
		Wall, adult height	0.2 ± 0.3
		Wall, child height	0.7 ± 0.8
	1,2-Benzisothiazol-3(2H)-one	Wipe (Day 1, n = 4):
		Floor	12.6 ± 6.9
		Wall, adult height	<LOD
		Wall, child height	8.2 ± 7.2
Biocide 3 5.5–6	Benzyldimethyldodecyl-ammonium chloride (C12-benzalkonium chloride)*	Dermal exposure:
		Arm	0.04
		Head	0.03
		Wipe:
		Floor	10.5 ± 1.7
		Wall, adult height	0.5 ± 0.3
		Wall, child height	0.2 ± 0.03
	Benzyldimethyltetradecyl-ammonium chloride (C14-benzalkonium chloride)*	Dermal exposure:
		Arm	0.02
		Head	0.02
		Wipe:
		Floor	4.0 ± 2.5
		Wall, adult height	0.4 ± 0.2
		Wall, child height	0.1 ± 0.03

* Active substance.

Figure 4. Concentration vs. time data for organic substances after spraying Biocide 2 in the chamber (data from one experiment).

Figure 5. Concentration vs. time data for active substances after spraying Biocide 3 in the chamber (data from one experiment). The lines are the fitted first-order decay functions (see Table 3). The ConsExpo Web curve is based on the many parameter scenario.

Figure 6. Comparison of simulated peak and experimental maximum exposure concentrations of Biocide 1 after one spray event. Columns termed Few and Many parameters are simulated exposure concentrations in ConsExpo Web and columns termed Aerosol and Chemical are exposure concentrations estimated based on aerosol and chemical measurements, respectively.