Sub-chronic lung inflammation after airway exposures to Bacillus thuringiensis biopesticides in mice.
BACKGROUND
The aim of the present study was to assess possible health effects of airway exposures to Bacillus thuringiensis (Bt) based biopesticides in mice. Endpoints were lung inflammation evaluated by presence of inflammatory cells in bronchoalveolar lavage fluid (BALF), clearance of bacteria from the lung lumen and histological alterations of the lungs. Hazard identifications of the biopesticides were carried out using intratracheal (i.t.) instillation, followed by an inhalation study. The two commercial biopesticides used were based on the Bt. subspecies kurstaki and israelensis, respectively. Groups of BALB/c mice were i.t instilled with one bolus (3.5 × 105 or 3.4 × 106 colony forming units (CFU) per mouse) of either biopesticide. Control mice were instilled with sterile water. BALFs were collected and the inflammatory cells were counted and differentiated. The BALFs were also subjected to CFU counts.


RESULTS
BALF cytology showed an acute inflammatory response dominated by neutrophils 24 hours after instillation of biopesticide. Four days after instillation, the neutrophil number was normalised and inflammation was dominated by lymphocytes and eosinophils, whereas 70 days after instillation, the inflammation was interstitially located with few inflammatory cells present in the lung lumen.Half of the instilled mice had remaining CFU recovered from BALF 70 days after exposure. To gain further knowledge with relevance for risk assessment, mice were exposed to aerosols of biopesticide one hour per day for 2 × 5 days. Each mouse received 1.9 × 104 CFU Bt israelensis or 2.3 × 103 CFU Bt kurstaki per exposure. Seventy days after end of the aerosol exposures, 3 out of 17 mice had interstitial lung inflammation. CFU could be recovered from 1 out of 10 mice 70 days after exposure to aerosolised Bt kurstaki. Plethysmography showed that inhalation of Bt aerosol did not induce airway irritation.


CONCLUSIONS
Repeated low dose aerosol exposures to commercial Bt based biopesticides can induce sub-chronic lung inflammation in mice, which may be the first step in the development of chronic lung diseases. Inhalation of Bt aerosols does not induce airway irritation, which could explain why workers may be less inclined to use a filter mask during the application process, and are thereby less protected from exposure to Bt spores.
Barfod
Kenneth K
KK
National Research Centre for the Working Environment, Copenhagen, Denmark.
Poulsen
Steen S
SS
Hammer
Maria
M
Larsen
Søren T
ST
D000818:Animals; D001413:Bacillus thuringiensis / Q000276:immunology* / Q000502:physiology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology / Q000382:microbiology; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D008168:Lung / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D023421:Models, Animal; D010572:Pest Control, Biological; D010575:Pesticides / Q000009:adverse effects* / Q000276:immunology; D012137:Respiratory System / Q000276:immunology / Q000382:microbiology
D010575:Pesticides
Arch Toxicol. 1993;67(7):478-90
8239997
J Appl Microbiol. 2007 Feb;102(2):303-12
17241334
J Bacteriol. 1993 Feb;175(4):1053-60
8432698
J Econ Entomol. 1990 Apr;83(2):347-55
2345219
Part Fibre Toxicol. 2009 Jan 12;6:2
19138394
Clin Microbiol Rev. 1993 Oct;6(4):324-38
8269390
Appl Environ Microbiol. 2002 Oct;68(10):4900-5
12324337
Int Arch Occup Environ Health. 2002 Mar;75(3):191-6
11954987
Am J Ind Med. 2004 Oct;46(4):404-7
15376210
Am J Respir Crit Care Med. 2000 May;161(5):1698-704
10806177
Toxicol Appl Pharmacol. 1982 Mar 30;63(1):72-90
6803401
Arch Toxicol. 1998 Apr;72(5):277-82
9630013
Arch Toxicol. 1994;68(8):490-9
7802589
Ann Occup Hyg. 1995 Jun;39(3):317-28
7793751
Appl Environ Microbiol. 2000 Jun;66(6):2627-30
10831447
Arch Toxicol. 1996;70(9):567-78
8831907
Regul Toxicol Pharmacol. 2007 Jun;48(1):6-18
17241726
Toxicol Lett. 2000 Apr 3;114(1-3):197-202
10713485
Hum Exp Toxicol. 2004 Nov;23(11):537-45
15625780
Occup Med (Lond). 1997 Jul;47(5):281-93
9302811
Microbiol Mol Biol Rev. 1998 Sep;62(3):775-806
9729609
J Appl Microbiol. 2008 May;104(5):1252-9
18042185
Hum Exp Toxicol. 1999 Jun;18(6):400-9
10413245
Microbiology (Reading). 2000 Nov;146 ( Pt 11):2825-2832
11065361
Nat Rev Immunol. 2008 Mar;8(3):183-92
18274560
Environ Health Perspect. 1999 Jul;107(7):575-82
10379004
Toxicology. 2003 Feb 14;184(1):51-68
12505376
Basic Clin Pharmacol Toxicol. 2008 Oct;103(4):386-8
18793270