TTS 2005 Chemical risks in agriculture
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Transcript of TTS 2005 Chemical risks in agriculture
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TTS 2005
Chemical risks in agriculture
Benoit Nemery, MD, PhDOccupational, Environmental & Insurance Medicine
& Pneumology
K.U.Leuven, [email protected]
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Respiratory diseases in agriculture
1. Infectious micro-organisms2. Organic dusts (+ microbial products)3. Inorganic dusts (silica, ...)4. Chemicals
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Literature
Schenker M.B. (Chair) et al. American Thoracic Society: Respiratory Health Hazards in Agriculture.Am J Respir Crit Care Med, 1998, 158, S1-S76.
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Chemical exposures in agriculture
1. Toxic gases2. Biocides and pesticides3. Fertilizers4. Feed additives
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Toxic gases
• Combustion • Decomposition gases
• Manure• Silo gases
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Pleura
Respiratory uptake of gasesWater solubility
+++ NH3, SO2 , HCl, R-CHO, ...
++ Cl2, CH3NCO, ...
+ O3, NO2, COCl2, ...
lipid soluble solvents, anaestheticsC6H6, CHCl3, F3C-CHBrCl, ...
→ irritation
rapid
slow
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Carbon monoxide (CO)
all types of combustion when O2 supply < exhaust of gases
indoor burning of biomass, wood, charcoal, coal, kerosene, diesel, gas, …
fires, stoves, ovens, heaters, vehicles, engines, compressors, … + insufficient ventilation (indoor confined spaces)
! also NOx and particles
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Decomposition gases
• Storage & putrefaction of organic matter• Liquid manure (pigs, cattle)• Solid manure (poultry)
production of H2S, CH4, NH3, CO2, CO accidental exposure (agitation + pumping
of liquid manure, repairs) chronic exposure in animal confinement
buildings
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Liquid manure storage
• Hydrogen sulfide (H2S)– heavier than air– odour +++ (except > 150 ppm); irritant ++– neurotoxicity (→ coma)– respiratory toxicity (→ lung oedema)
“dung lung”
• + CH4, CO2, … → O2 depletion– asphyxia
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Irritant gases
• Ammonia (NH3)– highly water soluble and potent irritant– affects mainly eyes, nose, upper airways– exposure levels often exceed recommended TLV
(25 ppm, 8 h), but no evidence that NH3 leads to excess symptoms or chronic airways disease
– possible accidental exposure to high amounts when use of anhydrous ammonia (fertilizer)
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Acute inhalation of NH3
Leduc et al. Thorax, 1992, 47, 755-7
Man, 28 y• explosion of tank in refrigeration
plant (NH3)• acute:
• corneal & dermal lesions• tracheobronchitis• respiratory insufficency
• 12 y later:• severe airway obstruction• bronchiectases
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Storage of forage/grain in silos
• Open silo - Trench or bunker• Sealed siloFermentation of silage
multiplying bacteria consume oxygen generation of CO2 and organic acids generation of nitrogen oxides
plant nitrates → NO → NO2, …
! Rapid process (hours)
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Irritant gases
• Nitrogen dioxide (NO2)– Heavier than air– Invisible → yellowish → orange-brown– (Sweet smell) – Poorly water soluble– Poor warning properties (mild irritation)– Potent oxidant– May cause delayed lung injury (permeability
lung oedema)
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Douglas W.M., Hepper N.G.G., Colby T.V.Silo-Filler’s Disease. Mayo Clin Proc 1989, 64, 291-304
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Silo-filler’s disease
Upon entering recently filled silo– asphyxia– airway irritation– after 4-24 h: non-cardiogenic lung oedema
- chemical pneumonitis (“silo filler’s disease”)
– after 3-4 weeks: bronchiolitis obliterans (+ malaise, fever, … DD. Miliary TB)
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Case
• Man, 34 y, smoker• Worker in small company making printed circuits• Friday: cleaning galvanisation baths with
concentrated HNO3 (instead of diluted solution)
• During work: mild irritation • At home: progressive cough and dyspnoea
“I could not lay down”• During night: hospitalization in respiratory
distress
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NO2-induced pneumonitis
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Case
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Chemical exposures in agriculture
1. Toxic gases2. Biocides and pesticides3. Fertilizers4. Feed additives
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Biocides and pesticides
• Disinfectants• Fumigants• Pesticides
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Disinfectants
• Bleach• Quaternary ammonium compounds• Chloramine T• Aldehydes (formaldehyde, glutaraldehyde,
glyoxal)
airway irritation allergic sensitization
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Bleach• Bleach (HClO) or “Bleach tablets” + water
! Mixing incompatibilities Bleach + acids → Cl2, HCl Bleach + ammonia → chloramines
NH2Cl, NHCl2, NCl3
– tracheo-bronchial irritation – chemical pneumonia– irritant-induced asthma
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Repeated exposure to cleaning agents
• Higher risk of asthma in female cleaners• Zock et al. SJWEH 2001, 27, 76-81: P.R. 1.7• Karjalainen et al. ERJ 2002, 19, 90-5: R.R. 1.50• Medina-Ramon et al. Thorax 2003, 58, 950-4: O.R. 1.46
exposure to irritants and sprays ? “hidden sensitizers”?
• Quaternary ammonium compounds (disinfectants / preservatives)• Isothiazolinones (preservatives)• Ethanol amines (wax-removal agents)• d-limonene, terpenes (perfumes)
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Quaternary Ammonium Compounds
• In pig farmers with frequent exposure to QAC sprayed under high pressure, higher risk of• asthma-like symptoms• low lung function• atopic sensitization• bronchial hyperreactivity
Preller et al. OEM 1995, 52, 654-660Preller et al. ERJ 1996, 9, 1407-1413Vogelzang et al. IAOEH 1997, 70, 327-333
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Fumigation and pest treatmentTreatment of soil, barn, greenhouse, … with highly
toxic volatile compounds • methyl bromide (CH3Br)• hydrogen cyanide (HCN) & other cyanides• carbon disulfide (CS2)• ethylene oxide• acrolein• chloropicrin• zinc phosphide (Zn3P2) → H3P
asphyxia respiratory irritation neurotoxicity
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SulfurizationKoksal N. et al. Apricot sulfurization: an occupation that induces an asthma-like syndrome in agricultural environments. Am J Ind Med 2003, 43, 447-453• Malatya (Turkey)• 15 apricot farms, 69 workers (31 y)• 20-25 days in summer• Melting of S → SO2 in sulfurization chambers (8-10 h)• Repeated exposures for ~1 h to 100-700 ppm SO2 Acute eye, nose and airway irritation (including
wheezing in 6) Acute decreases in FEV1 (-0.39 L, >20% in 10) and
FVC (-0.16 L)
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Pesticides• Substances intended for preventing, destroying,
repelling, mitigating pests (“toxic by design”) • Target specificity:
• Insecticides• Fungicides• Herbicides• Rodenticides• Acaricides• Nematocides
heterogeneous chemicals
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Agricultural pesticidesOccupational and para-occupational exposures
• Mixing and loading• Application (tractor, airplane, backpack)• Field workers (harvesting, handling)• Bystanders (! children)• Residents
• Misuse and accidental exposure• Spills (mass-poisoning)• Accidental ingestion • Suicide• Homicide
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Agricultural pesticides
• Most pesticides have low volatility• Inhalation exposure is generally low
• Large size droplets! Indoor spraying (greenhouses)
• Most occupational exposure is by dermal route
! Protective clothing
In general: few serious and specific respiratory effects reported, even after spraying
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Agricultural pesticidesHoppin J.A. et al. Chemical predictors of wheeze among farmer pesticide applicators in the Agricultural Health Study. Am J Respir Crit Care Med 2002, 165, 683-689
• Cohort of >20,000 pesticide applicators in Iowa & North Carolina
• Questionnaire: 19% wheeze in past year adjusted OR for wheeze for exposure to
paraquat, three organophosphates (parathion OR=1.5), one thiocarbamate, atrazine
Significance?
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Agricultural pesticides
• In general: few serious and specific respiratory effects reported, even after spraying
! Acute intoxication (accident or suicide) with organophosphates or paraquat
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Eddleston M. et al. Pesticide poisoning in the developing world - a minimum pesticides list. Lancet 2002, 360:1163-7.
Sri Lanka2 districts
Chandigahr, India
Samoa
Amman, Jordania
Ban of parathionControlled availability
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Organophosphates
Parathion (E605, …), ... • Excellent penetration through skin & mucosae inhibition of acetylcholinesterase
• Diarrhoea, sweating, salivation, lachrymation, miosis, bronchospasm, bronchorrhoea (pulmonary oedema)
• Muscle fibrillation → weakness → paralysis • CNS (anxiety, vertigo, tremor) → convulsions →
coma• Delayed neurological effects possible
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Paraquat
N-CH3CH3-N++
1,1’-dimethyl-4,4’-bipyridylium chloride
Contact herbicide
• Water-soluble concentrates 100-200 g/L(Gramoxone, Dextrone)
• Granular formulations 25-80 g/kg (Weedol, ...)
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Paraquat• Local toxicity: skin, nails, eyes, nose• Systemic toxicity after
• ingestion (accidental, suicidal)• dermal absorption
• poor penetration through intact skin• absorption and (fatal) toxicity possible if
– Prolonged skin contact (leaking spray equipment)– Skin damage– Contact with concentrated solution
• no substantial uptake via inhalation (droplet size > 200 µm)
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Paraquat
• Systemic toxicity to various organs, especially lungs• Accumulation in lung tissue: active uptake
in pneumocytes (via polyamine uptake system)
• Oxidative stress
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NADPH NADP+
O2O2
_.
NADPHreductase
PQ++
PQ+.
H2O2
OH. Fe
H2O
SOD
CAT
LipidsEnzymes
DNA
GSH
Lipid peroxidation
GSSG
Vit.E, C
NADP+ .
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Paraquat
Water-soluble concentrate: 100-200 g/L• < 20 mg PQ/kg:
Mild g-i symptoms• 20-40 mg PQ/kg:
Malaise, g-i symptoms Renal failure Pulmonary fibrosis → death in 2-3 wks
• > 40 mg PQ/kg (15 ml of 20% solution): Multiorgan failure → death in <1 week
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Paraquat
Proudfoot et al. Lancet, 1979, 2, 330-332
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Paraquat• Long-term effects of chronic paraquat exposure?• Schenker M.B. et al. Pulmonary function and exercise-
associated changes with chronic low-level paraquat exposure. Am J Respir Crit Care Med, 2004, 170, 773-779• Costa Rica• 338 plantation workers (banana, coffee, palm oil), 37 y• 66% paraquat handlers; index of cumulative exposure slight increase in prevalence of chronic cough no significant effect on spirometry and DLco slight effect on gas exchange during maximal exercise (200
subjects < 40y) : SpO2>5% (pulse oximetry) associated with higher PQ index
Subtle long-term effect on lung parenchyma?