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Table 2 Summary of toxicological endpoints for isocyanates. The endpoints include carcinogenicity, genotoxicity, effects on reproductive systems and teratogenic properties for the most commercially important isocyanates. Target organs for short term and long term exposure as well as sensitization are also summarised

From: The role of isocyanates in fire toxicity

Compound Carcinogenicity Genotoxicity Reproductive Teratogenetic Neurotoxic Target organ – single exposure Target organ – repeated dose Skin sensitization Respiratory sensitization Eye irritation Dermal irritation
Isocyanic acid (ICA) No N/A N/A N/A N/A N/A N/A N/A N/A Severe (rabbit) Severe (rabbit)
Methyl isocyanate (MIC) Possible Yes (Goswami et al. 1990) Yes Yes Yes (Gupta & Prabha 1996) Liver Chronic obstructive lung disease Yes (ACIGH 1986) Yes (human) Severe (human) Severe (human)
Ethyl isocyanate (EIC) N/A Yesa Yesa Yesa Cholinesterase Inhibitor Livera Chronic obstructive lung disease e Yesa Yesa Severea Severea
Phenyl isocyanate (PHI) Possible IARC rating: 2Bb Yes (Bureau 2000) No (Nehez et al. 1989) No (Nehez et al. 1989) N/A N/A Irreversible decline in pulmonary function (NIOSH 2004) Yes (Karol & Kramarik 1996) Yes (Pauluhn et al. 1995) Severe (O’Neil 2006; Berufsgenossenschaft der chemischen Industrie 1997) Yes (Berufsgenossenschaft der chemischen Industrie 1997)
Hexamethylene di-isocyanate (HDI) Possible IARC rating: 2Bb Yesb (Marczynski et al. 2005; Bilban 2004; Bolognesi et al. 2001) No (Sids OECD 2001) N/A Cholinesterase Inhibitor Lungs (Montelius & Sant 2009) Lesions in the nasal cavity (Sids OECD 2001) Yes (Centers for Disease Cotrol and Prevention 2015b) Yes (Centers for Disease Cotrol and Prevention 2015b) Severe (Vernot et al. 1977) Severe (Vernot et al. 1977)
Toluene-2,4-di-isocyanate (2,4-TDI) Possible IARC rating: 2B Contradictory (Mäki-Paakkanen & Norppa 1987; Lindberg et al. 2011) N/A N/A Cholinesterase Inhibitor Lungs (Lindberg et al. 2011) Irreversible decline in pulmonary function (The National Institute for Occupational Safety and Health (NIOSH) 2004) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c)
Toluene-2,6-di-isocyanate (2,6-TDI) Possible IARC rating: 2B Yes (Mäki-Paakkanen & Norppa 1987) Noc, (Le Quesne et al. 1976) N/A Yes Lungs (Fabbri et al. 1987) Irreversible decline in pulmonary function (NIOSH 2004) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c) Yes (Centers for Disease Cotrol and Prevention 2015c)
Methylenebis (phenylisocyanate) (MDI) Possible IARC rating: 2Bb Contradictory (Bolognesi et al. 2001) No (Zocca et al. 1990) Yes (Buschmann 1990) Insufficient evidence (Hughes et al. 2014) Lungs (Hughes et al. 2014) Irreversible decline in pulmonary function (Centers for Disease Cotrol and Prevention 2015e) Yes (Zocca et al. 1990) Yes (Zocca et al. 1990) Yes (Zocca et al. 1990) Yes (Zocca et al. 1990)
Isophorone di-isocyanate (IPDI) N/A No (European Aliphatic Isocyanate Producer Association 2013) N/A N/A N/A Lungs (NIOSH 2004) Irreversible decline in pulmonary function (Centers for Disease Cotrol and Prevention 2015d) Yes (Centers for Disease Cotrol and Prevention 2015d) Yes (Centers for Disease Cotrol and Prevention 2015d) Yes (Centers for Disease Cotrol and Prevention 2015d) Yes (Centers for Disease Cotrol and Prevention 2015d)
  1. aData extrapolated from toxic effects of MIC
  2. bData extrapolated from toxic effects of TDI
  3. cImpotence has been reported in fire fighters, though thought to be due to an indirect neurological effect rather than direct effect on the male genitals
  4. N/A indicates level not available/not applicable