Skip to main content

Suicidal chemistry: combined intoxication with carbon monoxide and formic acid


Herein, we present a rare case of suicidal intoxication with carbon monoxide produced via reaction of formic and sulphuric acid with additional toxic effect of formic acid. The deceased was a 22-year-old men found dead in the bathroom locked from the inside. A bucket filled with liquid was found next to him, together with an almost empty canister labeled “formic acid” and another empty unlabeled canister. The postmortem examination revealed corrosive burns of the face, neck and chest, cherry-pink livor mortis, corrosive injury to the oropharyngeal area and trachea, subpleural petechiae, 100 mL of blood in stomach and superficial erosions of stomach mucosa. Toxicology analysis revealed 30 % of carboxyhemoglobin in the femoral blood and the presence of the formic acid in various samples. Quantitative analysis of formic acid was performed by measuring methyl ester derivative of formic acid by using headspace gas chromatography with flame ionization detection. The highest concentration of formic acid was measured in the lungs (0.55 g/kg), gastric content (0.39 g/L), and blood (0.28 g/L). In addition, it was established that content of the unlabeled canister had a pH value of 0.79 and contained sulphuric ions. Morphological and toxicology findings suggested that the main route of exposure to formic acid was inhalation of vapors with a possible ingestion of only small amount of liquid acid. The cause of death was determined to be combined intoxication with carbon monoxide and formic acid.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5


  1. Anonymous (1997) Formic acid. International Programme on Chemical Safety, European Commission. Accessed 23 Apr 2015

  2. Kao DS, Hijjawi J (2012) Cold and chemical injury to the upper extremity. In: Song DH (ed) Plastic surgery 4: lower extremity, trunk and burns, 3rd edn. Elsevier Saunders, London, pp 456–468

    Google Scholar 

  3. Moody AJ (1991) Methanol and formic acid toxicity: biochemical mechanisms. Pharmacol Toxicol 69:157–163

    Article  Google Scholar 

  4. Seme MT, Summerfelt P, Henry MM, Neitz J, Eells JT (1999) Formate-induced inhibition of photoreceptor function in methanol intoxication. J Pharmacol Exp Ther 289:361–370

    CAS  PubMed  Google Scholar 

  5. Anonymous (2010) Formic acid. Incident management. Chemical Hazards and Poisons Division, Health Protection Agency. Accessed 23 Apr 2015

  6. Westphal F, Rochholz G, Ritz-Timme S, Bilzer N, Schütz HW, Kaatsch HJ (2001) Fatal intoxication with a decalcifying agent containing formic acid. Int J Legal Med 114:181–185

    Article  CAS  Google Scholar 

  7. Anonymous (2001) Sulfuric acid. UNEP publications. Accessed 23 Apr 2015

  8. Pritchard JD (2011) Sulphuric acid. Centre for Radiation, Chemical and Environmental Hazards, Health Protection Agency. Accessed 23 Apr 2015

  9. Palao R, Monge I, Ruiz M, Barret JP (2010) Chemical burns: pathophysiology and treatment. Burns 36:295–304. doi:10.1016/j.burns.2009.07.009

    Article  CAS  Google Scholar 

  10. Wehr K, Schäfer A (1987) An unusual case of suicidal carbon monoxide poisoning. Arch Kriminol 180:155–160

    CAS  PubMed  Google Scholar 

  11. Prahlow JA, Doyle BW (2005) A suicide using a homemade carbon monoxide “death machine”. Am J Forensic Med Pathol 26:177–180

    PubMed  Google Scholar 

  12. Yang CC, Ger J, Li CF (2008) Formic acid: a rare but deadly source of carbon monoxide poisoning. Clin Toxicol (Phila) 46:287–289. doi:10.1080/15563650701378746

    Article  CAS  Google Scholar 

  13. Lin PT, Dunn WA (2014) Suicidal carbon monoxide poisoning by combining formic acid and sulfuric acid within a confined space. J Forensic Sci 59:271–273. doi:10.1111/1556-4029.12297

    Article  CAS  Google Scholar 

  14. Wallage HR, Watterson JH (2008) Formic acid and methanol concentrations in death investigations. J Anal Toxicol 32:241–247

    Article  CAS  Google Scholar 

  15. Peters FT, Drummer OH, Musshoff F (2007) Validation of new methods. Forensic Sci Int 165:216–224

    Article  CAS  Google Scholar 

  16. Heilmeyer L (1933) Das Kohlendioxid-Haemoglobin. In: Heilmeyer L (ed) Medizinische Spektrophotometrie. Gustav-Fischer-Verlag, Jena, pp 86–92

    Google Scholar 

  17. Saukko P, Knight B (2004) Corrosive and metallic poisoning. In: Saukko P, Knight B (eds) Knight’s forensic pathology, 3rd edn. Arnold Publications, London, pp 585–594

    Chapter  Google Scholar 

  18. Bardale R (2011) Corrosive poisons. In: Bardale R (ed) Principles of forensic medicine and toxicology. Jaypee Brothers Medical Publishers (P) LTD, New Delhi, pp 437–444

    Chapter  Google Scholar 

  19. Naik RB, Stephens WP, Wilson DJ, Walker A, Lee HA (1980) Ingestion of formic acid-containing agents—report of three fatal cases. Postgrad Med J 56:451–456

    Article  CAS  Google Scholar 

  20. Rajan N, Rahim R, Krishna Kumar S (1985) Formic acid poisoning with suicidal intent: a report of 53 cases. Postgrad Med J 61:35–36

    Article  CAS  Google Scholar 

  21. Verstraete AG, Vogelaers DP, van den Bogaerde JF, Colardyn FA, Ackerman CM, Buylaert WA (1989) Formic acid poisoning: case report and in vitro study of the hemolytic activity. Am J Emerg Med 7:286–290

    Article  CAS  Google Scholar 

  22. Forbes WH, Sargent F, Roughton FJW (1945) The rate of carbon monoxide uptake by normal men. Am J Physiol 143:594–608

    Article  CAS  Google Scholar 

  23. Madea B, Grellner W, Kondo T (2014) Vital reactions and wound age estimation. In: Madea B (ed) Handbook of forensic medicine. Wiley-Blackwell, Chichester, pp 237–253

    Chapter  Google Scholar 

Download references

Ethical standards

The presented content completely complies with the laws in Croatia.

Conflicts of interest

The authors declare that they have no conflicts of interest.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Davor Mayer.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Bakovic, M., Nestic, M. & Mayer, D. Suicidal chemistry: combined intoxication with carbon monoxide and formic acid. Int J Legal Med 130, 723–729 (2016).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Intoxication
  • Carbon monoxide
  • Formic acid
  • Corrosive injuries