Sensory irritation due to methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate in mice.

The expiratory bradypnoea indicative of upper airway irritation in mice was evaluated during a period of 60 min of nasal exposure to methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate vapors using nose only exposure. Irritation of the upper respiratory tract caused a concentration-dependent decrease in the respiratory rate. The maximum effect occurred within the first 10 min of exposure and was followed by a drop-off in the response during the remainder of the exposure period. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD(50)) was calculated for each chemical. The results show that the four chemicals had similar irritant potencies. The RD(50) values of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate and 2-methoxyethyl-2-cyanoacrylate were 1.4, 0.7, 0.6 and 1.0 p.p.m. Tentative estimates of threshold limit values showed that 0.1 RD(50) was closer to the values recommended by the American Conference of Governmental Industrial Hygienists for methyl- and ethyl-2-cyanoacrylate than 0.03 RD(50). On the basis of a threshold limit value for short-term exposure limit (TLV STEL) equal to 0.1 RD(50), the TLV STELs for the four cyanoacrylates should not exceed 0.1 or 0.2 p.p.m.

Sensory irritation of acetic acid, hydrogen peroxide, peroxyacetic acid and their mixture in mice.

The expiratory bradypnoea indicative of upper airway irritation in mice was evaluated during a period of 60 min of oronasal exposure to acetic acid, hydrogen peroxide and peroxyacetic acid vapours. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each chemical. The concentration-response curves of acetic acid, hydrogen peroxide and peroxyacetic acid had similar slopes. The results did however show that the three chemicals had different irritant potencies. The RD50 values of acetic acid, hydrogen peroxide and peroxyacetic acid were 227, 113 and 5.4 p.p.m. respectively. Moreover, a mixture containing 53% acetic acid, 11% hydrogen peroxide and 36% peroxyacetic acid had an RD50 of 10.6 ppm, 3.8 ppm being peroxyacetic acid, which is 1.4 times lower than the theoretical value estimated from the fractional concentrations and the respective RD50s of the individual components. On the basis of a TLV-STEL (threshold limit value for short-term exposure limit) equal to 0.1 RD50, the TLV-STELs for acetic acid, hydrogen peroxide and peroxyacetic acid should not exceed 20, 10 and 0.5 p.p.m. respectively. On the basis of a TLV-TWA (time-weighted average) equal to 0.03 RD50, the TLV-TWAs for these same chemicals should not exceed 5, 3 and 0.2 p.p.m. respectively. Finally, these values and existing TLVs in Europe and the USA are compared.