Oxalyl dichloride

Endpoint summary

Additional information

Oxalyl chloride reacts with water giving off gaseous products only: hydrogen chloride (HCl), carbon dioxide (CO2), and carbon monoxide (CO). Therefore, the main target for environmental distribution will be air (independent on the entering compartment). Additionally, neither HCl, CO2 nor CO has to be classified for the environment. The hydrolysis products are with high probability not acutely harmful to aquatic organisms. In conclusion, oxalyl chloride has not to be classified for the environment.

HCl:

According to Annex VI of the Directive EC/1272/2008 and Annex I of the directive 67/548/EEC HCl is not classified for the environment.

According to the OECD SIDS on Hydrogen Chloride (SIAM 15, 2002), the physico-chemical properties indicate that hydrogen chloride released into the environment is distributed into the air and water.

Hydrogen chloride can react with hydroxyl radicals to form chloride free radicals and water and its half-life time is calculated as 11 days. No accumulation of hydrogen chloride per se in living organisms is expected due to its high solubility and dissociation properties.

The toxicity values to Selenastrum capriornutum 72h-EC50 is pH 5.1 (0.780 mg/L) for biomass, pH 5.3 (0 .492 mg/L) for growth rate and the 72h-NOEC is pH 6.0 (0 .097 mg/L) for biomass and growth rate. The 48h-ECso for Daphnia magna is pH 5.3 (0.492 mg/L) based on immobilization.

The hazard of hydrochloric acid for the environment is caused by the proton (pH effect). For this reason the effect of hydrochloric acid on the organisms depends on the buffer capacity of the aquatic ecosystem. Also the variation in acute toxicity for aquatic organisms can be explained for a significant extent by the variation in buffer capacity of the test medium. For example, LC50 values of acute fish toxicity tests varied from 4 .92 to 282 mg/L.

It is not considered useful to calculate a PNEC for hydrochloric acid because factors such as the buffer capacity, the natural pH and the fluctuation of the pH are very specific for a certain ecosystem.

There is a possibility that the emission of hydrochloric acid could locally decrease the pH in the aquatic environment. Normally, the pH of effluents is measured very frequently to maintain the water quality. In addition to that, water quality including the range of pH could be managed properly to prevent adverse effects on the aquatic environment based on the criteria of the pH in rivers and lakes. Therefore, a significant decrease of the pH of the receiving water is not expected. Generally the changes in pH of the receiving water should stay within the natural range of the pH, and for this reason, adverse effects on the aquatic environment are not expected due to anthropogenic or naturally occurring hydrochloric acid.

CO2:

Taylor (Taylor J.E., Transact. Nebraska Acad. Sci. 2, 176-181, 1976) conducted a bioassay on fish toxicity using brown trout (Salmo trutta) in a hatching troughs and a flow through test system. 22 fish were used and the concentrations of CO2 were 60, 100 and 150 mg/L.

In the 60 mg/L concentration the fish remained normal up to 96 h except for a a slight increase in depth of gilling. At 100 mg/L CO2 these fish showed some stress by hyper-activity when first introduced and deep gilling through-out the test. At 96 hours all fish alive and still feeding. At 150 mg/L CO2 the rate and depth of gilling were both increased and the fish were very sluggish during the test. At 48 hours two fish were dead, eight were on their backs and the remaining twelve react to stimuli. The test was terminated at this time as it was evident that the fish would not survive 96 hours. Due to these results it can be concluded that the LC50 for fish is between 100 mg/L CO2 (all fish alive after 96h) and 150 mg/L CO2.

No other tests on aquatic toxicity are available. However, the main target for environmental distribution will be air and it can be assumed that CO2 is with high probability not acutely harmful to aquatic organisms.

CO:

Carbon monoxide is slightly soluble in water (approx. 27 mg/L at room temperature) on one hand, while exhibiting a high vapour pressure on the other hand. There are no reliable information on the aquatic toxicology available. However, the physico-chemical properties of CO clearly indicate, that the main target for environmental distribution will be air. Therefore an assessment of aquatic ecotoxicology and therewith testing of carbon monoxide is not necessary. It can be assumed that CO is with high probability not acutely harmful to aquatic organisms. Additionally, according to Annex VI of the Directive EC/1272/2008 and Annex I of the directive 67/548/EEC CO is not classified for the environment.