Environmental Aspects of Isocyanates in Water and Soil

Abstract

Liquid TDI and most types of MDI which are liquid at room temperature if spilt in large amounts into stagnant or running water will become solid if the temperature of the water is below 10°C. The reaction of the liquid or solid products with water is relatively slow because the products are practically immiscible with water. The reaction products are solid, insoluble and biologically inert polyureas.

In order to investigate the fate of these polyureas contaminating soil after isocyanate spillages the influence of several types of soil was studied using radio-labelled materials. There was neither an indication of degradation observed nor radioactivity found in soil extracts.

TDI and MDI were of low acute or chronic toxicity to a variety of aquatic species in systems designed to simulate the environment in marine and river water. It has also been shown that these products were of negligible toxicity to growing bacterial cultures. This series of experiments has confirmed that effects of isocyanates on aquatic systems on longer term exposure are unlikely to persist and that aquatic systems should recover rapidly from accidental spillages of TDI and MDI.