An employee died from asphyxiation in a retention container associated with a tank of dichloromethane (or methylene chloride) at a plant producing decaffeinated coffee and employing a workforce of 25.  The victim died as a result of heavy inhalation of DCM combined with a high blood alcohol level of 2.3 g/l.

DCM is a solvent used to extract caffeine from green coffee. The process water containing the solvent is treated and the DCM is regenerated by a device consisting of a distiller, a condenser, a separator (or decanter) and an activated carbon adsorption unit. The inspection of classified installations (IIC) noted on site on 04/08/2004 the presence of more or less strong odours of solvent (DCM) on the samples taken at the bottom of 6 of the 9 activated carbon adsorption columns of the solvent regeneration unit and the presence of corrosion on some of them.

The accident was the result of a combination of inappropriate behaviour on the part of the victim who was drunk in a risk zone, a probable lack of prevention culture and anomalies linked to the operation of the equipment (performance of the installation, yield calculation, real-time monitoring of inlet and outlet flows, material balance, etc.) and its design (collection of vents, sizing and design of cooling and adsorption units, dust collectors, etc.). The IIC notes that the operator does not control its entire process, particularly with regard to the control of operating parameters such as temperature, pressure, flow rates, solvent flows circulating in the installation, quantities of solvent regenerated and emitted to the atmosphere, etc.

Following this accident, the operator set up an automated recovery system for the DCM coming out of the adsorber vents, transporting it in liquid form to storage. It installed 2 new dust collectors to prevent the dust from being captured by the air-cooling towers and particle filters on the water leaving the air-cooling tower before it enters the condensers to prevent the condensers from clogging, resulting in an increase in temperature in the DCM recovery process; in fact, if the cooling does not work properly, the solvent is then mainly in the gaseous phase. It adds a cooling unit to lower the temperature of the gases present in the safety tank upstream of the adsorbers and to renew the activated carbons in the adsorbers. Finally, it secures the retention basin of the DCM storage with a screen and establishes new safety instructions. In September 2004, the Prefect conditioned the resumption of the company’s activity to the demonstration of perfect control of the process.

On 18/09/2003, a major release of DCM into the atmosphere had inconvenienced local residents (ARIA 36653).