Study of Mercury-containing lamp waste management in Sub-Saharan Africa

Executive summary

Mercury hazard in the End-Of-Life cycle of MCLs

Mercury (Hg) is a highly toxic element that is found both naturally and as an introduced contaminant in the environment. Mercury hazard depends on how contamination occurs and on the quantity and duration of human exposure. Mercury contained in an MCL is elemental (or metal mercury), which is highly volatile; it can be transformed by bacteria in water into organic mercury (or methylmercury), which is even more harmful, and bioaccumulate through the food chain. Contamination by elemental mercury mostly happens through inhalation, while contamination through organic mercury usually happens through ingestion of food. In both cases, mercury intoxication is either chronic or acute.

An MCL contains a small amount of mercury (usually 2 to 15 mg per lamp). Mercury is sealed into the glass bulb during its entire lifetime and is released progressively over time after the lamp breaks. Lamp breakage happens during usage or, which is more likely, after it enters the End-Of-Life stage (i.e. as waste). Once mercury is emitted, there are two levels of exposure that can be addressed separately. (1) Direct exposure is the contamination of the environment close to the source of emission. The risk – associated with the characteristics of the surrounding area (settlements, soil quality, etc.) – is concentrated around the source of emissions and can be measured in terms of air or water mercury concentration and frequency. (2) Indirect exposure is related to medium to long-term deposition, breakdown as local, regional, and global deposition, resulting in a diffuse risk. When mercury enters this broader cycle, it is not possible to monitor the geographical routes of deposition or to identify the resulting risks.

The following table shows the types of possible mercury emissions during potential stages of the End-Of-Life cycle and the associated modes of contamination.

Stage	Type of emission	Potential mode of contamination
Household	Airborne emissions due to one lamp breakage	Inhalation of mercury vapor by residents
Collection	Airborne emissions due to breakage during transportation in the truck first and then in the surrounding area	Inhalation of mercury vapor by operator
Transshipment	Airborne due to lamps broken during transportation or airborne through breakage during handling, usually in a closed area	Inhalation of mercury vapor by operator
Incineration	Airborne due to mercury vaporization in the furnaces, which can be filtered	Inhalation of mercury vapor by operators or site neighbors if low quality filters
Incineration	Generated waste (used filters, bottom ash and fly ash) may induce further emissions in landfills	Cf. Landfill
Recycling	Airborne emissions occurring during cutting or shredding of the lamp, usually in closed area	Inhalation of mercury vapor by operator
Recycling	Elution in case of wet washing	Bioaccumulation of washed out mercury and ingestion of contaminated fish
Landfill	Airborne emissions due to lamps broken before disposal or due to breakage in the landfill, mixed with other biogas	Inhalation of mercury vapor by operators, scavengers or site neighbors
Landfill	Elution via leachate of airborne mercury not previously emitted	Bioaccumulation of washed out mercury and ingestion of contaminated fish
Total	Airborne emissions from all stages carried by air and deposited at a varying distances from the emission point	Bioaccumulation of washed out mercury and ingestion of contaminated fish

Low and manageable risks to human health

In order to quantify the potential risk related to end-of-life CFL management, a worst-case-scenario has been studied based on 1 million lamps per year being sent to the same landfill, which would be equivalent to a high-end estimate for a Johannesburg landfill CFL feedstock in 2020. These conservative assumptions lead to a total emission of about 8 kg of elemental mercury in the air and the release of 4 kg of elemental mercury to the ground. From these results, compared with European and World Health Organization (WHO) official thresholds, we can infer that the main risks to human health are either low or can be mitigated.

Airborne pollution may only become significant in closed spaces, which would happen only in very specific situations such as a combination of closed garbage trucks (large load capacity with press) and a high concentration of FLs, or the breakage of a large number of FLs in a closed unventilated location (may lead to blood poisoning by inhalation of elemental mercury) – preventable by simple safety measures.

Risk due to water pollution leading to bioaccumulation of organic mercury throughout the food chain is low, but should not be neglected, though it is very complex to assess with to a satisfactory level of accuracy.

Lamp breakage in the home is not a significant threat and can be prevented by simple precautionary measures (ventilating the room and avoiding vacuuming the mercury-containing powder).

Emission considered in the End-of-Life CFL treatment	Population exposed	Acceptable thresholds	Worst case scenario emission values	Estimated risk
Vapor mercury due to household lamp breakage	Household	1 mg/m^3 over several hours for AI	0.5 mg/m^3	Low
Vapor mercury due to lamp breakage during collection	Collection workers	0.1 mg/m^3 for CI 1 mg/m^3 over several hours for AI	0.04 mg/m^3 0.18 mg/m^3	Low Low
Vapor mercury due to lamp breakage during transshipment	Transshipment workers	0.1 mg/m^3 for CI	0.035 mg/m^3	Low
Vapor mercury due to breakage of a whole post-pallet during transshipment handling inside a building	Transshipment workers	1 mg/m^3 over several hours for AI	> 1 mg/m^3 at emission point < 1 mg/m^3 at 3 meters from emission point	Significant, but controlled with basic safety rules
Diffuse vapor mercury due to lamp breakage in landfill	Scavengers, neighboring households	0.1 mg/m^3 for CI	0.009 mg/m^3	Low
Peak vapor mercury due to lamp breakage in landfill	Scavengers	1 mg/m^3 over several hours for AI	> 1mg/m^3 at emission point over a few seconds and disseminated by wind	Not significant
Soil and water pollution due to washed out mercury from the landfill and to deposed airborne mercury emission	Neighboring population, consumers	0.5 µg/l in the water	0.3 µg/l	Low (but should be monitored)