2.2 Does the amount of mercury released by a broken CFL affect health?
The SCHER opinion states:
Exposure assessment
A fluorescent light bulb contains 5 mg of Hg. Assuming release of the total Hg- content of a lamp after breakage into an average room, Hg concentrations in the range of or above occupational exposure limits (100 μg/m3) can be derived. These concentrations are also well above regulatory limits for Hg in a general environment. Regarding environmental exposures, the US EPA has defined a reference concentration (RfC) of 300 ng/m3, and the US CDC derived a maximum residue limit (MRL) of 200 ng/m3. However, it needs to be recognized that these concentrations are applied to life-long inhalation exposures, are based on conservative extrapolations, and are considered protective for all groups of the population, including potentially sensitive subgroups. . The US EPA also has defined an acute RfC of 1.8 μg/m3 for Hg. The acute RfC is an estimate (with uncertainty spanning an order of magnitude) of an acute continuous inhalation exposure (time weighted average with a duration up to 24 hours) without appreciable risks of deleterious effects during a life time for the human population also including sensitive subgroups.
The simple assumption of a complete evaporation of the Hg content from a broken light bulb apparently results in a wide overestimation of air concentrations of Hg over time. Indeed, most of the released Hg may re-condense, due to the low volatility of Hg. Measured data suggest that a broken CFL may produce Hg concentrations of 8 to 20 μg Hg/m3 for a short time after the breakage. Air concentrations rapidly decline: concentrations ≤2 μg Hg/m3 have been measured in a house two days after an Hg spill from a CFL. An experimental study indicates even lower concentrations, between 0.8 and 0.1 μg/m3 Hg0, depending on CFL lamp type, in a room after CFL-breakage (Fig. 1 ).
Figure 1. Time course of average air concentrations of Hg in a standard room
However, the measured indoor air concentrations may not be indicative of the total Hg intake after a CFL breakage, since most of the Hg released may condense on surfaces, where it can persist if inadequate ventilation is present or in the absence of specific cleanup procedures. Equilibrium between Hg in air and condensed Hg will be reached and then Hg will be slowly oxidized to Hg ions. As a consequence, in addition to inhalation exposure, oral exposure to both elemental Hg and Hg ions may occur in children, due to ingestion of dust and hand-to-mouth contact. There are no data available on the potential contribution of such an exposure to total Hg-intake.
Compared to adults, children have higher exposure via various routes and internal doses of Hg due to several reasons. Children breathe more air per kg of body weight than adults at rest and tend to be more physically active than adults. Therefore, mercury vapours, if present in indoor air, may be delivered to children at higher internal doses than to adults (Miller et al. 2002). The foetus is also exposed during gestation as certain mercury species (HgCH3+) cross the placenta. A comprehensive review on mercury exposure in children is available in Counter and Buchanan (2004).
Since no data on the potential contribution of oral exposure to total Hg-intake are available for children, the SCHER recommends assessing potential Hg exposures from broken CFL lamps in an experimental setting specifically considering child behaviour. SCHER also recommends providing to customers specific instructions for Hg removal after breakage of a CFL and info for protecting children.
Based on the room air concentrations determined after breaking a CFL, a health risk for adults is not expected, since the exposure is in the range of occupational exposure limits for only a very short time. The occupational exposure limits are intended to protect adults for a 40-year work life. Due to the very low exposures and their very short duration, even sensitive subgroups in the adult population should be protected.
Given the measured Hg air concentrations after CFL breakage, the rapid decrease of these concentrations and the above-stated considerations on the RfC of Hg, the SCHER is of the opinion that a human health risk for adults due to CFL breakage is unlikely. Regarding risk for children, possible exposures from oral intake of dust and hand-to-mouth contact cannot be evaluated due to lack of scientific data; therefore, no conclusions on potential risk are possible. The external peak exposure to Hg0 by inhalation in adults after a CFL breakage is not translated into a sharp peak exposure of the foetus. Transfer of Hg0 from the maternal circulation to the foetus is limited. Therefore, foetal exposure is expected to be negligible.
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2.2 Does the amount of mercury released by a broken CFL affect health?
The SCHER opinion states:
Exposure assessment
A fluorescent light bulb contains 5 mg of Hg. Assuming release of the total Hg- content of a lamp after breakage into an average room, Hg concentrations in the range of or above occupational exposure limits (100 μg/m3) can be derived. These concentrations are also well above regulatory limits for Hg in a general environment. Regarding environmental exposures, the US EPA has defined a reference concentration (RfC) of 300 ng/m3, and the US CDC derived a maximum residue limit (MRL) of 200 ng/m3. However, it needs to be recognized that these concentrations are applied to life-long inhalation exposures, are based on conservative extrapolations, and are considered protective for all groups of the population, including potentially sensitive subgroups. . The US EPA also has defined an acute RfC of 1.8 μg/m3 for Hg. The acute RfC is an estimate (with uncertainty spanning an order of magnitude) of an acute continuous inhalation exposure (time weighted average with a duration up to 24 hours) without appreciable risks of deleterious effects during a life time for the human population also including sensitive subgroups.
The simple assumption of a complete evaporation of the Hg content from a broken light bulb apparently results in a wide overestimation of air concentrations of Hg over time. Indeed, most of the released Hg may re-condense, due to the low volatility of Hg. Measured data suggest that a broken CFL may produce Hg concentrations of 8 to 20 μg Hg/m3 for a short time after the breakage. Air concentrations rapidly decline: concentrations ≤2 μg Hg/m3 have been measured in a house two days after an Hg spill from a CFL. An experimental study indicates even lower concentrations, between 0.8 and 0.1 μg/m3 Hg0, depending on CFL lamp type, in a room after CFL-breakage (Fig. 1 ).
Figure 1. Time course of average air concentrations of Hg in a standard room
However, the measured indoor air concentrations may not be indicative of the total Hg intake after a CFL breakage, since most of the Hg released may condense on surfaces, where it can persist if inadequate ventilation is present or in the absence of specific cleanup procedures. Equilibrium between Hg in air and condensed Hg will be reached and then Hg will be slowly oxidized to Hg ions. As a consequence, in addition to inhalation exposure, oral exposure to both elemental Hg and Hg ions may occur in children, due to ingestion of dust and hand-to-mouth contact. There are no data available on the potential contribution of such an exposure to total Hg-intake.
Compared to adults, children have higher exposure via various routes and internal doses of Hg due to several reasons. Children breathe more air per kg of body weight than adults at rest and tend to be more physically active than adults. Therefore, mercury vapours, if present in indoor air, may be delivered to children at higher internal doses than to adults (Miller et al. 2002). The foetus is also exposed during gestation as certain mercury species (HgCH3+) cross the placenta. A comprehensive review on mercury exposure in children is available in Counter and Buchanan (2004).
Since no data on the potential contribution of oral exposure to total Hg-intake are available for children, the SCHER recommends assessing potential Hg exposures from broken CFL lamps in an experimental setting specifically considering child behaviour. SCHER also recommends providing to customers specific instructions for Hg removal after breakage of a CFL and info for protecting children.
Based on the room air concentrations determined after breaking a CFL, a health risk for adults is not expected, since the exposure is in the range of occupational exposure limits for only a very short time. The occupational exposure limits are intended to protect adults for a 40-year work life. Due to the very low exposures and their very short duration, even sensitive subgroups in the adult population should be protected.
Given the measured Hg air concentrations after CFL breakage, the rapid decrease of these concentrations and the above-stated considerations on the RfC of Hg, the SCHER is of the opinion that a human health risk for adults due to CFL breakage is unlikely. Regarding risk for children, possible exposures from oral intake of dust and hand-to-mouth contact cannot be evaluated due to lack of scientific data; therefore, no conclusions on potential risk are possible. The external peak exposure to Hg0 by inhalation in adults after a CFL breakage is not translated into a sharp peak exposure of the foetus. Transfer of Hg0 from the maternal circulation to the foetus is limited. Therefore, foetal exposure is expected to be negligible.
