One BIG fish story

The potential perils have been played up in the press, but if simple common sense is used when disposing of a broken compact fluorescent light bulb (CFL), the resulting exposure to mercury is equivalent to a mere nibble of tuna

From 1000Bulbs.com: For over 100 years the Illuminating Engineering Society (www.ies.org) has been dedicated to improving the lighted environment. LD+A, their monthly magazine, presents articles of interest to lighting professionals and the public at large. In the August 2009 issue three authors (including two scientists from the Lawrence Berkeley National Laboratory) compared the mercury hazard of a broken compact fluorescent light bulb with that of a tuna fish sandwich. If you ever break a CFL, their essay (presented here with permission) should put your mind at ease while providing practical cleanup suggestions. Please let us know if we can help in any other way. Paul Coppage, LC, LEED AP

VP Product Development and Training

1000Bulbs.com

[email protected]

By Robert Clear, Francis Rubinstein & Jack Howells

Illuminating Engineering Society, August 2009

Lighting professionals are presumably aware that used CFLs are supposed to be recycled, and not just sent to landfills, because of the small amount of toxic mercury they contain. But what do you advise your clients when they break a lamp? And just how dangerous is the mercury inside?

You may have heard that clean-up costs are exorbitant and that the mercury vapor concentration from a broken lamp is unsafe. Actually, the amount of mercury that you are likely exposed to after breaking a lamp is no more than you subject yourself to when eating a bite of tuna. In this paper, we review the concerns, describe why we believe that the fish comparison is valid and show that the real risk is negligible.

Let's start with the reports of exorbitant clean-up costs and dangerous mercury vapor levels. In April 2007, Brandy Bridges accidentally broke a CFL in her daughter's bedroom and was left wondering what to do next.[1] After several referrals, she phoned the Maine Department of Environmental Protection (MDEP), which sent a specialist to her home a day later. Airborne concentrations of mercury were generally low, but measurements in two areas - a 1-ft area around the breakage and a nearby bag of toys where some lamp fragments had fallen - exceeded the state's air quality standard. When Bridges expressed concern about long-term exposure, she was referred to a commercial clean-up contractor; the estimate for a professional clean-up was $2,000.

This incident was quickly seized upon as an argument against the use of CFLs. Why should consumers bear the risk of introducing a potential safety hazard into their own homes just to save a little energy? Against health concerns and clean-up costs on this scale, a lower utility bill and the satisfaction from a little environmentalism seem meager encouragement. In response to public outrage, especially in the blogosphere, MDEP posted a reply documenting its assurances to Bridges that, in her case, "potential mercury exposure would be very low and likely of negligible health concern." Unfortunately, this assurance is apparently true only as long as broken CFLs are "properly cleaned up."[2] These responses are hardly less alarming. Would exposure be potentially hazardous under different circumstances? And what does proper clean-up entail? MDEP couldn't find the information to actually answer these questions, so they ran a study which examined 45 different breakage/clean-up scenarios.[3] They found that altering the ventilation conditions, cleaning methods and equipment, sample CFL, and breakage conditions and surface (e.g., Lamp & Fixtures in the Field hardwood floor versus carpet), resulted in average first-hour mercury vapor concentrations that varied by a factor of 600. Many of these concentration levels exceeded the state air quality standard, and the report concluded that "… homeowners consider not utilizing fluorescent lamps … where they could easily be broken, in bedrooms used by infants, small children or pregnant women …" and, should a lamp be broken over a carpet, that "… homeowners consider removal of the area of the carpet where the breakage occurred as a precaution, particularly in homes with infants, small children, or pregnant women." This is not much better than the $2,000 clean-up, and, if taken seriously, is likely to discourage a lot of people from considering CFLs at all.

A QUESTION OF EXPOSURE

Those of us who remember mercury thermometers, which contained 100 or more times the amount of mercury in a CFL, may well wonder how we ever survived. In fact, the use of the state air quality standard to determine the acceptable level for a one-time or infrequent exposure is extremely conservative. The state standard is based on an estimate of the No Observable Adverse Effects Level (NOAEL) for continuous (life-time) exposure. The MDEP justifies using this ambient air quality (AAQ) standard for a single exposure because of a lack of information on the effects of prenatal exposure: "An important issue for which there are no data is the relative importance of a short spike in exposure versus a longer-term lower exposure in producing toxicity. The U.S. EPA considers that a single exposure may be sufficient to produce effects in a developing organism because of the recognition of potential critical windows of vulnerability." Based on this logic, a short spike in exposure could be as short as a single breath. MDEP, without any discussion of the issue, confines its analysis to situations where the average level exceeds the AAQ for one hour.

The problem with applying this principle to air concentrations is that exposure is not directly proportional to the current air concentration. Human beings are continually exposed to mercury - from inorganic mercury salts in food and water, elemental mercury in air (from natural and anthropogenic sources), and organic mercury, such as methylmercury, in fish. Mercury becomes bound within tissues in the body, and is only gradually released over time. Prenatal exposure actually results from the combination of mercury from the environment and any mercury remaining in the bloodstream from a history of exposure.

While the various forms of mercury appear to have similar mechanisms of toxicity, methylmercury is the most dangerous for the prenatal or young infant; it readily crosses the placental and blood-brain barriers and is much more likely to be bound to the developing brain.[4-6] Comparing the mercury dose from a meal of fish, or even a past history of eating fish, to the dose from a broken CFL therefore becomes a useful, while conservative, exercise in understanding the real danger posed by CFLs.

For those following an "average" diet, fish is one of the most common sources of mercury that we are exposed to in everyday life. The amount of methylmercury that accumulates in fish varies according to how high the fish is on the food chain (Figure 1, right) [4]. The FDA encourages people, including pregnant women, to eat fish, but recommends that they eat no more than one 6-ounce meal per week of fish such as Albacore tuna, which is relatively high in mercury content. Albacore tuna is one of the most commonly consumed fish.