Mercury in CFL bulbs

We've all heard the marketing spin about so-called "energy-saver" light bulbs: they last seven times longer than an ordinary bulb, they use only a fifth of the power. In theory, compact fluorescent lights are the way of the future, a solution to soaring energy wastage and a sure-fire way to go green in the home and save cash doing it.
In theory.

Sometimes what looks good on paper turns out to be not so flash in practice, and when politicians get involved it can be a recipe for disaster.

"The energy saving potential is of the order of 6% of domestic sector electricity use, or 2% of total electricity use," top science consultant David Cogan has told the New Zealand government in a briefing paper.1 Remember that figure: the banning of ordinary light bulbs will reduce total electricity demand by 2%. The question is, after you've read the full story, whether you think Labour and the Greens' plan to save 2% is worth the effort.

"Energy saving lamps contain a small amount of mercury which makes them operate much more efficiently than incandescent and halogen lamps. Mercury is toxic to human health and bioaccumulates [Bioaccumulate – the accumulation of a substance, such as a toxic chemical, in various tissues of a living organism.] in the environment but the amount inside an individual lamp is not large enough to pose a hazard to users."2

The spin is clear. The lamps are "energy saving", it is only a "small amount" of mercury, which makes the lights operate "much more efficiently". Importantly, on the safety side, the Ministry for the Environment assures New Zealanders that "the amount…is not large enough to pose a hazard to users".

In March last year, Brandy Bridges, a mother in the town of Prospect, Maine, in the US, heard the publicity about the new energy-saver light bulbs and went out and purchased two dozen of the CFLs for the family home.

While installing one in her young daughter's bedroom, Bridges accidentally broke the new CFL bulb, which shattered and fell to the carpet.

Remembering that the bulbs contained a trace amount of mercury, she called around for advice, eventually hitting the Maine Department of Environmental Protection (DEP) who suggested she call in a hazardous waste crew. When the hazard contractor quoted US$2,000 to clean the bedroom, Bridges decided simply to seal off the room and make her daughter sleep elsewhere in the house while the issue was sorted out. (See sidebar feature for Brandy's story)

As publicity from the unfortunate event spread across America, it quickly became apparent that neither the US Environmental Protection Agency (EPA) nor anyone else had up to date information on the hazards of household CFLs.

Not to be beaten, the Maine DEP called in its own science team to run some experiments on broken CFLs. The DEP team smashed dozens of bulbs in a series of tests to see just how much mercury they emitted, and how much was left in the environment after various clean-up scenarios were tried. The experiments were conducted over bare floors, and carpeted floors.

The study team reported back just a few months ago, in February 2008, and the findings in their massive 160 page report have stunned US safety authorities.

First off, the often-cited claim that bulbs contain only 5mg of mercury was clarified: it's an average.

"Without the mercury, the lamp would not produce visible light. The average amount of mercury in a CFL is 5 mg with a range of 0.9 to 18 mg."

Obviously, the smaller (in watts) the bulb, the less mercury. Higher power (brighter) bulbs generally have more, although there can be fluctuations between brands as well.

One busted bulb in a bedroom produced very disturbing results in their tests.

"Mercury concentration in the study room air often exceeds the Maine Ambient Air Guideline (MAAG) of 300 nanograms per cubic meter (ng/m3) for some period of time, with short excursions over 25,000 ng/m3, sometimes over 50,000 ng/m3, and possibly over 100,000 ng/m3 from the breakage of a single compact fluorescent lamp," the report confirms.

That's up to 300 times higher than the recommended safe level of inhalable mercury vapour. From just one light bulb.

when Maine DEP scientists went back to Brandy Bridges' house some three months after the breakage, they found mercury contamination in the bedroom was still as high as 2000 ng/m3 – three months later and despite following all the cleanup recommendations.

In the end, the DEP ripped out her carpet and disposed of it as toxic waste. And little wonder. According to the DEP scientific study, while the 300 ng/m3 limit is the maximum allowable daily dose of mercury for the sake of legislation, there is in fact no known safe level for mercury exposure.

"The Maine Ambient Air Guideline (MAAG) of 300 ng/m3 is identical to the EPA reference concentration (RfC), which is designed to protect against chronic exposure. The RfC is based on a number of occupational studies, in which tremor, fine motor deficits, electroencephalography (EEG) and autonomic nervous system abnormalities, and cognitive deficits were observed.

To make matters worse, scientists believe the 300 ng/m3 limit may not protect children or infants.

"Sensitive populations are of particular concern with mercury exposures for a number of reasons. Mercury exposures have serious impacts on fetal and infant brain development. Elemental mercury can cross the placenta from a mother to fetus. For these reasons, acute peaks could be particularly problematic during pregnancy. Infants and toddlers have much more vulnerable brains.

"Neurotoxicants identified in adults may have different and more severe effects in developing organisms. Infants and toddlers also have a much higher rate of respiration than adults. Therefore they have a higher exposure to similar concentrations. They also are lower to the floor and therefore closer to the source of the exposure and presumably more apt to obtain a concentrated dose of mercury.

"Elderly and unhealthy individuals may already be at comprised health and be more susceptible to mercury effects than a healthy individual. For example, mercury does kidney damage which could exacerbate an already existing kidney disease."

Additionally, pregnant women exposed to a broken CFL light bulb could literally destroy their baby, in the wrong circumstances:

"It is well established that the developing organism may be much more sensitive than the adult to neurotoxic agents," reports Maine's DEP study. "For example, methylmercury exposure can produce devastating effects in the fetus, including cerebral palsy, blindness, deafness, and even death, while producing no or minimal effects in the mother."

The Maine study is believed to be the first of its kind, and it was only published in February this year. New Zealand authorities appeared to be unaware of it when Investigate contacted them.

On its own website3, the US Environmental Protection Agency says it is now undertaking a "full review" of the Maine study with a view to updating its own recommendations on how to deal with CFL breakages in the home.

And it's not as if the EPA was already limp-wristed on the subject.

"Never wash clothing or other items that have come in direct contact with mercury in a washing machine, because mercury may contaminate the machine and/or pollute sewage. Clothing that has come into direct contact with mercury should be discarded," warns the EPA.

By "direct contact," the EPA is referring to clothes you were wearing if you happen to break a bulb while installing it, or if you were underneath it when it broke. If that happens, your clothes must be thrown out, in a sealed plastic bag, immediately.

If you attempt to clean up the broken light bulb, you can keep the clothes you are wearing, but only if they don't come into direct contact with lightbulb fragments or powder. Those clothes can be washed, but should be done so separately from other clothes. Whilst it is vital that your skin does not come into contact with the residue, that means you may also be up for the cost of a new pair of shoes.

"Never walk around if your shoes might be contaminated with mercury. Contaminated clothing can also spread mercury around," warns the EPA.

Another no-no is vacuuming. Although it might suck up glass fragments and powder residues, the mercury vapour molecules are so small the vacuum cleaner spits them back out through the exhaust into the whole atmosphere of the house, dramatically increasing the area of mercury contamination. Additionally, "agitating" the carpet via vacuuming or sweeping or even walking or playing on it throws more mercury back into the air and into your lungs.

"Never use a vacuum cleaner to clean up mercury," says the EPA. "The vacuum will put mercury into the air and increase exposure."

The Maine DEP study found there were three crucial areas of mercury exposure from a broken bulb:

"This study identified several potential exposures from the breakage of a CFL. The first is the air concentration from the initial break and cleanup. The next is the source left in the flooring surface. This ongoing emission affects both those using the surface in close contact and sometimes those more distant from the flooring, especially when the floor is agitated. The final piece is the emissions from the broken lamp debris once cleaned up. The three different potential mercury exposures each impact guidance for appropriate handling of a broken CFL."

The report also noted that following official clean-up guidelines was still not good enough to eliminate the pollution.

"Although following the pre-study cleanup guidance produces visibly clean flooring surfaces for both wood and carpets (shag and short nap), all types of flooring surfaces tested can retain mercury sources even when visibly clean. Flooring surfaces, once visibly clean, can emit mercury immediately at the source that can be greater than 50,000 ng/m3. Flooring surfaces that still contain mercury sources emit more mercury when agitated than when not agitated.

"This mercury source in the carpeting has particular significance for children rolling around on a floor, babies crawling, or non mobile infants placed on the floor.

"Cleaning up a broken CFL by vacuuming up the smaller debris particles in an un-vented room can elevate mercury concentrations over the MAAG in the room and it can linger at these levels for hours. Vacuuming tends to mix the air within the room such that the one foot and five foot heights are similar immediately after vacuuming. A vacuum can become contaminated by mercury such that it cannot be easily decontaminated. Vacuuming a carpet where a lamp has broken and been visibly cleaned up, even weeks after the cleanup, can elevate the mercury readings over the MAAG in an un-vented room."

In fact, the data showed that three weeks after the breakage had been cleaned to EPA standards, one vacuuming could send mercury levels in the room back up to 12 times higher than the maximum safe level, and keep them there for hours – cold comfort if you have kids in your house, and a major risk to your vacuum cleaner.

Additionally (and this is why carpets have to be destroyed), the scientific team repeatedly vacuumed carpets where bulbs had broken, to see if vacuuming did eliminate the residue. They found that even after several attempts, the mercury was still trapped in the carpet fibres. To make matters worse, some of the vacuum cleaners were so contaminated that cleaning them was impossible, meaning not only was the carpet over and out, so was the vacuum cleaner.

"Double re-sealable polyethylene bags…did not appear to retard the migration of mercury adequately to maintain room air concentrations below the MAAG… The significance of this issue is that cleanup material may remain in the home for some period of time and/or be transported inside a closed vehicle, exposing occupants to avoidable mercury vapors when improperly contained," report the Maine scientists. The best method of containing bulb waste is inside a glass jar with a hermetically sealed lid.

Surprisingly, plastic jars, like large peanut butter containers with screw top lids were little better than plastic bags, also failing to prevent mercury vapour from leaking into the house.

The scientific experiments proved that debris "sealed inside two polyethylene plastic bags and then placed in a clean room", sent atmospheric mercury levels up to more than three times the maximum allowable limit, for more than eight hours – the mercury vapour simply leached out of the bags into the air.

"Of the 12 different types of containers tested during the 23 different tests, the plastic bag was found to be the worst choice for containing mercury emissions. Based upon this study, the DEP now suggests that a glass container with metal screw lid with a gum seal be used to contain debris."

The US scientists say it is possible that one single "spike" dose of mercury could be enough to damage a baby or a child's brain, even if there is no further ongoing exposure. With the experiments showing a 20 watt CFL (equivalent to 100 watts ordinary) bulb can produce a spike of 100,000 ng/m3 of air, 300 times the recommended allowable maximum, this could be a major safety problem with making CFLs the light of choice when ordinary bulbs are banned.

"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," says the Maine report. "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. This implies that any exposure over an accepted toxicity value is potentially cause for concern, since a single exposure may produce a perturbation in a single or multiple processes in discrete brain areas, depending on the developmental stage of the exposure. Any such perturbations may have "downstream" consequences: if A doesn't happen, then B and C cannot happen in a normal manner.

"Repeated exposures would presumably increase the probability of untoward consequences. In addition, the relative risk of various exposure metrics is unknown: whether the greatest risk is posed by short-term higher level peak exposures or by the total area under the curve including higher and lower exposures."

To further muddy the waters, the scientists note that the mercury contamination was considerably worse – nearly double in fact – at summertime temperatures (32C) than winter (23C).