Heating & energy

CFLs and mercury

Updated: 07 Aug 2009

Introduction

How safe are broken compact fluorescent lamps (CFLs)? We find out.

The introduction of CFLs has seen some emotive claims made about the perceived hazard from the mercury released from a broken bulb.

We've looked at an extensive independent study into the health risks, and conclude that the tiny amount of mercury in a broken CFL is unlikely to be a health hazard.

What's the risk?

All CFLs contain very small amounts of mercury (less than 5mg), which is only released if the bulb is broken. The amount of mercury released depends on how used the CFL is – the amount reduces as the bulb ages.

Mercury is particularly toxic to children, pregnant women (and the baby they’re carrying), and people with kidney disease. When mercury vapour enters our bodies, it has a half-life of about two months. That is, it takes around two months for the mercury level to halve, another two months to halve again … and so on.

But how much mercury is toxic? The total amount that enters our bodies is dependent on the combination of the mercury concentration level and the exposure time.

Safe concentration levels have been established by several overseas studies. It varies with the exposure time and for continuous lifetime exposure the concentration level is much lower than for short durations.

The Ministry study

We were planning to do our own testing of the health hazards from broken CFLs – but when we heard in late 2008 of a study being conducted by the Ministry of Health we decided our test would be a waste of resources.

The scenarios

The Ministry’s study looked at two broken-CFL scenarios. In the first, mess from the broken bulb wasn’t cleaned up and the room wasn’t ventilated. In the second, the mess was cleared up and the room was ventilated by opening the window.

Mercury vapour concentration levels were measured 15, 30 and 60 minutes after the breakage at the breathing levels for a child (300mm above the floor) and an adult (1500mm).

The study concluded that

“The averaged one hour concentrations were not likely to be a health risk - even if the broken bulb was not cleaned up immediately”; and
“adequate ventilation and clean up results in lower mercury concentrations”.

For both scenarios “human health risk is unlikely”.

The report can be downloaded from the Ministry of Health website.

Who did this study?

This study was performed by US-based Toxicology Excellence for Risk Assessment (TERA), under contract to the Institute of Environmental Science and Research Limited (ESR) and the New Zealand Ministry of Health.

TERA’s business is to “protect public health by developing and communicating risk assessment values, improving risk methods through research, and educating the public on risk assessment issues.”

… “this assessment was conducted by an independent, non-profit organisation, using state-of-the-science chemical risk assessment methods to protect public health”.

TERA used data from several different laboratory experiments where CFLs were broken in a controlled environment and the mercury-vapour concentrations measured over time.

Broken CFL clean-up

Broken CFL clean-up kit

To clean up safely after a CFL is broken, follow these steps from the Right-Light website:

1. Mercury vaporises readily at room temperature, so ventilate the room (by opening all the windows) for 15 minutes before you start the clean-up. Turn off all heating/air conditioning systems, heat pumps and dehumidifiers.
2. Don’t use a vacuum or a broom - this could vaporise the mercury and spread it through the room (as well as contaminating the vacuum cleaner or broom).
3. Put on a pair of rubber of latex gloves before cleaning up. This will help protect you against any cuts from the broken bulb.
4. Sweep up the big pieces of broken glass with a piece of stiff paper or cardboard. Then wrap these pieces in newspaper and place in a plastic bag. Use the sticky side of duct or some other wide tape to clean up the smaller pieces. Wrap these in newspaper too and place in the bag.
5. Wipe down the area with a damp paper towel. Place the used paper towels (and your gloves) in the plastic bag.
6. Store the sealed bag outside until the next rubbish collection.

Our advice

Consumer endorses CFLs as a way of reducing household energy bills and the CO2 emissions from electricity generation.
Be careful when handling CFLs – try not to break them. Don't use excessive force and try to hold the CFL bulb by the base and not the tubes when fitting it.
Don't use them in places where they are likely to get broken.
If a breakage occurs, children and pregnant women should stay away from the room. Ventilate the room and use the recommended clean-up procedures.

More information

Ministry of Health CFL mercury report: www.moh.govt.nz
Ministry for the Environment CFL cleanup guide: www.mfe.govt.nz