Does Banning Chemicals help the Environment? Chromatography Investigates

Read any newspaper and sooner or later you will come across a story about man polluting the environment with some chemical or other. The effects can be devastating on the environment: habitat loss, population damage and human tragedies have all been the consequences of chemicals released into the wild.

Controlling and Banning — Reducing the Exposure

How can we reduce the risk of these accidental or irresponsible releases? Generating awareness of the environmental risks associated with chemical releases is one method used for consumer products — hence we are now encouraged to recycle old batteries responsibly rather than consigning them to landfill. Governments use legislation and regulations to reduce environmental exposure to chemicals due to manufacturing’s chemical use. As the public becomes more environmentally aware, companies have seen the benefit of using their green credentials as a marketing tool. But sometimes the only solution might be to ban the manufacture and use of a chemical. But does this work?

A team in California has been studying the ecosystem of the San Francisco Bay area to monitor the levels of chemicals that were banned in California almost ten years ago. The chemicals are known as PBDEs, polybrominated diphenyl ethers, a flame retardant used in many products from electronics to building materials to furniture.

Chromatography Separates the Samples

The team from the San Francisco Estuary Institute (SFEI) have been taking samples over the last ten years to track the levels of PBDEs in the water, sediment, fish, bird’s eggs and bivalves (mussels, oysters and clams) from the Bay Area as discussed in this report: Polybrominated Diphenyl Ethers (PBDEs) in San Francisco Bay: A Summary of Occurrence and Trends.

Gas chromatography was used to separate the samples into their components and allow analysis of the levels of PBDEs. The components were then detected using electron-capture detectors (ECD) or analysed using mass spectrometry.

ECDs and Electronegativity

ECDs are one of the prime detectors used to detect halogenated compounds such as PBDEs due to the sample’s electronegativity. An ECD counts the number of electrons that hit the detector. An electron source emits electrons which remove more electrons from a carrier gas. When no sample is present the number of electrons detected is the background count. If a sample is present, the sample captures some electrons and the signal changes. The change is proportional to the sample quantity.

For an in-depth article about detecting halogenated samples using ECD take a look at the article One Step Extraction, Cleanup and Concentration of Pesticides from Soil from Chromatography Today.

Reducing the Levels

The SFEI team found that over the ten year period, the overall levels of PBDEs dropped in all of the sample groups. The largest concentration drop was in bivalves with a reduction of between 74 and 95% from the levels measured before the ban.

Although banning a chemical might seem drastic in some cases, the results from San Francisco show that nature can work to repair the damage we cause.