Polybrominated biphenyls

Polybrominated biphenyls

Polybrominated biphenyls (PBBs) are a group of chemical compounds that are part of the broader family of flame retardants. PBBs were widely used in the past to reduce the risk of fire in a variety of consumer products, including electronics, textiles, and plastics. However, due to concerns over their environmental persistence, bioaccumulation, and potential health effects, the production and use of PBBs have been significantly restricted in many countries.

Chemical Structure and Properties

PBBs consist of a biphenyl molecule with two connected benzene rings that have been substituted with varying numbers of bromine atoms. The number and position of the bromine atoms on the biphenyl structure result in different congeners of PBBs, each with its own physical and chemical properties. PBBs are typically colorless to light yellow solids that are insoluble in water but soluble in organic solvents.

Uses

Historically, PBBs were added to a wide range of products to make them less flammable. They were used in the manufacture of electronic equipment, household appliances, textile back coatings, and plastic casings for consumer products. Their use peaked in the 1970s but declined sharply in the following decades as concerns over their safety and environmental impact grew.

Health and Environmental Concerns

PBBs have been found to be persistent in the environment, accumulating in soil, water, and living organisms. They can bioaccumulate in the food chain, leading to higher concentrations in animals and humans. Exposure to PBBs has been associated with several adverse health effects, including thyroid hormone disruption, reproductive and developmental toxicity, and potentially carcinogenic effects.

The most notable incident of human exposure to PBBs occurred in Michigan in 1973, when PBBs were accidentally mixed into livestock feed. This led to widespread contamination of the state's food supply and long-term health monitoring of exposed populations.

Regulation

In response to the growing evidence of their environmental and health risks, the production and use of PBBs have been restricted or banned in many countries. The Stockholm Convention on Persistent Organic Pollutants, an international environmental treaty, has listed certain PBBs for elimination or restriction.

Current Status

Today, the use of PBBs is limited, with safer alternatives being used in most applications where flame retardants are required. Ongoing research focuses on the environmental fate of PBBs, their mechanisms of action in living organisms, and the long-term health effects of exposure.

Polybrominated biphenyls Resources
Latest articles Most recent articles Ongoing trials	Wikipedia