When a light bulb goes “ Pop !”, few of us give it much more thought than : “ Wow , they just don ’ t make those like they used to .” The fact is they don ’ t make them like they used to . Today , many of us use CFLs ( compact fluorescent light bulbs ) instead of the old incandescent light bulb that was first invented in 1802 , perfected by Thomas Edison , and which we have been using for over 100 years . If you do still have an incandescent light burning somewhere in your home or business , enjoy its warm , comfortable glow : these lights are no longer being sold widely and the incandescent bulb has gone the way of leaded petrol and the thin plastic “ national flower ” shopping bags that once adorned our countryside . CFLs are the “ greener ” option , insofar as they use significantly less power — between one seventh and one third of the power of an equivalent incandescent light — and can last eight to fifteen times longer . And while we don ’ t give it much thought when these long-lived lamps finally do pop their clogs , perhaps we should , because these apparently eco-friendly lights have a dark side . Here ’ s a quick science lesson to bring you up to speed .
Why should we think about how we dispose of CFLs ? Fluorescent tubes , CFLs and other mercury-bearing lamps emit light by exciting electrons bound to mercury atoms , to states where they radiate ultraviolet light . When this “ black light ” strikes the fluorescent coating on the inside of the tubes , it glows , emitting visible light . The mercury in a fluorescent light tube poses little risk to human health , as long as it stays in that glass tube . But what happens when this lamp is disposed of ? Incorrect disposal of mercury-bearing electronic waste can have far-reaching environmental consequences . Although mercury is a naturally occurring element existing as a gas , liquid or solid in soil , air and water , certain forms are toxic . And mercury levels have been increasing significantly in the environment over the past few decades , no doubt as a result of human technological advancement . According to a 1997 report by the United States Environmental Protection Agency ( EPA ), mercury poisoning in humans can affect “ the nervous system , the kidneys , and the developing foetus . Other systems that may be affected include the respiratory , cardiovascular , gastrointestinal , hematologic , immune , and reproductive systems ”. Mercury is most dangerous when it reacts with other chemicals to form methylmercury , which targets the nervous system . “ The developing foetus ,” says the EPA report “ may be at particular risk from methylmercury exposure . Offspring born of women exposed to methylmercury during pregnancy have exhibited a variety of developmental neurological abnormalities , including ... delayed onset of walking , delayed onset of talking , cerebral palsy , altered muscle tone and deep tendon reflexes , and reduced neurological test scores . For the general population , the critical effects observed following methylmercury exposure are multiple central nervous system effects including ataxia [ the loss of full control of bodily movements ] and paresthesia [ tingling or pricking sensations ].” These symptoms are no doubt a result of relatively high levels of exposure , but the increasing levels of mercury in the environment and the disturbing ability of mercury to accumulate , are valid concerns . Mercury is , in fact , “ one of the few metals that is known to biomagnify in aquatic food webs ”, the EPA report points out .
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