244 www.thelancet.com/neurology Vol 13 March 2014

In Context

LifelineThomas Leist is an associate professor of neurology at Thomas Jeff erson University, Philadelphia, PA, USA, where he heads the Division of Clinical Neuroimmunology and is director of the Comprehensive Multiple Sclerosis Center. His research group uses MRI imaging techniques to assess functional plasticity in multiple sclerosis and studies the genetics and immune responses in individuals with multiple autoimmune manifestations.

What has been the greatest achievement of your career? Bringing together a team of professionals to carry out multidisciplinary research and deliver comprehensive specialty care to patients with multiple sclerosis and other neuroimmunological disorders.

Who inspires you?The patients who entrust me with their care. I learn something new and valuable every day by seeing how individuals and their families deal with a potentially devastating illness, working to regain and maintain quality and purpose of life.

What was your fi rst experiment as a child?I received a book with the loosely translated title “Chemical experiments that work”. The experiments were grouped according to diffi culty and hazard. As a 12-year old, my goal was to do all experiments marked with an exclamation mark for danger. It drove my parents crazy.

What one invention would most improve your life?A software that could transcribe reports from my thoughts. Obviously, it would have to have strong controls, not everything is fi t for transcription.

What is your idea of a perfect day?To have learned something new and to have touched lives in a positive way.

What is your favourite fi lm, and why?Babette’s Feast. It is a beautiful movie with a powerful message: an act of kindness and generosity can touch many, even the unwilling.

If you were Bill Gates, how would you spend your fortune?The Gates Foundation pretty much covers how I would spend the money, albeit with a tweak here and there.

Do you believe in ghosts?No, but we all have skeletons in the closet that haunt us.

If you could have dinner tonight with a famous person of your choice (dead or alive), who would it be?Bill Clinton, maybe I could convince him to help me raise money to endow the social workers and nurses at the center I work at.

If you knew you had a week to live, how would you live those days?I would have to let people know where things are, so no sitting at the beach watching the last sunsets.

Focal pointPlagues and pesticidesThe recognition of the organochloride pesticide Bis(4-chlorophenol)-1,1,1-trichloroethane (DDT) as a risk factor for developmental neurotoxicity might now fi nally draw a line under one strand of a debate that has been ongoing for some 70 years.1

DDT was fi rst synthesised in 1874, but it was not until more than 60 years later that the potential of its insecticidal properties was recognised. Commercial sales commenced in 1945, and by 1955 its name had become the byword in agricultural pest control. But its market supremacy was short lived. The backlash against DDT, which started in the late 1960s and early 1970s, was mainly based on ecological concerns and its unknown bioaccumulative eff ects.2 And by the end of the 20th century DDT was listed as one of the “dirty dozen” persistent organic pollutants regularly targeted for a global ban. It has been spared such a fate only by inclusion as one of the 12 insecticides recommended by WHO in the fi ght to eradicate malaria, although this endorsement has not been universally applauded.3

DDT has been shown to be toxic in mammals, but the reported adverse eff ects in humans have mostly focused on the eff ects of acute exposure and at levels that were far in excess of those encountered in routine insecticidal use.4 There have been reports of the neurological eff ects of chronic occupational exposure,5 and recently a report on the raised levels of a metabolite of DDT in the serum of patients with Alzheimer’s disease.6 However, it is only with the advent of sophisticated epidemiological methods that subclinical toxic eff ects, particularly during developmentally vulnerable periods, have been studied in depth. Although the question remains as to whether the risks of developmental injury through the controlled use of DDT will outweigh its benefi ts in the control of malaria in the absence of practical alternatives, at least now the wider spectrum of toxicity of DDT can be appreciated in the debate.

Steven Goodrick

1 Grandjean P, Landrigan PJ. Neurobehavioural eff ects of developmental toxicity. Lancet Neurol 2014; 13: 331–40.

2 Rogan WJ, Chen A. Health risks and benefi ts of bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT). Lancet 2005; 366: 763–773.

3 Ahmad K. WHO’s decision challenged. Lancet Infect Dis 2006; 6: 692.4 Case RAM. Toxic eff ects of DDT in man. BMJ 1945; 15: 842–45.5 van Wendel de Joode B, Wasseling C, Kromhout H, Monge P, Garcia M,

Merglier D. Chronic nervous-system eff ects of long-term occupational exposure to DDT. Lancet 2001; 357: 1014–16.

6 Richardson JR, Roy A, Shalat S, et al. Elevated serum pesticide levels and risk for Alzheimer’s disease. JAMA Neurol 2014; published online Jan 24. DOI:10.1001/jamaneurol.2013.6030.

See Articles page 257