[Note: To read the full text of this article free, click here. ]
Background: Chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) is characterized by persistent or recurrent incapacitating fatigue which can have a considerable impact on the function of the patients. A number of chemical substances have been reported to be associated with fatigue. However, it remains uncertain whether exposure to chemicals at levels usually considered safe is related to chronic fatigue.
This paper provides an overview of the existing evidence of association between chemical exposures, particularly in low levels, and CFS/ME.
Methods: The PubMed and the Scopus databases were searched using combinations of relevant terms, including ‘chronic fatigue’, ‘chronic fatigue syndrome’, ‘chemicals’, ‘toxicants’ and the names of specific ‘toxicants’ and classes of toxicants. Standard toxicology textbooks were also reviewed.
Results: The existing studies were in small number and had many limitations. Most studies were descriptive, and only a handful of analytic studies were located, which seldom compared cases of CFS/ME with healthy controls. None of them was prospective and they were commonly prone to selection and information biases.
The results are presented under the subheadings:
• Organophosphates and other pesticides/insecticides;
• Carbon monoxide (CO);
• Heavy metals;
• Solvents, ciguatera and other chemicals;
• And multiple exposures, including in Gulf War troops.
Conclusions: The existing evidence remains inconclusive as to the association between exposure to chemicals and chronic fatigue syndrome, and there is therefore a need for further well designed epidemiological studies.
Source: IACFS/ME Spring Bulletin 2009, March 5. 17(1) pp 3-15. By Luis Carlos Nacul, MD, MSc, PhD; Eliana Mattos Lacerda, MD, MSc, PhD; Dikaios Sakellariou, MSc, Doctoral candidate. Nutrition and Public Health Interventions Research Unit, London School of Hygiene and Tropical Medicine, London; Department of Occupational Therapy, School of Healthcare Studies, Cardiff University, Cardiff, UK. [E-mail: