Statement Of Jane Lipscomb
Environmental Protection Agency
Aging Initiative Public Listening Session
May 7, 2003
Jane Lipscomb RN, PhD, FAAN
University of Maryland School of Nursing
University of Maryland School of Nursing
Health Risk to the Elderly from Multiple Environmental Chemical Exposures
Thank you for this opportunity to testify this afternoon!
I would like to applaud the EPA for finally bringing attention to the "other end of the age continuum" in their consideration of the variable effect of environmental chemical exposures on human health. I urge the Agency to seize this opportunity to protect the health of the growing segment of our aging population by supporting research into the elderly's special vulnerability to the tens of thousands of synthetic chemicals that have been introduced to our environment over the past 50 years. It must be noted that our current elderly population has been exposed to a cumulative dose of environmental chemicals above and beyond that of past generations. Despite this, to date the elderly's lifetime exposure and unique vulnerability to synthetic chemicals in the environment has not been a focus of epidemiology or toxicologic study.
By contrast, there is a large and growing body of pharmacologic research describing the effect of the aging process on the uptake and metabolism of therapeutic chemicals, namely drugs. This increased susceptibility to adverse effect among the healthy elderly is no doubt exaggerated when combined with chronic disease and the multiple therapeutic agents used to manage these conditions. Pharmacotherapy is often the single most important medical intervention in the care of the elderly. Individuals aged 65 years or older living in the community take on average 1.8 over-the-counter drugs and a similar number of prescription drugs (Hanlon J, 2001). Prescription drug use is reported by 60-68% of men and 68-78% of women 65 and over. A similar proportion of both genders use non-prescription medications (Chrischilles 1992).
A rapidly accumulating literature regarding changes in the pharmacokinetics and pharmacodynamics with advancing age suggests that the elderly are particularly vulnerable to adverse drug reactions. In the absence of research exploring the harmful effects of multiple drug and environmental chemical interactions, we can only project the vulnerability of this population to the harmful effects of these complex chemical mixtures.
It is well recognized that aging is accompanied by marked changes in the physiology of many human organs, as well as their constituent cells. These non-pathological alterations in structure and/or function may affect normal physiological processes in the elderly, for example drug disposition and clearance (Schmucker, 2001). These age associated changes when superimposed upon the number and types of drugs taken at a time and underlying disease contribute to a high risk of adverse drug reactions among the elderly. In addition, drug therapy in the elderly may be complicated by factors such as decline in body weight, renal function, liver mass and hepatic blood flow making adverse drug reaction (including drug interactions) more frequent. Hepatic drug metabolism is mainly mediated by the cytochrome P(450) system and drug interactions in the elderly are likely related to the progressive decline of this system after the fifth decade of life and another decrease in individuals aged >70 (Anantharaju 2002). As such, drugs which are metabolized and excreted by the liver need to be prescribed with caution. Based on this evidence, gerontologist advise that therapeutics be prescribed for the elderly at a dose which is 30-40% smaller than the average dose used in middle-aged adults (Zeeh, 2002).
I challenge the EPA to consider the same level of protection of our elder from the adverse effects of environmental chemicals as has been recommended for therapeutics. Adherence to the Precautionary Principle clearly directs us to consider similar safeguards when it comes to exposure limits for environmental chemical exposures among our aging population.