Chronic stress exposure worsens effect of toxicants on blood pressure.
New research, published in Environmental Health, suggests that higher chronic stress exposure, or allostatic load, may intensify the adverse effects of lead on blood pressure among middle-aged U.S. adults.
The allostatic load (AL) is a composite measure of the wear and tear on the body that accumulates over time when a person is exposed to repeated or chronic stress.
Blood lead level (BLL), is a measure of lead that has entered the bloodstream. Exposure occurs through ingestion, inhalation, and dermal contact. A major source of exposure comes from factories and industries, vehicles exhausts, and even dust in the air. Other major sources include ingestion and contact with products such as paint and soil that may contain lead. Adults exposed to a dangerous amount of lead can experience hypertension, anemia, nervous system dysfunction, weakness, kidney problems, decreased fertility, increased miscarriages, and more. Children exposed to high levels of lead show similar symptoms and are more susceptible to damage from lower levels of exposure than adults.
For some time scientists have tried to understand the link between AL and susceptibility to the adverse effects of toxicant exposure. A toxicant is a type of poison that is made by humans or introduced into the environment by human activity, such as pesticides and lead.
In the new study, researchers from several U.S. universities analyzed associations between blood lead levels and blood pressure in a nationally representative sample of 8,194 U.S. adults, aged between 40-65 years, who participated in the 1999 — 2008 National Health and Nutritional Examination Survey.
Logistic regression models showed a direct relationship between blood lead and elevated systolic blood pressure among those with high AL, but not the low AL group. Similarly, the relationship between lead exposure and elevated diastolic blood pressure was stronger among the high AL group than the low AL group.
The researchers concluded that higher allostatic load may amplify the adverse effects of lead on blood pressure. However, they pointed to a need for future research to assess the implications of cumulative exposures to environmental and social stressors for regulatory decision-making.