Get the Lead Out
Dateline: 05/21/98
Scientists at Cornell University announced this week that lead in the drinking water of pregnant rats can have lifelong effects on their offspring. Increased risk of asthma, cancer, and allergies may result from the mother's exposure to lead. This study could help explain why some people are born with lifelong tendencies or predispositions to certain diseases and ailments, assuming the study holds true for humans.
The levels of lead in the test water were low enough not to seriously affect the mothers' immune systems. However, the immune systems of the developing fetuses were seriously impaired, affecting both their resistance to allergies and their immunity to certain kinds of tumors.
The rats whose mothers had been exposed to lead developed normally during the first few weeks of life. However, when tested at approximately 3 months of age, these rats showed serious impairments to the immune system. They had much greater type-2 helper T-cell activity than type-1 helper T-cell activity. They also displayed diminished production of gamma interferon and had a depressed cell-mediated immune function.
These manifestations indicate that the rats had an impaired immune response for warding off infections and cancers and were more susceptible to auto immune diseases and allergies.
Scientists have not yet determined if there is a critical window (or windows) of time when the developing fetuses were most vulnerable to lead exposure.
Future studies will use chickens as the animal model to attempt to further elucidate the effects of lead exposure on developing fetuses.
Since most humans are exposed to lead through drinking water, old paint, and a variety of other sources, human subjects for a similar study could be found. At present, scientists have no plans to conduct such a study.
What do you think? Can we lessen the impact of lead by disposing of lead based hazards, particularly paint? What about the water supply? Come over to the Biology Forum and share your thoughts, opinions, and feelings. 'Til next time...
