SOURCE: Immunopharmacology & Immunotoxicology, 13(3):311-327, 1991

Research compiled by chem-tox.com
Wayne Sinclair, M.D.
Richard Pressinger, M.Ed.

The effects of chemicals on the immune system has also reached our waterways. Recent years has shown an increase in the number of fish kills being reported along with the number of fish being caught with tumors.  To investigate the effects of river pollution on the immune systems of fish, researchers from the Virginia Institute of Marine Science collected groups of fish from five different locations in the lower Chesapeake Bay. All locations had varying levels of contamination with polycyclic aromatic hydrocarbons (PAH’s).  PAH’s are a by-product of wood preservative contamination and vehicle exhaust.

The researchers discovered that the fish from the polluted water had T-cells (a primary immune system fighting white blood cell) that did not multiply as quickly when exposed to foreign invaders such as bacteria and viruses.

Of special interest, when the fish in the most contaminated water were transferred to the cleanest water in York River, there was a ten fold improvement in their lymphocyte production responses. In other words, putting the fish in cleaner water resulted in a dramatic improvement in immune function in the fish.  Since lymphocytes protect any species from bacteria, viruses and cancer, the consequences of this become obvious.

The study, published in the 1991 journal Immunopharmacology & Immunotoxicology, is certainly strong evidence linking so-called "average" pollution with causing depressed immune system function.  

The study should raise a red flag when considering spraying communities with chemical pesticides for mosquitoes since wildlife also receives significant exposure as their entire habitats and food sources are covered with chemicals well documented for weakening immune function.  

Since birds (specifically crows and doves) are the critical link in the transmission of encephalitis, even subtle decreases in their immune system function would result in increasing the percentage of birds contracting the disease.

As suggested by this research from the Virginia Institute of Marine Science, removing the environmental source of pollution results in an improvement in immune function, thereby restoring critical defenses against bacteria and viruses.   

This research also provides a logical explanation for why increases in rates of encephalitis among wildlife and humans will continue to rise.  In other words, each time we spray chemicals, the problem continues to grow.

Virginia Institute of Marine ScienceSchool of Marine Science
College of William & Mary, Gloucester Point, Va, 23062
Dept. of Animal and Fish Medicine, Cairo University, Egypt.