Dr. Bruce Molholt has taught molecular biology in three United States colleges and universities. He has done research for six years in various European universities. His research activities include viruses and cancer, and the epidemiology of cancer. At present he is examining how carcinogenic chemicals change DNA to initiate cancer. Dr. Molholt earned his Ph.D. from Indiana University and is presently teaching at Haverford College in the Department of Biology.
This Water Fact Sheet will be divided into three parts:
- Water Carcinogens A National Problem
- The Water Problem
- Solutions to the Water Problem
1. Water Carcinogens A National Problem
In the United States, we have prided ourselves on uncontaminated drinking water supplies ever since the turn of the century. With no small amount of smugness we chortled at the Montezuma’s Revenge our friends brought back as a souvenir from Mexico. We avoided the waters of Rome and Paris, and were glad when we could come back home to that good clean chlorine taste. Chlorination has abolished water borne bacterial plagues such as cholera, dysentery and typhoid fever. However, chlorination has not stemmed the tide of another, more insidious plague, carried into each of our homes in the public water supply. This modern plague, cancer, is on the rise, and, think some experts, will reach epidemic proportions within this century. Chemicals in our water supply play a role in this cancer plague, how great a role we shall discuss further. Chlorination does not help remove carcinogenic chemicals. On the contrary, it exacerbates the problem by creating more of the same.
Industrial pollution of our drinking water supplies is nothing new, but has grown at an alarming rate. The synthetic chemical industry derived a dazzling array of new products such as DDT, PCBs, TCE and 2, 4, 5-T much faster than our ability to test them. Most adverse health effects of these chemical carcinogens take years to manifest their cancers and then we notice a cause-and-effect relationship only among discreet populations, such as pesticide workers. Between 1931, when PCBs were first synthesized, and 1971, when their manufacture was banned, over 300,000 tons of PCBs were produced, 60,000 tons of which have found their way into the environment. A similar story holds for DDT and many other chlorinated hydrocarbons, which have been the mainstays of the synthetic chemical industry. In addition to their other chemical properties they: 1) are very stable, and 2) they are fat-soluble. Hence, the final reservoir for many chlorinated hydrocarbons like PCBs and DDT is animal fat, measuring fat of an Antarctic penguin, of a fish two miles deep in the Atlantic trench or in human breast tissue, these substances are everywhere.
In addition to their direct contamination during manufacturing processes, many substances contaminated by these chlorinated hydrocarbons have been illicitly dumped. For example, at Love Canal it is estimated that at least 60 pounds of dioxin were among the thousands of tons of chemicals dumped into the canal. Dioxin, a contaminant of 2, 4, 5-T, is the most potent synthetic organic chemical known. This chlorinated hydrocarbon is carcinogenic in parts per trillion quantities. Whether dumped directly or contaminating the groundwater beneath an improperly designed dump, many of these synthetic organics have worked their way into our drinking water supplies.
Cities at the mouths of major rivers are especially privy to pollution by chemical carcinogens. New Orleans, at the end of the nation’s longest river system, is notorious for its bad water supply which has been recycled through innumerable industries and homes lining the Missouri-Mississippi system. New Orleans also has one of the nation’s highest cancer rates. But so does Philadelphia. And in a recent Ames test of the two cities’ water supplies, Philadelphia’s wound up containing more carcinogenic chemicals than did New Orleans.
2. The Water Problem
In the Northeast we have faced a drought this past year which may last as long as five years. As the volume of our river waters shrink the concentration of carcinogenic chemicals contaminating these waters increases proportionately.
An additional effect of the drought has been to increase fecal contamination of our rivers. In Passaic, New Jersey, in response to higher coliform counts due to the drought, chlorination levels were increased by four times the normal level. This heavy chlorination of organically polluted water will cause the formation of much more chloroform and other chlorinated hydrocarbons. The net effect of the drought for affected communities may be as much as a tenfold increase in the concentration of carcinogenic chemicals in their drinking water supplies from both industrial and chlorination sources.
In a preliminary study, the Environmental Cancer Prevention Center has compared cancer mortality rates in Philadelphians who consumed either Schuylkill River-derived or Delaware River-derived drinking water for the years 1968-78. The study was designed to compare cancers at different organ sites for these two populations who reside west or east of Broad Street, respectively. Residents on the west side of Broad St. (Schuylkill) were found to have had 67 percent more cancer fatalities due to cancer of the esophagus than residents on the east. East side residents (Delaware), on the other hand, suffered 83 percent more fatalities due to malignant melanoma, 59 percent to brain cancer and 32 percent more due to colorectal cancers than west side residents. These variations in cancer mortality patterns may be linked to contamination of the Delaware River by the chemical industries and variations in chlorination treatments accorded the two water supplies.
3. Solutions to the Water Problem
Although industries are changing their habits of water pollution either voluntarily or under pressure from environmentalists and regulatory agencies, it will be many years before our waters are free of chemical pollution. Stringent rules regulating hazardous waste disposal will prevent future abuses, but Superfund and other legislations to clean up extant, abandoned sites will have little immediate impact and represent less than 5 percent of the effort required to clean up all dangerous hazardous waste sites. Hence, in order to protect the public, we must find other short-term solutions.
One practicable solution is granular activated carbon (GAC) already used by some European metropolitan communities and commonly by industry in the U.S. to remove disagreeable tastes from water for the manufacture of beverages. Particles of GAC have enormous surface areas and absorptive properties for chlorinated hydrocarbons. Virtually all carcinogenic chemicals can be removed by filtration through GAC. It can be installed most conveniently above the sand beds normally employed in municipal water treatment plants. In Philadelphia, a pilot GAC filter is operating at the Torresdale Plant on the Delaware River. Installation of such a system would cost about $1 million and maintenance about $1 per month per household.
Filtration with GAC would remove carcinogenic chemicals contaminating our water supplies as they enter water treatment plants. To prevent further formation of carcinogenic chemicals through chlorination, ozone may be substituted for chlorine as disinfectant. Again, this substitution has met with success in European municipalities and would be inexpensive to adopt and maintain.