Health Effects of Acid Rain: Are There Any?

THE SCIENTIFIC and medical literature was reviewed to determine the relationship between acid rain and human illness. Rain and a pH below 5.6 is referred to as acid rain. Although 'acid rain' or more properly acid deposition is a relatively new environmental issue, Robert Angus Smith described the condition in the highly industrialized city of Manchester, England, in 1872.

While not precisely characterized, the mechanism of its formation appears to proceed from the photolytic transformation of sulfur and nitrogen oxides into sulfates and nitrates which in turn, in the presence of moisture, yield sulfuric and nitric acids.

The oxides of sulfur and nitrogen are by-products of fossil fueled power plant, automobile exhausts, smelting and chemical processing.

These oxides and acids have been associated with diminished fish populations, and malformations in a variety of estaurine species in Europe, the U.S. and Canada. Such destructive effects can signal potentially detrimental human health effects. Concern that acid rain may be a health hazard is widespread in our population. This review seeks to ascertain both the direct and indirect effects of acid precipitation by analyzing the salient scientific literature.

An exhaustive search of the pertinent literature indicates that deleterious human health effects, if there are any, remain to be established. As a consequence of pollution abatement efforts the next 15 to 20 years should witness a reduction in acid levels. Accordingly, a worsening of current levels of chemical pollutants is not anticipated. Hence, a significant threat to public health via acid rain currently or in the the foreseeable future, should not be expected.

Although acid rain' or more properly acid deposition, is a relatively new environmental issue in the United States, the term itself was advanced by Robert Angus Smith as early as 1872¹. Twenty years earlier in an article written for the Literary and Philosophical Society of Manchester (England) he remarked relative to that city's air that "we may therefore find easily three kinds of air, that with carbonate of ammonia in the fields at a distance, that with sulphate of ammonia in the suburbs, and that with sulphuric acid, or acid sulphate, in the town." He noted that it was the free sulfuric acid in Manchester's air which caused the fading of colors in textile as well as the rusting of metals² _.

Contemporary concern however was generated and focused by Oden's integration of both freshwater and atmospheric precipitation data reported in Sweden, and Schofields portentious observation of diminished fish populations in Adirondack Mountain lakes^3,4,5. Currently there is an emerging scientific consensus that acid precipitation has destroyed life in some fresh water lakes and streams, particularly in northeastern United States and Canada, and has damaged buildings and other structures. Debate continues about the effects of acid rain on trees and plants and on human health.

In August 1985, the U.S. EPA released a 1300 page document in which the studies of 50 environmental scientists were reported⁶. The following remark is contained in its summary: "acidic deposition (from precipitation) must contribute to acidification somewhere in the ecosystem. The deposition inputs may be over whelmed by the natural acidification process, however, and not cause measurable changes." Nevertheless, in January 1986, President Reagan's special representative on acid rain together with Canada's representative on the high-level acid rain panel, concluded in their report that acid rain is "a serious environmental problem". The scientific evidence, they find is "overwhelming"⁷. Whether acid rain is or is not a man-made pollutant, there is concern among the general public as to its potential for adverse health effects.

Although these concerns are widespread, there has generally been little information available to concerned professionals, administrators, as well as the public regarding the actual risks to human health. The conclusion that exposure is tantamount to illness may be overdrawn.

This review seeks to determine both the direct and indirect effects of acid precipitation on human health, by analyzing the salient scientific documents, published papers and summaries of national and international conferences.