The Journal of the Royal Medlco-Chlrurglcal Society of Glasgow, the Medlco-Chlrurglcal Society of Edinburgh, and the Scottish Society for Experimental Medicine ISSN: 0036-9330
Volume 21 JULY 1976 Number 3
ENVIRONMENTAL RESEARCH-ARE WE ASKING THE RIGHT QUESTIONS?
Environmental research at the present time is characterised by an abundance of answers but a shortage of meaningful questions. This situation is not surprising since the environment is a relatively recent discovery. In the 18th century, scenery that had not been improved by man was regarded with extreme distaste. When Dr Samuel Johnson, some 2 centuries ago, travelled through the highlands of Scotland he complained of 'this gloom of desolation' and described the surroundings of Loch Lomond as 'nothing more than uncultivated ruggedness'. In 1828 the Charter of the Institution of Civil Engineers described Civil Engineering (which then meant the whole of engineering) as 'the art of directing the great sources of power in nature for the use and convenience of man'. In those days the environment was a system quite separate from man, to be pillaged and enjoyed. More recently a different view of the environment has been brought about by 3 factors. Firstly, we are changing from a cowboy economy, with boundless frontiers and unlimited opportunities, to a spaceship economy in which consumption is regulated by conservation. Secondly we have, in the present century and more especially in the last 3 decades, introduced into the environment many exotic materials; their eventual fate is seldom straightforward or predictable. Thirdly we now know that major chronic degenerative diseases (of increasing importance in an ageing population) such as cancer and heart disease, have their causes in the environment -bu t we do not know exactly where. The new view of the environment gives us many problems. When a potentially toxic substance is presented to the body it is a matter of chance whether the subsequent enzyme manipulations will make it more harmful or less harmful. Some poisons, such as ethyl alcohol, are detoxified with moderate
Scottish Medical Journal
success in the liver. On the other hand tetraethyl lead, not itself very toxic, is converted in the body to triethyl lead which is much more dangerous. There is some evidence that inorganic mercury, which is relatively innocuous, can be methylated in the tissues of the body and therefore made much more toxic. Another aspect of this problem relates to the uncertain fate of new substances in the external environment. Over the course of evolutionary time, nature has devised methods for the recycling of body tissues, cellulose and many metals. But we are now adding to the environment a rapidly increasing load of new substances, such as plastics and organic chemicals used in agriculture, which do not occur in nature. For most of these substances there are as yet no microorganisms and no enzymes to provide reasonably rapid recycling. In time, the biological disposal system will develop but today we are in too much of a hurry. We no longer want to live in a world built of natural materials, as was substantially the case until the beginning of the present century. Much of our effort in environmental control is directed towards short-term problems often of great political importance. Unfortunately the technical effort involved in this work is not accompanied by enough of the basic scientific research needed as a guide to future policy. We need for example to know more about the biochemistry of inorganic elements; most biochemists are, not surprisingly, more enthusiastic about nucleic acids and molecular biology than about the metabolism of arsenic, mercury, lead or pesticides. The metabolism of the potentially toxic substances now being introduced into the environment is seldom a straightforward problem. Recent studies on microsomal enzymes-found in the intra-cellular membranes-have uncovered processes by which one chemical may stimulate or suppress the production of 101
Comments
enzymes required to deal with some other compound. For example phenobarbitol decreases the activity of many other drugs by stimulating the production of microsomal enzymes which accelerate their metabolism; some drugs, such as ethyl alcohol, stimulate their own metabolism. The problem is further complicated because all animals do not have the same patterns of enzyme activity. Consequently tests of toxicity in animals may give misleading results when extrapolated to man. Another activity in which well meant efforts may give misleading results is the measurement of environmental contamination. For some elements, such as mercury and arsenic, the environmental hazards are influenced by biological cycles (usually driven by microorganisms) for the synthesis and degradation of toxic compounds. Over the course of evolutionary time we have come to terms with the methyl mercury which appears in the biological cycle for mercury. When this cycle is disturbed, for example by industrial activity, methyl mercury accumulates faster
102
than it can be degraded and consequently finds its way into food chains. By studying the biological cycles more closely, we might find ways of altering the rate of synthesis or degradation of toxic compounds. It is also possible to predict the effects of new chemicals in the environment. For example it is known that platinum and palladium will be methylated in the environment-a matter of interest in view of the increasing popularity of these metals in systems to reduce pollution from motor vehicles. Since microorganisms can often be induced to change their diet, increased effort in biochemistry might lead to the improvement of natural disposal methods for toxic chemicals. Much effort in relation to environmental health is ineffective because-as in other problems-we ask the wrong questions. We have been led to this situation because technology is well ahead of science. Perhaps we should now help science to catch up. J. M. A.
LENIHAN
Volume 21 JULY 1976 Number 3
ENVIRONMENTAL RESEARCH-ARE WE ASKING THE RIGHT QUESTIONS?
Environmental research at the present time is characterised by an abundance of answers but a shortage of meaningful questions. This situation is not surprising since the environment is a relatively recent discovery. In the 18th century, scenery that had not been improved by man was regarded with extreme distaste. When Dr Samuel Johnson, some 2 centuries ago, travelled through the highlands of Scotland he complained of 'this gloom of desolation' and described the surroundings of Loch Lomond as 'nothing more than uncultivated ruggedness'. In 1828 the Charter of the Institution of Civil Engineers described Civil Engineering (which then meant the whole of engineering) as 'the art of directing the great sources of power in nature for the use and convenience of man'. In those days the environment was a system quite separate from man, to be pillaged and enjoyed. More recently a different view of the environment has been brought about by 3 factors. Firstly, we are changing from a cowboy economy, with boundless frontiers and unlimited opportunities, to a spaceship economy in which consumption is regulated by conservation. Secondly we have, in the present century and more especially in the last 3 decades, introduced into the environment many exotic materials; their eventual fate is seldom straightforward or predictable. Thirdly we now know that major chronic degenerative diseases (of increasing importance in an ageing population) such as cancer and heart disease, have their causes in the environment -bu t we do not know exactly where. The new view of the environment gives us many problems. When a potentially toxic substance is presented to the body it is a matter of chance whether the subsequent enzyme manipulations will make it more harmful or less harmful. Some poisons, such as ethyl alcohol, are detoxified with moderate
Scottish Medical Journal
success in the liver. On the other hand tetraethyl lead, not itself very toxic, is converted in the body to triethyl lead which is much more dangerous. There is some evidence that inorganic mercury, which is relatively innocuous, can be methylated in the tissues of the body and therefore made much more toxic. Another aspect of this problem relates to the uncertain fate of new substances in the external environment. Over the course of evolutionary time, nature has devised methods for the recycling of body tissues, cellulose and many metals. But we are now adding to the environment a rapidly increasing load of new substances, such as plastics and organic chemicals used in agriculture, which do not occur in nature. For most of these substances there are as yet no microorganisms and no enzymes to provide reasonably rapid recycling. In time, the biological disposal system will develop but today we are in too much of a hurry. We no longer want to live in a world built of natural materials, as was substantially the case until the beginning of the present century. Much of our effort in environmental control is directed towards short-term problems often of great political importance. Unfortunately the technical effort involved in this work is not accompanied by enough of the basic scientific research needed as a guide to future policy. We need for example to know more about the biochemistry of inorganic elements; most biochemists are, not surprisingly, more enthusiastic about nucleic acids and molecular biology than about the metabolism of arsenic, mercury, lead or pesticides. The metabolism of the potentially toxic substances now being introduced into the environment is seldom a straightforward problem. Recent studies on microsomal enzymes-found in the intra-cellular membranes-have uncovered processes by which one chemical may stimulate or suppress the production of 101
Comments
enzymes required to deal with some other compound. For example phenobarbitol decreases the activity of many other drugs by stimulating the production of microsomal enzymes which accelerate their metabolism; some drugs, such as ethyl alcohol, stimulate their own metabolism. The problem is further complicated because all animals do not have the same patterns of enzyme activity. Consequently tests of toxicity in animals may give misleading results when extrapolated to man. Another activity in which well meant efforts may give misleading results is the measurement of environmental contamination. For some elements, such as mercury and arsenic, the environmental hazards are influenced by biological cycles (usually driven by microorganisms) for the synthesis and degradation of toxic compounds. Over the course of evolutionary time we have come to terms with the methyl mercury which appears in the biological cycle for mercury. When this cycle is disturbed, for example by industrial activity, methyl mercury accumulates faster
102
than it can be degraded and consequently finds its way into food chains. By studying the biological cycles more closely, we might find ways of altering the rate of synthesis or degradation of toxic compounds. It is also possible to predict the effects of new chemicals in the environment. For example it is known that platinum and palladium will be methylated in the environment-a matter of interest in view of the increasing popularity of these metals in systems to reduce pollution from motor vehicles. Since microorganisms can often be induced to change their diet, increased effort in biochemistry might lead to the improvement of natural disposal methods for toxic chemicals. Much effort in relation to environmental health is ineffective because-as in other problems-we ask the wrong questions. We have been led to this situation because technology is well ahead of science. Perhaps we should now help science to catch up. J. M. A.
LENIHAN
