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Filtration of drinking water
1916.
93
PUBLIC HEALTH.
up to the smnmer of 1915. Some 2,ooo visits had been paid for purposes of ascertainment, and in the first six months the local voluutarf¢ society paid about I,OOO visits for supervision, apart from visits of after-care paid to Education Acts cases. The general condition had prevented all the cases in need of institutional care being at once placed therein, and delays nmst be anticipated so long as the Treasury limitations remained. To facilitate selection cases in need of institutional treatment had been classified by age into groups, under 7, 7- 1 6 , 16--35, and over 35. With cross classifications showing whether they were idiots, imbeciles, moral imbeciles, feeble-minded; whether they were of higher or lower social and moral classes ; and whether they were : (I) able with help and supervision to attend to their own wants, and do simple tests, or (2) would require little help, or (3) would need much assistance, or (4) were practically helpless, or (5) were epileptic, or (6) were epileptic and paralysed, or (7) would need much control. On the general medical side it has been noted that just one half the cases dealt with were not of hereditary nature, but due to disease or injury in some period of prenatal life, at birth, or in early postnatal life. In connection with the family histories of 6oo families containing defective members, as contrasted with I,OOO families of rtormal individuals, it is noted that if the birth-rate of the defectives was higher, the death-rate was also much higher, so that long before the reproduction passed the balance in favour of the defectives was destroyed. This selective death-rate is obviously nature's method of protection, and threw a heavy responsibility on the Society of Medical Officers of Health. Nature's verdict was the defective shall perish in infancy or early life ; the Society said, " Let us establish Midwives' Acts, compulsory notification of births, infant consultations, and the like, and interfere with nature's blind decrees." If the members do not also see to it that the defectives they help to preserve are segregated, they may do grave eugenic ill to the nation who now and in the future has need not only of the numbers but of the faculty of her citizens. Dr. W. It. SYMoNs, Bath, said that in working the Act in his area he had received a gratuity of £3o towards meeting the expenses incurred. He did not think it was part of the duty of medical officers of health to incur expense in supervising the working of the Act. DR. FRANI< ROBINSON having replied, the meeting adjourned. H o w SMALLPOX WAS ABOLISHED IN PORTO RICO.
- - A f t e r America took possession of Porto Rico the Government vaccinated over 800,000 persons during an epidemic of smallpox, and in four months smallpox was abolished.
FII,TRATION
OF
DRINKING
WATER,
BY
J. W. TALENT, M.D., M.R.C.S., D.P.H., Medical Officer o/Heallh, Ashlon-under-Lgne.
I
H A V E been led to present to y o u some remarks upon the purification of drinking water owing to the fact t h a t the water supplied to the area with which I am connected is now being subjected to v e r y complete and t h o r o u g h t r e a t m e n t b y chemical agents and mechanical filters. The works installed for this purpose came into action on S e p t e m b e r I p t h , 1912. Before describing this installation and its results I will refer briefly to the general characters of the w a t e r s u p p l y in question. I t is provided b y a joint w a t e r b o a r d k n o w n as the A s h t o n - u n d e r - L y n e , Stalybridge and Dukinfield (District) W a t e r w o r k s J o i n t Committee, and supplies the boroughs of Ashtonu n d e r - L y n e , Stalybridge, Dukinfield, and Mossley, and u r b a n districts of H u r s t , Audenshaw and Saddleworth, and the rural district of Limehurst. T h e t o t a l area is 33,793 acres~ or 52"8squafemiles, with a p o p u l a t i o n of I43,648. The c o n s u m p t i o n per h e a d per d a y for all purposes is 2o'6 gallons. The source of supply f r o m which the water is obtained consists of three gathering grounds, situate in the Pennine Range, some four or five miles due east and n o r t h - e a s t of the town of Ashton, and is m a d e up as follows : - Swineshaw Valley .. 1,3oo acres Greenfield Valley .. 1,17o ,, Chew Valley . . . . 1,73o ,, Total .. 4,200 The average rainfall in the Greenfield district for the past 30 years is 51"64 inches and in the Swineshaw district 46"86 inches. Mr. Dixon, w a t e r engineer to the committee, has kindly supplied me with the following general description of the source of supply. " Greenfield Valley S u p p l y . - - T h e gathering ground which supplies the t w o impounding reservoirs, ' Y e o m a n H e y ' and ' Greenfield,' is entirely moorland, and quite free of all habitation. P e a t covers n e a r l y the whole of the watershed, and varies in thickness from 12 in. to a m a x i m u m d e p t h of 15 ft., this resting upon the Millstone Grit, which f r e q u e n t l y crops out on the higher portions of the gathering ground, the surface being covered with coarse grass and some heather. In consequence of the v e r y precipitous character of the hillsides surrounding the
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PUBLIC ttEALTH.
reservoirs, t h e flow f r o m t h e surface is often e x t r e m e l y rapid. A t t h e ' Y e o m a n H e y ' reservoir it is f o u n d t h a t a s o m e w h a t larger p r o p o r t i o n of t h e s t r e a m s u p p l y consists of springs t h a n is t h e case a t Greenfield, where a considerable q u a n t i t y of p e a t y w a t e r is given off in t h e u p p e r reaches of t h e Greenfield Brook. F u r t h e r , during h e a v y rains, a large a m o u n t of s a n d a n d p e a t gets w a s h e d into the reservoirs b y erosion d o w n the steep watercourses which abound on t h e hillsides~ " Swineshaw Valley [email protected] g a t h e r i n g g r o u n d w N e h supplies the four i m p o u n d i n g reservoirs--' Higher Swineshaw,' ' Lower Swineshaw,' ' Brushes,' a n d ' W a l k e r W o o d ' respectively, consists of b o t h m o o r l a n d a n d r o u g h pasture. T h e r e are o n l y t h r e e h a b i t a tions on t h e d r a i n a g e area, a n d these are u n d e r the jurisdiction of t h e w a t e r a u t h o r i t y . P e a t is v e r y a b u n d a n t on the higher a n d flatter reaches of the d r a i n a g e area, especially on the B o a r F l a t a n d Sw-ineshaw Moor, whilst lower d o w n the valley, r o u n d t h e ' B r u s h e s ' a n d ' W a l k e r W o o d ' reservoirs, t h e hillsides are steep a n d the p e a t c o n s e q u e n t l y n o t so exten~ sive. T h e entire area is in t h e Millstone Grit formation. T h e o r d i n a r y r a t e of discharge f r o m t h e w a t e r s h e d into t h e ' B r u s h e s ' a n d ' W a l k e r W o o d ' reservoirs is f o u n d to b e m u c h higher t h a n t h a t f r o m t h e ' H i g h e r a n d L o w e r S w i n e s h a w ' reservoirs for t h e reason t h a t the hillsides are m o r e p r e c i p i t o u s . " I t will be seen t h a t the s u p p l y is a t y p i c a l m o o r l a n d water. Such w a t e r s are usually p u r e and soft, containing little or no m i n e r a l m a t t e r , b u t s o m e t i m e s yield evidence of the presence of considerable q u a n t i t i e s of organic m a t t e r , which m a y be e x p e c t e d to b e of v e g e t a b l e r a t h e r t h a n a n i m a l origin. In several t o w n s in t h e NOrth of E n g l a n d such w a t e r has given rise to lead-poisoning in persons w h o h a v e c o n s u m e d it. I n consequence of c o m p l a i n t s to t h e effect t h a t lead-poisoning, due to w a t e r supply, w a s v e r y p r e v a l e n t in t h e t o w n of Mossley, D r . M o n c k t o n C o p e m a n visited the Swineshaw a n d Greenfield g a t h e r i n g grounds in 1893, acting u n d e r t h e direction of the Local G o v e r n m e n t Board. I-Ie r e p o r t e d t h a t lead-poisoning was p r e v a l e n t o n l y in those districts supplied w i t h acid w a t e r f r o m L o w e r Swineshaw reservoir, a n d t h a t where the n e u t r a l w a t e r f r o m Brushes reservoir was supplied to the i n h a b i t a n t s , t h e r e was no leadpoisoning. After t r e a t i n g t h e a c i d S w i n e s h a w w a t e r with lime, it b e c a m e p r a c t i c a l l y n e u t r a l a n d free f r o m lead. A small a p p a r a t u s was
JANIJAI~V,
therefore installed a t this p a r t i c u l a r reservoir for ,nixing lime w i t h water, a n d b y this m e a n s t h e condition of t h e w a t e r was m a t e r i a l l y i m p r o v e d and cases of lead-poisoning ceased to occur in Mossley. T h e r e still, however, r e m a i n e d cause of c o m p l a i n t f r o m discolouration a n d the presence of m o r e or less sediment a r y m a t t e r , t h e result of p e a t y c o n t a m i n a t i o n . I n 19o8 the whole of this w a t e r s u p p l y was p l a c e d u n d e r the supervision, b o t h chemical a n d bacteriological, of Professor D~l@ine, who h a s recorded the results v e r y fully in his p a p e r o n " T h e Mechanical F i l t r a t i o n of M o o r l a n d W a t e r Supplies, a n d the Action of W a t e r on L e a d . " H e r e p o r t s u p o n the w a t e r as follows : The Swineshaw water was generally more aeid t h a n the Brushes, and the Brushes water contained a greater amount of soluble inorganic matter and of total solids than the Swineshaw water. Notwithstanding these marked differenees, the hardness of the Brushes water was not very materially greater than that of the higher reservoirs. As regards its action on lead, the Swineshaw was almost invariably more potent than the Brushes water. On one occasion while the Swineshaw water had an action equal to 2, that of the Brushes was only 0"3. Usually the difference was not so great, and on rare occasions was not appreciable. Tile fact t h a t the Upper Swineshaw water had in the past proved more dangerous, owing to its greater action on lead, had been a source of surprise to many, for the water of both reservoirs appeared to have the same source ; but the results which have just been mentioned show that these two waters are not alike. The difference between the Swineshaw and the Brushes reservoirs can be explained partly by the nature of the bed of each of these reservoirs, and partly by the fact that the water issuing from the Swineshaw reservoir passes down to the Brushes reservoir in a very long open stone channel, and I have aseertNned by direct observation that during its passage from the upper end of this channel to the lower, the mineral contents of the water increase in amount and the acidity was reduced. The rocky character of the slopes draining directly into the lower reservoirs would have the same effect. With regard to the Greenfield water, its characters resemble very much those of the Swineshaw water, but it is, generally speaking, more acid, and at times contains mtieh more suspended matter. Its hardness and action on lead are of the same type. From a ehemical point of view all these waters m a y be looked upon as examples of good upland water obtained from unpolluted peaty watersheds. They were frequently diseoloured, their eolour varying between greenish-yellow a n d brown. At times the
1916.
PUBLIC
amount of suspended matter was considerable. They had invariably a marked action on lead. T h e results of the bacteriological e x a m i n a t i o n showed t h a t the n u m b e r of bacteria in t h e unfiltered w a t e r n e v e r exceeded t h a t f o u n d usually in p u r e n a t u r a l waters or sand filtered waters. T h e position at this p o i n t of time (I9o8) Was, therefore, t h a t one portion of w a t e r was being t r e a t e d with whiting to neutralist acidity, whilst all the rest was practically neutral; b u t required t r e a t m e n t for discolouration and turbidity. T h e W a t e r C o m m i t t e e now considered t h e advisability of treating the whole w a t e r s u p p l y b y a comprehensive scheme, and, as a preliminary, Mr. Dixon, w a t e r engineer to tile Board, installed a trial p l a n t in the Greenfield area, designed to t r e a t and filter 432,ooo gallons of raw water per 24 hours. I t consisted of three filters, together with chemical plant, mixing tanks, etc., the whole being c o n t a i n e d in a substantial stone a n d brick house. Tile result of t h r e e years' trial being satisfactory, in 1911 t w o complete schemes were p r o c e e d e d w i t h t o deal with the whole of t h e w a t e r f r o m t h e Greenfield and Swineshaw valleys respectively. These were finished and b r o u g h t into o p e r a t i o n in September, 1912. T w o stone buildings were erected, ohe in the Greenfield, t h e o t h e r in the Swineshaw valley, and in these were installed the filters and chemical apparatus. T h e r e are I8 mechanical pressure filters in each building, the filters being 8 ft. i n t e r n a l d i a m e t e r and consisting of a closed cylinder containing specially graded q u a r t z crystals. T h e bed of q u a r t z crystals has an average thickness of 3 ft. 6 in., and filters between I8,OOO and 2o,ooo gallons per hour. A t certain intervals the sediment collected is w a s h e d o u t from the q u a r t z bed b y a n ingenious a r r a n g e m e n t of jets and agitating mechanism, and carried a w a y b y the washw a t e r t h r o u g h a wash-out discharge into a s e d i m e n t a t i o n tank. T h e r e is a v e r y m a r k e d difference in the clearness and brightness of t h e drinking w a t e r before it enters and a f t e r it has passed t h r o u g h t h e filters. T h e chemical p l a n t consists o f an a p p a r a t u s for mixing c a r b o n a t e of lime and alumina in the p r o p o r t i o n of lime o'44 grains per gallon, sulphate of alumina o'44 grains per gallon. As the raw w a t e r passes t h r o u g h the filter house the chemicals are first m i x e d with it ; n e x t it passes u n d e r pressure t h r o u g h the filters, and f r o m these it is c o n d u c t e d directly into the
HEALTH.
95
service mains. The two installations together can deal with 5,352,000 gallons in 24 hours. Tile cost of the whole scheme was £29,o91 6s. i d . A v e r y full description of all the works has been given b y Mr. DiXOn, who p l a n n e d and carried t h e m out, in his p a p e r on " T h e T r e a t m e n t of P l u m b o - S o l v e n t W a t e r b y Means of Mechanical Filters." Since completion, m o n t h l y samples of w a t e r h a v e been collected from the various sources of supply and s u b m i t t e d to Professor D616pine, who reports as follows : - (1) Ef/eet o/Trealmenl on Discolouralion and Suspended M a l l e r . - - T h e water which, before treatment, varied in colour from greenish or yellowish brown to brown or dark brown, was invariably deprived entirely, or almost entirely, of its colour. On examination in good daylight in a two-foot tube it had a clear blue or greenish blue colour ; in the latter case more than 95 per cent. of the original yellow or brown discolouration had been removed ; when the water had a pure blue colour no trace of original discolouration could be detected. With regard to the suspended matter, the coarse suspended matter which was present in most of the samples of raw water was invariably removed by treatment, and in ordinary daylight the treated water appeared to be quite clear. A certain quantity of insoluble solids was, however, found to remain, and these consisted entirely of very minute particles, the presence of which was revealed only when the water was strongly illuminated and examined against a dark background. These particles were in great part derived from the filtering material. This almost invisible suspended matter was quite different from coarse brownish or yellowish d~bris, which rendered the water more or less turbid, and to which a great part of the diseolouration was due. Mr. Heap, in analysing a similar sediment from a meehanicaUy filtered water, found t h a t it consisted of material derived f r o m (a) The broken quartz. (b) The walls a n d other parts of the filter, which are composed of iron. (c) Precipitates resulting from the addition of chemicals and h'om the re-arrangement of the constituents of the water during treatment. These materials m a y f o r m a thin coating to the pipes in course of time, b u t will give nothing comparable to the thick furred coating which results from an unfiltered p e a t y water. This is an a d v a n t a g e of t h e mechanical filtration process. (2) Ef[ect o/ ~>ealment on lhe Baclerial Conlenls.--The results of the bacteriological examinations show that the total number of bacteria was reduced by treatment, but on several occasions the reduction was slight.
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PUBLIC HEALTH.
This slight reduction was observed when the water was already very poor in bacteria before treatment. On the other hand, there was a very eonsiderable reduction when the original number of bacteria was fairly large, as it was several times, On several oeeasions no bacteria could be detected in treated water by the usual methods of cultivation. The Bacillus Coli, whieh oeeasionally appeared in small numbers in the untreated water, was never found in the treated water. (3) Effect of Treatment upon the Action of Lead.--The results show that the effects of treatment have been highly satisfactory, except on two occasions, when samples were taken before the chemical part of the treatment had been adjusted. A typical sample taken at the Brushes reservoir on April 29th, 1913, showed the action on lead of the unfiltered water to be Ol 4 , whereas of filtered water it was only 0'05 . Special experiments were made with these waters along with others by Mr. Heap. In these experiments he insists upon the observance of the following conditions :--(a) the employment of pure lead foil of such size t h a t a fixed surface is exposed to the action of a fixed amount of water, (b) the glass of the bottles used must be free from any lead contamination, (c) the water, during the test, must not be allowed to absorb more gases than it originally contained, (d) the temperature must remain constant. The rain-waters, which he studied, after stagnating in peaty, boggy, or marshy places become acid, this acidity being greater than t h a t which rain-water m a y acquire before falling on the ground. During storms and when wet succeeds dry weather, moorland water becomes very acid and acts strongly on lead, Houston attributes the action of moorland waters upon lead to their acidity, which he associates with the growth of certain acidproducing bacteria present in peat. This biological theory assumes t h a t certain forms of living matter produce substances which attack lead. There appears, however, to be a difference of opinion as to whether this acid, so produced, has anything to do with the solution of lead. Mr. Heap states t h a t he believes oxygen to be the chief causative agent. Another theory is t h a t carbon dioxide is the solvent agent; with this Mr. Heap does not agree, but considers t h a t the dangerous element in drinking water is the dissolved oxygen rather than the carbon dioxide or small amount of vegetable matter usually found in solution. I now come to the general question of the prevention of disease from drinking water, and
JANUARY,
the more particular one of whether the filtration of the A s h t o n water has had any effect in diminishing disease in the area of supply ? That serious epidemics have been caused by impure water cannot be doubted. The aim of a waterworks authority should be not merely to produce and distribute a water supply of excellent quality on the average, but also to prevent the possibility of accident. No workman who has ever had typhoid should be actively engaged on waterworks. In addition, the supply everywhere must be guarded both before and after filtration. Special attention should be paid to the following points : Protect as far as possible the river, espeeially just above the intakes, from all sources of pollution. Interpose adequate storage accommodation between the river and the filter beds, and prevent any pollution of the water in these reservoirs. Guard the filter beds, filter wells, etc., from all sources of contamination, and filter the water as efficiently as is reasonably practicable. Prevent the possibility of pollution of the water in the pump wells,' service reservoirs, and distributing mains. Remember t h a t accidents open the road to epidemies, and t h a t the worst form of accident is produced by contamination of water with the recent discharges of typhoid carriers. In the Ashton reservoirs for drinking water, fishing is prohibited and the public are not allowed access to the banks, but I am not aware of any examination to ensure t h a t the workmen shall not be typhoid carriers. The water is stored in the reservoirs before filtration. The various intakes are protected from pollution. The period of two years and three months which has elapsed since the filtering process commenced is too short to draw much evidence as to the incidence of local disease, but such as it is I have directed m y enquiry to two groups of disease: (a) lead poisoning and chronic nephritis ; (b) gastro-intestinal diseases, especially typhoid fever and diarrhoea. With reference to class (a)~lead poisoning and chronic nephritis--the two areas in which they h a d been manifested were Saddleworth and Mossley, which had been supplied with the most acid water. Dr. Healey, medical officer of health for Mossley, kindly replies to m y enquiries as follows : - - " It is m a n y years since we had any acute cases of lead poisoning, nol,
I916.
PUBLIC HEALTH.
in fact, since the water supplied to Mossley was specially treated with whiting after the acute cases occurred. The trouble we feel now is a great number of cases of chronic nephritis, a much larger average, I think, than occurs in the neighbouring towns. This all the doctors in the town find, and in my opinion is the result of the m a n y cases of plumbisnl we used to get, and m a n y which have never suffered sufficiently acutely to be treated for plumbism, and so were never discovered." Dr. Ramsden, medical officer of health for Saddleworth, says : - - " Since the Greenfield water has been rectified there have been occasional cases showing the typical blue line, but on enquiry I have found t h a t something had been done at the waterworks t h a t had allowed more peaty acids to get through t h a n usual. .Prior to the installation we were in an extremely bad way, e.g., several (at least eight) cases of puerperal eclampsia occurred, ending in four or five deaths. Cases of dyspepsia and colic were not at all uncommon ; a great m a n y showed the blue line on the gums. I have thought t h a t m a n y of the cases of increased arterial tension and kidney trouble, which are not at all uncommon, are due to the ingestion of lead at t h a t time." In Ashton the deaths from nephritis and Brigl~t's disease were 21 in 191o , 2o in 1911 , 15 in 1912, 22 in 1913, and only I I in 1914. We may, I think, conclude that the filtration of the water has abolished for the future all risk of lead poisoning from drinking water, and also we m a y reasonably expect t h a t cases of chronic nephritis will be diminished in the near future. In the group (b) of gastro-intestinal complaints, the cases notified in Ashton of typhoid have been much lessened since the filtration commenced; the average number notified during the years 19o4-1912 was 31, whereas the number in 1913 was only 13, and in 1914 was 12. I am inclined, however, to think this diminution has been brought about not by a n y change in the water but rather by such measures as early isolation in hospital of first cases and stricter .attention to removal of manure and other refuse. Still the fact remains t h a t there is a marked diminution. I n the case of diarrhoea there has been an increase of cases, both in 1913 and 1914 , but this was undoubtedly due to the prolonged fine weather we experienced in those years. A matter of interest is the relation of the filtration to trade processes. Since it was
97
filtered consumers for trade purposes state the quality of water is much improved, and there are no complaints of its dirtiness as there used to be before treatment. In the manufactories for rotated waters, iam, etc., where BerkefeId filters are installed, these used to be cleaned every two or three days ; now they are only cleaned once a month. General complaints of dirtiness of water, which used to be five or six a day, are now less than five or six per month. The general pressure has not been diminished, and the Supply is practically unlimited. I t is, therefore, clear t h a t this scheme of filtration is proving of advantage to the district in providing a drinking water which is clean, free from action on lead, and free from harmful bacteria. I desire, in conclusion, to express my grateful thanks to Professor Dflfpine and Mr. Dixon for their kind assistance in making suggestions and permitting me to make extracts from their published papers.
T H E MEDICAL E X A M I N A T I O N OF SCIiOOL C H I L D R E N IN VICTORIA. EYE-COLOIIR A N D ITS SIGNIFICATION. medical examination of the school child in T HEVictoria is constantly correlated with information as to hereditary and environmental factors afforded by the parents and teachers. Racial factors (birthplace of parents and grandparents) are noted, and an attempt is being made to discover what difference, if any, is manifest in each succeeding generation of Australians. Already the schools permit of the observation of immigrants and of Australians of three generations. Another hereditary factor of a racial type (noted by the teachers) is the degree of pigmentation of the hair and eyes. If it could be possiNe to discover the type of person who prefers the land to the city, the pressing problem of rural depopulation would be solved. In Victoria, our metropolis holds at least two-fifths of the popt~lation of the State, and, while the population increased by IIO,OOO during the last intercensal period, IOO,OOO of this increase belongs to Melbourne. Our constant obsel-vation goes to col~firm for Australia what has already been noted in British communities in the homeland and elsewhere, namely, that the blue-eyed components seek the land, the city populations being recruited largely from the brown-eyed. Eye-colour, it is well to emphasize, is unaffected by climate, and is a purely hereditary factor obeying certain laws. One of these is that two pure blue-eyed parents will only have offspring with pure blue eyes ; but, if a pure brown and a pure blue marry, the children tend all to be browneyed, the brown being dominant. In the next
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PUBLIC HEALTH.
up to the smnmer of 1915. Some 2,ooo visits had been paid for purposes of ascertainment, and in the first six months the local voluutarf¢ society paid about I,OOO visits for supervision, apart from visits of after-care paid to Education Acts cases. The general condition had prevented all the cases in need of institutional care being at once placed therein, and delays nmst be anticipated so long as the Treasury limitations remained. To facilitate selection cases in need of institutional treatment had been classified by age into groups, under 7, 7- 1 6 , 16--35, and over 35. With cross classifications showing whether they were idiots, imbeciles, moral imbeciles, feeble-minded; whether they were of higher or lower social and moral classes ; and whether they were : (I) able with help and supervision to attend to their own wants, and do simple tests, or (2) would require little help, or (3) would need much assistance, or (4) were practically helpless, or (5) were epileptic, or (6) were epileptic and paralysed, or (7) would need much control. On the general medical side it has been noted that just one half the cases dealt with were not of hereditary nature, but due to disease or injury in some period of prenatal life, at birth, or in early postnatal life. In connection with the family histories of 6oo families containing defective members, as contrasted with I,OOO families of rtormal individuals, it is noted that if the birth-rate of the defectives was higher, the death-rate was also much higher, so that long before the reproduction passed the balance in favour of the defectives was destroyed. This selective death-rate is obviously nature's method of protection, and threw a heavy responsibility on the Society of Medical Officers of Health. Nature's verdict was the defective shall perish in infancy or early life ; the Society said, " Let us establish Midwives' Acts, compulsory notification of births, infant consultations, and the like, and interfere with nature's blind decrees." If the members do not also see to it that the defectives they help to preserve are segregated, they may do grave eugenic ill to the nation who now and in the future has need not only of the numbers but of the faculty of her citizens. Dr. W. It. SYMoNs, Bath, said that in working the Act in his area he had received a gratuity of £3o towards meeting the expenses incurred. He did not think it was part of the duty of medical officers of health to incur expense in supervising the working of the Act. DR. FRANI< ROBINSON having replied, the meeting adjourned. H o w SMALLPOX WAS ABOLISHED IN PORTO RICO.
- - A f t e r America took possession of Porto Rico the Government vaccinated over 800,000 persons during an epidemic of smallpox, and in four months smallpox was abolished.
FII,TRATION
OF
DRINKING
WATER,
BY
J. W. TALENT, M.D., M.R.C.S., D.P.H., Medical Officer o/Heallh, Ashlon-under-Lgne.
I
H A V E been led to present to y o u some remarks upon the purification of drinking water owing to the fact t h a t the water supplied to the area with which I am connected is now being subjected to v e r y complete and t h o r o u g h t r e a t m e n t b y chemical agents and mechanical filters. The works installed for this purpose came into action on S e p t e m b e r I p t h , 1912. Before describing this installation and its results I will refer briefly to the general characters of the w a t e r s u p p l y in question. I t is provided b y a joint w a t e r b o a r d k n o w n as the A s h t o n - u n d e r - L y n e , Stalybridge and Dukinfield (District) W a t e r w o r k s J o i n t Committee, and supplies the boroughs of Ashtonu n d e r - L y n e , Stalybridge, Dukinfield, and Mossley, and u r b a n districts of H u r s t , Audenshaw and Saddleworth, and the rural district of Limehurst. T h e t o t a l area is 33,793 acres~ or 52"8squafemiles, with a p o p u l a t i o n of I43,648. The c o n s u m p t i o n per h e a d per d a y for all purposes is 2o'6 gallons. The source of supply f r o m which the water is obtained consists of three gathering grounds, situate in the Pennine Range, some four or five miles due east and n o r t h - e a s t of the town of Ashton, and is m a d e up as follows : - Swineshaw Valley .. 1,3oo acres Greenfield Valley .. 1,17o ,, Chew Valley . . . . 1,73o ,, Total .. 4,200 The average rainfall in the Greenfield district for the past 30 years is 51"64 inches and in the Swineshaw district 46"86 inches. Mr. Dixon, w a t e r engineer to the committee, has kindly supplied me with the following general description of the source of supply. " Greenfield Valley S u p p l y . - - T h e gathering ground which supplies the t w o impounding reservoirs, ' Y e o m a n H e y ' and ' Greenfield,' is entirely moorland, and quite free of all habitation. P e a t covers n e a r l y the whole of the watershed, and varies in thickness from 12 in. to a m a x i m u m d e p t h of 15 ft., this resting upon the Millstone Grit, which f r e q u e n t l y crops out on the higher portions of the gathering ground, the surface being covered with coarse grass and some heather. In consequence of the v e r y precipitous character of the hillsides surrounding the
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reservoirs, t h e flow f r o m t h e surface is often e x t r e m e l y rapid. A t t h e ' Y e o m a n H e y ' reservoir it is f o u n d t h a t a s o m e w h a t larger p r o p o r t i o n of t h e s t r e a m s u p p l y consists of springs t h a n is t h e case a t Greenfield, where a considerable q u a n t i t y of p e a t y w a t e r is given off in t h e u p p e r reaches of t h e Greenfield Brook. F u r t h e r , during h e a v y rains, a large a m o u n t of s a n d a n d p e a t gets w a s h e d into the reservoirs b y erosion d o w n the steep watercourses which abound on t h e hillsides~ " Swineshaw Valley [email protected] g a t h e r i n g g r o u n d w N e h supplies the four i m p o u n d i n g reservoirs--' Higher Swineshaw,' ' Lower Swineshaw,' ' Brushes,' a n d ' W a l k e r W o o d ' respectively, consists of b o t h m o o r l a n d a n d r o u g h pasture. T h e r e are o n l y t h r e e h a b i t a tions on t h e d r a i n a g e area, a n d these are u n d e r the jurisdiction of t h e w a t e r a u t h o r i t y . P e a t is v e r y a b u n d a n t on the higher a n d flatter reaches of the d r a i n a g e area, especially on the B o a r F l a t a n d Sw-ineshaw Moor, whilst lower d o w n the valley, r o u n d t h e ' B r u s h e s ' a n d ' W a l k e r W o o d ' reservoirs, t h e hillsides are steep a n d the p e a t c o n s e q u e n t l y n o t so exten~ sive. T h e entire area is in t h e Millstone Grit formation. T h e o r d i n a r y r a t e of discharge f r o m t h e w a t e r s h e d into t h e ' B r u s h e s ' a n d ' W a l k e r W o o d ' reservoirs is f o u n d to b e m u c h higher t h a n t h a t f r o m t h e ' H i g h e r a n d L o w e r S w i n e s h a w ' reservoirs for t h e reason t h a t the hillsides are m o r e p r e c i p i t o u s . " I t will be seen t h a t the s u p p l y is a t y p i c a l m o o r l a n d water. Such w a t e r s are usually p u r e and soft, containing little or no m i n e r a l m a t t e r , b u t s o m e t i m e s yield evidence of the presence of considerable q u a n t i t i e s of organic m a t t e r , which m a y be e x p e c t e d to b e of v e g e t a b l e r a t h e r t h a n a n i m a l origin. In several t o w n s in t h e NOrth of E n g l a n d such w a t e r has given rise to lead-poisoning in persons w h o h a v e c o n s u m e d it. I n consequence of c o m p l a i n t s to t h e effect t h a t lead-poisoning, due to w a t e r supply, w a s v e r y p r e v a l e n t in t h e t o w n of Mossley, D r . M o n c k t o n C o p e m a n visited the Swineshaw a n d Greenfield g a t h e r i n g grounds in 1893, acting u n d e r t h e direction of the Local G o v e r n m e n t Board. I-Ie r e p o r t e d t h a t lead-poisoning was p r e v a l e n t o n l y in those districts supplied w i t h acid w a t e r f r o m L o w e r Swineshaw reservoir, a n d t h a t where the n e u t r a l w a t e r f r o m Brushes reservoir was supplied to the i n h a b i t a n t s , t h e r e was no leadpoisoning. After t r e a t i n g t h e a c i d S w i n e s h a w w a t e r with lime, it b e c a m e p r a c t i c a l l y n e u t r a l a n d free f r o m lead. A small a p p a r a t u s was
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therefore installed a t this p a r t i c u l a r reservoir for ,nixing lime w i t h water, a n d b y this m e a n s t h e condition of t h e w a t e r was m a t e r i a l l y i m p r o v e d and cases of lead-poisoning ceased to occur in Mossley. T h e r e still, however, r e m a i n e d cause of c o m p l a i n t f r o m discolouration a n d the presence of m o r e or less sediment a r y m a t t e r , t h e result of p e a t y c o n t a m i n a t i o n . I n 19o8 the whole of this w a t e r s u p p l y was p l a c e d u n d e r the supervision, b o t h chemical a n d bacteriological, of Professor D~l@ine, who h a s recorded the results v e r y fully in his p a p e r o n " T h e Mechanical F i l t r a t i o n of M o o r l a n d W a t e r Supplies, a n d the Action of W a t e r on L e a d . " H e r e p o r t s u p o n the w a t e r as follows : The Swineshaw water was generally more aeid t h a n the Brushes, and the Brushes water contained a greater amount of soluble inorganic matter and of total solids than the Swineshaw water. Notwithstanding these marked differenees, the hardness of the Brushes water was not very materially greater than that of the higher reservoirs. As regards its action on lead, the Swineshaw was almost invariably more potent than the Brushes water. On one occasion while the Swineshaw water had an action equal to 2, that of the Brushes was only 0"3. Usually the difference was not so great, and on rare occasions was not appreciable. Tile fact t h a t the Upper Swineshaw water had in the past proved more dangerous, owing to its greater action on lead, had been a source of surprise to many, for the water of both reservoirs appeared to have the same source ; but the results which have just been mentioned show that these two waters are not alike. The difference between the Swineshaw and the Brushes reservoirs can be explained partly by the nature of the bed of each of these reservoirs, and partly by the fact that the water issuing from the Swineshaw reservoir passes down to the Brushes reservoir in a very long open stone channel, and I have aseertNned by direct observation that during its passage from the upper end of this channel to the lower, the mineral contents of the water increase in amount and the acidity was reduced. The rocky character of the slopes draining directly into the lower reservoirs would have the same effect. With regard to the Greenfield water, its characters resemble very much those of the Swineshaw water, but it is, generally speaking, more acid, and at times contains mtieh more suspended matter. Its hardness and action on lead are of the same type. From a ehemical point of view all these waters m a y be looked upon as examples of good upland water obtained from unpolluted peaty watersheds. They were frequently diseoloured, their eolour varying between greenish-yellow a n d brown. At times the
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amount of suspended matter was considerable. They had invariably a marked action on lead. T h e results of the bacteriological e x a m i n a t i o n showed t h a t the n u m b e r of bacteria in t h e unfiltered w a t e r n e v e r exceeded t h a t f o u n d usually in p u r e n a t u r a l waters or sand filtered waters. T h e position at this p o i n t of time (I9o8) Was, therefore, t h a t one portion of w a t e r was being t r e a t e d with whiting to neutralist acidity, whilst all the rest was practically neutral; b u t required t r e a t m e n t for discolouration and turbidity. T h e W a t e r C o m m i t t e e now considered t h e advisability of treating the whole w a t e r s u p p l y b y a comprehensive scheme, and, as a preliminary, Mr. Dixon, w a t e r engineer to tile Board, installed a trial p l a n t in the Greenfield area, designed to t r e a t and filter 432,ooo gallons of raw water per 24 hours. I t consisted of three filters, together with chemical plant, mixing tanks, etc., the whole being c o n t a i n e d in a substantial stone a n d brick house. Tile result of t h r e e years' trial being satisfactory, in 1911 t w o complete schemes were p r o c e e d e d w i t h t o deal with the whole of t h e w a t e r f r o m t h e Greenfield and Swineshaw valleys respectively. These were finished and b r o u g h t into o p e r a t i o n in September, 1912. T w o stone buildings were erected, ohe in the Greenfield, t h e o t h e r in the Swineshaw valley, and in these were installed the filters and chemical apparatus. T h e r e are I8 mechanical pressure filters in each building, the filters being 8 ft. i n t e r n a l d i a m e t e r and consisting of a closed cylinder containing specially graded q u a r t z crystals. T h e bed of q u a r t z crystals has an average thickness of 3 ft. 6 in., and filters between I8,OOO and 2o,ooo gallons per hour. A t certain intervals the sediment collected is w a s h e d o u t from the q u a r t z bed b y a n ingenious a r r a n g e m e n t of jets and agitating mechanism, and carried a w a y b y the washw a t e r t h r o u g h a wash-out discharge into a s e d i m e n t a t i o n tank. T h e r e is a v e r y m a r k e d difference in the clearness and brightness of t h e drinking w a t e r before it enters and a f t e r it has passed t h r o u g h t h e filters. T h e chemical p l a n t consists o f an a p p a r a t u s for mixing c a r b o n a t e of lime and alumina in the p r o p o r t i o n of lime o'44 grains per gallon, sulphate of alumina o'44 grains per gallon. As the raw w a t e r passes t h r o u g h the filter house the chemicals are first m i x e d with it ; n e x t it passes u n d e r pressure t h r o u g h the filters, and f r o m these it is c o n d u c t e d directly into the
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service mains. The two installations together can deal with 5,352,000 gallons in 24 hours. Tile cost of the whole scheme was £29,o91 6s. i d . A v e r y full description of all the works has been given b y Mr. DiXOn, who p l a n n e d and carried t h e m out, in his p a p e r on " T h e T r e a t m e n t of P l u m b o - S o l v e n t W a t e r b y Means of Mechanical Filters." Since completion, m o n t h l y samples of w a t e r h a v e been collected from the various sources of supply and s u b m i t t e d to Professor D616pine, who reports as follows : - (1) Ef/eet o/Trealmenl on Discolouralion and Suspended M a l l e r . - - T h e water which, before treatment, varied in colour from greenish or yellowish brown to brown or dark brown, was invariably deprived entirely, or almost entirely, of its colour. On examination in good daylight in a two-foot tube it had a clear blue or greenish blue colour ; in the latter case more than 95 per cent. of the original yellow or brown discolouration had been removed ; when the water had a pure blue colour no trace of original discolouration could be detected. With regard to the suspended matter, the coarse suspended matter which was present in most of the samples of raw water was invariably removed by treatment, and in ordinary daylight the treated water appeared to be quite clear. A certain quantity of insoluble solids was, however, found to remain, and these consisted entirely of very minute particles, the presence of which was revealed only when the water was strongly illuminated and examined against a dark background. These particles were in great part derived from the filtering material. This almost invisible suspended matter was quite different from coarse brownish or yellowish d~bris, which rendered the water more or less turbid, and to which a great part of the diseolouration was due. Mr. Heap, in analysing a similar sediment from a meehanicaUy filtered water, found t h a t it consisted of material derived f r o m (a) The broken quartz. (b) The walls a n d other parts of the filter, which are composed of iron. (c) Precipitates resulting from the addition of chemicals and h'om the re-arrangement of the constituents of the water during treatment. These materials m a y f o r m a thin coating to the pipes in course of time, b u t will give nothing comparable to the thick furred coating which results from an unfiltered p e a t y water. This is an a d v a n t a g e of t h e mechanical filtration process. (2) Ef[ect o/ ~>ealment on lhe Baclerial Conlenls.--The results of the bacteriological examinations show that the total number of bacteria was reduced by treatment, but on several occasions the reduction was slight.
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This slight reduction was observed when the water was already very poor in bacteria before treatment. On the other hand, there was a very eonsiderable reduction when the original number of bacteria was fairly large, as it was several times, On several oeeasions no bacteria could be detected in treated water by the usual methods of cultivation. The Bacillus Coli, whieh oeeasionally appeared in small numbers in the untreated water, was never found in the treated water. (3) Effect of Treatment upon the Action of Lead.--The results show that the effects of treatment have been highly satisfactory, except on two occasions, when samples were taken before the chemical part of the treatment had been adjusted. A typical sample taken at the Brushes reservoir on April 29th, 1913, showed the action on lead of the unfiltered water to be Ol 4 , whereas of filtered water it was only 0'05 . Special experiments were made with these waters along with others by Mr. Heap. In these experiments he insists upon the observance of the following conditions :--(a) the employment of pure lead foil of such size t h a t a fixed surface is exposed to the action of a fixed amount of water, (b) the glass of the bottles used must be free from any lead contamination, (c) the water, during the test, must not be allowed to absorb more gases than it originally contained, (d) the temperature must remain constant. The rain-waters, which he studied, after stagnating in peaty, boggy, or marshy places become acid, this acidity being greater than t h a t which rain-water m a y acquire before falling on the ground. During storms and when wet succeeds dry weather, moorland water becomes very acid and acts strongly on lead, Houston attributes the action of moorland waters upon lead to their acidity, which he associates with the growth of certain acidproducing bacteria present in peat. This biological theory assumes t h a t certain forms of living matter produce substances which attack lead. There appears, however, to be a difference of opinion as to whether this acid, so produced, has anything to do with the solution of lead. Mr. Heap states t h a t he believes oxygen to be the chief causative agent. Another theory is t h a t carbon dioxide is the solvent agent; with this Mr. Heap does not agree, but considers t h a t the dangerous element in drinking water is the dissolved oxygen rather than the carbon dioxide or small amount of vegetable matter usually found in solution. I now come to the general question of the prevention of disease from drinking water, and
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the more particular one of whether the filtration of the A s h t o n water has had any effect in diminishing disease in the area of supply ? That serious epidemics have been caused by impure water cannot be doubted. The aim of a waterworks authority should be not merely to produce and distribute a water supply of excellent quality on the average, but also to prevent the possibility of accident. No workman who has ever had typhoid should be actively engaged on waterworks. In addition, the supply everywhere must be guarded both before and after filtration. Special attention should be paid to the following points : Protect as far as possible the river, espeeially just above the intakes, from all sources of pollution. Interpose adequate storage accommodation between the river and the filter beds, and prevent any pollution of the water in these reservoirs. Guard the filter beds, filter wells, etc., from all sources of contamination, and filter the water as efficiently as is reasonably practicable. Prevent the possibility of pollution of the water in the pump wells,' service reservoirs, and distributing mains. Remember t h a t accidents open the road to epidemies, and t h a t the worst form of accident is produced by contamination of water with the recent discharges of typhoid carriers. In the Ashton reservoirs for drinking water, fishing is prohibited and the public are not allowed access to the banks, but I am not aware of any examination to ensure t h a t the workmen shall not be typhoid carriers. The water is stored in the reservoirs before filtration. The various intakes are protected from pollution. The period of two years and three months which has elapsed since the filtering process commenced is too short to draw much evidence as to the incidence of local disease, but such as it is I have directed m y enquiry to two groups of disease: (a) lead poisoning and chronic nephritis ; (b) gastro-intestinal diseases, especially typhoid fever and diarrhoea. With reference to class (a)~lead poisoning and chronic nephritis--the two areas in which they h a d been manifested were Saddleworth and Mossley, which had been supplied with the most acid water. Dr. Healey, medical officer of health for Mossley, kindly replies to m y enquiries as follows : - - " It is m a n y years since we had any acute cases of lead poisoning, nol,
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in fact, since the water supplied to Mossley was specially treated with whiting after the acute cases occurred. The trouble we feel now is a great number of cases of chronic nephritis, a much larger average, I think, than occurs in the neighbouring towns. This all the doctors in the town find, and in my opinion is the result of the m a n y cases of plumbisnl we used to get, and m a n y which have never suffered sufficiently acutely to be treated for plumbism, and so were never discovered." Dr. Ramsden, medical officer of health for Saddleworth, says : - - " Since the Greenfield water has been rectified there have been occasional cases showing the typical blue line, but on enquiry I have found t h a t something had been done at the waterworks t h a t had allowed more peaty acids to get through t h a n usual. .Prior to the installation we were in an extremely bad way, e.g., several (at least eight) cases of puerperal eclampsia occurred, ending in four or five deaths. Cases of dyspepsia and colic were not at all uncommon ; a great m a n y showed the blue line on the gums. I have thought t h a t m a n y of the cases of increased arterial tension and kidney trouble, which are not at all uncommon, are due to the ingestion of lead at t h a t time." In Ashton the deaths from nephritis and Brigl~t's disease were 21 in 191o , 2o in 1911 , 15 in 1912, 22 in 1913, and only I I in 1914. We may, I think, conclude that the filtration of the water has abolished for the future all risk of lead poisoning from drinking water, and also we m a y reasonably expect t h a t cases of chronic nephritis will be diminished in the near future. In the group (b) of gastro-intestinal complaints, the cases notified in Ashton of typhoid have been much lessened since the filtration commenced; the average number notified during the years 19o4-1912 was 31, whereas the number in 1913 was only 13, and in 1914 was 12. I am inclined, however, to think this diminution has been brought about not by a n y change in the water but rather by such measures as early isolation in hospital of first cases and stricter .attention to removal of manure and other refuse. Still the fact remains t h a t there is a marked diminution. I n the case of diarrhoea there has been an increase of cases, both in 1913 and 1914 , but this was undoubtedly due to the prolonged fine weather we experienced in those years. A matter of interest is the relation of the filtration to trade processes. Since it was
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filtered consumers for trade purposes state the quality of water is much improved, and there are no complaints of its dirtiness as there used to be before treatment. In the manufactories for rotated waters, iam, etc., where BerkefeId filters are installed, these used to be cleaned every two or three days ; now they are only cleaned once a month. General complaints of dirtiness of water, which used to be five or six a day, are now less than five or six per month. The general pressure has not been diminished, and the Supply is practically unlimited. I t is, therefore, clear t h a t this scheme of filtration is proving of advantage to the district in providing a drinking water which is clean, free from action on lead, and free from harmful bacteria. I desire, in conclusion, to express my grateful thanks to Professor Dflfpine and Mr. Dixon for their kind assistance in making suggestions and permitting me to make extracts from their published papers.
T H E MEDICAL E X A M I N A T I O N OF SCIiOOL C H I L D R E N IN VICTORIA. EYE-COLOIIR A N D ITS SIGNIFICATION. medical examination of the school child in T HEVictoria is constantly correlated with information as to hereditary and environmental factors afforded by the parents and teachers. Racial factors (birthplace of parents and grandparents) are noted, and an attempt is being made to discover what difference, if any, is manifest in each succeeding generation of Australians. Already the schools permit of the observation of immigrants and of Australians of three generations. Another hereditary factor of a racial type (noted by the teachers) is the degree of pigmentation of the hair and eyes. If it could be possiNe to discover the type of person who prefers the land to the city, the pressing problem of rural depopulation would be solved. In Victoria, our metropolis holds at least two-fifths of the popt~lation of the State, and, while the population increased by IIO,OOO during the last intercensal period, IOO,OOO of this increase belongs to Melbourne. Our constant obsel-vation goes to col~firm for Australia what has already been noted in British communities in the homeland and elsewhere, namely, that the blue-eyed components seek the land, the city populations being recruited largely from the brown-eyed. Eye-colour, it is well to emphasize, is unaffected by climate, and is a purely hereditary factor obeying certain laws. One of these is that two pure blue-eyed parents will only have offspring with pure blue eyes ; but, if a pure brown and a pure blue marry, the children tend all to be browneyed, the brown being dominant. In the next