Northamptonshire

Mass Miniature Radiography 1945-46

Occupational incidence of acute phthisis as shown by first survey of industrial centres in county
By C M Smith MD DPH County Medical Officer of Health

1.  This report covers the period from 1^st March, 1945, when the Unit began work at the County Hall, Northampton, until the completion of the survey in Wellingborough on 30^th May, 1946.  During this period the surveys carried out by the Unit were as follows:

		Period of Survey		No. of persons examined		Percentage examined
Preliminary Survey
(County Hall, Northampton)		March, 1945		1,054		--
Rushden		April, May, 1945		5,119		84
Kettering		June - October, 1945		9,806		81
Northampton		Oct., 1945 - March, 1946		14,544		70
Wellingborough		March - May, 1946		8,109		77
		Total		38,632

The percentage response is the percentage of persons who accepted invitations to be examined.  The preliminary survey included members and staffs of the Northamptonshire County Council and Northampton Corporation, and also the staff of Berrywood Mental Hospital and of one factory outside the County Borough.  The other surveys were restricted almost entirely to the examination of factory employees.

2.  The opportunity is thus present to submit a report giving a comparison of the findings in the various occupations in the main industrial areas of the geographical County excluding Corby.  Since the boot and shoe trade is the staple industry, the incidence of active tuberculosis in the industry has been compared with all other occupations followed by the workpeople examined.  The total number of persons examined in all the surveys was 38,632, of whom 17,436 were employed in the boot and shoe industry and 21,196 in other occupations.

Previous Reports

3.  It is not inopportune to refer to the report issued in 1915 by the Special Investigation Committee upon the Incidence of Phthisis in Relation to Occupations.  The first report of the Committee dealt with the boot and shoe industry and was published by the Medical Research Committee.  The summary of the conclusions was as follows:

	“ (i)	Phthisis is specially prevalent among workers in the boot and shoe industry, as compared with the general population.
	(ii)	The individual worker is predisposed to infection by the sedentary nature of his employment, and possibly by the attitude he adopts at works.
	(iii)	The infection is probably
			(a)	Increased by the number of infective workers, and
			(b)	Favoured by want of light, the presence of infected dust, and inadequate ventilation in the work‑rooms.”

Reference should also be made to the Registrar-General’s Decennial Supplement England and Wales, 1931, on Occupational Mortality.  As regards the boot and shoe trade, two main groups are dealt with in this report: group 36 – Boot and Shoe Makers (Hand‑workers) and Repairers, Census population (males) 49,998; and group 37 – Boot and Shoe, etc., Workers and Factory Operators, Census population (males) 45,038.  Taking the occupational mortality at ages 20–65 from tuberculosis of the lungs of all occupied males as 100, the occupational mortality for group 36 is shown as 131, and for group 37 as 188.  In the report, 86 occupations are put in order as regards respiratory tuberculosis mortality, occupations with the highest rates being placed at the bottom of the list.  In the table showing ranking of the 86 occupations, group 36 occupied 70^th position and group 37 ranked 81^st.

For purposes of comparison, occupations with a higher respiratory tuberculosis mortality rate were as follows:

				Registered Deaths per 100
Group				Standard at years 20 - 65
66.		Costermongers, Newspaper-sellers		200
78.		Barmen		212
26.		Glaziers, Polishers, Buffers, Moppers		230
14.		Potters, Ware-makers, Casters, Finishers		233
25.		Grinders		275

4.  Method of Presenting Results.

In this report newly-discovered active tuberculosis of the lungs in persons who require to stay off work for treatment, either at home or in Sanatoria, is dealt with.  Previously known cases of tuberculosis and observation cases have all been excluded.

In order that expert statistical help should be afforded, I consulted Dr Percy Stocks, Medical Statistician, General Register Office and Ministry of Health, who advised on the layout of the statistical tables and made the necessary calculations to determine whether the differences found were statistically significant.

5.  The Results of the Survey

Table I.

Northamptonshire – Mass Radiography Survey, 1945–46.

Rushden, Kettering, Northampton and Wellingborough Areas.

Analysis by Occupation,* Age and Sex of newly-discovered cases of Active Pulmonary Tuberculosis in persons who required to stay off work for treatment, either Sanatorium or Domiciliary.

Column:
(1)        Occupation
(2)        Sex
(3)        Number Examined
(4)        Number of Active P.T. Cases
(5)        Rate per 1,000
(6)        Number Examined
(7)        Number of Active P.T. Cases
(8)        Rate per 1,000
(9)        Expected Number of Active P.T. Cases at rates for occupations other than Boot and Shoe
(10)      Actual Number of Active P.T. Cases
(11)      Excess ± Standard Error
(12)      Is difference significant?

	* See Footnote			14 to 34 Years				35+ Years				All Ages
(1)		(2)		(3)	(4)	(5)		(6)	(7)	(8)		(9)	(10)		(11)	(12)
A.	Boot and Shoe	M.		1,756	10	5.69		7,775	46	5.92		21.86	56		34.1 ± 4.7	Yes
		F.		4,457	41	9.20		3,448	5	1.45		34.85	46		11.1 ± 5.9	Doubtful
		P.		6,213	51			11,223	51			56.71	102		45.3 ± 7.5	Yes
B.	Engineering	M.		1,662	2	1.20		2,062	5	2.42		7.23	7		-0.2 ± 2.7	No excess
		F.		1,086	10	9.21		164	--	--		7.68	10		2.3 ± 2.8	No
		P.		2,748	12	--		2,226	5	--		14.91	17		2.1 ± 3.9	No
C.	Clothing	M.		149	--	--		280	--	--		0.89	--		-0.9 ± 0.9	No excess
		F.		2,044	19	9.30		714	1	1.40		14.94	20		5.1 ± 3.9	No
		P.		2,193	19	--		994	1	--		15.83	20		4.2 ± 4.0	No
D.	Public Administration (including Civil Service and Local Government Officers, Clerical Staff, Police, Roadmen and other workmen)	M.		249	1	4.02		1,109	4	3.61		3.12	5		1.9 ± 1.8	No
		F.		456	1	2.19		285	--	--		3.48	1		-2.5 ± 1.9	No excess
		P.		705	2	--		1,394	4	--		6.60	6		-0.6 ± 2.6	No excess
E.	Transport and Communication (G.P.O., L.M.S. and Transport Lorry Drivers)	M.		528	--	--		982	1	1.02		3.13	1		-2.1 ± 1.8	No excess
		F.		333	3	9.01		103	1	9.71		2.42	4		1.6 ± 1.6	No
		P.		861	3	--		1,085	2	--		5.55	5		-0.5 ± 2.4	No excess
F.	Clerical Workers (Factory and Business Offices)	M.		231	--	--		276	--	--		0.98	--		-1.0 ± 1.0	No excess
		F.		1,113	3	2.70		206	--	--		7.92	3		-4.9 ± 2.8	No excess
		P.		1,344	3	--		482	--	--		8.90	3		-5.9 ± 3.0	No excess
G.	Leather Dressing	M.		249	--	--		1,003	3	2.99		2.85	3		0.1 ± 1.7	No
		F.		236	1	4.24		151	--	--		1.81	1		-0.8 ± 1.3	No excess
		P.		485	1	--		1,154	3	--		4.66	4		-0.7 ± 2.2	No excess
H.	Workers in Wood, Upholsterers, etc. (Carpenters, Last-makers, Upholsterers, Coachbuilders, Painters)	M.		269	1	3.72		399	2	5.01		1.34	3		1.7 ± 1.2	No
		F.		48	--	--		15	1	66.07		0.35	1		0.6 ± 0.6	No
		P.		317	1	--		414	3	--		1.69	4		2.3 ± 1.3	No
I.	Makers of Food and Drink (Cereal-makers, Pie Factories, Brewers)	M.		134	--	--		317	3	9.46		0.97	3		2.0 ± 1.0	No
		F.		139	--	--		62	--	--		1.03	--		-1.0 ± 1.0	No excess
		P.		273	--	--		379	3	--		2.00	3		1.0 ± 1.4	No
J.	Professional Occupations (Nurses, Teachers)	M.		14	--	--		78	--	--		0.21	--		-0.2 ± 0.5	No excess
		F.		194	--	--		236	--	--		1.62	--		-1.6 ± 1.3	No excess
		P.		208	--	--		314	--	--		1.83	--		-1.8 ± 1.4	No excess
K.	Foundry Workers	M.		138	--	--		351	--	--		1.06	--		-1.1 ± 1.0	No excess
		F.		--	--	--		--	--	--		--	--
		P.		138	--	--		351	--	--		1.06	--		-1.1 ± 1.0	No excess
L.	Warehouse and Storekeepers (Warehousemen, Storekeepers, Packers, Caretakers)	M.		92	--	--		238	--	--		0.71	--		-0.7 ± 0.8	No excess
		F.		68	3	44.12		50	--	--		0.53	3		2.5 ± 0.7	Doubtful
		P.		160	3	--		288	--	--		1.24	3		1.8 ± 1.1	No
M.	Other Occupations (Agricultural Workers, Gas Co. Chemical Products, Boxmakers, Printers, Rubber & Plastics, Shop Staff, Personal Service, Stationary Engine Drivers, Flax Mills, Berrywood, Tilemakers, Antenatal, Housewives, etc.)	M.		443	1	2.26		772	2	2.59		2.49	3		0.5 ± 1.6	No
		F.		964	6	6.22		504	--	--		7.25	6		-1.2 ± 2.7	No excess
		P.		1,407	7	--		1,276	2	--		9.74	9		-0.7 ± 3.1	No excess
N.	All Occupations except Boot and Shoe	M.		4,158	5	1.20		7,867	20	2.54		25	25		--
		F.		6,681	46	6.89		2,490	3	1.20		49	49		--
		P.		10,839	51	--		10,357	23	--		74	74		--
O.	All Occupations including Boot and Shoe	M.		5,914	15	2.54		15,642	66	4.22		46.86	81		34.1
		F.		11,138	87	7.81		5,938	8	1.35		83.85	95		11.1
		P.		17,052	102	--		21,580	74	--		130.71	176		45.3

* The Occupational Analysis has not been carried out strictly in accordance with the instructions of the Ministry of Health.  In the Boot and Shoe Industry all persons engaged in the industry have been shown in this group, instead of, for example, classifying clerks under Clerical and warehouse workers under Warehousemen.

Further, Public Administration includes all the various groups employed either in the Civil Service or Local Government Services, varying in social class from Administrative and Executive, Class 2, to unskilled labours, Class 5.  Again, in Transport and Communication, clerks were included in this group, instead of being shown under the correct category.  In all remaining occupations listed in the table, the Ministry’s instructions in regard to classification of occupations have been followed.

It should be explained that the preparation of this report has been carried out under some difficulty, because no separate clerk was appointed for the statistical work which has involved dealing with over thirty-eight thousand cards by manual methods, and the work has been done by one of the clerical staff of the Unit, who have been consistently working under pressure to keep abreast of routine duties.

In any event, the effect of including all workers in the Boot and Shoe Trade – that is, Management, Office Staff, Warehousemen and so on – is to make the ascertained rates in the industry possibly less than they would otherwise be, for the incidence of active tubercle in the Management and Clerical Staff, etc., is probably less than among the operatives.

6.  The above table may appear formidable, but it is necessary to present the figures in the manner shown in order to make allowances for differences in age and sex.  Two main age groups have been taken, viz. 14–34 years and 35+ years.  As is well recognized, tuberculosis of the lungs is generally more prevalent among young people, and there is also a greater tendency for young females to suffer from the disease.  In comparing one occupation, or one area with another, due allowance must accordingly be made for differences in age and sex constitution.

7.  In Column 10 of the Table it will be seen that in the boot and shoe trade, taking both age groups and both sexes, 102 cases of newly-discovered active pulmonary tuberculosis in persons who required to stay off work for treatment were discovered.  Throughout this Report these cases are referred to as active tuberculosis cases.  The number of cases that would be expected had the boot and shoe employees experienced the same rates as all other workpeople in the areas surveyed, excluding the boot and shoe trade, is 56.71; this figure is entered in Column 9.  The difference between the number of cases actually found and the expected number is shown in Column 11 to be 45.3, and the last column shows that the difference is statistically significant, i.e. the difference is more than would be found by errors of chance sampling.  When the sexes are considered separately, it will be observed from the table that, in the case of males, there is a statistically significant difference between the expected number of active tuberculosis cases and the actual number; the expected number (Column 9) was 21.86 and the actual number was 56 (Column 10).  In the case of females, the expected number was 34.85 and the actual number was 46; the difference is doubtful statistical significance, for the excess (11.1) is not quite twice the standard error (5.9).  The considerable difference between the expected and the actual number of active tuberculosis cases among males is noteworthy.

8.  The former Medical Director has informed me that he was struck by the number of men, middle-aged or older, who were found with comparatively slight symptoms but nevertheless were harbouring tubercle bacilli in the sputum and were consequently a source of infection.  It will be noted that among men under 35 years in the boot and shoe trade, the rate per 1,000 of active tuberculosis cases is 5.69 (Column 5) compared with 1.20 per 1,000 among men of similar age in all other occupations.  For men of 35+ years, the corresponding rates were 5.92 per 1,000 (Column 8) and 2.54 per 1,000.  For women under 35, the rate for the boot and shoe trade was 9.20 per 1,000 (Column 5) compared with 6.89 per 1,000 in other occupations, and in the 35+ group the rates were 1.45 per 1,000 (Column 8) and 1.20 per 1,000 respectively.  In men the higher rates were found in the older age groups as well as in the younger.  Of 46 active tuberculosis cases among men 35+ years in the boot and shoe trade, no less than 21 were found to have positive sputum.  The removal of these men as sources of infection from the factories represents an effective step to prevent further infection.

9.  The table also reveals that active tuberculosis cases among the remaining occupations included in the survey, viz. Engineering, Clothing, Leather Dressing, etc., showed no significant difference between the expected and the actual number of cases.

The incidence of active tuberculosis cases in the boot and shoe trade for all the areas surveyed was 5.85 per 1,000 (102 cases among 17,436 persons), compared with 3.49 in all occupations excluding the boot and shoe trade (74 cases among 21,196 persons).  The incidence of active tuberculosis cases for all occupations in all areas surveyed is 4.56 per 1,000 (176 cases among 38,632 persons).

10.  Departmental Analysis of the Boot and Shoe Trade.

Having ascertained that, allowing for differences of age and sex, the incidence at the time of the survey of active tuberculosis cases was significantly higher in the boot and shoe trade as compared with other occupations, the next question to be answered is – Can any difference be detected in the various departments of the Industry?  These have been taken as follows:

	Clicking.	Cutting upper leather into components.
	Closing.	Sewing component parts together to make complete upper.
	Rough Stuff.	Cutting out the inner and outer soles and stiffeners to make complete bottom.
	Lasting.	Attaching bottom to the upper.
	Finishing.	Trimming heels and edges and polishing heels and edges.
	Shoe Room.	Shoe cleaned and polished, and boxed ready for despatch.

Table II.

Northamptonshire – Mass Radiography Survey, 1945–46.

Rushden, Kettering, Northampton and Wellingborough Areas.

Boot and Shoe Industry – Analysis by departments of newly-discovered cases of Active Pulmonary Tuberculosis in persons who required to stay off work for treatment, either Sanatorium or Domiciliary.

Column:
(1)        Occupation
(2)        Sex
(3)        Number Examined
(4)        Number of Active P.T. Cases
(5)        Rate per 1,000
(6)        Number Examined
(7)        Number of Active P.T. Cases
(8)        Rate per 1,000
(9)        Expected Number of Active P.T. Cases at rates for occupations other than Boot and Shoe
(10)      Actual Number of Active P.T. Cases
(11)      Excess ± Standard Error
(12)      Is difference significant?

			14 - 34 Years				35+ Years				All Ages
(1)	(2)		(3)	(4)	(5)		(6)	(7)	(8)		(9)	(10)		(11)	(12)
Clicking	M.		447	4	8.95		1,417	8	5.65		4.14	12		7.9 ± 2.0	Yes
	F.		91	--	--		63	--	--		0.70	--		-0.7 ± 0.8	No excess
	P.		538	4	--		1,480	8	--		4.84	12		7.2 ± 2.2	Yes
Closing	M.		13	--	--		28	1	35.71		0.09	1		0.9 ± 0.3	No
	F.		2,530	22	8.70		2,077	2	0.96		19.92	24		4.1 ± 4.5	No
	P.		2,543	22	--		2,105	3	--		20.01	25		5.0 ± 4.5	No
Rough Stuff	M.		144	1	6.94		880	2	2.27		2.41	3		0.6 ± 1.6	No
	F.		208	--	--		258	--	--		1.74	--		-1.7 ± 1.3	No excess
	P.		352	1	--		1,139	2	--		4.15	3		-1.1 ± 2.0	No excess
Lasting	M.		664	2	3.01		2,618	18	6.88		7.45	20		12.5 ± 2.7	Yes
	F.		189	4	21.16		179	1	5.59		1.52	5		3.5 ± 1.2	Yes
	P.		853	6	--		2,797	19	--		8.97	25		16.0 ± 3.0	Yes
Finishing	M.		260	3	11.54		1,612	12	7.44		4.41	15		10.6 ± 2.1	Yes
	F.		47	--	--		37	--	--		0.37	--		-0.4 ± 0.6	No excess
	P.		307	3	--		1,649	12	--		4.78	15		10.2 ± 2.2	Yes
Shoe Room	M.		14	--	--		187	1	5.35		0.45	1		0.5 ± 0.7	No
	F.		455	7	15.38		406	--	--		3.62	7		3.4 ± 1.9	No
	P.		469	7	--		593	1	--		4.11	8		3.9 ± 2.0	No
Miscellaneous Boot and Shoe	M.		215	--	--		1,033	4	3.87		2.88	4		1.1 ± 1.7	No
	F.		936	8	8.55		427	2	4.68		6.96	10		3.0 ± 2.6	No
	P.		1,151	8	--		1,460	6	--		9.84	14		4.2 ± 3.1	No

Table III.

Northamptonshire – Mass Radiography Survey, 1945–46.

Rushden, Kettering, Northampton and Wellingborough Areas.

Analysis by area of newly-discovered cases of Active Pulmonary Tuberculosis in persons who required to stay off work for treatment, either Sanatorium or Domiciliary.

Column:
(1)        Occupation
(2)        Sex
(3)        Number Examined
(4)        Number of Active P.T. Cases
(5)        Rate per 1,000
(6)        Number Examined
(7)        Number of Active P.T. Cases
(8)        Rate per 1,000
(9)        Expected Number of Active P.T. Cases at rates for occupations other than Boot and Shoe in all areas combined
(10)      Actual Number of Active P.T. Cases
(11)      Excess ± Standard Error
(12)      Is difference significant?

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