Joan Walford

An investigation of lead absorption in an electric accumulator factory with the use of personal samplers

Williams, M. K., King, E., and Walford, Joan (1969).Brit. J. industr. Med.,26, 202-216. An investigation of lead absorption in an electric accumulator factory with the use of personal samplers. Thirty-nine lead workers and controls, in stable conditions of exposure, each wore personal lead-in-air samplers daily for two weeks. During the second week samples for blood lead, urinary lead, urinary coproporphyrin, urinary δ-aminolevulinic acid (ALA), the punctate basophil count, and haemoglobin were taken daily. Duplicate estimations were made on one day. The lead exposures of men doing almost identical jobs differed by ratios of up to four to one. This could be attributed only to personal differences in working habits. The correlation coefficients and regression equations of the biochemical tests with lead-in-air and with each other were determined. The mean values and 95% confidence limits of single determinations of some of the biochemical tests corresponding to the two commonly accepted TLVs of lead-in-air (0·20 and 0·15 mg./m.3) were calculated from the regression equations. For each biochemical test the variation due to analytical error, the variation from day to day within subjects and the residual variation due to analytical error, and the residual variation about the regression on lead-in-air were calculated. Previous estimates of the latter are not known. Excessive confidence may be placed in an index of exposure due to its low coefficient of variation within subjects unless the coefficient of variation between subjects about regression is taken into account. This correction for specific gravity of estimations of lead and ALA in spot samples of urine was found to reduce slightly the residual variation between subjects about the regression on lead-in-air and to increase the correlations with lead-in-air and with the other biochemical tests, but these changes were not statistically significant. The modified method used for estimating blood lead and urinary lead is described and validated.

Circadian variation of F.E.V. in shift workers

Guberan, E., Williams, M. K., Walford, Joan, and Smith, Margaret M. (1969).Brit. J. industr. Med.,26, 121-125. Circadian variation of F.E.V. in shift workers. The one-second forced expiratory volume (F.E.V.1·0), the forced vital capacity, and the oral temperature were measured in a group of men working a rotating three-shift system—2 to 10 p.m. one week, 10 p.m. to 6 a.m. the next week, and 6 a.m. to 2 p.m. the third week. The outside air temperature at the London Weather Centre was also obtained. Measurements were made on Mondays and Fridays at the beginning, middle, and end of the shift. The mean F.E.V.1·0 of 19 normal men showed an increase of 0·15 litre (4·1%) between the beginning and end of both the morning shifts, a mean decrease of some 0·05 litre (1·5%) between the beginning and end of the afternoon shifts, and little change during the night shifts. This circadian variation could not be attributed to industrial fume, smoking or a learning effect. The findings will be of practical importance when F.E.V. is measured in shift workers to determine the effects of toxic substances on ventilatory capacity.

A Study of Byssinosis, Chronic Respiratory Symptoms, and Ventilatory Capacity in English and Dutch Cotton Workers, with Special Reference to Atmospheric Pollution

An epidemiological survey of 414 English and 980 Dutch male cotton workers was undertaken to determine the prevalence of byssinosis and respiratory symptoms, and to compare the ventilatory capacities in the two populations, with particular reference to the influence of air pollution. The English workers were employed in six mills in Lancashire and the Dutch workers in three mills in Almelo spinning similar grades of cotton. The methods used included a questionnaire on respiratory symptoms and illnesses, the collection and examination of sputum, and the measurement of the forced expiratory volume over 0·75 sec. Concentrations of smoke and sulphur dioxide were measured in the English and Dutch towns. The crude rates for byssinosis were similar, 13·5% and 17% respectively in the English and Dutch card and blow rooms, and 1·5% and 1·6% respectively in the spinning rooms. The English workers had significantly higher prevalences of persistent cough and persistent phlegm and significantly lower indirect maximum breathing capacities. These findings were supported by the results of a sputum survey. Nearly twice as many English produced specimens, and the mean volume of sputum was greater for the English workers. The prevalence of bronchitis, defined as persistent phlegm and at least one chest illness during the past three years, causing absence from work, was higher in the English than in the Dutch workers in both types of work room, but not significantly so after standardizing for differences in age. Since there are important differences in the social security systems of the two countries, which may encourage more absence from illness among the Dutch, a comparison of bronchitis thus defined is likely to be invalid. The higher prevalences of respiratory symptoms and lower ventilatory capacities in the English are unlikely to be due to observer error. They are discussed in relation to smoking habits, exposure to cotton dust, and air pollution. The most likely explanation of the unfavourable picture presented by the English workers is the much higher level of air pollution in Lancashire.

Byssinosis in the Egyptian Cotton Industry: Changes in Ventilatory Capacity during the Day

A study in Egypt of 99 male cotton workers in a cotton ginnery and spinning mill, and of a control group of 12 power station workers, showed that the groups exposed to cotton dust had significantly greater falls in indirect maximum breathing capacity (I.M.B.C.) during the shift than groups not exposed to dust. Long-term effects of exposure to cotton dust were studied by examining the I.M.B.C.s measured at the beginning of the shift after adjustment to allow for differences in age and sitting height. The adjusted mean value for those with byssinosis was 10·1 litres/min. lower than for normal cotton workers and 19·6 litres/min. lower than for the power station workers. Four men were judged by their breathlessness on slight exertion and low ventilatory capacities to be seriously disabled with byssinosis. In four other mills, all spinning similar types of cotton, changes in I.M.B.C. during the shift correlated highly with dust concentrations and indicated a safe level of dustiness of 1 mg./m.3 (total dust) at which the effects on ventilatory capacity were minimal.

Diurnal Variation in Ventilatory Capacity: An Epidemiological Study of Cotton and other Factory Workers employed on Shift Work

The change in F.E.V.0·75 during a working shift was studied in a random sample of 473 men employed in three cotton mills in The Netherlands working a three-shift system. Results were also obtained for 198 men, not exposed to industrial dust, who were working in a biscuit factory and two textile factories in the same area. The men were seen only during the shift on which they were working at the time of the study. Men with byssinosis gave a typical picture of the effects of cotton dust on susceptible workers: a generally low F.E.V. with a marked reduction during the shift; –0·16 l. on the early morning shift, and –0·25 l. and –0·33 l. respectively on the afternoon and night shifts. Men without byssinosis in the card and blow rooms showed mean changes in F.E.V. during the shift similar to those of men working in the spinning room: a slight rise in the early morning shift of +0·02 l. followed by a fall in both afternoon and night shifts in the region of –0·10 litres. This pattern of change was also found among the workers in the non-dusty factories. The rise in the early shift cannot be explained by the clearing of mucus from the air passages; cotton workers without respiratory symptoms and men in the non-dusty factories who did not produce sputum still showed an increase in F.E.V. during the early shift, though less marked than that of men with respiratory symptoms or who produced phlegm. The evidence suggests that a diurnal variation in lung function exists and should be taken into consideration both in epidemiological studies and when ventilatory capacity tests are used in periodic medical examinations.

The Location of Personal Sampler Filter Heads

Abstract Fifteen pasters in an electric accumulator factory each wore two personal samplers simultaneously for two consecutive shifts. The filter heads were attached to the upper left chest, one about 5 inches below the other. During the second shift the locations of the two heads were interchanged. The mean concentration obtained with the filter heads in the upper position was 0.181 mg/m3, while that obtained in the lower position was 0.225 mg/m3. The difference was 22% of the overall mean, and statistically highly significant (p < 0.01). Differences between the six samplers used were not significant. It was concluded that the location of the filter head should be defined more precisely than has been suggested for other jobs, and that the findings will be of particular importance when deriving threshold limit values.

A study of rope workers exposed to hemp and flax.

Smith, G. F., Coles, G. V., Schilling, R. S. F., and Walford, Joan (1969).Brit. J. industr. Med.,26, 109-114. A study of rope workers exposed to hemp and flax. Respiratory symptoms and ventilatory capacities were studied in 54 men and 22 women exposed to the mixed dusts of hemp and flax in an English rope factory. The preparers and most of the spinners were exposed on average to concentrations of 1·7 mg./m.3 total dust and 0·5 mg./m.3 fine dust. Those employed on subsequent processes had lower exposures at concentrations of 0·5 mg./m.3 total dust and 0·1 mg./m.3 fine dust. Six men, all in the high exposure group, had symptoms of byssinosis. After adjustment for age and standing height there was no statistically significant difference in the forced expiratory volume (F.E.V.1·0) between those in high dust concentrations and those in low concentrations; neither was there a significant difference between the ventilatory capacities of men with and without byssinosis. This study shows that byssinosis is an occupational hazard confined to male workers in this factory. It does not appear to be a very serious problem and will diminish with the increasing use of synthetic materials instead of natural fibres.

STUDY OF RESPIRATORY SYMPTOMS AND VENTILATORY CAPACITIES AMONG ROPE WORKERS

In a rope works handling manila, sisal, and St. Helena hemps, the prevalence of respiratory symptoms and the change in forced expiratory volume (F.E.V.1·0) during the work shift were studied in a group of 41 women and 41 men who represented 93% of the population at risk. Dust concentrations, measured with a modified Hexhlet, ranged from 0·11 to 4·51 mg./m.3 for total dust and 0·02 to 1·46 mg./m.3 for fine dust. The highest concentrations were found in the preparing rooms, in which the workers, all of whom were women, showed on the average a fall in ventilatory capacity during the shift. The workers in the rope walk, all of whom were men, showed a rise in ventilatory capacity during the shift. The difference between the men and women was statistically significant (p < 0·05). No worker gave a characteristic history of byssinosis, although nine women complained of chest tightness associated with their work. Undue breathlessness on exertion and persistent cough and phlegm were also more common among the women, but they were on the average 18 years older than the men. When the ventilatory capacities and the prevalence of respiratory symptoms of women rope workers were compared with those of a group of women employed elsewhere in the dockyard, the only significant difference was that the rope workers had more chest tightness associated with their work (p < 0·02). Exposure of volunteers to St. Helena hemp, which is apparently the most likely of the hard hemps to give rise to respiratory symptoms, caused only a slight fall in ventilatory capacity and a small rise in airways resistance. A sample of St. Helena hemp assayed on guinea-pig ileum had only a relatively small degree of contractor activity. The evidence suggests that the dusts of hard hemps do not cause byssinosis under the conditions in this factory. However, the irritant nature of the dust indicates the need to prevent total dust levels exceeding about 2 mg./m.3.

Blood lead and the symptoms of lead absorption.

ABSTRACT Eighty-one percent of all hourly paid men who had been employed for more than six months in a factory making lead acid batteries and plastics completed a modified Cornell medical index health questionnaire. Blood lead and erythrocyte protoporphyrin (EPP) were also measured. The questions were grouped into symptom categories as follows: all physical, all psychological, “potentially lead induced,” pulmonary, cardiovascular, gastrointestinal, skin, nervous system, genitourinary, and fatigue. For each symptom category the pooled percentages of men whose symptom scores were above the common median of the three blood lead groups 10-, 40-, and 60 and over μg/100 ml (0·48-, 1·93-, and 2·90 and over μmol/l) within age/smoking subgroups were calculated. In every symptom category the percentages in the two lower blood lead groups differed little, but the percentages were consistently higher in men with blood concentration of 60 μg/100 ml (2·90 μmol/l) and over. Differences between a combined 10-59 μg/100 ml (0·48-2·85 μmol/l) blood lead group and the 60 and over μg/100 ml (≥2·90 μmol/l) group were statistically significant at the 0·01 level for “potentially lead induced” symptoms and at the 0·05 level for skin and psychological symptoms. Broadly similar results were obtained with four log10 EPP groups 0·6-, 1·5-, 1·7-, and ≥2·0, but differences did not reach statistical significance. There was no obvious explanation as to why symptoms that are not found in classic lead poisoning should be increased almost as much as those that are. It was thought that these results could be biased due to the mens knowledge of the symptoms associated with lead exposure, but the possibility that they may be partly due to lead absorption cannot be excluded.

A Trial of Terylene Overalls for Lead-Acid Electric Accumulator Pasters

A comparison of Terylene and cotton overalls has been made in the lead-acid electric accumulator industry. Six hand pasters wore personal lead-in-air samplers for two weeks. Three of the men wore cotton overalls the first week and Terylene overalls the second; the other three men wore Terylene overalls the first week and cotton overalls the second. The mean lead-in-air concentration in the breathing zone when the men wore Terylene overalls was slightly greater than when they wore cotton overalls but the difference was not statistically significant. Significant differences of lead-in-air concentrations were found between men and between the two weeks but not between days within the weeks. The lead-in-air concentration did not increase during the week. Neither a change to Terylene overalls nor more frequent laundering of overalls should be recommended for pasters in this factory on the basis of this study.