Sven Hernberg

The Treatment of Acute Low Back Pain — Bed Rest, Exercises, or Ordinary Activity?

BACKGROUND Bed rest and back-extension exercises are often prescribed for patients with acute low back pain, but the effectiveness of these two competing treatments remains controversial. METHODS We conducted a controlled trial among employees of the city of Helsinki, Finland, who presented to an occupational health care center with acute, nonspecific low back pain. The patients were randomly assigned to one of three treatments: bed rest for two days (67 patients), back-mobilizing exercises (52 patients), or the continuation of ordinary activities as tolerated (the control group; 67 patients). Outcomes and costs were assessed after 3 and 12 weeks. RESULTS After 3 and 12 weeks, the patients in the control group had better recovery than those prescribed either bed rest or exercises. There were statistically significant differences favoring the control group in the duration of pain, pain intensity, lumbar flexion, ability to work as measured subjectively, the Oswestry back-disability index, and number of days absent from work. Recovery was slowest among the patients assigned to bed rest. The overall costs of care did not differ significantly among the three groups. CONCLUSIONS Among patients with acute low back pain, continuing ordinary activities within the limits permitted by the pain leads to more rapid recovery than either bed rest or back-mobilizing exercises.

δ-Aminolevulinic Acid Dehydrase as a Measure of Lead Exposure

Close negative correlation between the concentration of lead in blood (Pb-B) and the logarithm of erythrocyte δ-aminolevulinic acid dehydrase (ALA-D) was found for 159 persons with Pb-B levels ranging from 5μg to 95μg per 100 ml. A statistically significant correlation (r = 0.59) between Pb-B and δ-aminolevulinic acid (ALA) in urine was obtained only for Pb-B values over 50μg/100 ml. These results indicate that erythrocyte ALA-D is more accurate and more sensitive than ALA in urine as an indicator of the amount of circulating lead. It is suggested that ALA-D assays can be used as a screening procedure to exclude a lead absorption over a given level. Fairly accurate estimates of the mean Pb-B of groups of people can also be made from their mean ALA-D activity.

Clozapine-induced agranulocytosis

SummaryAn epidemic of agranulocytosis and granulocytopenia occurred in 1975 in conjunction with clozapine treatment of mental patients in Finland. An attempt was made to assess the epidemiologic and genetic factors contributing to the adverse drug effect. The estimated incidence rate in Finland was 2.1/1000 patient-months. This figure could not be compared with rates from other countries because of the inexact nature of the figures reported so far. All 16 cases occurred in seven hospitals in southwestern Finland, whereas the overall hospital net use of the drug was geographically evenly distributed. The difference between the observed and the proportionally expected incidence of cases amongst the hospitals where clozapine was used was statistically significant. The average consumption of the drug did not differ between the hospitals where cases occurred and those where no definite cases could be diagnosed. Six-generation pedigree analyses failed to reveal significant parental consanguinity or genetic kinship between probands. Neither did the birth places of the ancestors of the probands disclose a typical isolate pattern. In conclusion, the cases appeared to be confined to a few hospitals in southwestern Finland. Although a genetic factor is not excluded, we found no evidence in support of a genetic mechanism.

Subclinical Neuropathy at “Safe” Levels of Lead Exposure

Electrophysiological methods revealed subclinical neuropathy in 26 workers, exposed from 1 to 17 years to lead and whose blood lead (PbB) values had never exceeded 70mu/100ml, as ascertained by checking the monitor reports of the factory and by careful exposure history. The PbB determinations had been tested repeatedly and had been found valid. The main findings were slowing of the maximal motor conduction velocities of the median and ulnar nerves and particularly the conduction velocity of the slower fibers of the ulnar nerve. Electromyographical abnormalities comprised fibrillations, diminution of the number of motor units on maximal contraction, and an abnormally long duration of the units. Earlier similar measurements from heavily exposed workers had been even more abnormal. Thus, a dose-response relationship exists on a group basis. Since the regular monitoring of PbBs in most workers during their entire period of exposure excludes the possibility of a body burden out of proportion to the PbB slight neurological damage is produced at exposures hitherto regarded as quite safe.

Parameters indicative of absorption and biological effect in new lead exposure: a prospective study.

Tola, S., Hernberg, S., Asp, S., and Nikkanen, J. (1973).British Journal of Industrial Medicine,30, 134-141. Parameters indicative of absorption and biological effect in new lead exposure: a prospective study. Determinations have been made of the blood and urinary lead concentrations (Pb-B, Pb-U), haemoglobin concentrations (Hb), packed blood cell volumes (Hcr), urinary δ-aminolevulinic acid (ALA-U) and coproporphyrin concentrations (CP-U), as well as erythrocyte δ-aminolevulinic acid dehydratase activities (ALA-D), in respect of 33 workers entering occupational lead exposure for the first time in their lives. In a follow-up study lasting from one to four months samples were taken before exposure began, initially at intervals of two days and subsequently at intervals of one to two weeks. Nine control subjects were studied for Pb-B once, and for Hb, Hcr, and ALA-D weekly. The Pb-B rose and the ALA-D activity fell with no demonstrable time lag, while the latency periods of ALA-U, Pb-U, and CP-U were about two weeks. All of these laboratory tests reached a steady state during the follow-up. ALA-D showed the highest correlation to Pb-B and proved to be the most sensitive indicator of lead effect. Both CP-U and ALA-U were useful indicators of the effect of lead upon the organism, although a stepwise regression analysis, and their correlation coefficients with Pb-B, led to the conclusion that CP-U had better explaining power than ALA-U. The mean Hb and Hcr values were significantly lower at the end of the observation period than at the beginning, providing an indication that anaemia begins to develop early in the course of lead absorption.

Neurological picture of organic solvent poisoning in industry. A retrospective clinical study of 37 patients.

SummaryA retrospective evaluation of neurological, neuroradiological, neurophysiological, psychological, and laboratory findings on 37 patients, remitted to the Institute of Occupational Health, Helsinki because of suspected poisoning due to organic solvents, was performed. Patient selection was made on the basis of performed pneumoencephalography (PEG). Most of the patients had been exposed to a mixture of solvents (19 cases). Carbon disulphide exposure had occurred in six cases, trichloroethylene in five cases, and the rest of the patients had been exposed to styrene (one case), thinner (two cases), toluene (1 case), methanol (1 case), and carbon tetrachloride (two cases). Clinical neurological findings comprised slight psycho-organic alteration, cerebellar dysfunction, and peripheral neuropathy. The PEG showed changes suggesting brain atrophy in 63% of the patients. Slight asymmetric central atrophy and localized cortical atrophy were the most frequent findings. The main electroencephalographic finding was slight diffuse slow-wave. Electroneuromyography showed slight changes suggesting peripheral neuropathy in 23 of the 28 patients examined. Psychological alterations were seen in all patients: personality changes and psychomotor disturbances were the most common findings. Because individual constitutional differences existed, no clear-cut exposure-effect relationship could be established. Thus, neurological evaluation of all those exposed to neurotoxic agents who present symptoms, regardless of the degree of current exposure, is important.

Lung cancer mortality among iron foundry workers.

The present study was designed to test earlier findings of increased risk of lung cancer among iron foundry workers and to define the cause of the risk. The subjects were 3,425 workers with at least one years employment in an iron foundry sometime between 1918 and December 31, 1972. The number (51) of cases of lung cancer which occurred prior to December 31, 1976 was statistically significantly higher than that expected, i.e., 35.3 based on proportional mortality. Molders and casters were determined to have the highest excess risk in a case-control study among the cohort. The worker groups with high exposure to polycyclic aromatic hydrocarbons (PAH) experienced a lung cancer risk higher than that of other groups, but the difference was not statistically significant.

Effects of intervention on the cardiovascular mortality of workers exposed to carbon disulphide: a 15 year follow up.

The cardiovascular mortality of a cohort of 343 Finnish men exposed for at least five years to carbon disulphide (CS2) in a viscose rayon plant has been monitored prospectively from 1967 to 1982. The results from the first five years of follow up in 1972 showed a 4.7-fold excess mortality for ischaemic and other heart diseases (ICD A83-A84) compared with a comparable reference cohort of paper mill workers. After 1972 a preventive intervention programme instituted at the rayon plant included removing all workers with coronary risk factors from exposure. Thus only 19% of the exposed cohort continued to be exposed in 1977 compared with 53% in 1972. Moreover, exposure levels were reduced after 1972 in compliance with the set hygienic standard of 10 ppm. These measures were reflected in a normalisation of the risk of cardiovascular death; the relative risk was 1.0 in the period after the intervention (1 July 1974 to 30 June 1982), whereas it had previously been 3.2 (from 1 July 1972 to 30 June 1974). The risk of a fatal heart attack remained at 11.6% throughout the 15 year follow up period (95% confidence limits 8.5%-15.4%) among the exposed compared with 7.8% (5.3%-11.2%) among the unexposed. The entire risk difference of 3.8% was accumulated during the first seven years of follow up. Thus we can estimate that 59 CS2-related cardiovascular deaths would have occurred during the next eight years (instead of the actual 19 deaths) had there been no preventive action. Calculations yielded a preventive fraction of 68%.

Chemical exposures and respiratory cancer among Finnish woodworkers

A case-control study of respiratory cancer, nested within a cohort of male woodworkers, was updated in Finland. The update extended the initial follow up of 3805 workers from 19 plants to 7307 workers from 35 plants. Each case of respiratory cancer (n = 136) diagnosed between 1957 and 1982 within the cohort was matched by year of birth with three controls (n = 408) from the cohort. Chemical exposures were assessed for the cases and the controls by a plant and period specific job exposure matrix. An excess of respiratory cancer was associated with phenol. Concomitant exposures to several other agents occurred as well, however, and no exposure-response relation for phenol was seen. An excess risk and an increasing exposure-response relation were found for engine exhaust from petrol and diesel driven factory trucks. The excess risk associated with pesticides was lower than in our previous study, an indication of qualitative and quantitative differences in exposure between the initial and augmented cohorts. Slightly increased risks were found for terpenes and mould spores, which may be due to chance although the contribution of occupational exposure cannot be ruled out. Exposure to wood dust, mainly from pine, spruce and birch, at a level of about 1 mg/m3, was not associated with lung cancer, upper respiratory cancer, or adenocarcinoma of the lung.

Erythrocyte δ -aminolevulinic Acid Dehydratase in New Lead Exposure

The time course of the lead-induced inhibition of erythrocyte δ-aminolevulinic acid dehydratase (ALA-D) was studied in 29 new lead workers. Samples were performed before commencement of exposure, two to three times during the first week, once a week for three months, and twice during the fourth month of exposure. The rise of the concentration of lead in the blood (Pb-B) was accompanied by a rapid decrease of ALA-D activity, measurable even during the first days of exposure. The rate of decrease of ALA-D was proportional to the rise in Pb-B. After ALA-D had reached a steady state, the variation within each subject was very small. Since ALA-D activity fell in all 29 subjects, the causative effect of lead must be considered proven. ALA-D provides a sensitive and accurate measure of circulating lead. The test is reliable even during the first few days of initial exposure.