Ulf Strömberg

Disorders of the neck and upper limbs in women in the fish processing industry

OBJECTIVE--The aim was to study the association between personal factors and physical and psychosocial work environment factors and disorders of the neck or upper limbs among women in the fish processing industry. METHODS--A cross sectional study was performed on 206 women in the fish processing industry and 208 control women. Several physical and psychosocial work environment factors were evaluated. Subjective complaints about the neck or upper limbs were assessed by questionnaire and by a clinical examination. RESULTS--The study showed a high prevalence (35%) of diagnoses in the neck or shoulders of the exposed women. All prevalence odds ratios (PORs) were substantially higher in young women. There was a pronounced dose-response relation between disorders of the neck or shoulders and duration of employment for women < 45 years old. When studying 322 former workers, the proportion who claimed musculoskeletal complaints as the reason for leaving was highest among the older women. Muscular tension, stress or worry, work strain, and the largest fraction of the work time spent with highly repetitive work tasks were clearly associated with disorders of the neck or shoulders. The measurements of the wrist movements also showed that the work was performed almost without any pauses and that the median flexion and extension velocity was high (41 degree/s). The results of observation showed good agreement with the measurements of wrist motion. CONCLUSION--Work in the fish processing industry is a risk factor for disorders of the neck and upper limbs. Due to the homogenity of the physical work load in the exposed group, we could not show any associations between the objective measurements and disorders. In cross sectional studies the risk may be underestimated due to a healthy worker effect.

Smoking and myelodysplastic syndromes

The purpose of this case-control study was to investigate tobacco smoking as a risk factor for myelodysplastic syndromes, emphasizing karyotypic aberrations as markers for exposure and risk differentiation with respect to morphology. We obtained smoking history by interview of 330 cytogenetically investigated adult myelodysplastic syndrome cases and 337 controls, matched with respect to sex, year of birth, and county of living. Smoking for at least 1 year at some time 20 years or less before diagnosis was associated with an elevated relative risk (RR) for primary myelodysplastic syndromes (odds ratio (OR) 1.8; 95% confidence interval (CI) = 1.2-2.7). The results indicated a relation with intensity and duration of smoking as well as a decrease in risk a few years after cessation of smoking. Smoking was associated with an increased RR for primary myelodysplastic syndromes with chromosome 7 abnormalities (OR 5.0; 95% CI = 1.1-23). Elevated RRs were also seen for refractory anemia (OR 2.5; 95% CI = 1.2-5.6) and for refractory anemia with ringed sideroblasts (OR 3.2; 95% CI = 0.88-12). The findings suggest that smoking is a risk factor for myelodysplastic syndromes.

Lead in fingerbone : A tool for retrospective exposure assessment

Exposure to inorganic lead may cause many adverse health effects. When absorbed, lead is accumulated in large part in bone. In this study, we investigated the relationship between lead concentration in fingerbone, exposure time, and lead in blood. We also sought to design a model that made it possible to use fingerbone lead as an indicator of earlier exposure. The study comprised 137 active workers from a secondary lead smeltery. Workers had undergone regular determinations of blood lead (i.e., up to 6 times/y) for up to 24 y. In addition, during the period 1979-1992, workers underwent up to four fingerbone lead assessments via noninvasive x-ray fluorescence. We calculated cumulative blood lead, adjusted for time-related reduction of bone lead according to a transfer of lead from bone to blood, for each worker. We obtained the best fit of bone lead to cumulative adjusted blood lead when we assumed a 14-y half-time for the transfer coefficient. This half-time was similar to the terminal half-time for lead in bone in retired smelters, whom we studied earlier by longitudinal in vivo measurements. We described models for the accumulation of bone lead on blood lead and exposure time. The combined data on bone lead and exposure time may be used to estimate a mean blood lead during previous exposure. Such estimates will be valuable in epidemiological studies aimed at evaluating the toxic effects of long-term lead exposure in lead workers for whom data on previous blood lead levels are lacking.

Does induction time have any bearing on definition of study base

A study population with either a low or high exposure prevalence usually results in a less efficient study, compared with a study on a population with an intermediate exposure prevalence. We discuss a strategy for improving efficiency when exposure is rare: one can include in the study base, for each individual, only follow-up corresponding to a potential exposure-associated increase in risk. This strategy is achieved by choosing so-called preinclusion and preexclusion periods, which, in turn, follow from relevant induction time assumptions.

Examining an increasing trend with non-parametric methods

Some distribution-free tests are presented that examine the assumption that there is an increasing relationship between a primary variable and a covariate. Having ascertained its presence, an increasing relationship is described more precisely by estimating the qth quantile functions for selected values of q. Furthermore, a non-parametric procedure for assessing points of increase of a qth quantile function is introduced and discussed. Finally, the methods to be presented are applied to serum cholesterol and age data.