Descriptive Epidemiology of Somatising Tendency: Findings from the CUPID Study.

Somatising tendency, defined as a predisposition to worry about common somatic symptoms, is importantly associated with various aspects of health and health-related behaviour, including musculoskeletal pain and associated disability. To explore its epidemiological characteristics, and how it can be specified most efficiently, we analysed data from an international longitudinal study. A baseline questionnaire, which included questions from the Brief Symptom Inventory about seven common symptoms, was completed by 12,072 participants aged 20-59 from 46 occupational groups in 18 countries (response rate 70%). The seven symptoms were all mutually associated (odds ratios for pairwise associations 3.4 to 9.3), and each contributed to a measure of somatising tendency that exhibited an exposure-response relationship both with multi-site pain (prevalence rate ratios up to six), and also with sickness absence for non-musculoskeletal reasons. In most participants, the level of somatising tendency was little changed when reassessed after a mean interval of 14 months (75% having a change of 0 or 1 in their symptom count), although the specific symptoms reported at follow-up often differed from those at baseline. Somatising tendency was more common in women than men, especially at older ages, and varied markedly across the 46 occupational groups studied, with higher rates in South and Central America. It was weakly associated with smoking, but not with level of education. Our study supports the use of questions from the Brief Symptom Inventory as a method for measuring somatising tendency, and suggests that in adults of working age, it is a fairly stable trait.

Trends in mortality from occupational hazards among men in England and Wales during 1979-2010.

OBJECTIVES: To monitor the impact of health and safety provisions and inform future preventive strategies, we investigated trends in mortality from established occupational hazards in England and Wales. METHODS: We analysed data from death certificates on underlying cause of death and last full-time occupation for 3 688 916 deaths among men aged 20-74 years in England and Wales during 1979-2010 (excluding 1981 when records were incomplete). Proportional mortality ratios (PMRs), standardised for age and social class, were calculated for occupations at risk of specified hazards. Observed and expected numbers of deaths for each hazard were summed across occupations, and the differences summarised as average annual excesses. RESULTS: Excess mortality declined substantially for most hazards. For example, the annual excess of deaths from chronic bronchitis and emphysema fell from 170.7 during 1979-1990 to 36.0 in 2001-2010, and that for deaths from injury and poisoning from 237.0 to 87.5. In many cases, the improvements were associated with falling PMRs (suggesting safer working practices), but they also reflected reductions in the numbers of men employed in more hazardous jobs, and declining mortality from some diseases across the whole population. Notable exceptions to the general improvement were diseases caused by asbestos, especially in some construction trades and sinonasal cancer in woodworkers. CONCLUSIONS: The highest priority for future prevention of work-related fatalities is the minority of occupational disorders for which excess mortality remains static or is increasing, in particular asbestos-related disease among certain occupations in the construction industry and sinonasal cancer in woodworkers.

Soft tissue sarcoma, non-Hodgkin's lymphoma and chronic lymphocytic leukaemia in workers exposed to phenoxy herbicides: extended follow-up of a UK cohort.

OBJECTIVES: To provide further information on the possible carcinogenicity of phenoxy herbicides, and in particular their relationship to soft tissue sarcoma (STS), non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukaemia (CLL). METHODS: We extended follow-up to December 2012 for 8036 men employed at five factories in the UK which had manufactured phenoxy herbicides, or in a contract spraying business. Mortality was compared with that for England and Wales by the person-years method. Nested case-control analyses compared men with incident or fatal STS (n=15) or NHL/CLL (n=74) and matched controls (up to 10 per case). RESULTS: 4093 men had died, including 2303 since the last follow-up. Mortality from all causes and all cancers was close to expectation, but an excess of deaths from NHL was observed among men who had worked for ≥1 year in jobs with more than background exposure to phenoxy herbicides (19 deaths, SMR 1.85, 95% CI 1.12 to 2.89). Four deaths from STS occurred among men potentially exposed above background (3.3 expected). In the nested case-control analyses, there were no significantly elevated risks or consistent trends across categories of potential exposure for either STS or NHL/CLL. Among men who had worked for ≥1 year in potentially exposed jobs, the highest OR (for STS) was only 1.30 (95% CI 0.30 to 5.62). CONCLUSIONS: Our findings are consistent with the current balance of epidemiological evidence. If phenoxy herbicides pose a hazard of either STS or NHL, then any absolute increase in risk is likely to be small.

Risk of cancer in workers exposed to styrene at eight British companies making glass-reinforced plastics.

OBJECTIVES: To provide further information on the risks of lymphohaematopoietic (LH) and other cancers associated with styrene. METHODS: We extended follow-up to December 2012 for 7970 workers at eight companies in England which used styrene in the manufacture of glass-reinforced plastics. Mortality was compared with that for England and Wales by the person-years method, and summarised by SMRs with 95% CIs. A supplementary nested case-control analysis compared styrene exposures, lagged by 5 years, in 122 incident or fatal cases of LH cancer and 1138 matched controls. RESULTS: A total of 3121 cohort members had died (2022 since the last follow-up). No elevation of mortality was observed for LH cancer, either in the full cohort (62 deaths, SMR 0.90, 95% CI 0.69 to 1.15), or in those with more than background exposure to styrene (38 deaths, SMR 0.82, 95% CI 0.58 to 1.14). Nor did the case-control analysis suggest any association with LH cancer. In comparison with background exposure, the OR for non-Hodgkin's lymphoma/chronic lymphocytic leukaemia in workers with high exposure (estimated 8-h time-weighted average of 40-100 ppm) for ≥1 year was 0.54 (95% CI 0.23 to 1.27). Mortality from lung cancer was significantly elevated, and risk increased progressively across exposure categories, with an SMR of 1.44 (95% CI 1.10 to 1.86) in workers highly exposed for ≥1 year. CONCLUSIONS: We found no evidence that styrene causes LH cancer. An association with lung cancer is not consistently supported by other studies. It may have been confounded by smoking, but would be worth checking further.

Upper airway cancer, myeloid leukemia, and other cancers in a cohort of British chemical workers exposed to formaldehyde.

The International Agency for Research on Cancer controversially has classified formaldehyde as causing nasopharyngeal carcinoma and myeloid leukemia. To provide further information on this question, we extended follow-up of a cohort of 14,008 chemical workers at 6 factories in England and Wales, covering the period 1941-2012. Mortality was compared with national death rates for England and Wales, and associations with incident upper airway cancer and leukemia were explored in nested case-control analyses. We observed excess deaths from cancers of the esophagus (100 observed vs. 93.1 expected), stomach (182 vs. 141.4), rectum (107 vs. 86.8), liver (35 vs. 26.9), and lung (813 vs. 645.8), but none of these tumors exhibited a clear exposure-response relationship. Nested case-control analyses of 115 men with upper airway cancer (including 1 nasopharyngeal cancer), 92 men with leukemia, and 45 men with myeloid leukemia indicated no elevations of risk in the highest exposure category (high exposure for ≥1 year). When the 2 highest exposure categories were combined, the odds ratio for myeloid leukemia was 1.26 (95% confidence interval: 0.39, 4.08). Our results provide no support for an increased hazard of myeloid leukemia, nasopharyngeal carcinoma, or other upper airway tumors from formaldehyde exposure. These results indicate that any excess risk of these cancers, even from relatively high exposures, is at most small.

Dupuytren's contracture and occupational exposure to hand-transmitted vibration.

AIMS: The relation between Dupuytren's contracture and occupational exposure to hand-transmitted vibration (HTV) has frequently been debated. We explored associations in a representative national sample of workers with well-characterised exposure to HTV. METHODS: We mailed a questionnaire to 21 201 subjects aged 16-64 years, selected at random from the age-sex registers of 34 general practices in Great Britain and to 993 subjects chosen randomly from military pay records, asking about occupational exposure to 39 sources of HTV and about fixed flexion contracture of the little or ring finger. Analysis was restricted to men at work in the previous week. Estimates were made of average daily vibration dose (A(8) root mean squared velocity (rms)) over that week. Associations with Dupuytren's contracture were estimated by Poisson regression, for lifetime exposure to HTV and for exposures in the past week >A(8) of 2.8 ms(-2) rms. Estimates of relative risk (prevalence ratio (PR)) were adjusted for age, smoking status, social class and certain manual activities at work. RESULTS: In all 4969 eligible male respondents supplied full information on the study variables. These included 72 men with Dupuytren's contracture, 2287 with occupational exposure to HTV and 409 with A(8)>2.8 ms(-2) in the past week. PRs for occupational exposure to HTV were elevated 1.5-fold. For men with an A(8)>2.8 ms(-2) in the past week, the adjusted PR was 2.85 (95% CI 1.37 to 5.97). CONCLUSIONS: Our findings suggest that risk of Dupuytren's contracture is more than doubled in men with high levels of weekly exposure to HTV.

Impact of carpal tunnel surgery according to pre-operative abnormality of sensory conduction in median nerve: a longitudinal study.

BACKGROUND: We have previously proposed that sensory nerve conduction (SNC) in the median nerve should be classed as abnormal when the difference between conduction velocities in the little and index fingers is > 8 m/s. In a prospective longitudinal study, we investigated whether this case definition distinguished patients who were more likely to benefit from surgical treatment. METHODS: We followed up 394 patients (response rate 56%), who were investigated by a neurophysiology service for suspected carpal tunnel syndrome. Information about symptoms, treatment and other possible determinants of outcome was obtained through questionnaires at baseline and after follow-up for a mean of 19.2 months. Analysis focused on 656 hands with numbness, tingling or pain at baseline. Associations of surgical treatment with resolution of symptoms were assessed by Poisson regression, and summarised by prevalence rate ratios (PRRs) and associated 95% confidence intervals (95% CIs). RESULTS: During follow-up, 154 hands (23%) were treated surgically, and sensory symptoms resolved in 241 hands (37%). In hands with abnormal median SNC, surgery was associated with resolution of numbness, tingling and pain (PRR 1.5, 95% CI 1.0-2.2), and of numbness and tingling specifically (PRR 1.8, 95% CI 1.3-2.6). In contrast, no association was apparent for either outcome when median SNC was classed as normal. CONCLUSIONS: Our definition of abnormal median SNC distinguished a subset of patients who appeared to benefit from surgical treatment. This predictive capacity gives further support to its validity as a diagnostic criterion in epidemiological research.

Symptoms, signs and nerve conduction velocities in patients with suspected carpal tunnel syndrome.

BACKGROUND: To inform the clinical management of patients with suspected carpal tunnel syndrome (CTS) and case definition for CTS in epidemiological research, we explored the relation of symptoms and signs to sensory nerve conduction (SNC) measurements. METHODS: Patients aged 20-64 years who were referred to a neurophysiology service for investigation of suspected CTS, completed a symptom questionnaire (including hand diagrams) and physical examination (including Tinel's and Phalen's tests). Differences in SNC velocity between the little and index finger were compared according to the anatomical distribution of symptoms in the hand and findings on physical examination. RESULTS: Analysis was based on 1806 hands in 908 patients (response rate 73%). In hands with numbness or tingling but negative on both Tinel's and Phalen's tests, the mean difference in SNC velocities was no higher than in hands with no numbness or tingling. The largest differences in SNC velocities occurred in hands with extensive numbness or tingling in the median nerve sensory distribution and both Tinel's and Phalen's tests positive (mean 13.8, 95% confidence interval (CI) 12.6-15.0 m/s). Hand pain and thumb weakness were unrelated to SNC velocity. CONCLUSIONS: Our findings suggest that in the absence of other objective evidence of median nerve dysfunction, there is little value in referring patients of working age with suspected CTS for nerve conduction studies if they are negative on both Tinel's and Phalen's tests. Alternative case definitions for CTS in epidemiological research are proposed according to the extent of diagnostic information available and the relative importance of sensitivity and specificity.

Psychological and culturally-influenced risk factors for the incidence and persistence of low back pain and associated disability in Spanish workers: findings from the CUPID study.

OBJECTIVE: To assess the importance of psychological and culturally-influenced factors as predictors of low back pain (LBP) incidence and persistence in Spanish workers. METHODS: As part of the international Cultural and Psychosocial Influences in Disability (CUPID) study, 1105 Spanish nurses and office workers answered questions at baseline about LBP in the past month and past year, associated disability, occupational lifting, smoking habits, health beliefs, mental health, and distress from common somatic symptoms. At 12-month follow-up, they were asked about LBP and associated disability in the past month. Associations with LBP incidence and persistence were assessed by log binomial regression, and characterised by prevalence rate ratios (PRRs) with associated 95% CIs. RESULTS: 971 participants (87.9%) completed follow-up. Among 579 with no LBP at baseline, 22.8% reported LBP at follow-up. After adjustment for sex, age and occupation, new LBP was predicted by poor mental health (PRR 1.5, 95% CI 1.0 to 2.2), somatising tendency (PRR 1.8, 95% CI 1.2 to 2.7) and presence of LBP for >1 month in the year before baseline (PRR 4.7, 95% CI 3.1 to 6.9). Among 392 subjects who had LBP at baseline, 59.4% reported persistence at follow-up, which was associated with presence of symptoms for >1 month in the 12 months before baseline (PRR 1.4, 95% CI 1.2 to 1.7) and more weakly with somatising tendency, and with adverse beliefs about LBP work-relatedness and prognosis. CONCLUSIONS: In Spain, as in northern European countries, psychological and culturally-influenced factors have an important role in LBP development and persistence.

The older worker with osteoarthritis of the knee.

BACKGROUND: Changing demographics mean that many patients with large joint arthritis will work beyond traditional retirement age. This review considers the impact of knee osteoarthritis (OA) on work participation and the relation between work and total knee replacement (TKR). SOURCES: Two systematic searches in Embase and Medline, supplemented by three systematic reviews. AREAS OF AGREEMENT: Probably, although evidence is limited, knee OA considerably impairs participation in work (labour force participation, work attendance and work productivity). AREAS OF UNCERTAINTY/RESEARCH NEED: Little is known about effective interventions (treatments, work changes and policies) to improve vocational participation in patients with knee OA; or how type of work affects long-term clinical outcomes (e.g. pain, function and the need for revision surgery) in patients with TKRs. The need for such research is pressing and opportune, as increasing numbers of patients with knee OA or TKR expect to work on.

Work-related mortality in England and Wales, 1979-2000.

BACKGROUND: To explore time trends in deaths attributable to work in England and Wales, and identify priorities for prevention, we conducted a proportional analysis of mortality by occupation over a 22-year period. METHODS: Analysis was based on deaths in men aged 20-74 years during 1979-1980 and 1982-2000 with a recorded occupation. Proportional mortality ratios, standardised for age and social class, were calculated for pre-specified combinations of occupation and cause of death, for which excess mortality could reasonably be attributed to work. Differences between observed and expected numbers of deaths by cause and occupation were expressed as annual excess death rates. RESULTS: Mortality attributable to work declined substantially over the period of study, with total excess death rates of 733.2 per year during 1979-1990 and 471.7 per year during 1991-2000. The largest contributing hazards were chronic obstructive pulmonary disease and pneumoconiosis in coal miners, pleural cancer from asbestos, and motor vehicle accidents in lorry drivers. In contrast to most other hazards, there was no clear decline in excess mortality attributable to asbestos, or in deaths from sino-nasal cancer associated with exposure to wood dust. CONCLUSIONS: The overall decline in mortality attributable to work is likely to reflect reduced employment in more hazardous occupations, as well as improvements in working conditions. It is imperative to ensure that occupational exposures to asbestos and wood dust are now adequately controlled. Further research is needed on accidents involving lorries with the aim of developing more effective strategies for the prevention of injury.

Case-control study of low-back pain referred for magnetic resonance imaging, with special focus on whole-body vibration.

OBJECTIVES: This study investigated risk factors for low-back pain among patients referred for magnetic resonance imaging (MRI), with special focus on whole-body vibration. METHODS: A case-control approach was used. The study population comprised working-aged persons from a catchment area for radiology services. The cases were those in a consecutive series referred for a lumbar MRI because of low-back pain. The controls were age- and gender-matched persons X-rayed for other reasons. Altogether, 252 cases and 820 controls were studied, including 185 professional drivers. The participants were questioned about physical factors loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about low-back pain. Exposure to whole-body vibration was assessed by six measures, including weekly duration of professional driving, hours driven in one period, and current root mean square A(8). Associations with whole-body vibration were examined with adjustment for age, gender, and other potential confounders. RESULTS: Strong associations were found with poor mental health and belief in work as a causal factor for low-back pain, and with occupational sitting for > or =3 hours while not driving. Associations were also found for taller stature, consulting propensity, body mass index, smoking history, fear-avoidance beliefs, frequent twisting, low decision latitude, and low support at work. However, the associations with the six metrics of whole-body vibration were weak and not statistically significant, and no exposure-response relationships were found. CONCLUSIONS: Little evidence of a risk from professional driving or whole-body vibration was found. Drivers were substantially less heavily exposed to whole-body vibration than in some earlier surveys. Nonetheless, it seems that, at the population level, whole-body vibration is not an important cause of low-back pain among those referred for MRI.

Acute symptoms following work with pesticides.

BACKGROUND: Serious accidental poisoning by pesticides is rare in the UK, but more minor pesticide-related illness may be under-reported. Anecdotally, use of sheep dip has been linked with flu-like symptoms. AIM: To explore the frequency, nature and determinants of acute symptoms following work with pesticides. METHODS: A postal survey of men in three rural areas of England and Wales provided data on occupational use of five categories of pesticide, occurrence of 12 specified symptoms within 48 h of using pesticides and tendency to somatize. Risk factors for pesticide-related symptoms were assessed by modified Cox regression. RESULTS: Of 10 765 responders (response rate = 31%), 4108 had at some time used pesticides occupationally, including 935 (23%) who reported symptoms following such work on at least one occasion. In two areas, acute symptoms were most frequent following use of sheep dip (29 and 32% of users), but in the third area the rate was significantly lower (13% of users). The relative frequency of symptoms was similar for all five categories of pesticide, and flu-like symptoms did not cluster unusually among users of sheep dip. Risk of pesticide-related symptoms increased with somatizing tendency (prevalence ratio for highest versus lowest category 2.4, 95% confidence interval 2.0-3.0) and was higher in men who had used pesticides most often or handled concentrate. CONCLUSION: Acute symptoms are common following work with pesticides, but in many cases the illness may arise through psychological rather than toxic mechanisms.

Neuropsychiatric symptoms in past users of sheep dip and other pesticides.

OBJECTIVES: To explore the prevalence and pattern of neuropsychiatric symptoms in past users of sheep dip and other pesticides. METHODS: From a postal survey of men born between 1933 and 1977 and resident in three rural areas of England and Wales (response rate 31%), data were obtained on lifetime history of work with pesticides, neurological symptoms in the past month, current mental health and tendency to be troubled by non-neurological somatic symptoms (summarised as a somatising tendency score). Risk factors for current neuropsychiatric symptoms were assessed by modified Cox regression. RESULTS: Data were available for 9844 men, including 1913 who had worked with sheep dip, 832 with other insecticides but not sheep dip and 990 with other pesticides but never with sheep dip or insecticides. Neurological symptoms were consistently 20-60% more common in past users of sheep dip than in men who had never worked with pesticides, but their prevalence was also higher in men who had worked only with pesticides other than sheep dip or insecticides. They clustered strongly within individuals, but this clustering was not specific to men who had worked with sheep dip. Reporting of three or more neurological symptoms was associated with somatising tendency (prevalence ratio (PR) 15.0, 95% CI 11.4 to 19.5, for the highest vs the lowest category of somatisation) and was more common in users of sheep dip (PR 1.3, 95% CI 1.0 to 1.6), other insecticides (PR 1.4, 95% CI 1.0 to 1.8) and other pesticides (PR 1.3, 95% CI 1.0 to 1.7) than in non-users. Among users of sheep dip, prevalence was higher in men who had dipped most often, but not in those who had worked with sheep dip concentrate. Past use of pesticides was not associated with current anxiety or depression. CONCLUSION: Neurological symptoms are more common in men who have worked with sheep dip, but the association is not specific to sheep dip or insecticides. A toxic cause for the excess cannot be ruled out, but several features of our observations suggest that psychological mechanisms have a role.

Risk factors for specific upper limb disorders as compared with non-specific upper limb pain: assessing the utility of a structured examination schedule.

BACKGROUND: Few community-based epidemiological investigations of upper limb disorders (ULDs) have classified cases by validated procedures involving a structured clinical examination. AIM: To compare risk factor profiles for different diagnostic categories of ULD using one such examination scheme. METHODS: A questionnaire about upper limb pain and demographic, occupational and psychosocial risk factors was mailed to 10,264 adults from two English general practices, followed by standardized physical examination in those with arm or neck pain. Logistic regression was used to compare those with specific ULDs and non-specific arm pain with those who had no neck or arm symptoms. RESULTS: There was a 59% response rate. A total of 1,197 subjects with arm or neck pain underwent standardized physical examination and were classified as having one or more of 11 specific ULDs or non-specific regional pain. Among these, 250 subjects with specific ULDs and 176 with only non-specific arm pain were compared with 2,248 subjects who had no neck or arm symptoms. Certain physical risk factors were more strongly associated with specific disorders than with non-specific pain. In comparison with pain-free subjects, the odds ratios (ORs) in keyboard users (>or=1 h versus <1 h/day) were 3.1 (95% CI 1.3, 7.8) for hand-wrist tendonitis but 1.3 (0.8, 2.1) for non-specific hand-wrist pain. Other differential associations were found with age, sex, manual versus non-manual employment and smoking. Unexpectedly, low vitality was similarly associated with both specific disorders and non-specific pain. CONCLUSION: These findings suggest that the schedule may usefully distinguish disorders that differ in their association with physical risk factors.

A case-control study of risk factors for arm pain presenting to primary care services.

OBJECTIVES: To investigate the association of occupational activities, mental health and comorbidity with care seeking for arm pain, and to test the hypothesis that specific disorders arise from physical risk factors and non-specific pain from psychological ones. METHODS: Patients with a new episode of arm pain and matched controls were recruited from eight general practices. A questionnaire about risk factors was completed and cases were classified using a validated examination schedule. Questions were asked about occupational activities and psychosocial stressors. Mental health was assessed using the Hospital Anxiety Depression Scale, elements of the Brief Symptom Inventory (somatizing tendency) and the Whiteley Index (health anxiety); comorbidity from chronic fatigue syndrome (CFS) and chronic widespread pain (CWP) was ascertained using standard definitions. Associations were explored using logistic regression and summarized as odds ratios (ORs) with 95% confidence intervals (95% CIs). RESULTS: Altogether, 132 cases and 127 controls were studied. Consulting with arm pain was strongly associated with all of the mental health variables and with CFS and CWP, irrespective of the site of arm pain or diagnosis. The OR in those with >3 versus <3 distressing somatic symptoms was 3.9 (95% CI 1.7-9.0). There were several significant associations with physical activity, but none with occupational psychosocial stressors. Repeated wrist/finger movements and carrying weights were more strongly associated with specific diagnoses than with non-specific pain. CONCLUSIONS: Somatizing tendency, health anxiety, low mood, CFS and CWP are more common in arm pain consulters. Certain mechanical activities are also overrepresented, particularly in those with specific pathology.

The anatomical pattern and determinants of pain in the neck and upper limbs: an epidemiologic study.

Little is known about the distribution and determinants of pain at multiple sites in the neck and upper limb. To investigate the prevalence, pattern, and clustering of such pains and the association of extensive involvement with putative risk factors, we mailed a questionnaire to a community sample of 9696 working-aged adults. Age-sex specific prevalence rates for pain were estimated and the frequency of bilateral involvement, pairwise overlap at different sites, and extent to which reports clustered within individuals were explored. Associations of multi-site involvement with age, gender, psychological health, smoking, and employment status were assessed by logistic regression. Among 6038 responders, 2657 reported at least a day of neck or upper limb pain in the past 7 days, including 1843 whose symptoms rendered normal activities difficult or impossible. Pain was frequently bilateral or in the dominant arm. Significant associations were seen for pain at anatomically adjacent sites. Pain affecting every site considered (neck, shoulders, elbows, wrists/hands) was far more common than might be expected if each site were statistically independent (observed/expected ratio 8750). Being female, unemployed, a blue-collar worker, or a smoker were independent risk factors for such extensive pain, but the strongest association was with psychological ill-health (odds ratio for worst vs. best third of the SF-36 low vitality score, 30.3, 95% CI 7.1-129.0). Neck and upper limb pain commonly cluster, and frequently display symmetry and adjacent patterns of involvement. Extensive neck and upper limb pain is far more strongly associated with poor mental vitality than localised pain.

Extended follow-up of a cohort of british chemical workers exposed to formaldehyde.

BACKGROUND: Formaldehyde is mutagenic and, when inhaled at high concentrations, carcinogenic in rats. Some epidemiologic studies have linked occupational exposure to formaldehyde with cancers of the nose, nasopharynx, and lung, but the evidence for human carcinogenicity has been inconsistent and requires clarification. METHODS: We extended by 11 years the follow-up of an existing cohort of 14 014 men employed after 1937 at six British factories where formaldehyde was produced or used. Subjects had been identified from employment records, and their jobs had been classified for potential exposure to formaldehyde. Standardized mortality ratios (SMRs) were derived using the person-years method and were compared with the expected numbers of deaths for the national population. RESULTS: During follow-up through December 31, 2000, 5185 deaths were recorded, including two from sino-nasal cancer (2.3 expected) and one from nasopharyngeal cancer (2.0 expected). Relative to the national population, mortality from lung cancer was increased among those who worked with formaldehyde, particularly in men in the highest of four estimated exposure categories (>2 ppm) (SMR = 1.58, 95% confidence interval = 1.40 to 1.78), and the increase persisted after adjustment for local geographic variations in mortality (SMR = 1.28, 95% confidence interval = 1.13 to 1.44). However, there was a statistically nonsignificant decrease in the risk of death from lung cancer with duration of high exposure (P(trend) =.18), and this risk showed no trend with time since first high exposure (P(trend) =.99). CONCLUSIONS: The evidence for human carcinogenicity of formaldehyde remains unconvincing. Although a small effect on sino-nasal or nasopharyngeal cancer cannot be ruled out, a possible increase in the risk of lung cancer is a greater concern.