Hilda Firth

Noise exposure and hearing loss in agriculture: a survey of farmers and farm workers in the Southland region of New Zealand.

Farmers are known to be exposed to intermittent intense noise from a variety of sources, but long-term exposure and the resulting risk of hearing loss have not been well characterized. We studied a cross-sectional random sample of farms on which agricultural workers completed an audiometric test and questionnaire, and performed noise dosimetry on a subsample. Sixty-five percent of farms and a total of 586 workers participated. Noise on the subsample of 60 farms lay in a range between 84.8 to 86.8 dB(A) and hearing losses were consistent with this level of exposure. Age, driving tractors without cabs, and working with metal were important risk factors. Reported compliance with hearing protection was higher than that actually observed. The majority of farmers have a moderate risk of hearing loss, but a significant minority is at high risk. Elimination and isolation of noise sources are the control methods of choice, and if residual hearing protection is required, compliance must be improved.

Suicide by occupation: does access to means increase the risk?

Objective: To examine suicide by identified occupational groups in New Zealand over a period of 30 years, focusing on groups predicted to have high suicide rates because of access to and familiarity with particular methods of suicide. Method: Suicide data (including open verdicts) for the period 1973–2004 were examined, excluding 1996 and 1997 for which occupational data were not available. Occupational groups of interest were dentists, doctors, farmers (including farm workers), hunters and cullers, military personnel, nurses, pharmacists, police and veterinarians. Crude mortality rates were calculated based on numbers in each occupational group at each quinquennial census, 1976–2001. Standardized mortality ratios were calculated using suicide rates in all employed groups (the standard population). Results: Few of the occupations investigated had high risks of suicide as assessed by standardized mortality ratios, and some were at lower risk than the total employed population. Standardized mortality ratios were elevated for male nurses (1.7; 95% CI: 1.2–2.5), female nurses (1.3; 95% CI: 1.0–1.6), male hunters and cullers (3.0; 95% CI: 1.7–4.8), and female pharmacists (2.5; 95% CI: 0.8–5. 9). Doctors, farmers and veterinarians were not at high risk, and men in the police and armed forces were at low risk. Access to means appeared to have influenced the method chosen. Nurses, doctors and pharmacists were more likely to use poisoning than were other employed people (3, 4 and 5 times respectively, compared with all others employed). Farmers and hunters and cullers were more than twice as likely as all others employed to use firearms. Conclusions: Access to means may be less important in some circumstances than in others, perhaps because of the presence of other factors that confer protection. Nevertheless, among the groups we studied with access to lethal means were three groups whose risk of suicide has so far received little attention in New Zealand: nurses, female pharmacists, and hunters and cullers.

Assessing individual employee risk factors for occupational asthma in primary aluminium smelting

Aims: To assess the significance of individual risk factors in the development of occupational asthma of aluminium smelting (OAAS). Methods: A matched case-control study nested in a cohort of 545 workers employed in areas with moderate to high levels of smelting dust and fume. The cohort comprised those who had their first pre-employment medical examination between 1 July 1982 and 1 July 1995; follow up was until 31 December 2000. Forty five cases diagnosed with OAAS and four controls per case were matched for the same year of pre-employment and age within ±5 years. The pre-employment medical questionnaires were examined, blinded as to case-control status, and information obtained on demographics and details of allergic symptoms, respiratory risk factors, respiratory symptoms, and spirometry. Data from the subsequent medical notes yielded subsequent history of hay fever, family history of asthma, full work history, date of termination or diagnosis, and tobacco smoking history at the end-point. Results: There was a significant positive association between hay fever diagnosed either at or during employment and OAAS (adjusted OR 3.58, 95% CI 1.57 to 8.21). A higher forced expiratory ratio (FEV1/FVC%) at employment reduced the risk of developing OAAS (adjusted OR 0.93, 95% CI 0.88 to 0.99). The risk of OAAS was more than three times higher in individuals with an FER of 70.0–74.9% than in individuals with an FER ⩾80.0% (adjusted OR 3.46, 95% CI 1.01 to 11.89). Conclusions: Individuals with hay fever may be more susceptible to occupational asthma when exposed to airborne irritants in aluminium smelting. The pathological basis may be reduced nasal filtration and increased bronchial hyperresponsiveness.

Historical cohort study of a New Zealand foundry and heavy engineering plant.

OBJECTIVES: To investigate the mortality of workers who had been exposed to asbestos, machining fluids and foundry work in a foundry and heavy engineering plant in the railway rolling stock manufacturing industry in New Zealand. METHODS: Historical cohort study design. RESULTS: For the total workforce of 3522 men employed between 1945 and 1991, follow up was 90% of person-years to 31 December 1991. Significantly increased standardised mortality ratios (SMRs) were found for all causes of death combined (SMR 1.07; 95% confidence interval (95% CI) 1.01 to 1.14), all malignancies (SMR 1.15; 95% CI 1.01 to 1.31), circulatory (SMR 1.16; 95% CI 1.07 to 1.27) and musculoskeletal diseases (SMR 3.06; 95% CI 1.39 to 5.84), all digestive cancers (SMR 1.29; 95% CI 1.04 to 1.59), all respiratory cancers (SMR 1.34; 95% CI 1.08 to 1.65), cancer of the oesophagus (SMR 1.97; 95% CI 1.01 to 3.45), and mesothelioma of the pleura (SMR 6.58; 95% CI 1.24 to 19.49). Three deaths from pleural mesothelioma were recorded, with latency times of 51, 53, and 57 years. There were no dose-response relations between exposure to asbestos, machining fluids or foundry work, or by duration of employment in the plant, and any cause of death. CONCLUSIONS: This study found small increases in risk for several causes of death among foundry and heavy engineering workers; however, these increases were small and the possible effects of smoking and other lifestyle factors could not be excluded. There was evidence of asbestos related disease in those involved in engineering work in the past.

Ascertainment of occupational histories in the working population: The occupational history calendar approach

BACKGROUND self-reported occupational histories are an important means for collecting historical data in epidemiological studies. An occupational history calendar (OHC) has been developed for use alongside a national occupational hazard surveillance tool. This study presents the systematic development of the OHC and compares work histories collected via this calendar to those collected via a traditional questionnaire. METHODS the paper describes the systematic development of an OHC for use in the general working population. A comparison of data quality and recall was undertaken in 51 participants where both tools were administered. RESULTS the OHC enhanced job recall compared with the traditional questionnaire. Good agreement in the data captured by both tools was observed, with the exception of hazard exposures. CONCLUSIONS a calendar approach is suitable for collecting occupational histories from the general working population. Despite enhancing job recall the OHC approach has some shortcomings outweighing this advantage in large-scale population surveillance.

Chemical exposure among NZ farmers.

Abstract The objectives were to describe chemical use among farmers; to develop an exposure intensity score for three chemicals of interest: organophosphates (OPs), glyphosate (GP), and phenoxy herbicides (PHs). This was a cross-sectional study of a stratified random sample of farmers. Demographic, health and chemical use information were collected via questionnaire and an exposure level score developed. Within a sample of 586 farmers, 16 – 54% applied one or more of the chemicals. A high proportion of pastoral farmers used all the chemical types with 65% applying GP, 29% OPs and 19% PHs. Mean exposure scores were higher among women OP users, younger PH users, and arable farmers using PHs. This pesticide exposure score based on self-reported work practices among farmers can give an estimate of comparative annual exposure level. It can be used in analytical epidemiological studies and allows the identification of priority areas for intervention.

Combined exposures to workplace psychosocial stressors: Relationships with mental health in a sample of NZ cleaners and clerical workers

BACKGROUND A combined measure of two common psychosocial stressors, called job pressure has previously been shown to be strongly associated with poor mental health in high status workers. This study tests the generalizability of this association to lower status workers. METHODS A national random sample of cleaners and clerical workers was obtained from the New Zealand (NZ) electoral roll by occupational title (n = 596). Cross-sectional data on job stressors, demographics, and mental health (GHQ-12) was collected by computer-assisted telephone interviews. RESULTS Combined exposure to low job control, high job demands, and job insecurity (high job pressure) was associated with markedly elevated odds (13-fold or higher) of poor mental health after adjustment for age, sex, occupation, and education. CONCLUSION Combined with previous findings this suggests simultaneous exposure to more than one occupational psychosocial stressor may greatly increase the risk of poor mental health among both lower and higher status workers. This report adds to the larger literature in this area, supporting the need for expanded policy and practice intervention to reduce job stressors across the working population.

Surveillance of working conditions and the work environment: development of a national hazard surveillance tool in New Zealand

ObjectivesChanges to work and the impact of these changes on worker health and safety have been significant. A core surveillance data set is needed to understand the impact of working conditions and work environments. Yet, there is little harmony amongst international surveys and a critical lack of guidance identifying the best directions for surveillance efforts. This paper describes the establishment of an instrument suitable for use as a hazard surveillance tool for New Zealand workers.MethodsAn iterative process of critical review was undertaken to create a dimensional framework and select specific measures from existing instruments. Pilot testing to ascertain participant acceptability of the questions was undertaken.ResultsThe final questionnaire includes measures of socio-demographic characteristics, occupational history, work organisation, physicochemical, ergonomic and psychosocial hazards. Outcome measures were also included.ConclusionA robust New Zealand hazard surveillance questionnaire comprehensively covering the key measures of work organisation and work environments that impact upon worker health and safety outcomes was developed. Recommended measures of work organisation, work environment and health outcomes that should be captured in work environment surveillance are made.