Dave McLean

Mortality in New Zealand workers exposed to phenoxy herbicides and dioxins.

Aims: To evaluate mortality in New Zealand phenoxy herbicide producers and sprayers exposed to dioxins. Methods: Phenoxy herbicide producers (n = 1025) and sprayers (n = 703) were followed up from 1 January 1969 and 1 January 1973 respectively to 31 December 2000. A total of 813 producers and 699 sprayers were classified as exposed to dioxin and phenoxy herbicides. Standardised mortality ratios (SMR) were calculated using national mortality rates. Results: At the end of follow up, 164 producers and 91 sprayers had died. Cancer mortality was reduced for sprayers (SMR = 0.82, 95% CI 0.57 to 1.14) and increased in exposed production workers (SMR = 1.24, 95% CI 0.90 to 1.67), especially for synthesis workers (SMR = 1.69), formulation and lab workers (SMR = 1.64), and maintenance/waste treatment/cleaning workers (SMR = 1.46). Lymphohaematopoietic cancer mortality was increased in exposed production workers (SMR = 1.65, 95% CI 0.53 to 3.85), especially for multiple myeloma (SMR = 5.51, 95% CI 1.14 to 16.1). Among sprayers, colon cancer (SMR = 1.94, 95% CI 0.84 to 3.83) showed increased mortality. Conclusions: Results showed 24% non-significant excess cancer mortality in phenoxy herbicide producers, with a significant excess for multiple myeloma. Associations were stronger for those exposed to multiple agents including dioxin during production. Overall cancer mortality was not increased for producers and sprayers mainly handling final technical products, although they were likely to have been exposed to TCDD levels far higher than those currently in the general New Zealand population.

Gender differences in occupational exposure patterns

Objectives The authors conducted a population-based survey to examine gender differences in occupational exposure patterns and to investigate whether any observed differences are due to: (a) gender differences in occupational distribution; and/or (b) gender differences in tasks within occupations. Methods Men and women aged 20–64 years were randomly selected from the Electoral Roll and invited to take part in a telephone interview, which collected information on self-reported occupational exposure to specific dusts and chemicals, physical exposures and organisational factors. The authors used logistic regression to calculate prevalence ORs and 95% CIs comparing the exposure prevalence of males (n=1431) and females (n=1572), adjusting for age. To investigate whether men and women in the same occupation were equally exposed, the authors also matched males to females on current occupation using the five-digit code (n=1208) and conducted conditional logistic regression adjusting for age. Results Overall, male workers were two to four times more likely to report exposure to dust and chemical substances, loud noise, irregular hours, night shifts and vibrating tools. Women were 30% more likely to report repetitive tasks and working at high speed, and more likely to report exposure to disinfectants, hair dyes and textile dust. When men were compared with women with the same occupation, gender differences were attenuated. However, males remained significantly more likely to report exposure to welding fumes, herbicides, wood dust, solvents, tools that vibrate, irregular hours and night-shift work. Women remained more likely to report repetitive tasks and working at high speed, and in addition were more likely to report awkward or tiring positions compared with men with the same occupation. Conclusion This population-based study showed substantial differences in occupational exposure patterns between men and women, even within the same occupation. Thus, the influence of gender should not be overlooked in occupational health research.

Worker exposures to airborne dust, endotoxin and β(1,3)-glucan in two New Zealand sawmills.

BACKGROUND Sawmill workers have an increased risk of developing occupational asthma and other respiratory symptoms. Wood dust and microorganisms have both been suggested to play a role, but few studies have measured microbial exposure levels in sawmills. METHODS The preliminary study reported in this paper assessed airborne dust, bacterial endotoxin and beta(1,3)-glucan levels in 37 samples from two New Zealand sawmills. RESULTS Nearly one-third of the measured dust levels exceeded 1 mg/m(3) and only one sample exceeded the legal limit of 5 mg/m(3). Endotoxin levels were clearly elevated with 50% of all measured exposures above 50 EU/m(3) (range: 7-588 EU/m(3)). beta(1,3)-glucan levels were comparable with levels measured in other industries where workers are exposed to organic dust. Workers in the planing department had the highest mean exposures to dust, endotoxin and beta(1,3)-glucan. Dust levels were only weakly correlated with endotoxin and beta(1,3)-glucan levels. CONCLUSIONS Endotoxin exposures in sawmill workers are at levels sufficient to potentially contribute to the development of respiratory symptoms. Moreover, measurement of dust exposure is a poor proxy for beta(1,3)-glucan and endotoxin exposure in sawmill workers.

Case-control study of high risk occupations for bladder cancer in New Zealand

We conducted a nationwide case‐control study of bladder cancer in adult New Zealanders to identify occupations that may contribute to the risk of bladder cancer in the New Zealand population. A total of 213 incident cases of bladder cancer (age 25–70 years) notified to the New Zealand Cancer Registry during 2003 and 2004, and 471 population controls, were interviewed face‐to‐face. The questionnaire collected demographic information and a full occupational history. The relative risks for bladder cancer associated with ever being employed in particular occupations and industries were calculated by unconditional logistic regression adjusting for age, sex, smoking and socio‐economic status. Estimates were subsequently semi‐Bayes adjusted to account for the large number of occupations and industries being considered. An elevated bladder cancer risk was observed for hairdressers (odds ratio (OR) 9.15 95% Confidence Interval (95%CI) 1.60–62.22), and sewing machinists (OR 3.07 95%CI 1.35–6.96). Significantly increased risks were not observed for several other occupations that have been reported in previous studies, including sales assistants (OR 1.03 95%CI 0.64–1.67), painters and paperhangers (OR 1.42 95%CI 0.56–3.60), sheet metal workers (OR 0.39, 95%CI 0.15–1.00), printing trades workers (OR 1.11 95%CI 0.41–3.05) and truck drivers (OR 1.36 95%CI 0.60–3.09), although the elevated odds ratios for painters, printers and truck drivers are consistent with excesses observed in other studies. Nonsignificantly increased risks were observed for tailors and dressmakers (OR 2.84 95%CI 0.62–13.05), rubber and plastics products machine operators (OR 2.82 95%CI 0.75–10.67), building workers (OR 2.15, 95%CI 0.68–6.73), and female market farmers and crop growers (OR 2.05 95%CI 0.72–5.83). In conclusion, this study has confirmed that hairdressers and sewing machinists are high risk occupations for bladder cancer in New Zealand, and has identified several other occupations and industries of high bladder cancer risk that merit further study.

Mortality and cancer incidence in New Zealand meat workers

Aims: To ascertain whether there is an increased risk of cancers of the lung and lymphohaematopoietic tissue in workers employed in the New Zealand meat processing industry, and to identify exposures associated with any increased risks. Methods: A cohort of 6647 individuals assembled from personnel records from three plants was followed from 1988 until 2000. The observed number of deaths and cancer registrations was compared with expected numbers using five year age and gender specific rates for the New Zealand population. Subgroup analyses evaluated the effect of duration of exposure to selected agents, based on job titles and departments. Results: Vital status was determined for 84% of the cohort, and 92% of the total possible person-years. Mortality from all causes and all cancers was increased, and there was a significant excess of lung cancer. There were significant trends of increasing risk of lung and lymphohaematopoietic cancer with increasing duration of exposure to biological material. Conclusions: Excess risks were observed for mortality from all causes, all cancers, and lung cancer. Although the increased risk of lung cancer may be partly due to confounding by smoking, it is unlikely to be entirely due to this cause. Furthermore, the dose-response relation observed for lung cancer suggests the effect is related to exposure to biological material contained in animal urine, faeces, and blood. Although numbers were small, the risk of lymphohaematopoietic cancer was also associated with increasing duration and level of exposure to biological material.

The New Zealand Workforce Survey I: Self-Reported Occupational Exposures

INTRODUCTION This study examines the prevalence of a range of occupational risk factors reported by a random sample of the New Zealand working population. METHODS Men and women aged 20-64 were selected from the New Zealand Electoral Roll and invited to take part in a telephone interview, which collected information on lifetime work history, current workplace exposures and organizational factors, and various health conditions. The prevalences of occupational risk factors in each occupational and industry group are reported. RESULTS Three thousand and three interviews were completed (37% of the eligible sample and 55% of those that could be contacted). Trades workers reported the highest prevalences of exposure to dust (75%) and oils and solvents (59%). Agriculture and fishery workers reported the highest prevalences of exposure to pesticides (63%) and acids or alkalis (25%). Plant and machine operators and assemblers reported the highest prevalences of exposure to smoke/fume/gas (43%), working night shift in the previous 4 weeks (18%), and working irregular hours (33%). In the high exposure occupational and industry groups, males reported a higher prevalence of exposure than females. Lifting, exposure to loud noise, and the use of personal protective equipment were reported by >50% of the manual occupational groups. CONCLUSIONS This study indicates that occupational exposure to risk factors for work-related disease and injury remains common in the New Zealand working population. While these occupational exposures are disproportionately experienced by workers in certain industries, they also occur in occupational groups not traditionally associated with hazardous exposures or occupational disease.

The New Zealand Workforce Survey II: Occupational Risk Factors for Asthma

INTRODUCTION We conducted a cross-sectional population-based survey in New Zealand that collected information on work history, current workplace exposures, and selected health outcomes. We report here the findings on occupational risk factors for asthma symptoms. METHODS A random sample of men and women aged 20-64 years were selected from the New Zealand Electoral Roll and invited to take part in a telephone survey. Current asthma was defined as: (i) woken up by shortness of breath in the past 12 months; or (ii) an attack of asthma in the past 12 months; or (iii) currently taking asthma medication. Adult-onset asthma was defined as first attack of asthma at age 18 or over. Prevalence odds ratios (ORs) for all occupations were calculated using logistic regression adjusting for sex, age, smoking, and deprivation. RESULTS Totally, 2903 participants were included in the analyses. The prevalence of current asthma was 17% and the prevalence of adult-onset asthma was 9%. Prevalence ORs for current asthma were elevated for ever working as a printer [OR = 2.26; 95% confidence interval (CI) = 1.09-4.66], baker (OR = 1.98; 95% CI = 1.02-3.85), sawmill labourer (OR = 3.26; 95% CI = 1.05-10.16), metal processing plant operator (OR = 2.48; 95% CI = 1.22-5.05), and cleaner (OR = 1.60; 95% CI = 1.09-2.35). Excess risks of adult-onset asthma were also found for ever working as a printer, baker, and sawmill labourer as well as ever-working as a market-oriented animal producer (OR = 1.66; 95% CI = 1.14-2.41), and other agricultural worker (OR = 2.08; 95% CI = 1.03-4.20). A number of occupations not previously considered at high risk for asthma were also identified, including teachers and certain sales professionals. CONCLUSION This population-based study has confirmed findings of previous international studies showing elevated risks in a number of high-risk occupations. The strongest risks were consistently observed for printers, bakers, and sawmill labourers. Several occupations were also identified that have not been previously associated with asthma, suggesting that the risk of occupational asthma may be more widely spread across the workforce than previously assumed.

Cancer incidence, mortality, and blood lead levels among workers exposed to inorganic lead.

PURPOSE We aimed to measure mortality and cancer incidence in a cohort of lead-exposed workers by using blood lead levels to assess exposure. METHODS The cohort comprised male lead workers. Subjects were matched to cancer and death registries. Observed death and cancer incidence rates were compared with population rates to obtain standardized mortality ratios (SMR) and standardized incidence ratios (SIR). RESULTS There were 4114 male subjects with average follow-up time of 16.2 years, and 406 deaths were observed. There were significant results for overall death (SMR, 111; 95% confidence interval [95% CI], 101-123), digestive system deaths (SMR, 167; 95% CI, 110-250), and deaths from external causes (SMR, 135; 95% CI, 105-174). A total of 228 subjects had cancer, with an overall SIR of 83 (95% CI, 73-95); liver cancer SIR of 217 (95% CI, 103-454) and esophageal cancer SIR of 240 (95% CI, 129-447). The latter was seven-fold greater (SIR 755; 95% CI, 314-1813) among those with a blood lead level result above 30 μg/dL compared with population rates. No other increases in cancers were observed. CONCLUSIONS Overall mortality was elevated. Although incidence rates of overall cancer were low, further studies and analysis are required to investigate any biologically plausible associations between inorganic lead and liver or esophageal cancer.

Pine dust, atopy and lung function: a cross-sectional study in sawmill workers

An increased risk of asthma symptoms has previously been shown in 772 pine sawmill workers. The aim of the current study was to assess the association between dust exposure, lung function and atopy. Subjects with (n = 59) and without (n = 167) asthma symptoms were randomly selected from the previous survey. Lung function and atopy were determined using spirometry and skin-prick tests, respectively. Inhalable dust levels were measured on the same day. The geometric mean dust concentration was 0.52 mg·m-3. Exposure to dry but not to green dust was associated with asthma symptoms. Green dust was associated with atopic sensitisation, particularly against outdoor allergens; no association was found for dry dust. Forced vital capacity, forced expiratory volume in one second and peak expiratory flow were significantly lower in workers exposed to high levels of green dust (-350 mL, -260 mL and -860 mL·s-1, respectively) and dry dust (-230 mL, -190 mL and -850 mL·s-1, respectively). These associations were observed both in subjects with and without asthma symptoms. No associations with cross-shift changes in lung function were found. Exposure to green pine sawdust may be a risk factor for atopy. Both green and dry dust were associated with obstructive as well as restrictive pulmonary effects.

Developing a General Population Job-Exposure Matrix in the Absence of Sufficient Exposure Monitoring Data

In New Zealand, there is a need for a comprehensive and accessible database with national occupational exposure information, such as a general population job-exposure matrix (GPJEM). However, few New Zealand-specific exposure data exist that could be used to construct such a GPJEM. Here, we present the methods used to develop a GPJEM for New Zealand (NZJEM), by combining GPJEMs from other countries with New Zealand-specific exposure information, using wood dust as an example to illustrate this process. The assessments of GPJEMs from other countries were made available to a New Zealand expert in occupational wood dust exposure, who then provided a preliminary NZJEM assessment (including the percentage exposed and the level of exposure for each occupation). Where possible, this assessment was based on New Zealand exposure measurements. In the next step, information from a nationwide workplace exposure survey of 3000 members of the New Zealand workforce was used to finalize the NZJEM assessments. The final NZJEM listed 104 of the 956 New Zealand occupational codes as exposed to wood dust. The percentage of workers exposed within an occupation ranged from 5% (e.g. boiler attendants) to 100% (e.g. cabinet makers). The level of exposure ranged from 0.05 mg m(-3) (e.g. electricians) to 3 mg m(-3) (e.g. carpenters). Of these assessments, 23% were mainly based on New Zealand exposure data, 37% on overseas GPJEMs and exposure data, and for 40% the national survey data served as the main source of information for the expert assessment. Combining the NZJEM assessments with national employment statistics indicated that 5.6% of the New Zealand workforce is occupationally exposed to wood dust, corresponding to a total of 97 000 workers (86% male and 14% female). Construction-related occupations included the largest number of exposed workers.