Media release
8 November 2005
Ministry receives report on hospital discharge rates during painted apple moth eradication programme
The Ministry of Health has received a report on hospital discharge rates for respiratory illness before and during the painted apple moth eradication programme in West Auckland.
The Ministry of Agriculture and Forestry aerially applied the insecticide Foray 48B over parts of West Auckland from January 2002 to May 2004 to eradicate the exotic pest, the painted apple moth.
The report: Descriptive Study of Hospital Discharges for Respiratory Diseases in Spray Zone for Painted Apple Moth (Auckland) relative to local and national statistics 1999-2004 was written by the Institute of Environmental Science and Research Limited (ESR). It was commissioned by the Ministry of Health in February 2004 in response to concerns in the community about respiratory illness.
The Health Impact Assessment, written prior to the eradication programme commencing, identified that some people may have minor skin, eye and upper respiratory tract irritation, or aggravation of existing asthma or allergies if directly exposed to the spray.
Aer’Aqua Medical Services, funded by the Ministry of Agriculture and Forestry, which provided health support service during the programme, found that approximately 1.6% of the population in the residential area included in the eradication programme reported health concerns. Most commonly reported symptoms were respiratory or skin ailments and headaches.
In its report, ESR found that there was no difference in the before-spray and during-spray monthly discharge rates for influenza and pneumonia.
ESR found there was an increase in asthma discharge rates in the period 2002 to mid 2004 for boys aged 0-4 years old in the exposed population. There was a small increase observed for girls aged 0-4 and 5-14 years old.
However ESR concluded that the underlying trend in hospital discharges for respiratory disease and asthma in the spray zone was evident before spraying began and cannot therefore be attributed to this exposure.
ESR stated that while there were several findings pointing to a real increase in asthma discharges that could plausibly be associated with the spray programme, chance, bias and other confounding factors were possible explanations for the result and the authors stressed that the results do not prove that the elevations seen for some age groups were caused by exposure to the spray.
Chief advisor Public Health, Dr Ashley Bloomfield said he hoped the findings would be reassuring to the West Auckland community.
“Given the increases occurred prior to the spraying, and the increases were very small numbers, there is nothing to suggest a significant adverse impact on the incidence of respiratory diseases for the West Auckland population. It is pleasing to be able to report this to the community as we know some people have been concerned about the effects that this eradication programme may have had on health.”
The report is the first community-based study of hospital discharge data in response to long-term aerial application of a biological insecticide.
The Ministry of Health is expecting a number of further reports from MAF. Once these reports are available, the Ministry will review all the information it has received in relation to health issues associated with the eradication programme and recommend to the Ministry of Agriculture and Forestry (MAF) what, if any, further investigation or action is required.
The Ministry of Health is one of several agencies who have provided advice to MAF on this programme.
For further information
For further information please phone
Karen Roe
Media Advisor
Ministry of Health
04 496 2265 or 021 542 467
Alison Corich
Communications Manager, ESR
04 914 594 or 0274 209 434
Brett Sangster
Communications Manager, Ministry of Agriculture and Forestry
04 8190165 or 027 247 8777
Full report
The full report is on the Ministry of Health’s website www.moh.govt.nz
Descriptive Study of Hospital Discharges for Respiratory Diseases in Spray Zone for Painted Apple Moth (Auckland) relative to local and national statistics 1999-2004
Background information
In the New Zealand population, monthly hospitalisation rates fore respiratory illness remained steady with a slightly lower-than-usual winter peak in 2000. In the exposed population, there was an increase in hospitalisations beginning in 2001 (one year before spraying began), continuing into 2004.
There was no difference between before-spray (1998-2001) and during-spray (2002-mid 2004) monthly hospital discharge rates for influenza/pneumonia, but asthma discharge rates doubled over the period 2002-mid 2004 for boys aged 0 to 4 years old in the exposed population (from 6.5 per 10,000 to 13,4 per 10,000).
A similar but less dramatic increase was observed for girls aged 5 to 14 (from 1.8 per 10,000 to 3.2 per 10,000) Overall, the age-adjusted and sex-adjusted monthly hospital discharge rate for asthma conditions increased by 40% (from 1.6 per 10,000 to 2.3 per 10,000) between the two time periods (before and during spray-time) for the exposed population and decreased 11% for the national population.
The underlying trend in hospital discharges for respiratory diseases and asthma in the spray zone was evident before spraying began and cannot therefore be attributed to this exposure. However, there are several findings pointing to a real increase in asthma discharges that could plausibly be associated with the spray programme.
Age and sex-adjusted monthly asthma and influenza/pneumonia hospitalisation rates per 1000 population for the Auckland spray zone, 1999 to mid-2004
Note: the vertical line indicates when spraying began in mid 2002.
As can be seen from the graph: an increase occurs prior to spraying beginning and the hospitalization rate is not consistent and varies before and during the spray.
Average monthly asthma hospitalisation rate per 1000 population for each age and sex group, before spraying (1999 – 2002) and during spraying (2002-mid 2004)
| Sex | Age Group (Years) | Exposed Population | National Population minus exposed population 1 |
| Rate before spray (number) | Rate during spray (number) | % Change | Rate before spray (number) | Rate during spray (number) | % Change |
| Female | 0 - 4 | 0.53 (4) | 0.78 (5) | +47 | 0.66 (71) | 0.66 (71) | 0 |
 | 5 - 14 | 0.18 (2) | 0.32 (4) | +78* | 0.22 (51) | 0.16 (37) | -28* |
| 15 - 44 | 0.14 (6) | 0.17 (6) | +29 | 0.16 (110) | 0.14 (90) | -18 |
| 45+ | 0.14 (4) | 0.16 (3) | +8 | 0.13 (73) | 0.10 (58) | -20 |
| Male | 0 - 4 | 0.65 (5) | 1.34 (12) | +106* | 1.05 (119) | 0.90 (102) | -14 |
| 5 - 14 | 0.20 (3) | 0.30 (5) | +53 | 0.27 (67) | 0.20 (49) | -27* |
| 15 - 44 | 0.09 (3) | 0.09 (4) | +2 | 0.08 (50) | 0.06 (41) | -18 |
| 45+ | 0.07 (2) | 0.06 (2) | -11 | 0.06 (31) | 0.05 (26) | -14 |
| Weighted Average | 0.16 | 0.23 | +42* | 0.19 | 0.16 | -17 |
Spray population: Average number of monthly asthma hospitalisations, minimum and maximum
| Sex | Age Group | Before Spray (1999 to 2001) | After Spray (2002 to May 2004) |
| Average | Min | Max | Stdev | Average | Min | Max | Stdev |
| F | 0-4 | 3.33 | 0 | 12 | 2.44 | 5.15 | 1 | 13 | 2.92 |
| F | 5-14 | 2.11 | 0 | 5 | 1.55 | 3.96 | 0 | 8 | 2.37 |
| F | 15-44 | 5.31 | 0 | 12 | 2.96 | 6.51 | 2 | 17 | 3.67 |
| F | 45+ | 3.53 | 0 | 9 | 1.89 | 3.56 | 1 | 9 | 2.35 |
| M | 0-4 | 4.33 | 0 | 13 | 3.53 | 9.92 | 2 | 22 | 3.94 |
| M | 5-14 | 2.50 | 0 | 6 | 1.86 | 4.09 | 1 | 8 | 1.91 |
| M | 15-44 | 3.25 | 0 | 10 | 2.57 | 3.56 | 0 | 9 | 2.42 |
| M | 45+ | 1.47 | 0 | 6 | 1.73 | 1.09 | 0 | 4 | 1.23 |
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