Health effects of dioxins

There has been longstanding community concern over the possibility of health effects, including cancer and birth defects, on the local population from 2.4.5-T manufacture between 1962 and 1987 at the former Ivon Watkins-Dow (IWD) chemical plant in Paritutu, New Plymouth.

The dioxin TCDD is present in 2,4,5-T as a contaminant. As a consequence, the following studies have been carried out.

Cancer incidence and mortality in New Plymouth

(October 2005) Added December 2005

Neural tube defects, Westown Maternity Hospital, New Plymouth

August 2002

During the years 1965-71, the Charge Nurse at Westown Maternity Hospital collected information about birth defects at the hospital. In response to information from her, an investigation has taken place, based on labour ward records from Westown. Information has been collected regarding neural tube defects during the years 1965-72.

Birth defects report 2010

Birth Defects in Taranaki

A study on the rates of birth defects in Taranaki, compared with the rest of New Zealand, has been completed by Associate Professor Barry Borman and Dr Deborah Read*, for Massey University's Centre for Public Health Research. The report looks at information available on birth defects in the 1960s and 1970s and compares locally reported defects with those from other centres or other studies done at the time. It shows high rates of birth defects, but not at levels substantially different from other parts of the country. However, the data are limited as national records are only regularly available after 1977 and detailed information about individual birth defects isn’t readily available for some time periods.

The higher rates of birth defects which were seen in New Plymouth are reported as being no different to other parts of the country when congenital dislocation of the hips and club feet were accounted for. Both of these deformities are regarded as deformations (often caused by physical pressure in the womb from the way the baby lies or grows). Rates of spina bifida - which have been linked to dioxin exposure - were no different between New Plymouth and the rest of country even during 1965-71 when New Plymouth's birth defect rates were highest.

*About the authors
Dr Barry Borman is an epidemiologist and Associate Professor at the Centre for Public Health Research, Massey University. He has been Director of the New Zealand Birth Defects Monitoring Programme since 1986 and was formerly the Manager of Public Health Intelligence, the epidemiology group of the Ministry of Health. Dr Deborah Read is a independent consultant in public health medicine. She is a Honorary Research Fellow at the Centre for Public Health Research, Massey University and provides contract advice to the Ministry of Health on organochlorines.

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