Dioxins
The toxic effects of dioxins

The toxic effects of dioxin include:

• high acute toxicity
• chloracne, a characteristic chronic skin disease in humans
• cancer; TCDD has been classified as a proven human carcinogen
• developmental effects in laboratory tests on animals, eg physical, behavioural and reproductive abnormalities
• reduced immunity in laboratory tests on animals.

The Institute of Medicine (IOM) of the National Academy of Sciences in the United States of America carries out regular reviews on all the evidence (animal and human) to create a list of conditions that are accepted as being associated (at high levels) with exposure to TCDD.

The conditions that have been accepted in the sufficient evidence of health effects category by the Institute of Medicine, are:

• Hodgkin’s disease
• non-Hodgkin’s lymphoma
• soft tissue sarcoma
• chronic lymphocytic leukaemia, and
• chloracne.
  

There is limited or suggestive evidence that exposure to dioxins may help to cause respiratory cancers (lung, larynx and trachea), prostate cancer, multiple myeloma, acute and sub-acute transient peripheral neuropathy, porphyria cutanea tarda, Type II diabetes, and spina bifida in off-spring.

In 1998, a WHO group of experts reviewed information on dioxins, with a view to revising the tolerable daily intake (TDI) of dioxins.

There were a number of striking outcomes from the review. The WHO group considered toxic effects that occurred at the lowest doses were those associated with developmental effects, although the classification of TCDD as an A1 human carcinogen was taken into account.

The WHO group derived a TDI range of 1-4 pg TEQ/kg bw/day that includes PCDDs, PCDFs and PCBs. In relation to New Zealand estimated intakes are believed to be currently lower than the WHO range for most of the population, though they appear to have been higher in earlier years.

The relatively low levels in the New Zealand population have been confirmed by the serum dioxin report from the Ministry for the Environment (2001).

Cancer incidence and mortality in New Plymouth (October 2005)- added December 2005
Cancer incidence and mortality in New Plymouth (Word, 219 KB)
Cancer incidence and mortality in New Plymouth (PDF, 536 KB)

Cluster investigation of New Plymouth residents
This study is one of a number that have investigated, or are investigating, concerns about possible adverse health effects from dioxin, which originated from 2,4,5-T manufacture in New Plymouth.

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.

Neural Tube Defects At Westown Maternity Hospital, 1965-72 (PDF, 170 kB)
Neural Tube Defects At Westown Maternity Hospital, 1965-72 (Word, 1.25 MB)