The Tauranga City Council is today being invited to join the glyphosate debate by becoming involved in research into the post Roundup market.

The council's policy and strategy committee meeting is being asked today for council support into further study because of issues uncovered by the Toxic Agrichemical Advisory Forum.

Since the patents on Roundup and its active ingredient glyphosate expired in 2000, about 90 competing weedkillers have appeared – all containing gylphosate as the active ingredient, but with different chemicals in the mix.

The TAAF forum's concern is some of the additional chemicals are even more toxic than the weedkiller itself.

The council policy approves glyphosate for use on city reserves, but doesn't differentiate between brands.

The law doesn't require the additives to be disclosed. Manufacturers claim commercial sensitivity and often choose not to disclose them.

The TAAF forum is asking council staff to independently research the additives so the council will only buy the ‘safest' brands for use on the city's parks reserves and playing fields.

The study is outside the scope of the TAAF forum, which is an informal advisory body set up in 2009 to advise the Tauranga City Council on agrichemicals issues.

Glyphosate products are the most widely used weedkillers in New Zealand and are the main tool used by the Tauranga City Council for vegetation and weed control.

The council policy permits the use of glyphosate, but makes no other differentiation.

Recent research finds the previously supposed inert additives are not inert.

They have toxic health and environmental effects. At least one, polyethoxylated tallow amine, POEA, is several times more poisonous than glyphosate itself.

The issue the TAAF forum is raising with the council is that exposure to glyphosate-based herbicides entails exposure to a range of other chemicals, about which little information is available and the full health effects have not been established.

Some agrichemicals are more poisonous at minuscule concentrations than at higher levels of exposure, yet regulatory bodies generally only look at linear dose-response research as the mainstay of their assessment of their safety.

Laboratory studies show glyphosate and RoundUp are genotoxic and endocrine disrupting, affecting both oestrogens and androgens.

Endocrine disruption can cause a range of developmental impacts on sexual and other cell differentiation, bone metabolism, liver metabolism, reproduction and pregnancy, and may be implicated in hormone-related diseases such a breast and prostate cancer.

Several studies have linked exposure to glyphosate with non-Hodgkin's lymphoma, hairy cell leukaemia, multiple myeloma, DNA damage and one study found an association with spontaneous abortions and pre-term deliveries in humans.

Roundup, but not isolated glyphosate, was found to interfere with the production of a

hormone which may have an impact on reproduction in humans, other mammals, birds, and amphibians.

The US Environmental Protection Agency (EPA) didn't require neurotoxicity studies to be carried out for the registration of Roundup in the 1970s. There is now evidence glyphosate can affect the nervous system.

It has adverse effects on a number of enzymes involved in metabolic processes, according to some studies, and evidence of damage to the liver, and birth defects involving the formation of the skeleton.

Several researchers have reported that glyphosate appears to accumulate in human cells.

Laboratory studies have shown that very low levels of glyphosate. Roundup, POEA, and the metabolite AMPA all kill human umbilical, embryonic and placental cells. Roundup can reduce sperm numbers, increase abnormal sperm, retard skeletal development, and cause deformities in amphibian embryos.

Laboratory studies suggest glyphosate is toxic to human placental cells and may interfere with the production of reproductive hormones, and potentially with the functioning of the adrenal gland.

An UK report refers to acute toxicity causing balance disorder, vertigo, reduced cognitive capacity, seizures, impaired vision, smell, hearing and taste, headaches, drop in

blood pressure, twitches and tics, muscle paralysis, peripheral neuropathy, loss of gross and fine motor skills, (in particular in areas of the brain associated with Parkinson's disease) plus excessive sweating, and severe fatigue.

Recently, the acute toxic effect of four different RoundUp formulations were studied in different human cell types. Each formulation caused cell death at concentrations well below their recommended dilution rate, says the TAAF forum report to the council.

Tauranga City Council currently accepts all glyphosate products on Schedule 1 of approved chemicals, while the city's spray policy's aim is "to protect the health of the general public".

• TAAF proposes that by June 2012 only glyphosate products with known ingredients be

included in Schedule 1, and

• Tauranga City Council should selectively approve for use the least toxic of the many

glyphosate products available.

The full report is available here.