Contamination at Mapua

The area surrounding Mapua made for prime conditions for the cultivation of a variety of commercial fruits. In 1932, Mapua would have been a logical place for the Fruitgrowers Chemical Company (FCC) to build its plant for manufacturing pesticides. Thirteen years later, production of the powerful new organochlorine pesticides began. The FCC plant was established in a time of far less scientific understanding of chemical toxins, and consequently little appreciation of the need for protecting people or the environment from exposure to them. There was virtually no care taken in the disposal of the factory’s waste products. The FCC plant site was abandoned in 1988, yet the organochlorine pesticides it produced were particularly persistent. Furthermore, in a mismanaged, inefficient, and ultimately ineffective attempt by the New Zealand government to “clean up” the toxic site lead to a release of a variety of additional toxins to the air and water. Discharges to the air pose potential risk to human health, while the discharges to the water threaten the ecology of the Waimea Estuary.
Prior to the clean up attempts, several investigations into contamination on the site, surrounding marine sediments, and adjacent residential lots identified the presence of some of the substances known to have been stored or manufactured on-site, including:
· Extensive contamination with organochlorine pesticides, especially DDT and its breakdown products, aldrin, dieldrin, and lindane
· Occasionally elevated levels of heavy metals (including chromium, arsenic, lead, cadmium and mercury) and elemental sulfur.
· Occasionally elevated levels of petroleum hydrocarbons
· Traces of chlorophenoxyacetic acid herbicides, phenoxy herbicides, organophosphates, triazines and other related nitrogen containing pesticides
· Traces of polychlorinated biphenyls (PCBs)
Marine sediment samples from the Waimea Inlet revealed contamination mainly by organochlorine compounds, particularly DDT and its metabolites. Metal and organochlorine levels in the groundwater exceeded guidelines for the protection of aquatic ecosystems and recreational water quality.
This clean up effort was a high risk strategy, as it was the first commercial application of a new technology in the middle of a village and close to a sensitive estuary. Mechano-chemical dehalogenation (MCD) was the method of clean up. This used a heated tumbling drier with a proprietary mixture of reagents to enhance treatment in hopes of degrading the toxic chemicals to inert products. One of these reagents was copper sulfate. The site auditor and the Engineer to the Contract warned the company managing the cleanup that they had serious concerns over the use of copper sulfate; yet at least 13 tons of copper was added to the site soils in the treatment process. Copper is highly toxic to marine ecosystems so it poses a particular hazard on the coastal Mapua site. Although the amount of copper sulfate was gradually reduced by about a third during the works, a large amount of copper remained behind at the site. There may be significant risks to the estuarine environment and plant life on the site, but no site-specific assessment criteria have been set for these receptors, so these risks have not been formally evaluated. Diammonium phosphate (DAP) and urea were also used as additives. At least 730 tons of DAP and 36 tons of urea were added to the site soils in this way. This is of concern because these nutrients are readily leachable and could be discharged to the estuary in groundwater, causing weed growth and eutrophication. Groundwater monitoring results show that DDT, lindane, nitrate and ammoniachemical nitrogen frequently exceeded consent threshold concentrations throughout the works often by orders of magnitude. Concentrations of copper, increased erratically throughout the works. Nitrate and DDT still exceed limits in some areas.
Not only was the selected method of cleanup inadequate, the process itself was seriously mismanaged. According to the Official Report released by the Parliamentary Commissioner for the Environment in July 2008, dioxin was released from the drier, but it is impossible to know now much due to inadequate monitoring. Why? The conditions in the soil drier were right for creating dioxin. For the MCD process to function efficiently, the soil being decontaminated must be dry. However, if contaminated soil particles in the drier come in contact with air above 250°C, organochlorine compounds in the soil may be converted to form dioxin (which did happen in one of the proof of performance trials) so specific precautions were included to prevent this situation arising during normal operations. In essence, the condition required the hottest part of the drier (the inlet) to be fitted with a temperature cut off, which would shut the drier down if the temperature exceeded 120°C. This was to reduce the volatilization of OCPs and prevent the formations of dioxins.
Inspections of the clean up process showed the temperatures of the drier inlet ranged from 250-396°C (the temperature depends on the water content of the soil). The design of the drier was such that, had this resource consent condition regarding the temperature cutoff been implemented, the soil output would likely have been about 15 percent of what was actually processed. This means that the MCD plant installed was not capable of complying with the temperature consent condition and functioning at the output envisaged.
Unfortunately, the impact of pollution on the estuarine water has not been investigated. So what’s the big fuss? Humans and other organisms in this community seem to be going about their business as usual, largely unaffected by this pollution. Before such an assertion can be made with confidence, the nature of these man made toxins must be carefully considered. The most profound impacts of these toxins on a given organism would occur at the molecular level, and therefore the consequences may seem less obvious. Although every user of bleach and swimming pools is familiar with chlorine, the element rarely exists in free form in nature: It is man-made. Chlorine is also extremely unstable and volatile, easily recombining with other elements. When combined with hydrocarbons and other chemicals, chlorine produces a bewildering number of molecular compounds that are almost universally poisonous to invertebrates, plants, animals, and humans. Although most organochlorine compounds are produced intentionally, they can also be produced unintentionally. Dioxins, one of the most deadly family of compounds known to man, are created when chlorine bleaches are used to treat lumber or pulps, and also during incineration of other compounds as was observed at Mapua. The family of organochlorines includes many famous chemicals now banned or restricted, such as DDT, chlordane, Mirex, Dieldrin, Heptaclor, all the PCB’s and ozone-disrupting CFCs as well.
Organochlorines are remarkably persistent and cannot be incorporated into the metabolic process of any organism on earth. Because organochlorines do not break down in water, they accumulate in the fatty tissues of organisms. Species that are higher on the food chain, such as humans, accumulate organochlorines to a far greater degree than might be anticipated by their exposure. There is every reason to believe that concentrations of these compounds in wildlife and humans will continue to increase as they move up the food chain. The implication of recent studies on effects of these compounds on human development is that we have within the human race a biological ozone hole, a series of chemical compounds whose effect will expand throughout the entire world population for decades, even if all such compounds ceased being manufactured today. Tests show that these compounds have adverse effects in very low concentrations, and because their widespread use and persistence, we face continuous re-exposure over our lifetime. Currently, human exposure to such substances in the United States is well within the tolerances where hormonal disruption can occur. An accumulation of forty years’ worth of such substances in the environment may require only a few minutes in the body at a critical time to cause genetic changes that are permanent and irreversible. The most disturbing suggestion of the research in this area is that because organochlorines clearly react with and disrupt sexual hormones, both androgens and estrogens, they can alter the function of the brain, and thus affect behavior, thought, and intelligence. Biologically speaking, our metabolic processes have little or no effect in rendering these substances into more harmless ones because humans and other organisms have never in their evolutionary history encountered similar compounds. Because of the slow maturation of human beings, we have not had sufficient time since the introduction of such chemicals to understand the multigenerational health consequences of exposure to organochlorines. It is well known that these compounds do play havoc with human physiology, with effects that include cancer, infertility, immune suppression, birth defects, and still births. More disturbing, is the ability of several organochlorine compounds to disrupt the endocrine system. They are mistakenly “recognized” by the human body as hormone messengers, thereby signaling the wrong information to cells and bodily functions. Because the compounds in question mimic the actions of natural hormones, binding to receptor sites in the body, they can alter the embryonic development of the organism in ways that are irreversible, although the effects may not be experienced until maturity. In wildlife, these chemicals cause decreased fertility, behavioral abnormalities, compromised immune systems, and monstrous defects, such as fish born with both male and female sex organs but incapable of reproduction.
The contamination at Mapua showed just how difficult cleaning up a toxic site can be. Perhaps the real issue at hand is not improving waste disposal and clean up technology, but rethinking if we as a society should find the production of these compounds acceptable in the first place. To err on the side of caution and acknowledge the things we still do not understand would be wise. I strongly urge others to analyze issues such as these critically, and bear in mind that common practice does not infer safe or sustainable.