The SPCC report also criticised the heavy metals report for only including mean levels of metals in fish caught at each site, since the mean could mask a large range. (Surprisingly, given the SPCC's regulatory role, it had not at the time been able to get the raw data from the Water Board although they had asked for it.) It argued that analysis of the fish livers should have been done since metals tend to be stored firstly in the livers as a detoxifying mechanism. The livers would therefore be a better indicator of bioaccumulation of heavy metals.

The heavy metals report was not the first report to be disputed in this way. Water Board officers had questioned the reliability of the analysis of the fish for organochlorines in the first Malabar bioaccumulation study. They stated "It is not unusual for studies of this nature to have high errors associated with them due to natural variations within the sample population." They claimed that the large amounts of Heptachlor Epoxide found in the study were really a sulphur compound.[2] The SPCC officers had defended the results obtained. The second study had included an interlaboratory comparison study of four different laboratories so as to meet criticisms of the laboratory that had done the analyses for the first study. It concluded that only that laboratory and one other laboratory accurately detected a wide range of organochlorines. A third laboratory was found to be unsuitable for such analyses and a fourth was limited to accurate determinations of DDT compounds.[3]

This interlaboratory study raised even more disputes. A senior chemist at the Department of Agriculture laboratories which was one of those included in the interlaboratory study was extremely critical of the second organochlorine report:

This report should not have been published because conclusions drawn from the findings are not supported by scientific evidence and lack credibility...I request that the SPCC be asked to retract those conclusions that suggest that our laboratory is unable to analyse fish for pesticide residues.[4]

The Minister for Agriculture wrote to Tim Moore after both studies had been released to express his concern about the continuing publicity being given to the contamination of fish. He argued that very small errors in technique or measurement could seriously flaw the results when measuring minute amounts of chemicals in fish. He argued that reports of both studies were potentially erroneous because they had not been referreed "in the standard scientific manner".

I would appreciate it if you would ensure that media reporters are fully aware that these reports do not have the scientific standing that is being attributed to them... we should take all possible action to prevent the continuation of the unsubstantiated reporting which is doing so much needless damage to one of our State's most important industries.[5]

An independent referees report subsequently procured generally approved of the studies saying that the "basic nature of the problem has been adequately identified and evaluated.[6] Another review was made by the Director of the Southern California Coastal Water Research Project. He had no major criticisms of the studies. He commented that detection limits were very high so that some substances may have gone undetected and he suggested that polyethylene bags were not appropriate for storing samples in. Otherwise he agreed that both showed that red morwong were contaminated near the outfalls. He suggested, as a public relations strategy (and as a way of shaping perceptions of the meaning of the results):

After evaluating the best world-wide evidence for health risk from the various organochlorines, you might want to release to the press a comparative table to put the risks in line with others commonly accepted by the public.[7]

The NH&MRC maximum residue limits also came under attack since it was those limits which were enabling the media to interpret the concentrations of organochlorines in fish as dangerous. When the red morwong in the second bioaccumulation study were found to have levels of mercury above NH&MRC maximum limits, those limits were described by various groups as being too low. For example, the Fisheries Division of the Department of Agriculture argued that background levels of mercury were naturally high in Sydney waters and the Health Department representative on the Water Board's environmental monitoring steering committee argued that the NH&MRC limits should not be interpreted as health limits.

The NH&MRC maximum residue limits are based on Australian dietary habits and what little is known about the toxicology of the substances in question. For example, for mercury, it has been estimated that an "average" human of 70 kg (which seems to imply an average adult male) can consume 0.3 mg of mercury each day and just be on the borderline of showing clinical symptoms of toxicity. It is assumed that such a person would eat no more than 59 g of fish a day or 410 g per week. From these assumptions the theoretical blood levels are calculated. A safety factor of ten is applied (and these safety factors vary for each toxic substance) and the maximum residue limit for mercury in fish is thereby worked out.[8] The safety factor is necessary because many people, particularly children weigh a lot less than 70kg, because people may eat more than 410g of fish per week, because some people may be more sensitive than others and because little is known about long-term effects of eating mercury contaminated fish.

The Fisheries Research Institute has regular discussions with the Department of Health on this subject and the Institute Director noted that in those discussions

it normally becomes obvious that the health limits for some metals have been set far too low and even though it normally takes time we have managed to get these levels changed in some cases, again zinc levels in oysters is a good example.[9]

Mercury was one of the limits that the Institute together with the Fish Merchants Association had been trying to get changed, yet it is difficult to see what basis these changes are made on, especially when, in the case of mercury, the safety factor is so small. The safety factors are larger for organochlorines, sometimes more than 100.

The larger safety factors for organochlorines have been used to argue that the fish sampled in the bioaccumulation studies were in fact not so bad. An SPCC information bulletin reassured the public:

The Department of Health considers that very large quantities of contaminated fish (e.g. a tonne) would have to be eaten before a person suffered pesticide poisoning. However the long-term effect of consuming fish and invertebrates containing organochlorines is not known.[10]

In answering the letter from the woman whose daughter had been born with abnormalities, the Environment Minister's senior policy advisor, used similar reasoning to argue that the NH&MRC limits, "if just exceeded", were unlikely to produce symptoms in humans if ingested because of safety factors of at least 100 times. One would have to consume many thousands of kilograms of fish that had NH&MRC limits in them in order to acquire a lethal dose, she was told.[11] This was of course of no comfort to the woman who was concerned about subtle reproductive effects not immediate toxic symptoms and who knew that the NH&MRC limits had been grossly exceeded, in some cases by more than 100 times.

The letter also included other 'reassurances' such as: chlordane has "not been shown" to be teratogenic in humans, HCB has "never been proven" to be a terotogenic compound (no mention of whether BHC or heptachlor expoxide were terotogenic), traces of pesticides occur in other foodstuffs, aldrin and deildrin are imported, heptachlor (found as heptachlor epoxide in fish), is imported and repackaged in Sydney, the discharge of HCB into the sewerage system "is strictly controlled".[12] The woman naturally felt that the letter did not really address the issues and concerns she raised.

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