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Statement relating to death of Sarah Carter in Chiang Mai

Ron Laurence McDowall New Zealander Aged 59 Years

I have been working in the area of toxic, dangerous and hazardous chemicals since 1971. I am a consultant for toxic chemicals to the United Nations working for UNEP Geneva(Basel Convention) UNEP- Stockholm convention and UNEP FAO.

I am a scientist/ Engineer and I am mission specialist for UN-FAO in POPs. The toxic chemicals I work (and specialize) with are PCBs (Polychlorinated biphenyl’s), OC (Organochlorines), OPs (Organophosphates) and POPs (Persistent Organic Pollutants) including Dioxins and furans. The chemicals and their wastes are the most dangerous on the planet.

I have been responsible for the clean up of these dangerous chemicals from hundreds of towns and cities all over the undeveloped world. For 40 Years I have been working with local health authorities and governments in more than 130 countries analyzing deaths from agrichemicals, reading toxicology and pathology reports for more than 1250 such deaths in the last forty years.

Many of the deaths involving OPs were from women using paraquat or Chlorpyrifos as a suicide agent. Over many years I have seen many pathologies and toxicology reports related to these deaths. My PhD is in the area of toxic chemicals including OPs and their effects on humans. I have also studied many deaths in the various agriculture sectors around the world, particularly related to OPs, but also OCs.

The interesting thing about the pathology of OPs cases (in my experience) is that they often don’t have common metrics. You can see miosis in one patient but not another. In the severe acute phase you may well have depressed cholinesterase but in other cases it can still be above 20%.

When I have been involved in a developing country such as Mali or Senegal assisting a local health person with differential diagnosis I use a pathology pathway involving absence or otherwise of Diarrhoea, sweating, hypertension, miosis, Urination, Lung spasm, Emesis, Tears, Salivation. In addition I look for paralysis, CNS depression, respiratory distress, low BP pulse etc.

In many cases we actually know what the poison is because a family member has brought the bottle into the clinic, yet we may only see half the symptoms mentioned here and rarely miosis until near death. In addition I have seen several cases of inflammatory myocarditis with OP poisoning and have witnessed the severe and death stage of many of the patients. Again I have seen myocarditis in some but not all patients.

OP poisoning is complex and difficult to diagnose. LD 50 thresholds also are variable and often I have seen death where a tenth of the LD 50 has been consumed or inhaled. The LD 50 for many OPs is often completely unreliable and death may occur at levels far below the quantity indicated in the MSDS sheets.

The case in hand.

Clearly as most readers will know, you will NOT get OP poisoning from the application of “standard” insecticide spray even if it has a OP component. (Note: Many countries have banned Chlorpyrifos for use in houses, residential units and hotels, because even very small quantities can harm children and it has been causative in human development problems for pregnant women. Many countries have also banned the substance for agricultural use and most countries do not allow OPs including Chlorpyrifos to be used on export fruit but may permit it to be used on domestic supplied food, including NZ.

I was called in late in this case and asked to look at the pathology reports for the NZ victims, Sarah Carter who passed away and her companions who all slept in the same room.

These reports were incomplete and somewhat incoherent but when I read them in their totality I realized I had seen the pathology many times before. So I asked the TV3 crew to swab the room.

When the crew brought back the room swabs I asked the  laboratory in NZ to look for four chemicals; viz Cyfluthrin, Cypermethrin, Proxpoxur and Chlorpyrifos. I felt at the time that it was probably a waste of time (swabbing) and was very surprised to see that at least two of the swabs returned a level of chlorpyrifos.

In my experience we should not have able to see Chlorpyrifos in the room swabs. I have only seen this (room swab result) 2 or 3 times before and that usually involved another OP Malathion. As mentioned above it is not feasible to get OP poisoning from NORMAL insecticide spraying. However, in my experience there have been many occasions that the spray has been NOT NORMAL.

In the case of bed bugs, which are very difficult to eradicate, the best chemical to deal to these is Chlorpyrifos. I have on many occasions taken samples of spray tanks for insecticide spraying (when applicators presented with OP symptoms) and found that the Chlorpyrifos levels were very high. So we had a pathology that indicated possible OP poisoning, even if we did not have all the classical symptoms, and we had chlorpyrifos in the room and an indication that the mixing of the chemicals was NOT NORMAL and we know that for some people fatal dosages of OPs can be fractions of the LD 50.

It was my opinion that the sprayer may have either tripled up the standard dosage by reducing the amount of solvent added to the spray OR introduced technical Chlorpyrifos into the mix taking the active ingredient to around 25 -40 %. It would probably need to be this level to be fatal. It is also likely that the sprayer sprayed the floor ceiling, all bed linen and mattress followed by a wide broadcast all round the room before leaving.

In summary I have seen it all before, the high level chlorpyrifos (amping up the standard spray mechanism) used in the countries of Asia to battle bed bugs, I have seen the pathology before in many many suicides with Chlorpyrifos and while the swab test can only be a proxy I am greatly concerned that Sarah may have died from OP poisoning at very low levels.

One of the other two women in the room required emergency heart surgery and the other was very sick but recovered without surgery. In the absence of food poisoning, virus and any other pathology the OP poisoning was put forward as a theory.

Dr.Ir. Ron McDowall  PhD,
MPhil, BBS/BSc, CPEng, Int PE, F.IPENZ, F.NZIM, M.RSNZ

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