Sunday, July 22, 2012

West Nile Returns to Stamford

We go through this now annually since the early 1990's.
First it is the dead birds, then Mosquito's , then Humans.
West Nile virus is here to stay and because we had a very mild winter and early, warm Spring.
The virus is present in the mosquitoes that bite humans a month or so early.
Limit activities in the early morning and early to late evening.
Wear long sleeves
Put on insect repellent.
If you have a party outside in the evening, put fans out - mosquitoes have a hard time navigating in wind.
Eliminate any standing water that you can.  Mosquitoes do not travel very far.
If the water can not be eliminated, us BT dunks.
This bacteria is effective against mosquito larva only, so very safe and effective!
Be safe!

Saturday, July 14, 2012

The numbers reported on pesticides are not what we gave

The percentages that are being reported in the local papers are not correct.
Some of my issues my have a small bit to do with it,
but nothing is as high as is being reported concerning pesticides.
First the Percentages below the merrit parkwat were 25% presence - not above action levels.
Second, when doing calculations, the query for all tests, included a numebr of repeat positive tests.
Why, because i made a mistake:
In gathering all the information that i could on wells, there were times that the presence of a pool was not recorded or a well depth was recorded as what an owner remembered, not what a well drillers report showed.  Since the query was a "grouped" query, so that the highest level of pesticide found would show, individual properties were counted twice.
This increased the number of tests significantly.
So in this blog, i am trying to give the most accurate information that i can.

The current number of 30% above action level is being reported and yet even with all my mistakes, it never was that level.
24% presence level and above the action level was less.
so here is what i have, correcting previous mistakes:

total wells tested 766
less early test 713 (not using current methods and with poor detection levels.)

Summary of extra information collected

House Built Well depth well distance pool Onsite
Average 1958 250 33
Max 2008 1100 200
Min 1730 30 0
count 741 134 97 55
median 1962 200 25

Sum of pesticides

Chlordane Dieldren Heptachlor epoxide Transnonchlor alpha chlordane gamma chlordane
max 7.400 1.300 0.240 0.100 0.930 0.740
not 0 75 108 7 6 19 18
above AL 26 54 - - - -
above MCL 2 - 1.000 - - -

Percentages (Dieldren and chlordane only)

dieldren and chlordane both present? percent
both 33 4.31%
either 117 16.41%
both dieldren and chlordane >= AL percent
18 2.35%
44 6.17%

In the meantime i am doing one last study on nitrate levels in the wells found with pesticides and not found a significant correlation

To those reviewing this, know there are probably more mistakes that i have made and i will correct them when i find them

Monday, July 9, 2012

Pesticides and personal experience

many years ago before i was a chemist, i had a cat.
The cat was Siamese and was unusual the way Siamese cats often are.
He caught, one spring 4 baby quail and brought them to us unharmed.
We decided to raise them and built a large cage on the side of the yard.
The quail lived several years until a neighbor decided to spray their entire yard for insects.
Being in the 1960's - Chlordane was the probable agent and maybe mixed with dieldren.
The quailed died immediately after the spraying, along with a Horn Toad that liked our rock garden and a Red eared terrapin (turtle).
I did not understand all of it at that time, but it left an impression that i would not use pesticides when ever possible.
Fast forward to 2012 and a discussion with a state person asking for the original copies of test results from 1990.
The strange thing about this is that things have changed.
In 1990,the current method used for detection was not widely used.
The best Gas Chromatography used capillary tubes and the best detection level i saw was 0.5 ppb -
the current action level for chlordane is 0.3 ppb and 0.03 for dieldren and most levels are below 0.5 ppb.
There was an experimental method (at the time) that reached 0.1 ppb,
but the reality is you are comparing apples and squash - not even the same classification.

How we learn