All ages study of blood-lead and bone-lead in urban Toronto: lessons learned

from a collaborative study

T Arbuckle, F McNeill, M Inskip, D Chettle, WI Manton, M Fisher, N Healey, R Bray, L. Marro

Main funding: Health Canada, [Chemicals Surveillance Bureau,

Environmental and Radiation Health Sciences Directorate]

Co-investigators and groupsHealth Canada

• Tye Arbuckle (Co -PI)• Mandy Fisher • Mike Inskip (now with McMaster University)• Norm Healey (now with Azimuth Consulting Group)• Leonora Marro

Department of Health Physics, McMaster Univ• David Chettle• Fiona McNeill (Co-PI)• Sepideh Behinaein (Ph.D student)

University of Texas at Dallas• William Manton

Hospital coordinating centre – St Joseph’s Hospital, Toronto• Jessica Tyrwhitt

Toronto Public Health• Riina Bray

Talk outline

• Goals, study design and context• Techniques used • Results so far …..• Lessons learned • Discussion / summary

Study goals

The first Canadian study that we are aware of which attempts to measure bone Pb in young children. The pilot study goals were to demonstrate:• the feasibility of including in vivo XRF measurements of Pb in bone for young children in future surveys [like the ‘Canadian Health Measures Survey’]•the feasibility of 1) remote bone Pb measurements; •2) partnership with a local community health centre for recruitment and subject measurement; •3) quantification of serum Pb concentrations in environmentally exposed subjects •4) recruitment of childhood subjects for venous blood sampling; •5) development and delivery of appropriate risk communication materials.

Testing and recruitment successTOTAL: 263/272 Participants

Age Expected Tested

Males Females Males Females

1 to 5 10 10 10 6

6 to 10 23 20 23 16

11 to 19 23 20 23 20

20 to 35 21 25 21 25

36 to 50 25 29 25 29

51 to 64 21 24 21 24

65 to 85 10 11 9 11

Total 133 139 132 131

•1 participant cancelled; 2 participants did not assent to participate in the study;•5 appointments were cancelled - equipment malfunction (participants rescheduled)

Methods / techniques for success:plans and reality #1

• Very effective (and persistent) hospital coordinator for reaching potential volunteers / scheduling visits

• Patient-friendly & very skilled child phlebotomist and measuring staff and well-designed procedures for family groups being measured + questionnaire time allowed.

• Financial ($50) incentive

• YES

• YES – but early-on suspected a brief contamination event; Used TV games and books & adult distractions to keep children engaged

• YES – but poorer participation rate by young girls vs the boys

Methods / techniques for success:plans and reality # 2

• Training for obtaining serum samples (Class-100 clean room, gloves etc., centrifuge on site) and pre-cleaned sample tubes, sample dispatch

processes. • Choice of experienced

analytical lab for Pb

• Communications with volunteers about health risk by Toronto Public Health personnel very familiar with PbB exposure routes in homes.

• YES – but Couriers lost one batch of samples

• YES: …although challenges.

• Low blood lead values did not necessitate many home visits.

1st blood sample - venipuncture for:

whole blood and hematocrit

Place a drop of blood sample onto slide and draw

into a capillary tube.  The capillary tube is then spun to

separate the red blood cells from the plasma at which

time a Hematocrit value can then be measured. 

Bluetop Vacutainertube

2nd sample : Venipuncture for: blood serum sample

•Use butterfly +syringe to slowly collect 5ml blood. Remove butterfly tip, leave sample stand 20 minutes. NB The following are done in CLEAN BOX•Slowly transfer blood to centrifuge tube*•Spin down using bench centrifuge•Decant plasma (Special tip*) into Teflon jar*•Record patient I.D. against jar number•Tighten lid & freeze sample * provided

Why is use of a HEPA Clean Box (Class-100 air) important?

• Differences: at least 100 times (!) less Pb is present in Plasma vs. whole blood– E.g., If PbB = 1 ug/dL, plasma Pb = 0.01

ug/dL or 100 pg/ml• Where things can get contaminated

– Pb on airborne particles – Pb on hands or any surfaces. – One speck of dust enough to contaminate sample– Pb can also leach-out from plastics

Blood collection protocol

• Blood volume: the phlebotomist must do their best to obtain as much as possible - up to the desired amount of 5mL.

• For the serum sample, the tube is left to stand for 20 minutes

• After centrifuging, a dedicated pipeter is used to transfer plasma; when not in use, it is kept in the clean box as the photo shows (hanging).

• The rack of pre-cleaned 15 mL teflon jars and the centrifuge tubes must never leave the clean box.

• The transfer of the supernatant plasma to the tubes must be done in the box.

Treatment of sample when taken

Benchtop centrifuges for plasma / hematocrit

Results: Blood lead vs age (*male / *female)

Systematic representation of vascular organisation in the diaphysis of a long-bone (From Mayo Foundationfor Medical Education and Research)

Summary• Blood lead levels were lower than expected …but in the

range found for the CHMS survey; Lead levels in serum required special attention for analysis

• Serum lead levels were so low that the Texas laboratory

had to develop a new technique to measure them. • Special attention to training of collection staff was a good

investment (and critically important for obtaining reliable data).

• Bone lead data were successfully obtained for young children by in vivo XRF; The method is being further evaluated as a tool for measuring children’s skeletal burden.

• A multi-disciplinary team approach was considered essential for this study.

Summary (2)

• Analysis of data continues: e.g.:– Bone/PbB/serum data– Questionnaire results related to values– Additional information on isotope ratios in blood samples &

possible source of environmental Pb