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Mercury

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... sensory neuropathy. Assessments. Pernicious ... Neuropathy. Constricted visual fields. Loss of teeth. Duke ... Neuropathy. 18/51 with concerns. 14/18 ... – PowerPoint PPT presentation

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Title: Mercury


1
Mercury Chlorine ExposuresResidual Effects
4-20 Years After Exposure
  • Woodhall Sandy Stopford, MD, MSPH
  • Duke University Medical Center

2
Objectives
  • List major long-term health concerns from
    excessive occupational exposure to mercury and
    chlorine.
  • Identify appropriate studies to evaluate exposure
    to mercury and chlorine.

3
Background
  • Chloralkali plant in operation 1956-1994
  • Cleanup 1994-1997
  • Poor ventilation/repair 1988-1994
  • 350 workers total, maximum 150
  • Major environmental releases felony convictions
    to owners/management

4
Mercury Exposure Data
  • Frequent air data
  • Urine data quarterly, QC program since 1988
  • Average exposures 2-106 µg/m3
  • Maximum air levels 7-147 µg/m3
  • Urine levels 13-173 µg/L, average 72
    µg/LCorrected for specific gravity.
    Equivalent to 35 ?g/gm creatinine 25 µg/m3
    exposure

5
Chlorine Exposure Data
  • TWA exposures 0.1-0.8 ppm
  • Peak exposures 0.01-1.4 ppm
  • Exposures at 35 chloralkali plants averaged
    0.006-1.4 ppm
  • TLV 0.5 ppm
  • STEL 1.0 ppm

6
Group Evaluations
  • 1988 NIOSH
  • 16 workers. No neurological abnormalities or
    symptoms
  • 1988 Duke
  • 79 workers high Hg exposures
  • No relationship between symptoms and exposure
    measures
  • Slight tremors more common in highest exposure
    group

7
NIOSH 1997 Evaluation
  • 139 exposed, 107 controls
  • Increased symptoms as a group
  • Renal function normal
  • Reproductive outcomes normal
  • No relationship between symptoms and exposure

8
NIOSH 1997 Evaluation
  • Visual contrast sensitivity normal
  • 8/8 NCV measures normal
  • Grip strength normal
  • Increased tremor
  • Balance normal
  • Decreased vibratory sensation

9
NIOSH 1997 Evaluation
  • Multivariate exposure-effect analysis
  • Overall 5/87 measures worse than expected
  • 9/87 better than expected
  • For multiple comparisons use cut point of p
    0.002 no significant relationships

10
Case Study
  • GB is a 73 year old gentleman who was diagnosed
    as having memory problems, cognitive impairment,
    a gait disorder, impairment of fine motor speed
    and dexterity secondary to mercury exposure.

11
Case Study
  • Exposure
  • Assistant cell operator from 1963-1966
  • Products operator 1966-76
  • 1976-87 relief operator in products area and cell
    room
  • 1987-93 shift foreman
  • Chlorine no medical treatment, respirator when
    ever saw plume

12
Case Study
  • Monitoring
  • Urine mercury levels 1978-1992 range nd-29,
    average 11 mcg/L
  • Pulmonary function normal 1979
  • Neurological exams normal 1981-1991

13
Case Study
  • Medical History
  • Pernicious anemia first noted 1985. Vit.
    B12 treatment stopped 1997
  • Low Vit. B12 2001
  • Memory problem, mood swings, difficulty with
    balance, numbness and tingling starting 1998 with
    worsening in 2003.

14
Case Study
  • .Neuropsychiatric findings
  • Deficits in attention and concentration
  • Poor visual and recognition memory
  • Difficulty with fine motor speed and dexterity
  • Positive sleep study with low blood oxygen

15
Case Study
  • Exam
  • Peripheral sensory neuropathy
  • Assessments
  • Pernicious anemia
  • Obstructive sleep apnea with hypoxemia

16
Case Study
  • Recommendations
  • Institute treatment for Vit. B12 deficiency
    associated with brain effects
  • CPAP for obstructive sleep apnea
  • Consider cognitive training for memory defect
  • Repeat neuropsychological testing in 1 year

17
Duke 2001 Evaluation
  • 80 self-selected ex-workers
  • 52 found to have exposure-related problems on
    screening study
  • 51/52 had confirmatory assessments

18
Duke 2001 Evaluation
  • Mercury-related concerns
  • Depression
  • Poor concentration/memory
  • Personality changes
  • Tremor
  • Neuropathy
  • Constricted visual fields
  • Loss of teeth

19
Duke 2001 Evaluation
  • Chlorine-related concerns
  • Reactive upper airways
  • Reactive lower airways
  • Aggravation of asthma

20
Duke 2001 Evaluation
  • Components of Evaluation
  • Occupational and medical history (duplicate of
    1988 evaluation)
  • General examination

21
Duke 2001 Evaluation
  • Components of Evaluation
  • Specialists evaluations
  • Neuropsychologists
  • Neurologists
  • Otolaryngologists
  • Peridontists
  • Pulmonologists

22
Duke 2001 Evaluation
  • Components of Evaluation
  • Confirmatory studies
  • Neuropsychological testing
  • EMG/NCV
  • MRI/CT of Brain/EEG
  • CT/MRI of sinuses
  • Spirometry/lung volumes/diffusion before and
    after bronchodilators or exercise

23
Duke 2001 Evaluation Results
  • Memory/Neuropsychological Abnormalities
  • 20 of 51 with concerns
  • 14/20 not confirmed
  • 13/20 depressed
  • 2 not evaluated (both pre/post exposure)
  • 5/18 tested malingering
  • 2 with strokes
  • 1 with ADD
  • 1 with psychotic depression

24
Duke 2001 Evaluation Results
  • Neuropathy
  • 18/51 with concerns
  • 14/18 not confirmed
  • 4/18 not tested, all with symptoms pre/post
    exposure

25
Duke 2001 Evaluation Results
  • Tremor
  • 11/51 with concerns
  • 10/11 not confirmed
  • 1 confirmed onset after exposure (caffeine)
  • Tooth loss
  • 3/51 with concerns
  • 3/3 not confirmed (poor dental hygiene/caries)

26
Duke 2001 Evaluation Results
  • Chlorine-related Concerns
  • RUDS 5/51
  • 5/5 evaluated not confirmed
  • RADS 14/51
  • 8/14 not confirmed
  • 2 severe post pneumonia/ rheumatoid arthritis
  • 4/14 mild all smokers

27
Duke 2001 Evaluation
  • Exposure Correlates
  • Mercury high/medium vs low
  • Depression (17 cases) OR 1.1
  • Carpal tunnel (5 cases) OR 1.2
  • Chlorine high/medium vs low
  • Airway reactivity (7 cases) OR 0.95

28
Duke 2001 Evaluation
  • Conclusions
  • Screening studies during high exposures to Hg
    found no consistent effects except increased
    symptoms and more mild tremors in high exposure
    group (NIOSH and Duke)
  • NCV studies during high exposure normal
  • Screening testing 4-20 years post exposure
    unremarkable

29
Duke 2001 Evaluation
  • Conclusions
  • Specialty studies 4-20 years post exposure did
    not identify mercury or chlorine-specific effects
    of neuropsychological or pulmonary function
  • Clinical screening and removal based on
    biological monitoring appears to be effective in
    preventing long term consequences
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