RAYMOND SINGER, PH.D.
A Professional Association
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office:
Telephone: (505) 466-1100 / Fax: (505) 466-1101
Website: www.neurotox.com/ E-mail: raysinger@aol.com
Neurotoxicity from Municipal Sewage Sludge
Raymond Singer, Ph.D.
Reference: Singer, R.
(1999). Neurotoxicity from municipal sewage sludge. Archives of Clinical Neuropsychology,
14, 160; also presented at the 18th Annual Meeting of the
Purpose: To evaluate the neurobehavioral effects of municipal sewage
sludge in a family whose members were exposed for 8 or more years.
Municipal sewage sludge, a mixture of household sewage along with industrial
waste, is routinely applied as fertilizer to some farms in the
This complex substance poses a significant neurotoxic threat to farmers, their workers, nearby residents, and possibly to the general population through the food supply. Recently, the FDA attempted to allow food grown with such materials to be labeled as "organic", but is now reconsidering due to massive citizen protest. However, such food is still permitted in the general food supply.
In this case, industrial waste in the subject's household water supply included numerous chemicals such as lead (1000 ppb) and manganese (100 ppb) (these values above the maximum concentration levels permitted). Due to the clay under the soil, the drainage flowed towards the subject’s property. The family's livelihood, a herd of 150 cattle, deteriorated to the point where they were given up and the property was abandoned.
Method: Neuropsychological testing of 9 family members.
Results: Based on results of the Neurotoxicity Screening Survey, symptoms consistent with neurotoxicity were found in all who completed the test. The two children born and raised on the farm have been classified by their schools as mildly retarded and having attention-deficit disorders, although there was no family history of these illnesses.
Similar results were found in numerous family members. Case 1 will be presented here.
Case 1 was a 56 year old grandmother in prior good health, with a B.A. degree. Estimated pre-morbid FSIQ was 114. Current FSIQ was 98, with specific deficits in immediate memory, arithmetic, visual memory and visuo-spatial organization (scaled scores of 8,7,8,9); visual retention (14 errors); verbal fluency (COWAT of 18); visual figure-ground perception (Embedded Figures Test (5%tile)); learning (Expanded Paired Associate Test (1%tile immediate, 4%tile delayed)); manual dexterity (Grooved Pegboard Test (<1%tile)); attentional skills (PASAT (<1%tile)); executive function ( Stroop (<1%tile), Trails (<5%tile)); Logical memory (<1%tile); Visual Search and Attention Test (<1%tile); with mild anxiety, mild-moderate depression, normal mood; no indication of malingering on several specific tests of this function; and personality testing showing no personality disorders, high levels of conscientiousness and extraversion, low in neuroticism, average in openness and agreeableness. Similar results of cognitive testing were found in other family members.
Sural nerve testing found slowed velocity on the left (33 M/s), and abnormal amplitude and evoked potential dispersion on the right.
Conclusion: Municipal sewage sludge poses a measurable neurotoxic hazard to nearby residents and farm workers, who need to be informed of possible neurotoxic injury from their exposure, and then monitored using repeated neurobehavioral tests.
1. Municipal Sewage Sludge : Scope of the Problem
a. Nearly
1/2 of all the municipal sludge produced in the
b. Although the U.S. EPA has minimal guidelines, local agencies can also issue sludge application permits.
c. Of 30 municipal sludges analyzed, 90 percent had levels of toxic metals above federal guidelines permitted for sludge.
d. There
are no federal guidelines for the testing of dioxin and a myriad of other
highly toxic industrial byproducts currently found in most municipal sludge.
Most of the over 60,000 chemicals currently used in
e. The
f. When long-term accumulative effects are considered, livestock are particularly vulnerable to subtle degradation of food and water, due to bio-accumulation. Cows may consume soil -- up to 14 percent of dry matter intake -- when available forage is low and no supplemental feed is available (Haag, 1992).
g. References
i. Haag, Ed, 1992. Farm Journal, March, pp. 16 -- 19.
ii. National
Sludge
2. EXPOSURE ANALYSIS
Family years on the property: 26
Activities on the family farm: Dairy production
Number of family members
living on the property: 2 great-grandparents, 2 grandparents, 3 adult children, 2 great-grandchildren
Type of pollution: Wetland municipal sewage dump site
Years that the dumping occurred: Last 8 years of residence and milk production
Acres of the dumpsite 70
Proximity of the family property
to the dumpsite: Adjacent
Routes of exposure: Air, water, dust
Onset of symptoms: One year after dumping began
Systems affected: Mucous, respiratory, nervous
Type of pollution: Household sewage mixed with industrial waste
Use of the pollutant: Fertilizer for public food supply
Specific chemicals found
a. Toxic levels found at the subject's property: This analysis is incomplete at this time. Possible contaminants include solvents, pesticides, PCB, formaldehyde, etc.
b. Metals can combine with sewage to form organic metals, more toxic (bio-available) than simple metals.
c. The actual individual toxic substances would vary from day-to-day, depending upon the industry discharging the waste.
d. The potential for the presence of neurotoxic substances is large.
3. INDIVIDUAL ANALYSIS
a. See Appendix 1. The subject showed signs and symptoms consistent with neurotoxicity from sewage sludge.
4. GROUP ANALYSIS
a. See Appendix 2.
i. There was a significant decline in observed versus predicted cognitive function as measured by WAIS-R FSIQ.
ii. There was a significant difference between Vocabulary and Digit Symbol subscale scores (resistant versus susceptible cognitive functions)
iii. Significant symptoms of neurotoxicity were reported by family members.
iv. Distortion was within normal limits.
v. No malingering was found.
Appendix 1: Case Data
Test date: 1997
Gender: Female
Age: 56
Educational level: 16 years, B.A.
Marital Status: Married
Ethnicity: White
Number of Children: 7
(Note: WNL means within normal limits for the individual.)
Premorbid IQ Estimates:
Based on a demographic formula (Reference: Vanderploeg, R. & Schinka, J. (1995). Predicting WAIS-R Premorbid Ability: Combining Subtest Performance and Demographic Variable Predictors. Archives of Clinical Neuropsychology, 10(3), 230 & 232) which considers education, occupation, and vocabulary, expected premorbid IQ would be approximately:
Score Percentile
Full Scale 114 82%
In
Cognitive Testing Standard: Scores significantly below the standard are considered abnormal for the subject and deficit.
Overall Percent Scaled Score Cutoff
IQ equiv. Scaled/Percentile
114 82 13 9/37
Wechsler Adult Intelligence Scale, Revised: WAIS-R
Age - Adjusted
Scaled Scores Percentile Classification
Verbal Subscales
Information 10 50%
Digit Span 8 25% *
Vocabulary 14 91%
Arithmetic 7 16% *
Comprehension 14 91%
Similarities 11 63%
Performance Subscales
Picture
Completion 8 25% *
Picture
Arrangement 11 63%
Block Design 9 37% *
Object
Assembly 10 50%
Digit Symbol 11 63%
Verbal IQ: 103 58% Average
Performance IQ: 95 37% Average *
Full Scale IQ: 98 45% Average *
Interpretation: An overall decline in IQ was found, with specific deficits in immediate memory, arithmetic, visual memory and visuo-spatial organization.
Expected for IQ Observed Difference
Number correct 7-1=6 2 4
Number errors 4+2=6 14 8
Interpretation:
Number correct score: Strong indication of acquired impairment of cognitive function
Number of errors score: Strong indication of acquired impairment of cognitive function
Controlled Oral Word Association Test evaluates verbal fluency, the ability to find and use words.
Total number: 17 - 7 = 10 Percentile: 1%
Interpretation: Deficit
Embedded Figures Test evaluates the ability to detect visual figure-ground relationships (the use of the eyes to make sense out of what the eye sees).
Number detected out of 40 objects: 20
Percentile for age and education: 5%
Interpretation: Deficit
Expanded Paired Associate Test evaluates ability to learn pairs of words (verbal learning ability). (Norms based on age; gender and education not correlated.)
Immediate recall Delayed recall
Score: 9 4
Percentile: <1% 4%
Interpretation: Deficit Deficit
Grooved Pegboard Test evaluates manual dexterity (the ability to use hands in a sensitive and productive way).
Dominant Hand: Right Dominant Non-dominant
Time for completion: 175" 197"
Percentile: <1% <1%
Interpretation: Deficit Deficit
Neurotoxicity Screening Survey:
Factor Results
Score Classification
Memory and Concentration...... 91 Elevated
Autonomic Nervous System...... 88 Elevated
Vision........................ 22 Elevated
Hearing....................... 9 Elevated
Balance....................... 4 Elevated
Smell-Taste................... 7 Elevated
Peripheral Numbness........... 21 Elevated
Sensory-Motor................. 72 Elevated
Chemical Sensitivity.......... 10 Elevated
Emotionality.................. 47 Elevated
Distortion I.................. 15 WNL
Distortion II................. 10 WNL
Overall Neurotoxicity Indicator 371 Elevated
Interpretation: Symptoms consistent with patients with neurotoxicity.
Paced Auditory Serial Addition Test evaluates auditory information processing and tracking.
Number correct of 60: 23 Percentile: 0.7%
Interpretation: Deficit
Stroop Color and Word Test evaluates mental flexibility (45 sec administration).
Number T-Score Percentile Interpretation
Word reading: 57 24 <1% Deficit
Color naming: 24 <20 <1% Deficit
Color/Word: 18 23 <1% Deficit
Trailmaking Test evaluates visuomotor tracking (the ability to search and locate with the eyes) and attention (the ability to concentrate on a task so learning and other mental functions can take place). (Norms based on gender, age and education.)
Part A Part B
Time for completion: 60" 122"
Scaled score: 5 6
Percentile: 3.5% 5%
Interpretation: Deficit Deficit
Wechsler Memory Scale: Logical Memory evaluates the ability to remember a chain of logically related cognitive elements, like a simple story. (Norms based on IQ and age).
Estimated verbal IQ: 114
Immediate recall Delayed recall
Number expected: 27 16
Number observed: 19 11
Probability of normality: 0.0005 0.019
Interpretation: Deficit Deficit
Visual Search and Attention Test
Left Right Total
Score 24 18 42
Percentile 1% 1% 1%
Interpretation: Deficit Deficit Deficit
EMOTIONAL FUNCTION
Beck Anxiety Inventory measures emotional anxiety. Score: 12. Interpretation: Mild anxiety
Beck Depression Inventory measures emotional depression. Score: 16. Interpretation: Mild-moderate depression
Profile of Mood States
Raw Score T Score %
Tension 6 33 4%
Depression 4 35 7%
Anger/Hostility 11 47 40%
Vigor 18 64 92%
Fatigue 17 55 70%
Confusion/Bewilderment 13 49 45%
Interpretation: Low levels of tension and depression.
WELL-BEING MEASURES
General Well Being Schedule evaluates general well-being compared
with the population of the
Score: 58
0-60 Severe Distress
61-72 Moderate Distress
73-110Positive Well-being
Human Activity Profile measures levels of physical activity.
ScorePercentile
Maximum Activity Score 62 <1%
Adjusted Activity Score 57 <1%
Activity Age 70+
Interpretation: Deficit
DISTORTION AND MALINGERING TESTS
Endorsement of Rare Symptoms. The Neurotoxicity Screening Survey presents 14 symptoms that are rare. If a number of these symptoms are endorsed, the question of distortion is highlighted.
Number endorsed:
Distortion I: 4
Distortion II: 1
Interpretation: A low level of distortion was present.
Memorization of "16" Items (Iverson & Franzen, 1991) requires the subject to memorize a list of 16 items. Because the 16 items are grouped into four conceptual categories, the task is easier than it looks. A cutoff of 6 is used to suggest malingering.
Number correct: 12
Interpretation: Non-malingering
Portland Digit Recognition Test, a memory recognition test, requires the subject to memorize a 5 digit number and recognize the same number when given two choices of 5 digit numbers. By chance alone, the subject should respond correctly 50% of the time.
Percent correct responses (5 sec delay): 3/3
Percent correct responses (15 sec delay): 3/3
Percent correct responses (30 sec delay): 2/2
Interpretation: Within normal limits
Twenty-one Item Memory Test assesses the probability of malingering based on a forced choice comparison (Iverson and Franzen, 1989). If the subject does not remember correctly nine of the 21 items on the forced choice test, the subject may be malingering.
Number of words correctly recalled:
Free recall: 7
Forced choice: 13
Interpretation: Non-malingering
Appendix 2: Group Analysis
Predicted IQ 
v Observed IQ
Number of subjects: 8
Mean Standard Deviation
Age: 41 16
IQ (percentiles):
Predicted: 66 22
Observed: 23 15
Prob. of normal t-value, 1 tailed test = < .0001
Vocabulary minus Digit Symbol
Number of subjects: 6
Mean Standard Deviation
Vocabulary (percentiles) 66 25
Digit Symbol 23 20
Prob. of normal t-value, 1 tailed test = < .0003
Neurotoxicity Screening Survey Results
Number of subjects: 5
Number with positive scores: 5
Number with positive distortion: 0
Malingering Test Results
Number of subjects: 6
Number of tests administered: 17
Number with positive malingering: 0
Sural Nerve Conduction Velocity Results
Number of subjects: 6
Number of nerves tested: 12
Number with slowed nerves: 10
Immune Testing
Number of subjects: 6
Number of tests positive for exposure to:
Formaldehyde: 4
TMA: 3
Isocyanate: 1
Number of tests positive for auto-immunity to:
Stomach: 3
Small intestine: 4
Kidney: 3
Liver: 2
Nuclei: 3
Myelin: 5
Number of tests showing:
Abnormal TA-1: 3
Elevated IL-1: 2
Decreased IL-1: 2