Initial Steps to Prevent Lead Exposure and Poisoning (part 2)

Initial Steps to Prevent Lead Exposure and Poisoning from the Model National Lead Safety Policy Proposal created by The LEAD Group – iv-vi

Prevent Lead Exposure and Poisoning

iv) Promote blood lead testing of individuals and inclusion in blood lead surveys of categories of people at risk of historical, current or future lead exposure

It is vitally important to identify individuals and populations at risk of historical, current or future lead exposure and ensure that they receive access to blood lead testing as soon as they have been identified and that they are informed of the results.

Targets will be set for the screening of at-risk sub-populations will ensure that blood lead testing is adequate. In the US, the target is that 100% of young children are screened via questionnaire and that 50% of children below 2 years of age are screened via blood lead testing. In Australia, the target is that 100% of lead-exposed workers are blood lead tested.

Once the National Lead Policy is finalised and adopted, the first round of media activity to raise awareness of the new policy will publicise the list of categories of individuals at risk of lead exposure and advise them to seek medical advice and referral for blood lead testing. Contemporaneously, researchers will be funded to carry out blood lead surveys of the following categories of people.

This list is a good starting point for identifying individuals who could benefit from a blood lead test and categories of people who are at risk of current or past lead exposure and who require a blood lead test.

Any child or adult who presents for a or medical check-up or with any of the following signs or symptoms associated with lead exposure, or occupations, hobbies, behaviours or beliefs which result in lead exposure:

  • Medical check-ups for pre-employment, pre-insurance, annual health check
  • Vomiting, diarrhoea, constipation, abdominal pain
  • Foreign body ingestion
  • Anaemia or iron-deficiency
  • Seizures
  • Pica
  • Behavioural problems
  • Aggression and/or contrariness, including in the elderly
  • Delinquency
  • Violent crime (including homicide and domestic violence)
  • Possible Autism Spectrum Disorder (ASD)
  • Attention Deficit Disorder (ADD) or Attention Deficit Hyperactivity Disorder (ADHD)
  • Speech and other developmental delays
  • IQ less than expected or less than 80 
  • Learning or development problems
  • Depression, anxiety, and panic disorder
  • Dementia, including Alzheimer’s Disease
  • Parkinson’s Disease
  • Essential tremor
  • Amyotrophic Lateral Sclerosis (ALS)
  • Multiple Sclerosis (MS)
  • Motor Neurone Disease (MND)
  • Hypertension, stroke, heart attack, heart disease
  • Unexplained hearing loss and/or balance problems
  • Cataracts
  • Any person planning to conceive
  • Pregnancy (blood lead testing will be carried out on anyone who is pregnant, in the first and third trimesters, and cord blood will be tested for lead at the birth)
  • Lactation
  • Preeclampsia
  • Pre-term birth and low birth weight babies (test cord blood for lead at the birth)
  • Babies born with unexplained birth defects (test cord blood for lead at the birth)
  • Delayed achievement of developmental milestones (crawling, walking, speech, and others)
  • Delayed puberty
  • Loss of libido, reduced sperm count, sub-fertility, or miscarriage (spontaneous abortion)
  • Menopause (including perimenopause)
  • Joint pain
  • Bone fractures, loss of bone density, or osteoporosis
  • Dental caries
  • Kidney disease
  • Reduced kidney function
  • Tobacco smokers, given that lead is found in tobacco and that smoking interferes with vitamin C metabolism which has lead removal/chelation role
  • Possible alcoholism, given that lead can be found in alcohol and consumption of alcoholic beverages will increase the rate of absorption of lead from the gut
  • People with occupation or hobby lead exposure, such as plumbers, radiator repairers, ship breakers, DIY renovators, bullet- or fishing sinker makers, scrap metal merchants, leadlighters
  • A belief that lead and other toxic metals are therapeutic, for example, people who take Ayurvedic medication containing metal bhasmas
  • Anyone who has been shot and has retained lodged lead shot, bullets, or shrapnel – these people require at least annual blood lead monitoring until the lead is removed from the body

This would mean a very high proportion of the population will be tested for blood lead. The reality is that all these symptoms may be exacerbated by lead and it is important to begin to track down those who may have a link that is caused by environmental lead.

All of these individuals will be monitored for blood lead and iron levels, have their environment tested and nutrition assessed, and be retested for blood lead following abatement measures. The awareness that lead may be involved in many of the underlying conditions outlined above will begin by making a blood lead test part of routine testing for annual check-ups and other testing regimes, such as in pregnancy and via up-to-date and enforced occupational lead health and safety regulations, prior to, and during, occupational exposure to lead (see ii, above).

v) Ensure that all blood lead results and patients’ details are uploaded to the National Blood Lead Surveillance System

National governments will require pathology laboratories to upload ALL blood lead results with the patient’s health system number, name, address, date of birth, gender and lead-risk occupation to the National Blood Lead Surveillance System (see i, above).

Further, the doctor who receives subsequent blood lead results of one of their patients, will be required to upload information on any efforts to made to reduce the blood lead level, the date of changes, and so on, and whether that resulted in a reduction or rise in the subsequent blood lead results, to the National Blood Lead Surveillance System.

The initial benefits of uploading ALL blood lead results to the System is that when an individual’s reduction in blood lead level is observed in conjunction with doctor-documented interventions uploaded to the system, and when the government’s target blood lead level is reduced and government interventions implemented, longitudinal analysis in the Blood Lead Surveillance data over time will demonstrate:

  • Trends within different lead-risk groups
  • Trends in those individuals who have further or ongoing blood lead monitoring
  • The success or otherwise of the implemented interventions.

The other major benefit is that the National Blood Lead Surveillance System data can be de-identified and made available to researchers to form the basis of cohorts to examine lead-associated health, behavioural and longevity outcomes in longitudinal studies, as well as cohorts to examine the synergistic effects of exposure to lead and other toxicants, such as other heavy metals, and conditions, such as COVID-19 (see xiv, 3.0, 3.1 and 3.2, below).

The cost-benefit analysis of the blood lead research findings will justify increased expenditure in prevention of lead exposure and tertiary lead poisoning, as all previous lead longitudinal studies have done.

vi) Use pathology reports to re-educate lead-workers, employers, trade unions and health professionals as to current blood lead target and blood lead action levels, and new levels as revised

Many doctors are reliant on statements provided by laboratories on the pathology report of blood lead levels when interpreting the results to the patient, rather than to continuing medical education.

Employers and health professionals will be re-educated if their current understanding is that 20 or 30 or 50 µg/dL is the appropriate blood lead action level for workers or that an elevated blood lead level above the national target level is only of concern in young children.

Currently in Australia and New Zealand, pathology reports state the blood lead result and a range, e.g., 3.5 µg/dL (0-5 µg/dL). Unlike other pathology parameters, such as iron or cholesterol, where the range provided on the report is actually the healthy range, there is no healthy range for blood lead levels. The LEAD Group advises that all blood lead results above 1µg/dL will be followed-up by actions/interventions which aim to bring the blood lead level to below 1µg/dL. However, many patients receive the message from their doctor that their blood lead level is “normal” or “average” when it is below the government’s “action blood lead level” or “notifiable blood lead level”, for instance, in Australia of 5 µg/dL.

It has always been wrong to report blood lead results together with a range that can be misinterpreted as being “healthy”, “average” or “acceptable”. Blood lead results will only be reported by pathology laboratories in such a way that they can be compared to the recommended levels and action levels, and for the sake of the patient (or their parent/caregiver) to the average blood lead level for their age range.

In the United States in the 2017-2018 national blood lead survey, the average blood lead levels are below 1 μg/dL in all age ranges and for all races, except Asians (CDC n.d.). Perhaps this is due to the continued use of Ayurvedic medicines containing metal bhasmas by some Asians in the US. As reported in Angelon-Gaetz et al (2018), in the period 2011-2018, close to 70% of 61 lead-poisoned children averaging 17 µg/dL in North Carolina were identified as Asian, including from India and Pakistan. In the Indian subcontinent, over 80% of the population use Ayurvedic medicines and 20% of Ayurvedic medicines contain lead and other heavy metals (O’Brien 2020).

One microgram per decilitre is about 60 times higher than pre-industrial humans whose blood lead levels were 0.016 μg/dL (Flegal and Smith 1992) (see Figure 2, above).

Using the statements on this laboratory report well becomes the challenge for good public health policy.

The following are example statements that could be included on a report: 

  • There is no threshold below which lead exposure causes no harm, however, less lead exposure means less damage. Pre-industrial blood lead levels of humans were 0.016 µg/dL.
  • This laboratory has a limit of detection of 0.2 µg/dL.
  • The national target blood lead level is to be below 3.5 µg/dL.
  • The national blood lead “action level” is above 5 µg/dL – this is the level at which the government recommends that action be taken to reduce the blood lead level.
  • Laboratory lead testing of paint, soil, surface dust wipes, ceiling dust, water, backyard eggs, food, traditional and complementary medicines, traditional cosmetics and other consumer products provide the most accurate guidance to potential current sources of lead. (See vii, below)

In most countries, the average blood lead level is unknown. This will remain the case until national blood lead surveys are conducted. Once averages are known by age range, pathology reports will include the average relevant to the age range of the patient. This will prevent the assumption being made by the doctor or patient that any ranges are “averages”, as noted above.

Governments also have a role in requiring pathology laboratories to continually upgrade their equipment if the limit of detection of blood lead results is higher than, say, half the average blood lead result as determined by the national survey.

For example, blood lead levels in all age groups in the United States currently average <1 µg/dL, yet numerous Australian laboratories have a limit of detection of 2.1 µg/dL resulting in most patients being told that they have non-detectable lead in their blood, when they could in fact have more than twice the US average.

In some countries, blood lead levels are reported in micromoles per litre (µmol/L) or micrograms per litre (µg/L) rather than the international units of micrograms per decilitre (µg/dL). This leads to confusion among doctors and patients and makes it difficult to compare results to international guidelines and literature. It’s recommended that these countries shift to the international reporting units (as used by WHO) as soon as possible, until the international community agrees to shift entirely to µg/L (this has been recommended by Taylor and Lanphear 2020). When people see a blood lead result of 10 µg/L (equivalent to 1 µg/dL), it’s easier to conceptualise that they have a long way to go to get to a non-detectable blood lead level.

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