A few weeks ago, I came across a press release issued by the Health and Environment Alliance (HEAL), a European-based non-governmental (NGO) organization dedicated to environmental health activism, in which they trumpeted the release of a new U.S. government funded study claiming that environmental chemical exposures were annually costing society more than 10% of global gross domestic product.
HEAL and other like-minded NGOs are using these results in an effort to grab the attention of policy makers who, based on the best available evidence, view chemical exposure as less of a threat to human health than other more pressing factors. HEAL is also using this study to counter claims by the agricultural community that the current EU hazard-based approach to regulating crop protection products suspected of being endocrine disruptors (EDCs) is too costly (estimated at as much of 70 Billion Euros annually in one study).
Since I have high interest in these topics (see several past blogs published at this site), I decided to dig into the underlying study to learn more about what was done and whether its conclusions are justified. As you will see below, the study is largely a rehash and repackaging of work that was reported in 2015 , 2016 and earlier that was based on some flawed methods which I and others have critiqued. The assigned disease burden costs are highly speculative and should not be considered in any serious policy discussions serving to protect public and regulate chemicals.
Screenhot of part of Table 1, Estimates of economic costs associated with lead and other neurotoxicant exposure
- The authors simply cut and pasted the findings from prior publications by Attina and Trasande, Attina et al , Bartlett and Trasande, Bellanger et al, Grandjean et al, Trasande and Liu, Trasande et al into their report and then summed them together.
- Thus, the numerous derivative papers should not be considered as independent of one another, and in many respects, the current paper is simply a rehash and repackaging of the earlier work.
- Moreover, these same authors have individually engaged in extensive lobbying of governments on these topics, something which they do not declare in the Competing Interests section of Disclaimers.
- Grandjean is co-editor-in-chief of the journal in which this report is published with one other colleague. Although he claims he wasn’t involved in the editorial decision to publish his own manuscript, it cannot be credibly argued that others who were involved in the decision weren’t influenced in some manner by his leadership role.
Read on for the details.
Methods and Conclusions
Prior work done by others had suggested that environmental and occupational factors1 were likely to be responsible for an important, but relatively small share (5.18%) of the total global Burden of Disease (BoD) compared to other established risk factors such as dietary risks, elevated systolic blood pressure, maternal and childhood malnutrition, elevated Body Mass Index (a measure of obesity), tobacco smoke, unsafe sexual practices, etc. Grandjean and Bellanger reviewed that prior estimate, which was made using Disability-Adjusted Life Year (DALY), a single common metric which combines duration and quality of life, and opined that it is likely to be too low because it: (1) disregarded subclinical dysfunctions; (2) adhered to overly stringent causal criteria; and (3) was hampered by gaps in environmental exposure data, especially from developing countries.
Grandjean and Bellanger then set-out to calculate what they considered to be more extensive estimates of the BoD for environmental and occupational exposures using what they referred to as a “toxicology-based, health economics approach.” In essence, they used the same questionable methodology as Trasande et al employed in a series of papers published in 2015/2016.
The Trasande work engaged five separate panels comprised of a handful of scientists. Each assessed the toxicology and epidemiology evidence linking selected chemicals to certain clusters of diseases and related conditions. They assigned a probability of causation for each exposure-disease cluster, calculated Attributable Fraction estimates, and combined them with available biomonitoring data, population estimates and estimated societal cost data using a human capital approach to derive estimates of the annual cost burden of exposures to those chemicals first in the EU and later in the US.
It would appear that Grandjean and Bellanger used this methodology to calculate BoD and cost estimates for exposures to lead and other neurotoxicants, air pollution and a set of chemicals they allege are endocrine disruptors (EDCs). In reality, they simply cut and pasted the findings from prior publications by Attina and Trasande, Attina et al , Bartlett and Trasande, Bellanger et al, Grandjean et al, Trasande and Liu, Trasande et al into their report and then summed them together.
To quantify and compare the costs of adverse health end points, the monetary value of a DALY or QALY (Quality-Adjusted life years) needed to be ascertained. Although the authors acknowledged that no official consensus of the appropriate value of a DALY/QALY has been reached, they chose the median Value of Life Year (VOLY) of $52,320 [$32,700 - $130,800] as the basis for the DALY value estimate.
Grandjean and Bellanger reported the following findings:
Lead — The estimated costs of cognitive impairment (lost IQ points) associated with known childhood lead exposure were 1.83% [range of 1.39% – 2.18%] of the global GDP in 2010, which is more than 4-fold greater than the similar value for DALYs valued by the GBD study (0.45%) which did not consider IQ losses among children who were shifted within the normal range of cognitive function.
Methylmercury — Methylmercury was not considered in the GBD study report. Relying on recently updated dose-response data, annual costs for cognitive deficits (lost IQ points) for the EU and the US they estimated a total of about $15.6 Billion [range of $13.8 – $16.9] — less than 0.01% of total global GDP. As the distribution of methylmercury exposures varies substantially with dietary intake of predatory fish, the authors did not venture an estimate of cost burden for the rest of the world.
Organophosphate Pesticides — The authors allege that exposures to organophosphate pesticides (OPs) may elicit similar deficits in cognitive function. In the EU, IQ losses due to OPs were calculated to have resulted in lost economic productivity of $194 [$62 – $259] billion annually. In the U.S., where exposures are lower, using similar data they suggest annual losses of $44.7 [$14.6 – $59.5] billion. No estimates were made for cost burdens due to OP exposures for the rest of the world, but the authors did list a combined estimate of cost burden of OP exposures of 0.38% of global GDP.
Polybrominated diphenyl ethers (PBDEs) — The authors also allege that PBDE exposures in utero/or in early development also result in lost IQ points among children. They estimated that exposure to PBDEs resulted in annual economic productivity losses of $12.6 [$2.8 – $29.4] billion in the EU, whereas, in the US, where exposures were assumed to be higher, the annual losses they estimated were at $266 [$133 – $367] billion. No estimates were made for cost burdens due to PBDE exposures for the rest of the world, but they did list a combined estimate of cost burden of PBDE exposures of 0.42% of global GDP. The authors also reference the possibility that PBDE exposures could be associated with increases in the occurrence of ADHD and autism, but conclude that these costs are likely to be much smaller and therefore were not considered in their paper.
Air Pollution — The authors criticize the GBD study for focusing solely on the role of air pollution in increasing the risks of pulmonary disease, lung cancer, and cardiovascular disease and of ignoring impacts on increased incidence of preterm birth or low birth weight which are associated with direct medical care costs for the neonate, as well as long-term costs associated both with medical care and as a result of lower IQ. They estimate that if you combine all health effects attributable to air pollution, the cost burden exceeds 1.8% of annual global GDP.
Purported EDCs — Reproducing published tables from Trasande et al and Attina et al, the authors conclude that exposure to a set of select alleged EDCs are responsible for costs of 0.88% of annual global GDP [range 0.17-1.54%]. Once again, they made this estimate based on estimated costs for the EU and US and ignored the rest of the world.
The authors consider that their numbers constitute a minimum cost estimate, as calculations were carried out only for substances and outcomes with a high probability of causation and for which exposure data were available.
Grandjean and Bellanger concluded that their “…findings suggest that a revised paradigm is required for evaluating and prioritizing the environmental contribution to human illness and the associated costs. As an important requirement for proper assessment of the environmental BoD, lack of complete documentation should not be misconstrued to mean that an environmental risk factor has no adverse impact on health. A revised paradigm will have to use systematic, though less restricted, criteria for causal attribution.”
They further assert that their methods suggest “…the total cost estimated for specific risk factors with known toxicology and exposure data were evaluated at 5.3% of the global GDP. “ The authors then added this estimate to estimates made by others of 6.5% by the WHO and 2.55% estimated from the GBD study, to arrive at a conclusion that the total environmental and occupational BoD costs likely exceed 10% of the global GDP. Their justification for adding the three estimates was that they judged the risk factors considered by the three different approaches only partially overlap.
The authors of the subject paper, Grandjean and Bellanger, were extensively engaged as panelists and co-authors of the series of papers published in 2015/2016 by Trasande et al that used identical methods and arrived at similar conclusions. Actually, they often simply cut and pasted the numbers from those publications into their own paper. Thus, the numerous derivative papers should not be considered as independent of one another, and in many respects, the current paper is simply a rehash and repackaging of the earlier work.
Moreover, these same authors have individually engaged in extensive lobbying of governments on these topics, something which they do not declare in the Competing Interests section of Disclaimers. Grandjean is the author of a book entitled Only One Chance: How Environmental Pollution Impairs Brain Development -- and How to Protect the Brains of the Next Generation (ISBN-13: 978-0190239732) that alleges chemicals such as mercury, polychlorinated biphenyls (PCBs), arsenic, and certain pesticides pose an insidious threat to the development of the next generation's brains placing them at risk for mental retardation, cerebral palsy, autism, ADHD, and a range of learning disabilities and other deficits that will remain for a lifetime. To prevent chemical brain drain, Grandjean urges tighter controls on 200 industrial chemicals he considers neurotoxicants, more routine testing for brain toxicity, stricter regulation of chemical emissions, and more required disclosure on the part of industry.
The paper by Grandjean and Bellanger was published in the journal Environmental Health. Grandjean is co-editor-in-chief of this journal with one other colleague. Although he claims he wasn’t involved in the editorial decision to publish his own manuscript, it cannot be credibly argued that others who were involved in the decision weren’t influenced in some manner by his leadership role.
Academic journals are rated by their impact factor which is a measure reflecting the yearly average number of citations to recent articles published in that journal. It is frequently used as a proxy for the relative importance of a journal within its field; journals with higher impact factors are often deemed to be more important than those with lower ones. Environmental Health has an impact factor of 3.453 — which is relatively low.
The same criticisms that Bond and Dietrich have leveled at the Trasande et al papers also apply to this paper by Grandjean and Bellanger. Specifically, the subject paper suffers from the following:
- The authors assumed causal relationships between putative chemical exposures and selected diseases, e.g., “loss of IQ”, but did not establish them via thorough evaluation of strengths and weaknesses of the underlying animal toxicology and human epidemiology evidence.
- The authors failed to use accepted systematic review methodology to conduct their review, and indeed failed to provided a description for the methods used to search the literature and select studies for evaluation. Absent adequate descriptions, authors leave themselves open to concerns of bias and of “cherry picking” the literature.
- Although it was claimed that a weight of the evidence approach was taken to assess probability of causation, no description was provided for how this was done and no weighing of evidence was apparent. Furthermore, critical analysis of individual studies relied upon was severely lacking.
- Consequently, assigned disease burden costs are highly speculative and should not be considered in any serious policy discussions serving to protect public and regulate chemicals.
The problems are best illustrated by an example using the work done to attribute cost burden associated with IQ loss purportedly due to OP exposures. At least 5 other critical reviews have been published that examined the link between OPs and neurobehavioral deficits and diseases -- and reported it as essentially non-persuasive. These reviews concluded that in animals, effects are seen only at doses that were high enough to produce significant brain or red blood cell acetylcholinesterase inhibition in dams or offspring. These reviews also concluded that the human epidemiology evidence is weak, and criticized the few studies available for problems related to their design, exposure and outcome measurements, and inadequate control of potential confounding variables (i.e., other risk factors).
Grandjean and Bellanger made no reference to the other reviews, nor attempted to explain why conclusions differed. Original human epidemiology studies actually report relatively few statistically significant findings suggestive of adverse effects, and no consistent patterns can be found across them. In addition, Grandjean and Bellanger ignored two more recent epidemiology studies (Donauer et al and Cartier et al) that were published in 2016 and which explored the link between OP exposures and IQ loss and found no associations.
The author’s methods for assigning costs to DALY and for calculating estimates of percentage of global GDP deserve further scrutiny by trained economists. At a minimum, the authors should have first tested their methods by applying them to established risk factors such as those identified by the GBD study to determine if they generate credible results.
To this writer, it stretches credulity to assert that costs of environmental and occupational exposures could be as high as 10% or more of GDP. According to the World Bank, global health care expenditures due to diseases and injuries caused by all risk factors combined are estimated to be slightly less than 10% of global GDP. Although Grandjean and Bellanger have included other costs — such as those due to lost productivity - in their analysis, the math still seems to be highly suspect. And to make matters worse, the authors even go so far as to assert that their methods are likely to have underestimated the true cost burden of environmental exposures.
The authors’ motivation for undertaking this work was to try to grab the attention of policymakers to influence their understanding and appreciation of the “full costs of inaction” so that they would give sufficient attention to identifying and controlling purported health risks from environmental exposures to chemicals. The authors’ argue that too often governments, particularly in the industrializing world, see spending on pollution control as a drag on development rather than an investment that can improve their economies. Although this is likely to be true in many circumstances, and it certainly needs to be rectified, one has to question whether Grandjean and Bellanger have more likely overstated the costs and in doing so, actually undermine their goals by damaging the credibility of the cause. There are other negative consequences to their work as well, as they impugn specific chemicals without having undertaken a sufficiently rigorous evaluation of the underling scientific evidence.
As noted above, this study is largely a rehash and repackaging of some work that was reported in 2015 and 2016 that was based on some flawed methods that have been criticized. The assigned disease burden costs are highly speculative and should not be considered in any serious policy discussions serving to protect public and regulate chemicals.
1For the Global Burden of Disease project, environmental and occupational factors were defined to include: (1) unsafe water, sanitation and hand-washing; (2) air pollution; (3) residential exposure to radon; (4) lead exposure; (5) occupational exposures to a number of chemical and physical hazards; (6) occupational injuries; and (7) occupational ergonomic factors. Specifically excluded from the definition lifestyle factors such as dietary choices, smoking, alcohol use, and various sexual practices.